Radar system using a digitally controllable oscillator for radar signal transmission

Abstract

A radar system comprising: a digitally controlled oscillator (DCO) to generate a DCO output signal having a frequency based on a control input; a transmitter to transmit one or more signals using the DCO output signal; a memory; and a controller. A transmission process performed by the radar system comprises: the DCO generating a DCO output signal having a frequency based on a control input; the transmitter transmitting a first transmission signal using the DCO output signal; and the controller loading data from the memory and using the data to provide the control input to the DCO.

Description

Technical Field

[0001] This disclosure relates to radar systems. In particular, this disclosure relates to radar systems that use a digitally controlled oscillator to generate a DCO output that can be used for radar signal transmission. Background Technology

[0002] Radar systems can be configured to transmit radar signals at a specific center frequency (e.g., in the case of pulse radar, a set of one or more pulses). In applications such as ultra-wideband, it may be important to ensure that the frequency band of the transmitted pulses is within the permissible frequency range, for example, to ensure compliance with radio regulations or coexistence with other users of the radio spectrum.

[0003] Typically, radar systems use a reference oscillator, such as a crystal oscillator, to provide a reference signal for generating the transmitted radar signal. Monostatic radar systems may also use the reference signal to receive signals (e.g., reflections of the transmitted signal). Such reference oscillators can provide a reference signal with a very accurate known reference frequency. However, reference oscillators, such as crystal oscillators, consume relatively large amounts of power and have relatively long startup times before the amplitude and / or frequency of the signal generated by the reference oscillator sufficiently stabilizes at the reference frequency. In applications requiring low power consumption and / or fast startup, it is desirable to reduce the startup time and / or power consumption of the radar system. Summary of the Invention

[0004] According to a first aspect, the present invention provides a radar system comprising:

[0005] Digitally controllable oscillator;

[0006] Transmitter;

[0007] Memory; and

[0008] Controller;

[0009] The radar system is configured to perform the transmission process, wherein:

[0010] The digitally controlled oscillator is configured to generate a DCO output signal with a frequency based on the control input;

[0011] The transmitter is configured to transmit a first transmission signal using the DCO output signal; and

[0012] The controller is configured to load data from memory and use the data to provide control input to the digitally controlled oscillator.

[0013] This arrangement significantly reduces power consumption because transmission can be completed without using an external reference oscillator, such as a crystal oscillator, to start the DCO. Therefore, the present invention recognizes that once the control word for the DCO is determined for a given set of conditions, the control word can be stored and reused without recalibrating the DCO using a reference oscillator. This saves both the time required for the reference oscillator to stabilize and the power required to operate the reference oscillator during stabilization. Thus, faster startup and lower power operation can be achieved.

[0014] The transmitter can be configured to transmit a first transmission signal within a first time period. For example, the radar system can be a pulse radar system, and the first transmission signal can be a first set of pulses.

[0015] This invention may be particularly applicable to pulse radar systems, where there is often a relatively long time interval between pulse transmissions, during which the DCO can be powered off to save power. However, although this time interval is long relative to the time spent transmitting the pulse, it may still be short relative to the timescale of how environmental conditions (such as temperature, DCO power supply voltage, etc.) affect the operation of the DCO.

[0016] The radar system can be a pulse radar system. For example, the radar system can be an ultra-wideband pulse radar system. For example, the transmitter can be configured to transmit signals with a frequency bandwidth falling within a specified ultra-wideband frequency range. Current regulations, for example, specify an ultra-wideband frequency range of 3.1 GHz to 10.6 GHz (for the United States) or 6.0 GHz to 8.5 GHz (for Europe), or a similar range for other countries. However, this range changes as regulations evolve.

[0017] The DCO output can be used by the transmitter as a clock signal, or it can be used to generate a clock signal for the transmitter. The clock signal can be used for either or both of carrier generation and envelope generation of the transmitted signal.

[0018] For example, in pulse radar systems, the pulses generated by the system can have a pulse shape that is substantially the same as that of a Gaussian-like function (e.g., a Gaussian function, a Kaiser window, a Hermitian polynomial function, etc.). This type of pulse shape can efficiently utilize bandwidth, allowing each pulse to transmit a large amount of power while still complying with radio regulations. Gaussian-like pulse shapes also have low sidelobes, characterized by a favorable zero Doppler ambiguity function, and are preferred for radar applications. Other pulse shapes with different advantages for different implementations can also be used.

[0019] A digitally controlled oscillator (DCO) can be a voltage-controlled oscillator (VCO), a numerically controlled oscillator (NCO), etc.

[0020] In some embodiments, the data loaded from memory may include a function that defines a specific relationship between a particular input and a control word value, i.e., that when a particular input, such as temperature, the power supply voltage of the DCO, or usage data, is provided to the function, the function generates an appropriate control word. However, in some embodiments, the data loaded from memory is numerical data. Loading numerical data from memory is particularly fast and efficient in terms of the amount of storage required and the speed at which an appropriate control word can be generated.

[0021] Depending on the implementation, the numerical data loaded from memory may require some additional processing (e.g., scaling, compensation, interpolation, extrapolation) to produce the final control word. However, in some embodiments, the data loaded from memory includes control inputs. Loading the control word and providing it directly to the DCO is fast and highly efficient in terms of speed and processing resources.

[0022] In some embodiments, when the radar system performs a transmission process:

[0023] The controller is configured to acquire temperature measurements and / or DCO power supply voltage measurements; and

[0024] The controller is configured to adjust the control input based on temperature measurements and / or DCO power supply voltage measurements before providing the control input to the digitally controlled oscillator.

[0025] As previously mentioned, temperature and / or power supply voltage changes may occur slowly relative to the time between signal transmissions. The obtained temperature and / or power supply voltage measurements do not need to be taken immediately prior to the transmission process. For example, temperature can be measured periodically, and the controller can be configured to obtain the most recent measurement. Therefore, it should be understood that if more than one transmission occurs between power supply voltage / temperature measurements, the controller can obtain the same power supply voltage / temperature measurements for each transmission process.

[0026] In many applications, the power supply voltage of the DCO is controlled with high precision because changes in the DCO's power supply voltage can alter its output. However, drift can occur over time. Therefore, by obtaining a measurement of the DCO's power supply voltage and using that measurement to adjust the DCO's control input, a more accurate DCO output can be produced, and / or the power supply voltage can be controlled with lower precision, thus providing greater freedom in radar system design.

[0027] The frequency of the DCO output can fluctuate with temperature or supply voltage. In particular, the degree of variation with temperature or supply voltage can be significantly greater than that of the crystal oscillator or other reference oscillator. For example, in some implementations, the degree of variation in the DCO output is expected to be up to 1000 times greater than that of the crystal oscillator output within a typical operating range of approximately -40°C to 85°C. Therefore, even relatively small changes in ambient temperature can cause changes in the DCO output frequency, potentially violating regulatory spectrum requirements. If the radar system temperature is within a specific range of the known effective temperature of the control word (e.g., the calibration temperature) (e.g., depending on the application, within 0.1°C, 1°C, 5°C, 10°C, etc.), the control word can be slightly adjusted to compensate for temperature variations without requiring recalibration of the reference oscillator for the new temperature. For example, the DCO control word can be increased or decreased based on temperature measurements (e.g., based on the difference between the measured temperature and the known effective temperature of the loaded DCO control word). Similar methods can be used for the supply voltage, for example, in addition to or substituted for temperature. For example, if the power supply voltage is within a specific range of the known effective power supply voltage for the control input (e.g., depending on the application, within 1%, 2%, 5%, 10%, etc.), the control input can be increased or decreased based on the measured power supply voltage (e.g., based on the difference between the measured power supply voltage and the known effective power supply voltage of the loaded DCO control word). Depending on the architecture of the DCO's oscillator core, a change of a few percentage points in the power supply voltage can lead to a significant change in the oscillation frequency when using the same control input.

