A method and device for controlling delay stability of spread spectrum signal transmission equipment

Abstract

The present invention provides a method and device for controlling the delay stability of a spread spectrum signal transmitting device. The method comprises: generating a ranging baseband spread spectrum signal through a baseband signal generating unit; controlling the ranging baseband spread spectrum signal delay using a Farrow filter; coupling a radio frequency signal through a coupler and collecting it through an ADC; capturing and tracking the collected digitized signal through a pseudorange measurement unit to obtain a real-time pseudorange measurement value; calculating a delay control code based on the real-time pseudorange measurement value and a delay setting value and outputting the code to a Farrow filter control terminal, wherein the Farrow filter delay varies linearly with the delay control code setting value. The present invention utilizes the original spread spectrum signal of the transmitting device during normal operation to be directly collected through high-speed radio frequency and then fed back to the signal processing unit to achieve real-time closed-loop tracking and control of the transmitting device delay. When the delay fluctuates rapidly or slowly, the fluctuation of the transmitting device delay stability can be guaranteed to be less than 0.1ns.

Description

Technical Field

[0001] The present invention relates to the field of time-frequency technology, and in particular to a method and device for controlling delay stability of a spread spectrum signal transmitting device. Background Art

[0002] In the field of time-frequency technology, spread spectrum signals are often used to transmit time and frequency information. The essence of time-frequency transmission is to measure the clock difference between the transmitter and the receiver. Figure 1 This is the principle diagram of time-frequency one-way transmission, A is the transmitter, B is the receiver, Figure 1 The physical meanings of the symbols in are as follows:

[0003] It is the starting point of the transmitter time system;

[0004] It is the transmission time reading of the spread spectrum signal in the transmitter time system;

[0005] is the delay of the transmitting device;

[0006] It is the starting point of the receiving end time system;

[0007] It is the reception time reading of the spread spectrum signal in the receiving end time system;

[0008] is the delay of the receiving device;

[0009] is the clock difference between the receiving end and the transmitting end;

[0010] is the delay of the transmission channel;

[0011] The receiving end uses the locally reproduced ranging code to perform correlation calculation with the received spread spectrum signal to obtain the time difference measurement value. The delay composition of the time difference measurement value is shown as follows:

[0012]

[0013] Then, the clock difference between the transmitter and the receiver can be calculated, and its expression is shown as follows:

[0014]

[0015] As can be seen from the above formula, the transmitter device delay is a significant component of the clock error measurement error and directly affects the clock error measurement accuracy. If the transmitter device delay is fixed, its impact on the clock error measurement can be eliminated through prior calibration. However, in reality, factors such as power cycling, temperature changes, power amplifier power reduction, and aging drift of electronic components may cause the transmitter device delay to vary, thereby introducing clock error measurement errors.

[0016] To ensure the stability of the transmitter equipment delay, the following measures are generally taken:

[0017] a) Avoid using electronic components with poor delay stability (such as surface acoustic wave filters);

[0018] b) Try to use broadband RF devices while ensuring out-of-band suppression;

[0019] c) Select digital devices with deterministic delay;

[0020] d) Accurately control the ambient temperature of the transmitting equipment;

[0021] e) Avoid uncertainty in the zero value of device restart delay through reasonable power-on synchronization timing design, such as described in patent CN112187262B "A method for controlling synchronous acquisition delay of DBBC";

[0022] f) Measuring device delay through an additional calibration loop so that the device delay can be deducted from the actual measurement results, such as described in the document "Research on Device Delay Calibration Technology for Bidirectional Time Synchronization Systems".

[0023] Measures a), b), and c) above impose significant constraints on the selection of electronic components. Furthermore, even after implementation, they still cannot completely address the rapid or slow variations in device latency caused by factors such as temperature fluctuations, power amplifier power backoff, and component aging drift. For a well-designed L-band transmitter, the latency variation due to temperature fluctuations is approximately 1ns per 30°C, and the latency variation due to a 3dB power amplifier backoff is approximately 0.5ns. Measure d) can effectively address device latency variations caused by temperature fluctuations, but it increases device cost, size, weight, and power consumption, thus limiting the locations or platforms where the device can be used. Measure f) can measure device latency in near real time, allowing it to be deducted from subsequent measurements to eliminate errors. However, measuring device latency interrupts the normal operation of the device and cannot track rapid latency variations caused by temperature fluctuations in real time.