[0028] In some embodiments, the radar system is configured to record device usage data; and, when the radar system performs a transmission process, the controller is configured to adjust the control input based on the device usage data before providing control input to the digitally controlled oscillator (DCO). Device usage data may include any data indicating DCO usage, such as the total cumulative operating time of the DCO, the number of times the radar system or DCO has been activated, the number of signals transmitted by the radar system, etc. This can help account for DCO aging, as the DCO output for a given control input may vary with use, for example, with component degradation. If used at high temperatures or high supply voltages, the DCO output may vary differently (e.g., more quickly), therefore the radar system may be configured to record device usage data in conjunction with the temperature and / or supply voltage during its use, or to store usage or aging values ​​based on a combination of usage and temperature / supply voltage. It should be understood that any combination of aging data, temperature data, and supply voltage data can be used to adjust the control input.

[0029] Other methods can be used to measure the aging of the DCO to provide device usage data, for example, in combination with or as an alternative to the methods described above. For instance, a radar system may include a second DCO configured to be infrequently operated and thus age slowly, such that the second DCO can be used as a reference to determine the effects of aging on the first DCO by comparing the DCO outputs of the first and second DCOs.

[0030] A similar approach can also be used, in which the radar system includes a first component that ages during DCO aging (e.g., when the DCO is used), and a second component, the second component which can be used as a reference to determine the aging effects of the first component. DCO usage / aging data can be determined based on the aging effects of the first component. This may be more efficient in terms of size and / or cost compared to including a second DCO.

[0031] In some embodiments, a lookup table is stored in the memory, in which each of a plurality of control inputs is stored in association with the value of one or more lookup variables. For example, a control input may be stored in association with a particular temperature, DCO power supply voltage, and / or device usage. Subsequently, the appropriate control input can be looked up in the lookup table using the measured values ​​of the temperature, DCO power supply voltage, and / or device usage.

[0032] Data loaded from memory may include a first set of control inputs applicable to a first set of operating conditions, such as DCO power supply voltage, temperature, and / or usage, and a second set of control inputs applicable to a second set of operating conditions, such as DCO power supply voltage, temperature, and / or usage. In such examples, the controller may provide control inputs to the DCO using data loaded from memory by interpolating (or extrapolating from) the control inputs (e.g., control inputs obtained or measured for operating conditions such as DCO power supply voltage, temperature, and / or usage).

[0033] In some embodiments, when the radar system performs a transmission process, the controller is configured to obtain one or more lookup variables. For example, lookup variables may include DCO power supply voltage, temperature, device usage, etc.

[0034] In some embodiments, the data loaded from memory includes control inputs corresponding to one or more lookup variables obtained. Therefore, appropriate control inputs for the current operating conditions can be obtained from the lookup table.

[0035] In some embodiments, the data loaded from the memory includes a first control input corresponding to one or more lookup variables in a first group and a second control input corresponding to one or more lookup variables in a second group; and the control input is obtained by interpolation between the first and second control inputs based on the obtained one or more lookup variables. In other embodiments, the control input can be obtained by extrapolation from the first and second control inputs based on the obtained one or more lookup variables.

[0036] In some embodiments, at least one lookup variable is temperature.

[0037] In some embodiments, at least one lookup variable is the DCO power supply voltage.

[0038] In some embodiments, at least one lookup variable is related to device usage.

[0039] In some embodiments, the memory is persistent memory, meaning that data stored in the memory can be retained even when the radar system is powered off. For example, the memory can be volatile memory, and the radar system can include a battery configured to power the volatile memory when the radar system (or at least the transmitter) is turned off. In some embodiments, the memory is non-volatile memory. Such non-volatile memory can retain data stored therein even without power, so that when the radar system is turned off, the memory does not require a battery or the like to retain the data stored therein.

[0040] In some embodiments, the controller is configured to obtain control inputs based on data loaded from memory without using feedback from the DCO output signal. For example, control inputs obtained from data loaded from memory can be directly passed to the DCO, and the DCO simply starts operating and is used without any checks on the appropriateness of its outputs. This enables rapid startup of the DCO and thus the radar system, and also saves power, but it relies on the trust and / or certainty that the data loaded from memory will cause the DCO to operate and subsequently transmit without violating the spectral mask, interfering with other systems, etc. Such methods can also rely on the trust that the DCO will operate as expected, for example, that the DCO will not fail to start, and / or that conditions (e.g., temperature) have not changed significantly, thus not rendering previously valid control inputs invalid.

[0041] In some embodiments, when the radar system performs a transmission process:

[0042] The digitally controlled oscillator is configured to shut down after the transmitter transmits the first transmit signal to stop generating the DCO output signal.

[0043] Therefore, power can be saved by turning off the DCO when it is not needed.

[0044] In some embodiments, when the radar system performs a transmission process: the digitally controlled oscillator is configured to turn on after being turned off to recover the generation of the DCO output signal; and

[0045] The transmitter is configured to transmit a second transmission signal using the DCO output signal;

[0046] The digitally controlled oscillator uses the same control input to generate the first and second transmit signals.

[0047] Using the same control input for the DCO for the second transmission signal as for the first transmission signal is highly efficient and requires minimal operation (e.g., simply reloading the control input). For example, to achieve the fastest possible startup of the second transmission signal, no new temperature or usage data is acquired. Instead, since no data changes, the exact same control input is obtained and provided directly to the DCO with minimal processing. This process also relies on the trust and / or certainty that environmental conditions have not changed significantly. However, this is a reasonable assumption in many radar operations, such as pulse radar applications.

[0048] In pulse radar applications, it is typically desirable to transmit a set of pulses, consisting of one or more pulses, for a single measurement (usually several pulses are used to allow for integration of the received signal, thereby improving the signal-to-noise ratio). This first set of pulses can be called a frame. Pulse radar can transmit several frames per second, i.e., several sets of pulses per second, but there can be an idle state between these sets of pulses. The typical frame rate range for ultra-wideband pulse radar systems can be between one frame per second (or less) and thousands of frames per second (depending on the application); however, ultra-wideband pulse radar systems can also operate outside this range. Therefore, the time between each set of pulses can be only a fraction of a second, during which environmental conditions are extremely unlikely to change. However, being able to shut down the DCO during the time interval between pulses can result in significant power savings. The fact that there is no need to start the reference oscillator to restart the DCO provides further power savings. This technique is still available even at lower frame rates, for example, when the interval between sets of pulses is several seconds. The time period during which the control input can be considered effective can depend on the operating environment and can be user-programmable or selectable. It can be noted that as the time between frames becomes longer, the power savings from shutting down the DCO between frames become more valuable. The power savings from fast startup are only per frame applied, thus contributing less absolute power savings in applications with low frame rates. However, such applications are typically highly power-constrained, so the technique remains very valuable.

[0049] In some embodiments, the radar system includes a receiver configured to sample a received signal using the DCO output signal to detect a reflection of the first transmitted signal. Monostatic radar systems (i.e., including both a transmitter and a receiver) use the DCO output signal for both the transmission and reception processes, thus exhibiting greater tolerance for small drifts in the DCO output frequency (i.e., drifts small enough that there is no risk of non-compliance with radio regulations, interference with other coexisting systems, etc.). Compared to bistatic radar or communication systems (where the receiver is a separate system from the transmitter), monostatic systems are more tolerant of such drifts because the effect is equal on both the transmitter and receiver. Therefore, in monostatic radar systems, control inputs can be reused for longer periods as long as the drift remains within a certain tolerance. On the other hand, bistatic radar systems (or communication systems) require maintaining their reference frequency with high accuracy to match the frequency of another separate system. Therefore, bistatic systems will need to continuously recalibrate their oscillators using a stable reference oscillator, such as a crystal oscillator (e.g., a controlled oscillator such as a DCO) (which may be difficult in practice), or use a stable reference oscillator instead of a controlled oscillator to limit frequency mismatch between the transmitter and receiver.

[0050] In some embodiments, data stored in memory can be loaded from a database. For example, each radar system may store the same data in memory, based on which the controller obtains the control input for the DCO.

[0051] In some embodiments, the radar system is configured to perform a calibration process to determine the data to be loaded from memory, wherein:

[0052] The controller is configured to provide one or more candidate control inputs to the digitally controlled oscillator;

[0053] The digitally controlled oscillator is configured to generate one or more corresponding candidate output signals;

[0054] The radar system is configured to compare one or more candidate output signals with a reference signal;

[0055] The radar system is configured to select a candidate control input that best matches the reference signal; and

[0056] The controller is configured to store data associated with the selected control input in memory.

[0057] The calibration process provides a mechanism by which the radar system determines the data to be stored in memory, and subsequently, the control inputs for the DCO can be derived from this data. The calibration process allows the DCO output to be matched to a reference frequency in a manner largely similar to that traditionally employed at each DCO startup. However, in this case, the calibration process additionally stores the resulting control inputs in memory so that they can be reused subsequently without undergoing the calibration process again. Because the calibration process is performed on the device (as opposed to storing non-device-specific data in memory), the data stored in memory takes into account device-specific factors and thus adapts to variations between devices, such as those caused by component changes between devices. The calibration process can be used as needed; for example, it can be performed at frequencies required to reset the DCO and avoid non-compliance with radio regulations. To save power, the calibration process can be used only when necessary.

[0058] A desired relationship can exist between the reference frequency and the frequency of the DCO output. For example, the desired relationship could be that the DCO output frequency is the same as the reference frequency. Alternatively (and more commonly), the desired relationship could be that the DCO output frequency is a specific multiple of the reference frequency. Therefore, the control input that best matches the reference frequency could be a control input that produces a DCO output whose frequency most closely matches its desired relationship with the reference frequency. For example, in some embodiments, the reference signal frequency is on the order of tens of MHz, while the desired DCO output frequency is in the range of hundreds of MHz to several GHz, and there is some known (integer or non-integer) ratio between these two frequencies.

[0059] In some embodiments, the radar system includes a phase-locked loop; wherein the phase-locked loop is configured to compare one or more candidate output signals with a reference signal and adjust candidate control inputs based on the comparison.

[0060] Phase-locked loops (PLLs) enable controllers to determine the appropriate control inputs for the DCO in a simple and direct manner. For example, PLLs can be implemented primarily in hardware, requiring minimal software / firmware programming to determine the appropriate control inputs for the DCO.

[0061] In some embodiments, in order to compare the frequencies of one or more candidate output signals with a reference signal, the controller is configured to:

[0062] Count the number of cycles for each candidate output signal within a given time period; and

[0063] Compare the count with the target number of cycles for a given time period.

[0064] For example, the controller can be configured to determine a given time period using a reference signal, for instance, by counting the number of cycles of the reference signal corresponding to the given time period. The given time period can be limited to a specific number of cycles of the reference signal.

[0065] In some embodiments, when the radar system performs a calibration process, the controller is configured to acquire temperature measurements and / or DCO power supply voltage measurements and / or device usage data measurements; and

[0066] The data associated with the selected control input stored in the memory includes the relationship between the selected control input and temperature and / or DCO power supply voltage and / or device usage data.

[0067] Storing the control inputs in association with their effective temperature and / or DCO power supply voltage essentially allows for the creation of lookup tables when covering multiple temperatures and / or DCO power supply voltages. This can be done piecemeal when encountering new temperatures and / or DCO power supply voltages, or it can be done as part of a more formal calibration process.

[0068] In some embodiments, the calibration process can be performed against multiple temperatures. For example, the calibration process can be an iterative process performed at multiple temperatures. The calibration process can be performed as part of the production process and can include adjusting the temperature between iterations. In this way, the radar system can be calibrated for a certain temperature range during production, so the radar system may not require a reference oscillator at all. For example, if the relationship between temperature and control input remains stable over time, a sufficiently detailed lookup table can provide appropriate control input for any measured temperature. As mentioned above, interpolation and / or extrapolation can be used as needed.

[0069] In some embodiments, the calibration process can be performed against multiple DCO power supply voltages, for example, the calibration process can be performed against multiple DCO power supply voltages at multiple temperatures. For example, the calibration process can be an iterative process performed at multiple DCO power supply voltages. The calibration process can be performed as part of the production process and can include adjusting the DCO power supply voltage between iterations. In this way, the radar system can be calibrated in production for a certain range of DCO power supply voltages, and optionally combined with multiple temperatures, so that the radar system may not require a reference oscillator at all. As mentioned above, interpolation and / or extrapolation can be used as needed.

[0070] In some embodiments, the radar system is configured to perform at least two launches without performing a calibration process between launches. For example, the radar system may be configured to perform a calibration process only during production or in a dedicated calibration session, or it may be configured to perform calibration periodically (e.g., every N launches or every N DCO power outages). In other examples, a calibration process may be performed only when a temperature change of a threshold amplitude is detected (or more generally, when any relevant operating condition changes by a threshold amount). In still other examples, a calibration process may be performed only when the radar system encounters an operating temperature and / or DCO power supply voltage for which the radar system does not have data in its memory available to obtain appropriate control input. This may occur, for example, if the radar system encounters an abnormally high or low temperature or an abnormally high or low DCO power supply voltage and has not yet (or recently) been calibrated. In some examples, the calibration process may be a periodic process, for example, performed after a certain number of launches and / or after a certain period of time. Performing calibration procedures periodically can help account for radar aging, such as DCO aging, and thus be able to adapt to relevant changes in the DCO output frequency.

[0071] In some embodiments, the radar system is configured to receive the reference signal from an external reference oscillator. As previously mentioned, a reference oscillator can be used to calibrate the radar system, but the radar system does not necessarily include a reference oscillator. For example, an external reference oscillator can be used to calibrate the radar system during its manufacturing process. This can result in a lower-cost and / or smaller radar system, which may be particularly convenient for certain applications, such as portable or wearable devices that include the radar system. The radar system can be periodically connected to an external reference oscillator for calibration / recalibration.

[0072] In some embodiments, the radar system includes a reference oscillator configured to generate a reference signal. As previously mentioned, if the radar system includes a reference oscillator, periodic calibration can be performed, for example, to account for aging or to identify appropriate control inputs suitable for a specific operating temperature or DCO supply voltage. Including a reference oscillator as part of the system also allows for functions such as on-demand calibration, for example, for newly encountered conditions as described above.

[0073] In some embodiments, the reference oscillator is a crystal oscillator.

[0074] In some embodiments, the launch process includes operating the radar system without generating a reference signal.

[0075] In some embodiments, when the radar system performs a transmission process:

[0076] The controller is configured to acquire temperature measurements and / or DCO power supply voltage and / or device usage data measurements; and

[0077] The controller is configured to obtain control input to the digitally controlled oscillator based on the loaded data, temperature measurements, and / or DCO power supply voltage and / or device usage data measurements.

[0078] For example, the stored data (i.e., the loaded data) can define the relationship between temperature and / or DCO power supply voltage and the control input. For instance, the stored data could be the coefficients of a known relational function. Therefore, loading the data and combining it with the measured temperature and / or DCO power supply voltage allows for the rapid determination of the appropriate control input based on the stored data. As mentioned above, the stored data can, of course, be updated periodically after calibration.

[0079] In some embodiments, the radar system is configured to perform a calibration process if control input cannot be obtained for the acquired temperature measurements and / or DCO power supply voltage and / or device data measurements.

[0080] In some embodiments, the radar system is battery powered. For example, portable or wearable devices may include radar systems. Therefore, energy efficiency in the radar system to extend battery life may be particularly important.

[0081] The above-described techniques are applicable to a variety of different radar systems. For example, the radar system may be a frequency-modulated continuous wave (FMCW) radar, a pulse radar, or any other type of monostatic radar system. In some embodiments, the radar system is a pulse radar system, and the first transmitted signal is a first set of one or more pulses. For example, the pulse radar system may be an ultra-wideband pulse radar system.

[0082] According to a second aspect, the present invention provides a method for operating a radar system, comprising:

[0083] The launch process includes:

[0084] Load data from memory and use the data to provide control input to the digitally controlled oscillator;

[0085] A digitally controlled oscillator (DCO) is used to generate a DCO output signal with a frequency based on the control input; and

[0086] The first transmit signal is transmitted using the DCO output signal.

[0087] It should be understood that the method according to the second aspect of the invention can be performed by any embodiment of the radar system according to the first aspect. Therefore, optional features of the first aspect of the invention can also be applied to the second aspect, and vice versa. In particular (but not limited to):

[0088] In some embodiments, the data loaded from the memory is numerical data.

[0089] In some embodiments, the transmission process includes:

[0090] Obtain temperature measurements and / or DCO power supply voltage measurements; and

[0091] Before providing control input to the digitally controlled oscillator, adjust the control input based on temperature measurements and / or DCO power supply voltage measurements.

[0092] In some embodiments, the transmission process includes:

[0093] Before providing control input to the digitally controlled oscillator, the control input is adjusted based on the device's data.