[0024] Therefore, when it is necessary to increase the clock error measurement accuracy to above 0.1ns at a lower cost, lower complexity, high real-time performance and without changing the normal working process, the above measures are difficult to meet the needs. Summary of the Invention

[0025] In response to the problems existing in the above-mentioned prior art, the present invention provides a method and device for controlling the delay stability of a spread spectrum signal transmitting device. The method and device utilize the original spread spectrum signal of the transmitting device during normal operation to directly collect it via high-speed radio frequency and then feed it back to a signal processing unit, thereby realizing real-time closed-loop tracking and control of the delay of the transmitting device. When the delay fluctuates rapidly or slowly due to ambient temperature, drift and aging of electronic components, or power amplifier power fallback, the delay stability fluctuation of the transmitting device can be ensured to be less than 0.1ns.

[0026] The present invention provides a method for controlling delay stability of a spread spectrum signal transmitting device, comprising the following steps:

[0027] Step S1: generating a ranging baseband spread spectrum signal through a baseband signal generating unit in a signal processing unit;

[0028] Step S2: Using a Farrow filter in the signal processing unit to control the ranging baseband spread spectrum signal delay;

[0029] Step S3: A radio frequency signal is coupled through a coupler at the output end of the power amplifier unit and directly sampled via a high-speed ADC, and the sampled signal is output to the signal processing unit;

[0030] Step S4: in the signal processing unit, the pseudorange measurement unit captures and tracks the collected digitized signal to obtain a real-time pseudorange measurement value;

[0031] Step S5: using the real-time pseudo-range measurement value and the delay setting value as input, the delay controller calculates the delay control code;

[0032] Step S6: The delay control code is output to the Farrow filter control terminal, and the Farrow filter delay changes linearly with the value set by the delay control code.

[0033] Furthermore, the calculation steps of step S5 are as follows:

[0034] Step S51: Initialize variables at time 0, so that , , , ;

[0035] Step S52: The first iterative calculation starts at time T, and then one iteration is completed every time T. The iterative calculation formula and calculation sequence are as follows:

[0036]

[0037]

[0038]

[0039] in:

[0040] N is the number of Farrow filter control code bits, dimensionless;

[0041] T is the iterative calculation time interval, in seconds;

[0042] It is the delay setting value, in ns;

[0043] is the pseudorange measurement value of the pseudorange measurement unit i, in ns;

[0044] is the delay control code output to the Farrow filter control terminal for the i-th time, dimensionless;

[0045] 、 is the intermediate variable in the calculation process;

[0046] 、 Calculation factors selected to suit specific application scenarios;

[0047] It is the ratio coefficient of the Farrow filter delay adjustment amount and the delay control code, and the unit is ns.

[0048] Furthermore, the proportional coefficient of the Farrow filter delay adjustment amount and the delay control code The calculation formula is as follows:

[0049]

[0050] Where, The Farrow filter operating clock frequency, in Hz.

[0051] Furthermore, the ranging baseband spread spectrum signal generated by the baseband signal generating unit is a typical QPSK spread spectrum signal, and its mathematical expression is:

[0052]

[0053] Where s represents the output signal of the baseband signal generation unit, A represents the signal amplitude, 、 Indicates the ranging code of the I branch and the Q branch, Indicates the symbol of Q branch modulation, is the intermediate frequency carrier frequency.

[0054] Furthermore, the pseudo-range measurement unit reproduces the ranging code locally based on the universal spread spectrum signal ranging principle, and obtains the real-time pseudo-range measurement value by performing a cross-correlation operation with the collected digitized signal.