[0094] In some embodiments, the data loaded from memory includes control inputs. In other embodiments, the data loaded from memory may not include control inputs. For example, the data loaded from memory may include a first set of control inputs applicable to a first set of operating conditions such as temperature, DCO power supply voltage, and / or usage, and a second set of control inputs applicable to a second set of operating conditions such as temperature, DCO power supply voltage, and / or usage. In such examples, the controller can provide control inputs to the DCO using the data loaded from memory, for example, for obtaining operating conditions such as temperature, DCO power supply voltage, and / or usage, by interpolating between the control inputs.

[0095] In some embodiments, a lookup table is stored in the memory, in which each of a plurality of control inputs is stored in association with the value of one or more lookup variables.

[0096] For example, the launch process may include acquiring one or more lookup variables; and the data loaded from memory may include one or more control inputs corresponding to the acquired lookup variables. For example, two or more control inputs corresponding to the acquired lookup variables may be interpolated to provide control inputs for the DCO.

[0097] In some embodiments, at least one lookup variable is temperature.

[0098] In some embodiments, at least one lookup variable is the DCO power supply voltage.

[0099] In some embodiments, at least one lookup variable is related to device use.

[0100] In some embodiments, the memory is non-volatile memory.

[0101] In some embodiments, control input is obtained based on data loaded from memory without using feedback from the DCO output signal.

[0102] In some embodiments, the transmission process further includes:

[0103] Turn off the digitally controlled oscillator to stop generating the DCO output signal;

[0104] Turn on the digitally controlled oscillator to recover and generate the DCO output signal; and

[0105] Use the DCO output signal to transmit the second transmission signal;

[0106] The digitally controlled oscillator uses the same control input to generate the first and second transmit signals.

[0107] In some embodiments, the method further includes a receiving process, which includes:

[0108] The received signal is sampled using the DCO output signal to detect the reflection of the first transmitted signal.

[0109] In some embodiments, the method further includes performing a calibration process to determine data to be loaded from the memory, the calibration process including:

[0110] Provide one or more candidate control inputs to the digitally controllable oscillator to generate one or more corresponding candidate output signals;

[0111] Compare one or more candidate output signals with a reference signal;

[0112] Select the candidate control input that best matches the reference signal; and

[0113] The data associated with the selected control input is stored in memory.

[0114] In some embodiments, the calibration process includes: comparing one or more candidate output signals with a reference signal using a phase-locked loop, and adjusting the candidate control inputs based on the comparison.

[0115] In some embodiments, the comparison step of the calibration process includes:

[0116] Count the number of cycles for each candidate output signal within a given time period; and

[0117] Compare the count with the target number of cycles for a given time period.

[0118] For example, the comparison step may include determining a given time period using a reference signal, for instance, by counting a specific number of cycles of the reference signal corresponding to the given time period.

[0119] In some embodiments, the calibration process includes obtaining temperature measurements and / or DCO power supply voltage measurements and / or device usage data measurements;

[0120] The data associated with the selected control input stored in the memory includes the relationship between the selected control input and temperature and / or DCO power supply voltage and / or device usage data.

[0121] In some embodiments, the calibration process is performed at multiple temperatures and / or multiple DCO power supply voltages. For example, the calibration process may be an iterative process performed at multiple temperatures and / or multiple DCO power supply voltages.

[0122] In some embodiments, the method includes performing at least two launch processes without performing a calibration process between launch processes.

[0123] In some embodiments, the calibration process includes receiving the reference signal from an external reference oscillator.

[0124] In some embodiments, the calibration process includes generating a reference signal.

[0125] In some embodiments, the reference oscillator is a crystal oscillator.

[0126] In some embodiments, the launch process includes operating the radar without generating a reference signal.

[0127] In some embodiments, the transmission process further includes obtaining temperature measurements and / or DCO power supply voltage measurements and / or device usage data measurements; and

[0128] The control input for the digitally controlled oscillator is obtained based on the loaded data, temperature measurements, and / or DCO power supply voltage measurements and / or device usage data measurements.

[0129] In some embodiments, the method further includes performing a calibration process if control input cannot be obtained for the acquired temperature measurement and / or DCO power supply voltage measurement and / or device data measurement.

[0130] According to a third aspect, the present invention provides a method for operating a battery-powered radar system, employing the method of any example of the second aspect of the present invention. Attached Figure Description

[0131] One or more non-limiting examples will now be described by way of example and with reference to the accompanying drawings, in which:

[0132] Figure 1 This shows the main components of a pulse radar system;

[0133] Figure 2 Show operation Figure 1 Methods for pulse radar systems;

[0134] Figure 3 Another example showing the main components of a pulse radar system, which can be used Figure 2 The method used to operate the pulse radar system;

[0135] Figure 4 This shows when pulse radar systems, such as Figure 1 and Figure 3 Example waveforms of current draw and power consumption relative to time in a pulse radar system that uses a reference oscillator to transmit and receive a set of pulses; and

[0136] Figure 5 This shows when another pulse radar system, such as Figure 1 and Figure 3 An example waveform of the power consumed relative to time when a pulse radar system uses a DCO to transmit and receive a set of pulses (e.g., without using a reference oscillator). Detailed Implementation

[0137] Figure 1 The main components of a pulse radar system 100 are shown, which may be an ultra-wideband pulse radar system. System 100 includes a memory 101, a digitally controlled oscillator (DCO) 102, a transceiver 103, and a controller 104. In this example, system 100 also includes a temperature sensor 105 and a reference oscillator 106.

[0138] In this example, memory 101 is non-volatile memory, such that data stored in memory 101 is retained even when the radar system is powered off. It should be understood that in other examples, memory 101 may be volatile memory, which may not retain data stored therein in the absence of power, and the pulse radar system 100 may include a power source (e.g., a battery) to power memory 101 when the pulse radar system 100 is turned off.

[0139] The DCO 102 can be any suitable type of digitally controlled oscillator. In use, the DCO 102 receives control input in the form of a digital control word (N-bit digit) and produces a DCO output in the form of a periodic waveform, the frequency of which is determined by the received control input. For example, the control word can take values ​​between 0 and 2^N-1, and the DCO can output a waveform with a frequency between the lowest frequency (corresponding to the "0" input) and the highest frequency (corresponding to the "2^N-1" input), where each digital input produces a different discrete frequency output.

[0140] In use, radar transceiver 103 transmits electromagnetic signals and receives reflections of these transmitted signals. It should be understood that separate transmitters and receivers can also be used. Separate transmitters and receivers operating using the same clock can still constitute a monostatic radar system. In this example, transceiver 103 receives the DCO output signal as a clock and uses this clock to generate the transmitted signal. Parameters of the signal transmitted by the transceiver (e.g., the carrier frequency and / or envelope of the transmitted signal) can be based on the clock signal (i.e., based on the DCO output).

[0141] To comply with radio regulations, it may be necessary to control certain parameters of the transmitted signal. For example, the bandwidth and center frequency of the transmitted pulse need to be controlled to ensure that the spectrum of the transmitted pulse does not violate spectrum regulations.

[0142] Controller 104 controls the operation of DCO 102 and can control other aspects of the operation of pulse radar system 100. In this example, a specific function of controller 104 includes frequency counter 107. Frequency counter 107 can be used to count the number of cycles of a signal. In this example, controller 104 is configured to execute search algorithm 108 to identify appropriate control inputs for DCO 102.

[0143] In this example, the radar system 100 includes multiple sensors 105. The sensors include: a temperature sensor 105a configured to measure the temperature associated with the pulse radar system 100; a voltage sensor 105b configured to measure the voltage supplied to the DCO 102; and an aging sensor 105c configured to measure the aging of the DCO 102. In this example, during use, the controller 104 obtains the temperature measurement associated with the pulse radar system 100 from the temperature sensor 105a, and / or the voltage measurement supplied to the DCO 102 from the voltage sensor 105b, and / or the aging measurement from the aging sensor 105c. Although in this example the pulse radar system 100 includes all three sensors—temperature sensor 105a, voltage sensor 105b, and aging sensor 105c—in other examples, any one of these sensors may be an external sensor providing measurements to the radar system 100. In other examples, only one of the sensors 105a, 105b, and 105c may be used. Any combination of sensors may be used.