[0055] The present invention also provides a delay stability control device for a spread spectrum signal transmitting device, which is used to implement the delay stability control method for the spread spectrum signal transmitting device. The delay stability control device for the spread spectrum signal transmitting device includes:

[0056] A local clock source, a signal processing unit, a DAC, a low-pass filter, an up-conversion unit, a power amplifier unit, a coupler and an antenna unit are connected in sequence, as well as an ADC connected to the coupler and the signal processing unit; the signal processing unit includes a baseband signal generation unit, a Farrow filter, a delay controller and a pseudo-range measurement unit; the local clock source is connected to the DAC in sequence via the baseband signal generation unit and the Farrow filter; the ADC is connected to the Farrow filter in sequence via the pseudo-range measurement unit and the delay controller.

[0057] Furthermore, the baseband signal generating unit, the Farrow filter, the delay controller and the pseudo-range measuring unit are implemented by programmable logic devices.

[0058] Furthermore, the Farrow filter includes FIR filter 1, FIR filter 2, FIR filter 3, FIR filter 4, multiplier 1, multiplier 2, multiplier 3, adder 1, adder 2 and adder 3; the ranging baseband spread spectrum signal is input into FIR filter 1, FIR filter 2, FIR filter 3 and FIR filter 4 respectively; the output end of FIR filter 1 is connected to multiplier 1, the output end of FIR filter 2 is connected to adder 1, the output end of FIR filter 3 is connected to adder 2, and the output end of FIR filter 4 is connected to adder 3; the delay control code is input into multiplier 1, multiplier 2 and multiplier 3 respectively; multiplier 1, adder 1, multiplier 2, adder 2, multiplier 3 and adder 3 are connected in sequence.

[0059] Furthermore, the FIR filter 1, FIR filter 2, FIR filter 3 and FIR filter 4 are all 4th-order FIR filters.

[0060] Furthermore, assuming that the input signal sequence of FIR filter 1, FIR filter 2, FIR filter 3, and FIR filter 4 is x(n), and the output sequence is y(n), the relationship between the input and output of the fourth-order FIR filter is:

[0061]

[0062] in, h ( k ) are the coefficients of each FIR filter.

[0063] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0064] 1. The present invention can automatically track and compensate for the delay fluctuation of the spread spectrum signal transmitting equipment caused by the temperature change of the working environment in real time.

[0065] 2. The present invention can automatically track and compensate for the delay fluctuation of spread spectrum signal transmission equipment caused by the drift and aging of electronic components in real time.

[0066] 3. The present invention can automatically track and compensate in real time for the time delay jump of the spread spectrum signal transmitting equipment caused by re-opening and closing the power.

[0067] 4. The present invention can automatically track and compensate for the delay fluctuation of the spread spectrum signal transmitting equipment caused by the power back-off of the power amplifier in real time.

[0068] 5. The automatic tracking and compensation process of the transmitting equipment of the present invention utilizes the existing spread spectrum signal and does not affect the normal working process of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings in the embodiments will be briefly introduced below. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0070] Figure 1 The present invention provides a flow chart of a method for controlling delay stability of a spread spectrum signal transmitting device.

[0071] Figure 2 This is the principle diagram of time-frequency one-way transmission.

[0072] Figure 3 This is a block diagram of a typical spread spectrum signal transmitting device.

[0073] Figure 4 A block diagram of a delay stability control device for a spread spectrum signal transmitting device provided by an embodiment of the present invention.

[0074] Figure 5 A typical Farrow filter structure block diagram provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0075] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0076] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are intended to fall within the scope of protection of the present invention.

[0077] Example

[0078] like Figure 1 As shown, this embodiment provides a method for controlling delay stability of a spread spectrum signal transmitting device, comprising the following steps:

[0079] Step S1: In the signal processing unit, a baseband signal generating unit generates a ranging baseband spread spectrum signal. The ranging baseband spread spectrum signal generated by the baseband signal generating unit is a typical QPSK spread spectrum signal, and its mathematical expression is:

[0080]

[0081] Where s represents the output signal of the baseband signal generation unit, A represents the signal amplitude, 、 Indicates the ranging code of the I branch and the Q branch, Indicates the symbol of Q branch modulation, is the intermediate frequency carrier frequency.

[0082] Step S2: Using a Farrow filter in the signal processing unit to control the ranging baseband spread spectrum signal delay;

[0083] Step S3: A radio frequency signal is coupled through a coupler at the output end of the power amplifier unit and directly sampled via a high-speed ADC, and the sampled signal is output to the signal processing unit;

[0084] Step S4: In the signal processing unit, the pseudorange measurement unit captures and tracks the collected digitized signal to obtain a real-time pseudorange measurement value. The pseudorange measurement unit reproduces the ranging code locally based on the general spread spectrum signal ranging principle, and obtains the real-time pseudorange measurement value by performing a cross-correlation operation with the collected digitized signal.

[0085] Step S5: using the real-time pseudo-range measurement value and the delay setting value as input, the delay controller calculates the delay control code;

[0086] Step S6: The delay control code is output to the Farrow filter control terminal, and the Farrow filter delay changes linearly with the value set by the delay control code.

[0087] The calculation steps of step S5 are as follows:

[0088] Step S51: Initialize variables at time 0, so that , , , ;

[0089] Step S52: The first iterative calculation starts at time T, and then one iteration is completed every time T. The iterative calculation formula and calculation sequence are as follows:

[0090]

[0091]

[0092]

[0093] The variables involved in the above steps S51 and S52 are defined as follows:

[0094] N is the number of Farrow filter control code bits, dimensionless;

[0095] T is the iterative calculation time interval, in seconds;

[0096] It is the delay setting value, in ns;

[0097] is the pseudorange measurement value of the pseudorange measurement unit i, in ns;

[0098] is the delay control code output to the Farrow filter control terminal for the i-th time, dimensionless;

[0099] 、 is the intermediate variable in the calculation process;

[0100] 、 Calculation factors selected to suit specific application scenarios;

[0101] is the proportional coefficient of the Farrow filter delay adjustment amount and the delay control code, in ns, and is calculated as follows:

[0102]

[0103] Where, The Farrow filter operating clock frequency, in Hz.

[0104] Figure 3 This is a block diagram of a typical spread spectrum signal transmission device. Figure 4 The present invention provides a delay stability control device for a spread spectrum signal transmitting device. The device comprises the following functional units: a local clock source, a signal processing unit, a DAC, a low-pass filter, an up-conversion unit, a power amplifier unit, a coupler, and an antenna unit connected in sequence, and an ADC connected to the coupler and the signal processing unit; the signal processing unit comprises a baseband signal generating unit, a Farrow filter, a delay controller, and a pseudo-range measurement unit; the local clock source is connected to the DAC in sequence via the baseband signal generating unit and the Farrow filter; the ADC is connected to the Farrow filter in sequence via the pseudo-range measurement unit and the delay controller. The baseband signal generating unit, the Farrow filter, the delay controller, and the pseudo-range measurement unit are implemented by programmable logic devices.

[0105] Figure 5 A typical Farrow filter structure block diagram is provided for an embodiment of the present invention. The Farrow filter includes FIR filter 1, FIR filter 2, FIR filter 3, FIR filter 4, multiplier 1, multiplier 2, multiplier 3, adder 1, adder 2, and adder 3; ranging baseband spread spectrum signals are input into FIR filter 1, FIR filter 2, FIR filter 3, and FIR filter 4 respectively; the output end of FIR filter 1 is connected to multiplier 1, the output end of FIR filter 2 is connected to adder 1, the output end of FIR filter 3 is connected to adder 2, and the output end of FIR filter 4 is connected to adder 3; the delay control code is input into multiplier 1, multiplier 2, and multiplier 3 respectively; multiplier 1, adder 1, multiplier 2, adder 2, multiplier 3, and adder 3 are connected in sequence. Among them, FIR filter 1, FIR filter 2, FIR filter 3 and FIR filter 4 are all fourth-order FIR filters. Assuming that the input signal sequence of FIR filter 1, FIR filter 2, FIR filter 3 and FIR filter 4 is x(n) and the output sequence is y(n), the relationship between the input and output of the fourth-order FIR filter is:

[0106]

[0107] Wherein the filter coefficient h(k) is determined by Table 1.