[0144] In use, controller 104 can receive a reference signal from reference oscillator 106 to calibrate pulse radar system 100. In this example, reference oscillator 106 is part of pulse radar system 100. In other examples, reference oscillator 106 may be an external oscillator that provides a reference signal to radar system 100. For example, an external reference oscillator may be used to calibrate pulse radar system 100 during its manufacturing process, or pulse radar system 100 may be periodically connected to an external reference oscillator for recalibration.

[0145] In this example, the reference oscillator 106 is a crystal oscillator. A crystal oscillator can generate a reference signal with a highly accurate and stable frequency. Although a crystal oscillator is used as the reference oscillator 106 in this example, in other examples, any oscillator capable of generating a stable reference signal with a well-defined frequency can be used as the reference oscillator 106.

[0146] However, as will be discussed in more detail below, it should be understood that for some basic implementations of the radar system 100 according to embodiments of the present invention, the reference oscillator 106, frequency counter 107, search algorithm 108, and sensor 105 are not required.

[0147] The pulse radar system 100 can be a battery-powered pulse radar system. For example, it can be suitable for use in portable devices such as laptops and mobile phones. Applications of such pulse radar systems can include, for example, presence detection, i.e., detecting the presence of a user.

[0148] Figure 2 A method 200 for operating a pulse radar system 100 is shown. Method 200 includes a transmission process 220. In this example, method 200 also includes a calibration process 210. In other examples, the calibration process 210 may be omitted.

[0149] In this example, calibration process 210 is performed to determine the data to be stored in memory 101 of the pulse radar system 100, which is then used to determine the control inputs of DCO 102. In other examples, data stored in memory 101 (e.g., provided by a database) may be loaded without calibration. Therefore, calibration of the pulse radar system 100 may not be necessary. However, calibration process 210 may help, for example, account for any parameters that may vary between devices, such as those resulting from process variations that lead to component dimensions or values ​​specific to a particular device.

[0150] The calibration process 210 includes a first step 211 in which the controller 104 provides candidate control inputs to the DCO 102.

[0151] In the second step 212, DCO 102 uses the candidate control input to generate the candidate DCO output.

[0152] In the third step 214, the controller 104 compares the candidate DCO output with a reference signal. In this example, the reference signal is generated by the reference oscillator 106, as shown in optional step 213. However, in other examples, the reference signal can be received from an external source (e.g., an external reference oscillator). The external reference oscillator can be part of the radar system (but used at a lower frequency than the rest of the system), or it can be located outside the radar system, requiring a dedicated connection for the external reference oscillator for the calibration process (e.g., in factory calibration). A crystal-based reference oscillator will always be an off-chip component, but can still be part of the overall radar system. Other reference oscillators can be on-chip oscillators (i.e., part of a silicon die), such as CMOS-MEMS resonators. The pulse radar system 100 can be calibrated using an external reference oscillator in production, after which the external reference oscillator may no longer be needed, thereby enabling a reduction in the cost and / or size of the pulse radar system.

[0153] The third step 214 of the calibration process 210 includes comparing the candidate DCO output with a reference signal. This may include comparing the frequencies of the signals. For example, the third step 214 of the method may include the controller 104 using the frequency of the reference signal to determine a specific time period. This time period may correspond to a specific number of cycles of the reference signal, and the controller 104 may determine the time period by counting that number of cycles using a frequency counter 107. Therefore, comparing the reference frequency with the DCO output frequency may include: the controller 104 using the frequency counter 107 to count the number of cycles of the DCO output signal and comparing the statistically significant number of cycles of the DCO output signal with the expected number of cycles for the determined time period.

[0154] In this example, steps 211, 212, and 214 can be repeated to iterate over a number of candidate control inputs. The iteration of steps 211, 212, and 214 may include using feedback from the comparison performed in step 214 of the calibration process 210 to select the next candidate control input to be provided to DCO 102. For example, controller 104 may be configured to use search algorithm 108, which uses feedback to select the next candidate control input for DCO 102 (e.g., a binary search strategy). In other examples, controller 104 may alternatively use exhaustive search algorithm 108 to select candidate control inputs for DCO 102, e.g., where controller 104 sequentially selects each possible control input as a candidate control input.

[0155] The calibration process 210 includes a fourth step 215, in which the controller 104 selects a candidate control input based on a comparison of one or more candidate control inputs with a reference frequency. The selected candidate control input is the one that best matches the reference frequency.

[0156] In some examples, a desired relationship can exist between the reference frequency and the frequency of the DCO output. For example, the desired relationship could be that the DCO output frequency is the same as the reference frequency. Alternatively, the desired relationship could be that the DCO output frequency is a specific multiple of the reference frequency.

[0157] Once a candidate control input is selected, the fifth step 217 of the calibration process 210 includes storing data associated with the selected candidate control input in memory 101. The data associated with the selected candidate control input may include the selected candidate control input itself, or, for example, data from which the candidate control input can be derived. The stored data may also include other parameters associated with the current operating state for which the control input has been determined, such as temperature measurements, DCO power supply voltage, and / or usage data.

[0158] Optionally, the calibration process 210 includes step 216, in which the controller obtains, for example, a DCO power supply voltage measurement and / or a temperature measurement from sensor 105. In the example including this optional step 216, data related to the obtained temperature measurement and / or DCO power supply voltage and data related to the selected candidate control input can be stored in memory 101 in association. For example, the selected candidate control input, the temperature measurement, and the DCO power supply voltage can be stored together in a lookup table.

[0159] In some examples, the calibration process includes an optional step 218 of adjusting operating conditions, such as temperature and / or DCO power supply voltage, for example, to iterate the calibration process 210 under different operating conditions. For example, the pulse radar system 100 can be calibrated for a specific temperature range during the manufacturing process, for example, to minimize or potentially eliminate the need for any subsequent calibration of the device. Alternatively or additionally, the power supply voltage can be varied (e.g., as part of the manufacturing process or at any later time), and the pulse radar system 100 can be calibrated for a specific power supply voltage range. It is even possible to calibrate the pulse radar system 100 for a specific DCO power supply voltage range at each temperature within a specific temperature range.

[0160] During production, temperature calibration may be easier, for example, if the temperature can be changed in the test setup. However, calibration of the DCO power supply voltage can be performed in the production test setup or later on the device (e.g., in the field).

[0161] Having control inputs for a specific temperature and / or DCO supply voltage can be useful, as the frequency of the DCO output may vary with temperature and / or DCO supply voltage. Therefore, different control inputs may be required to generate a DCO output with the desired frequency for different operating conditions.

[0162] As previously mentioned, in some examples, the pulse radar system 100 receives a reference signal from an external reference oscillator. This can allow the pulse radar system 100 to be smaller, cheaper, and / or more energy-efficient. In these examples, performing the calibration process 210 over a certain temperature range and / or DCO power supply voltage range may be particularly useful, since the pulse radar system may not receive a reference signal during use and therefore may not be able to be calibrated during use. However, even in examples where the pulse radar system 100 does include a reference oscillator 106, calibrating the pulse radar system 100 over a certain range of operating conditions (as part of its manufacturing process or during subsequent measurements) may be more energy-efficient than performing the calibration process 210 every time the pulse radar system 100 is used. For example, if the temperature does not change or does not change significantly, it may be sufficient (from a regulatory compliance perspective, for example) to simply load the same data used in the last operation, i.e., use the same control inputs used in the last operation. This can be improved by performing new temperature measurements and obtaining new control inputs based on the new temperature measurements (this can be done at each DCO startup, or it can be done less frequently). If conditions have changed significantly, or if a certain amount of time has passed since the last calibration, a full calibration can be performed relative to the reference frequency to ensure compliance.

[0163] The method 200 of operating the pulse radar system 100 includes a transmission process 220 through which the pulse radar system 100 transmits a series of pulses.

[0164] The transmission process 220 may optionally include a first step 221 of obtaining one or more variables. Variables may include, for example, a temperature measurement, DCO power supply voltage, or device usage information. For instance, the first step may include: controller 104 obtaining a temperature measurement, for example, from a temperature sensor 105a included in sensor 105, and / or controller 104 obtaining usage information, for example, from memory 101 or an aging sensor 105c. Usage information may include, for example, an estimate of degradation due to the current age of the system. This can be estimated, for example, using cumulative operating time, cumulative operating time at temperature, number of DCO 102 activations, number of pulses transmitted by the pulse radar system 100, etc.

[0165] Alternatively or additionally, the effect of aging on DCO 102 can be determined by comparing the DCO output with the DCO output of a second DCO, which is similar to the first DCO 102 and is used only as a reference for determining the aging effect of the first DCO 102. Therefore, for example, the second DCO will not age significantly compared to the aging of the first DCO 102. Thus, the second DCO can be used as an aging sensor 105c.

[0166] Another approach could involve providing a first component that ages at the same rate as DCO 102 and a second similar component that serves as a reference to the first component and, for example, does not age significantly compared to the aging of the first component. The aging of DCO 102 can be estimated using a comparison between the first and second components. Therefore, the second component can be used as an aging sensor 105c.

[0167] The launch process 220 includes a second step 222 in which the controller 104 loads data from the memory 101. This step 222 may include selecting data to load from the memory 101 based on variables obtained in the first step 221. For example, the memory may have stored control inputs associated with a specific temperature, DCO power supply voltage, and / or usage, and the step of loading data from the memory 101 may include loading appropriate data from the memory for the obtained temperature, DCO power supply voltage, and / or usage. For example, the data stored in the memory 101 may include a lookup table that provides specific control inputs for a specific variable, such as temperature, DCO power supply voltage, and / or usage. In this example, method 200 includes performing a calibration process 210 if no data associated with the obtained variable is stored in the memory 101. However, if data associated with the obtained variable is stored in the memory 101, the calibration process 210 may be omitted. Alternatively, the stored data may be interpolated or extrapolated to produce appropriate control inputs.

[0168] The launch process 220 includes a third step 223 in which the controller 104 provides control input to the DCO 102 using data loaded from the memory 101. For example, the data may include control inputs to be provided to the DCO 102. Alternatively, the data may be data from which the control inputs are derived.

[0169] In some examples, the third step 223 may include the controller adjusting the control input before providing the control input to the DCO 102. For example, the control input may be adjusted based on one or more variables (such as usage, temperature, etc.) obtained in the first step 221.

[0170] As previously mentioned, different control inputs may be required to generate a DCO output with a desired frequency under different operating conditions. Therefore, obtaining temperature and / or DCO supply voltage information before obtaining the control input for DCO 102 can be useful, allowing the use of appropriate control inputs for the obtained operating conditions. For example, the obtained control inputs can be adjusted based on the obtained temperature measurements. Alternatively, obtaining the control inputs may include using the obtained temperature measurements, for example, using the obtained temperature measurements as lookup variables to determine the appropriate control inputs in a lookup table.

[0171] Aging can affect the frequency of DCO output. Therefore, obtaining data indicating the age of DCO 102 allows for the use of appropriate control inputs suitable for the age of the DCO. For example, control inputs obtained, for instance, for a specific temperature, can be adjusted based on the age of DCO 102. Alternatively, obtaining control inputs can include using data associated with the age of the DCO to obtain appropriate control inputs, for example, by looking up the appropriate control input in a lookup table using data associated with the age of the DCO.

[0172] The transmission process 220 includes a fourth step 224, in which DCO 102 generates a DCO output using the control input provided by the third step 223. The frequency of the DCO output is based on the control input.

[0173] Transmission process 220 includes a fifth step 225, in which transceiver 103 transmits a first set of pulses using the DCO output. For example, transceiver 103 may directly receive the DCO output, or it may receive a signal generated using the DCO output (e.g., a signal generated via a frequency multiplier). Transceiver 103 may use the received signal as a clock to generate pulses with the same center frequency as the received signal.

[0174] In this example, method 200 includes an optional sixth step 226: sampling the received signal using the DCO output to detect reflections of a set of pulses transmitted in step 225. More specifically, in method 200, transceiver 103 uses the DCO output as a clock signal to sample the received signal, which may include reflections of the transmitted pulses, for example, when the transmitted pulses reflect from an object. Thus, in this example, the transmission process 220 is both a transmission and reception process. In other examples, the transmitted pulses may be received by another system. However, using a pulse radar system 100 to transmit and receive a set of one or more pulses allows the DCO output to be used for both the transmission and reception processes. For monostatic radar systems, it is advantageous to make the reception process coherent with the transmission process, thereby achieving a good signal-to-noise ratio when sampling the received signal to detect reflections of the transmitted pulses, and / or ensuring accurate recovery without loss of any information encoded in the phase of the received signal. It should be understood that in other examples, coherence may be sacrificed to simplify the design and reduce costs. When the transmitter and receiver are clocked from a common source (e.g., the same DCO), any drift in the DCO will have the same effect on both the transmitter and receiver. Therefore, monostatic radar systems are more adaptable to DCO drift, meaning they can particularly benefit from the energy efficiency of the process described here, as the DCO output does not require frequent calibration, provided regulatory requirements are met.

[0175] For example, in some ultra-wideband applications, while a 10 MHz frequency drift may be tolerable for ensuring compliance with radio regulations, it could lead to complete loss of coherence in a bistatic radar system where the transmitter and receiver are driven separately. Therefore, in some ultra-wideband applications, it is desirable to keep the clock signals used for both transmission and reception within 100 ppm, preferably within 10 ppm, and more preferably less than 1 ppm. For example, a frequency drift of less than 1 MHz (at an 8 GHz carrier frequency) is preferred, and more preferably, less than 0.1 MHz. By way of example only, the IEEE 802.15.4z wireless communication standard requires a carrier frequency offset (CFO) of less than + / - 20 ppm from the nominal frequency in both transmission (TX) and reception (RX). During packet reception of reflected signals, the CFO is typically tracked and compensated to a range below 1 ppm.

[0176] In this example, the transmit (and receive) process 220 includes an optional seventh step 227 of shutting down the DCO 102. This step may occur, for example, after the fifth step 225 of transmitting the first set of pulses, or after the sixth step 226 of sampling the received signal using the DCO output. Shutting down the DCO 102 when it is not in use results in power savings, which can be particularly advantageous for battery-powered radar systems to extend battery life, reduce battery size, and / or lower costs, etc. However, power savings may also be important in other applications, for example, to save on operating costs, etc.

[0177] In this example, the transmit (and receive) process 220 includes an optional eighth step 228: reactivating the DCO 102 using the same control inputs used to generate the DCO output in the fourth step 224. For example, the eighth step 228 may not require repeating the first step 221, the second step 222, and / or the third step 223 of the transmit process 220 to determine the control inputs used in the eighth step 228. Instead, the eighth step may include the controller 104 providing the DCO 102 with the same control inputs used in the third step 223 without further processing.

[0178] In this example, the transmit (and receive) process 220 includes an optional ninth step 229: transmitting a second set of pulses consisting of one or more pulses using the DCO output provided by the eighth step 228. For the second set of pulses, a corresponding sampling step such as the sixth step 226 may be present. For the second set of pulses, a corresponding step such as the seventh step 227 may be present for shutting down the DCO 102.

[0179] As described above, in certain applications, such as those requiring fast startup and / or low power consumption of the DCO 102, skipping the step of determining the control input between pulse sets is particularly advantageous, as these steps are time-consuming and power-intensive. Therefore, the pulse radar system 100 can be configured to perform the step associated with determining which control input to provide to the DCO 102 only periodically. For example, the pulse radar system 100 can be configured to perform the step associated with determining which control input to provide to the DCO 102 only once every two pulse sets, every three pulse sets, etc.

[0180] Alternatively or additionally, the pulse radar system 100 can be configured to perform the step associated with determining which control input to provide to the DCO 102 only once per second, every few seconds, every minute, every hour, etc. The time period for which the step associated with determining which control input to provide to the DCO 102 is repeatedly performed can depend on the application for which the pulse radar system 100 is intended and the likelihood of changes in relevant variables such as temperature and DCO power supply voltage.

[0181] Alternatively or additionally, the pulse radar system 100 may be configured to perform the steps associated with determining the control input to DCO 102 only when one or more environmental conditions change by a threshold amount (e.g., a temperature change of more than two degrees or a change in the power supply voltage of DCO of more than 5%).

[0182] Therefore, in normal operation, once transmission process 220 has been performed, another transmission process 220 can be performed without necessarily performing calibration process 210. Avoiding calibration every time the pulse radar system 100 needs to transmit one or more sets of pulses eliminates the need for a reference oscillator 106. Reference oscillators typically require a long time to stabilize, thus consuming significant power before they are usable.

[0183] Figure 3 Another pulse radar system 300 is shown. The pulse radar system 300 includes a DCO 302, a memory 301, and a transceiver 303. These components of the pulse radar system 300 can be connected to… Figure 1 The corresponding components in the pulse radar system 100 shown are similar. Figure 3 The pulse radar system 300 also includes sensors 305, which include temperature sensors, voltage sensors, and aging sensors, similar to... Figure 1 The pulse radar system 100 shown includes corresponding sensors. The pulse radar system 300 also includes a reference oscillator 306, which, similarly, is connected to... Figure 1 The corresponding reference oscillator 106 in the pulse radar system 100 is similar.

[0184] The pulse radar system 300 also includes a controller 304 and a phase-locked loop (PLL) 308, which in this example is a fully digital phase-locked loop (ADPLL). In other examples, the PLL 308 may be at least partially analog. The PLL 308 includes a comparator 307 and a digital oscillator (DCO) 302. The comparator 307 compares the output of the DCO 302 with the output of a reference oscillator 306. The PLL 308 adjusts the control input of the DCO 302 based on the comparison between the DCO output and the signal generated by the reference oscillator 306.

[0185] Figure 3 The operation of the pulse radar system 300 can be combined with... Figure 1 The operation of the pulse radar system 100 is basically similar, for example, largely the same. For instance, it can be achieved by executing... Figure 2 Method 200 is used to operate the pulse radar system 300. However, the controller 304 does not use a frequency counter and search algorithm to perform this operation. Figure 2The third step 214 of the calibration process 210 involves the controller 304 using a phase-locked loop 308 to compare the candidate DCO output with a reference signal and adjusting the control input accordingly to provide new candidate control inputs for the first step 211 of the calibration process. This process is repeated until a control input is found that produces a DCO output that matches the reference frequency, for example, the frequency of the DCO output is a multiple (integer or non-integer) of the reference frequency. The phase-locked loop 308 can then be disabled, meaning that the DCO 302 continues to operate in free-running mode using the most recent candidate control input. The phase-locked loop 308 compares the DCO output with the reference signal. The frequency of the DCO output is adjusted by changing the control input until the DCO output signal has the desired frequency relationship with the reference signal, and in this case, also the desired phase relationship.

[0186] Figure 4 This diagram shows example waveforms of current draw and power consumption relative to time when a pulse radar system, in conjunction with a DCO, uses a reference oscillator (a crystal oscillator in this example) to transmit and receive a set of pulses. In this example, the reference oscillator is always used as the reference for the DCO; therefore, it is activated whenever the pulse radar system transmits and receives a set of pulses. The DCO output is used to transmit a set of pulses.

[0187] During the first time period 1, as the pulse radar system is turned on, it performs a series of startup operations. These operations include turning on the radar system controller and initializing the memory.

[0188] During the second time period 2, the local power regulator (low dropout regulator or LDO regulator) is activated.

[0189] During the third time period 3, a series of configuration operations are performed, including turning on the reference oscillator (in this case, a crystal oscillator) at the time indicated by 1a. During this time period 3, the controller configures the radar (e.g., by reading from memory and setting the configuration register accordingly).

[0190] During the fourth time period, the pulse radar system waits until the reference oscillator generates a stable signal. (As from...) Figure 4 It is evident that the time period 4 spent waiting for the reference oscillator to generate a stable signal is very significant (approximately 1.7 ms).

[0191] During the fifth time period (5), the pulse radar system transmits and optionally receives a set of pulses using the DCO output. During this process, the radar subsystem is activated, which transmits and receives pulses, and is then shut down again.

[0192] During the sixth time period 6, the pulse radar system, including the reference oscillator, is shut down. Once the transmission and reception process is complete, the reference oscillator and radar subsystem are shut down at the time indicated in 1b. The remainder of the sixth time period 6 may include copying radar data from the frame buffer to memory and subsequent signal processing.

[0193] During the seventh time period (7), the auxiliary processor or main processor reads out the sampled frames. After completion, the system enters deep sleep mode.

[0194] Figure 5 An example waveform is shown, illustrating the effect of a pulse radar system (e.g., Figure 1 and Figure 3 The pulse radar systems 100 and 300 use DCO (e.g., Figure 1 and Figure 3 The power consumed by the DCO 102, 302 (without using a reference oscillator, such as a crystal oscillator) as a function of time when transmitting a set of pulses is described. This can be compared with... Figure 4 The power consumption and timeline are shown for comparison when using a crystal oscillator.

[0195] During the first time period 1', as the pulse radar system is turned on, the pulse radar system performs a series of startup operations.

[0196] During the second time period 2', the local power regulator (LDO) is enabled, but the local reference oscillator is not started.

[0197] During the third time period (3'), a series of configuration operations are performed. Figure 4 The third time period shown is different from 3, which does not include turning on the reference oscillator (because...). Figure 5 The transmission process shown does not use a reference oscillator.

[0198] During the fourth time period 4', the radar acquisition process is initiated. This includes loading control inputs from memory, providing control inputs to the DCO, and starting DCO operation. It can be seen that this fourth time period 4' (approximately 35 microseconds) is much shorter than... Figure 4 The corresponding time period 4 (approximately 1600 microseconds) is because there is no reference oscillator, and therefore there is no need to wait for the reference oscillator to stabilize. Instead, the system quickly enters the fifth time period 5'. This is similar to the usage used each time the pulse radar system is turned on. Figure 4 Compared to pulse radar systems using a reference oscillator, this allows the pulse radar system to turn on and transmit a set of pulses much faster. Furthermore, since reference oscillators consume a relatively large amount of power, avoiding their use can significantly save power.

[0199] During the fifth time period 5', the pulse radar system transmits and receives a set of pulses using signals from the DCO, after which the DCO is turned off. As can be understood from these two figures, the actual transmission time period is very short compared to the start-up time of the reference oscillator.

[0200] During the sixth time period (6'), radar data is copied from the frame buffer to memory for subsequent signal processing.

[0201] During the seventh time period (7'), the auxiliary processor or main processor reads out the sampled frame. After completion, the system transitions to deep sleep (where the DCO control word and / or other relevant data are stored and retained for future use).

[0202] By comparison Figure 4 and Figure 5 It can be seen that, compared to waiting for the reference oscillator to turn on and generate a stable reference signal, obtaining the DCO control input from memory and immediately starting the DCO can significantly save time (and correspondingly save power). Furthermore, by comparing... Figure 4 and Figure 5 It is clear that eliminating the use of a reference oscillator significantly reduces power consumption. This is evident when examining... Figure 4 This is most evident in the duration of the fourth time period, during which the pulse radar system waits for a stable reference signal from the reference oscillator, and this duration is much longer than [the duration of the fourth time period]. Figure 5 The duration in the example shown.

[0203] Those skilled in the art will understand that this disclosure has been described by way of one or more specific examples, but the disclosure is not limited to these examples; various variations and modifications may be made within the scope of the appended claims.

Claims

1. A radar system, comprising: Digitally controllable oscillator; Transmitter; Memory; and Controller; The radar system is configured to perform a transmission process, wherein: The digitally controllable oscillator is configured to generate a DCO output signal with a frequency based on the control input; The transmitter is configured to transmit a first transmission signal using the DCO output signal; and The controller is configured to load data from the memory and use the data to provide the control input to the digitally controlled oscillator.

2. The radar system according to claim 1, wherein, The data loaded from the memory is numerical data.

3. The radar system according to claim 1 or 2, wherein, The data loaded from the memory includes the control input.

4. The radar system according to claim 1, 2 or 3, wherein, When the radar system performs the transmission process: The controller is configured to acquire temperature measurements; and The controller is configured to adjust the control input based on the temperature measurement before providing the control input to the digitally controlled oscillator.

5. The radar system according to any one of the preceding claims, wherein, When the radar system performs the transmission process: The controller is configured to obtain a DCO power supply voltage measurement; and The controller is configured to adjust the control input based on the DCO power supply voltage measurement before providing the control input to the digitally controlled oscillator.

6. The radar system according to any one of the preceding claims, wherein, The controller is configured to acquire device usage data; and When the radar system performs the transmission process, the controller is configured to adjust the control input based on the device's data before providing the control input to the digitally controlled oscillator.

7. The radar system according to any one of the preceding claims, wherein, The memory stores a lookup table in which each of a plurality of control inputs is stored in association with the value of one or more lookup variables; When the radar system performs the transmission process, the controller is configured to obtain one or more lookup variables; and The data loaded from the memory includes control inputs corresponding to one or more lookup variables obtained.

8. The radar system according to claim 7, wherein, At least one lookup variable is temperature; and / or Wherein, at least one lookup variable is the DCO power supply voltage; and / or At least one of the lookup variables is related to the use of the device.

9. The radar system according to any one of the preceding claims, wherein, The memory is a non-volatile memory.

10. The radar system according to any one of the preceding claims, wherein, The controller is configured to obtain the control input based on data loaded from the memory without using feedback from the DCO output signal.

11. The radar system according to any one of the preceding claims, wherein, When the radar system performs the transmission process: The digitally controllable oscillator is configured to turn off after the transmitter transmits the first transmit signal to stop generating the DCO output signal, and turn on to resume generating the DCO output signal. and The transmitter is configured to transmit a second transmission signal using the DCO output signal; The digitally controllable oscillator uses the same control input to generate the first transmission signal and the second transmission signal.

12. The radar system according to any one of the preceding claims, comprising a receiver configured to sample a received signal using the DCO output signal to detect a reflection of the first transmitted signal.

13. The radar system according to any one of the preceding claims, wherein, The radar system is configured to perform a calibration process to determine the data to be loaded from the memory, wherein: The controller is configured to provide one or more candidate control inputs to the digitally controllable oscillator; The digitally controllable oscillator is configured to generate one or more corresponding candidate output signals; The radar system is configured to compare the one or more candidate output signals with a reference signal; The radar system is configured to select a candidate control input that best matches the reference signal; and The controller is configured to store data associated with the selected control input in the memory.

14. The radar system according to claim 13 further includes a phase-locked loop; in, The phase-locked loop is configured as follows: Compare the one or more candidate output signals with the reference signal; The candidate control inputs are adjusted based on the comparison.

15. The radar system according to claim 13, wherein, In order to compare the one or more candidate output signals with the reference signal, the controller is configured to: Count the number of cycles for each candidate output signal within a given time period; and The count is compared with the target number of cycles for the given time period.

16. The radar system according to claim 13, 14 or 15, wherein, When the radar system performs the calibration process, the controller is configured to acquire temperature measurements and / or DCO power supply voltage measurements and / or device usage data measurements; and The data associated with the selected control input stored in the memory includes the correlation between the selected control input and the temperature and / or the DCO power supply voltage and / or the device usage data.

17. The radar system according to claim 16, wherein, The calibration process is performed for multiple temperatures and / or multiple DCO power supply voltages.

18. The radar system according to any one of claims 13 to 17, wherein, The radar system is configured to perform the launch process at least twice without performing the calibration process between launch processes.

19. The radar system according to any one of claims 13 to 18, wherein, The radar system is configured to receive the reference signal from an external reference oscillator.

20. The radar system according to any one of claims 13 to 18, comprising a reference oscillator configured to generate the reference signal.

21. The radar system according to claim 19 or 20, wherein, The reference oscillator is a crystal oscillator.

22. The radar system according to any one of claims 13 to 21, wherein, The launch process includes operating the radar system without generating the reference signal.

23. The radar system according to any one of the preceding claims, wherein, When the radar system performs the transmission process: The controller is configured to acquire temperature measurements and / or DCO power supply voltage measurements and / or device usage data measurements; and The controller is configured to obtain the control input of the digitally controlled oscillator based on the loaded data, the temperature measurement and / or the DCO power supply voltage measurement and / or the device usage data measurement.

24. The radar system according to claim 23, wherein, The radar system is configured to perform a calibration process if a control input cannot be obtained using data measurements of the acquired temperature and / or the DCO power supply voltage and / or the device.

25. The radar system according to any one of the preceding claims, wherein, The radar system is powered by batteries.

26. The radar system according to any one of the preceding claims, wherein, The radar system is a pulse radar system; optionally, The pulse radar system is an ultra-wideband pulse radar system.

27. A method of operating a radar system, comprising: The launch process includes: Load data from memory and use the data to provide control input to the digitally controlled oscillator; The digitally controlled oscillator is used to generate a DCO output signal with a frequency based on the control input; and The first transmission signal is transmitted using the DCO output signal.

28. The method according to claim 27, wherein, The data loaded from the memory is numerical data.

29. The method according to claim 27 or 28, wherein, The launch process includes: Obtain temperature measurements and / or DCO power supply voltage measurements and / or device usage data; and Before providing the control input to the digitally controlled oscillator, the control input is adjusted based on the temperature measurement and / or the DCO power supply voltage measurement and / or device data.

30. The method according to any one of claims 27 to 29, wherein, The data loaded from the memory includes the control input.

31. The method according to claim 30, wherein, The memory stores a lookup table in which each of a plurality of control inputs is stored in association with the value of one or more lookup variables.

32. The method according to claim 31, wherein, At least one lookup variable is temperature; and / or wherein at least one lookup variable is DCO power supply voltage; and / or wherein at least one lookup variable is related to the use of the device.

33. The method according to any one of claims 27 to 32, wherein, The memory is a non-volatile memory.

34. The method according to any one of claims 27 to 33, wherein, The control input is obtained based on data loaded from the memory without using feedback from the DCO output signal.

35. The method according to any one of claims 27 to 34, wherein, The launch process also includes: Turn off the digitally controlled oscillator to stop generating the DCO output signal; Turn on the digitally controlled oscillator to recover and generate the DCO output signal; and The second transmission signal is transmitted using the DCO output signal; The digitally controllable oscillator uses the same control input to generate the first transmission signal and the second transmission signal.

36. The method according to any one of claims 27 to 35, further comprising a receiving process, the receiving process including: The received signal is sampled using the DCO output signal to detect the reflection of the first transmitted signal.

37. The method of any one of claims 27 to 36, further comprising performing a calibration process to determine data to be loaded from the memory, the calibration process comprising: One or more candidate control inputs are provided to the digitally controllable oscillator to generate one or more corresponding candidate output signals; Compare the one or more candidate output signals with a reference signal; Select a candidate control input that best matches the reference signal; and The data associated with the selected control input is stored in the memory.

38. The method according to claim 37, wherein, The calibration process includes: using a phase-locked loop to compare the one or more candidate output signals with the reference signal, and adjusting the candidate control input based on the comparison.

39. The method according to claim 37, wherein, The comparison steps in the calibration process include: Count the number of cycles for each candidate output signal within a given time period; and The count is compared with the target number of cycles for the given time period.

40. The method according to any one of claims 37 to 39, wherein, The calibration process includes obtaining temperature measurements and / or DCO power supply voltage measurements and / or device usage data measurements; and The data associated with the selected control input stored in the memory includes the correlation between the selected control input and the temperature and / or the DCO power supply voltage and / or the device usage data.

41. The method according to claim 40, wherein, The calibration process is performed for multiple temperatures and / or multiple DCO power supply voltages.

42. The method according to any one of claims 37 to 41, wherein, The method includes: If the calibration process is not performed between launches, the launch process shall be performed at least twice.

43. The method according to any one of claims 37 to 42, wherein, The calibration process includes receiving the reference signal from an external reference oscillator.

44. The method according to any one of claims 37 to 43, wherein, The calibration process includes generating the reference signal.

45. The method according to claim 43 or 44, wherein, The reference oscillator is a crystal oscillator.

46. ​​The method according to any one of claims 37 to 45, wherein, The launch process includes operating the radar without generating the reference signal.

47. The method according to any one of claims 27 to 46, wherein, The launch process also includes obtaining temperature measurements and / or DCO power supply voltage measurements and / or device usage data measurements; and The control input for the digitally controlled oscillator is obtained based on the loaded data, the temperature measurement value, and / or the DCO power supply voltage measurement value, and / or the device usage data measurement value.

48. The method of claim 47, further comprising: If a control input cannot be obtained from the acquired temperature measurement and / or DCO power supply voltage measurement and / or the device using data measurements, a calibration process is performed.

Images