[0108] Table 1, FIR filter coefficients:

[0109]

[0110] For a certain L-band spread spectrum signal transmitting device, the delay of the transmitting signal device changes with temperature under normal circumstances up to 1ns / 30℃; using the present invention, and typically taking , , , , The pseudo-range measurement unit is designed to have a pseudo-range measurement accuracy of 0.03ns(1 ), which can reduce the temperature variation of the transmitting signal equipment delay to below 0.1ns / 60℃, effectively realizing the delay stability control of the transmitting equipment.

[0111] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for controlling delay stability of a spread spectrum signal transmitting device, characterized in that: The steps include: Step S1: generating a ranging baseband spread spectrum signal through a baseband signal generating unit in a signal processing unit; Step S2: Using a Farrow filter in the signal processing unit to control the ranging baseband spread spectrum signal delay; Step S3: A radio frequency signal is coupled through a coupler at the output end of the power amplifier unit and directly sampled via a high-speed ADC, and the sampled signal is output to the signal processing unit; Step S4: in the signal processing unit, the pseudorange measurement unit captures and tracks the collected digitized signal to obtain a real-time pseudorange measurement value; Step S5: using the real-time pseudo-range measurement value and the delay setting value as input, the delay controller calculates the delay control code; Step S6: The delay control code is output to the Farrow filter control terminal, and the Farrow filter delay changes linearly with the value set by the delay control code; The calculation steps of step S5 are as follows: Step S51: Initialize variables at time 0, so that , , , ; Step S52: The first iterative calculation starts at time T, and then one iteration is completed every time T. The iterative calculation formula and calculation sequence are as follows: in: N is the number of Farrow filter control code bits, dimensionless; T is the iterative calculation time interval, in seconds; It is the delay setting value, in ns; is the pseudorange measurement value of the pseudorange measurement unit i, in ns; is the delay control code output to the Farrow filter control terminal for the i-th time, dimensionless; 、 is the intermediate variable in the calculation process; 、 Calculation factors selected to suit specific application scenarios; It is the ratio coefficient of the Farrow filter delay adjustment amount and the delay control code, and the unit is ns.

2. The delay stability control method of a spread spectrum signal transmitting device according to claim 1, wherein: The proportional coefficient of the Farrow filter delay adjustment amount and the delay control code The calculation formula is as follows: Where, The Farrow filter operating clock frequency, in Hz.

3. The delay stability control method of a spread spectrum signal transmitting device according to claim 1, wherein: The pseudo-range measurement unit is based on the universal spread spectrum signal ranging principle, reproduces the ranging code locally, and obtains the real-time pseudo-range measurement value by performing cross-correlation operation with the collected digitized signal.

4. A delay stability control device for a spread spectrum signal transmitting device, configured to implement the delay stability control method for a spread spectrum signal transmitting device according to any one of claims 1 to 3, characterized in that: The delay stability control device of the spread spectrum signal transmission equipment includes: A local clock source, a signal processing unit, a DAC, a low-pass filter, an up-conversion unit, a power amplifier unit, a coupler and an antenna unit are connected in sequence, as well as an ADC connected to the coupler and the signal processing unit; the signal processing unit includes a baseband signal generation unit, a Farrow filter, a delay controller and a pseudo-range measurement unit; the local clock source is connected to the DAC in sequence via the baseband signal generation unit and the Farrow filter; the ADC is connected to the Farrow filter in sequence via the pseudo-range measurement unit and the delay controller.

5. The delay stability control device for spread spectrum signal transmission equipment according to claim 4, characterized in that: The baseband signal generating unit, Farrow filter, delay controller and pseudo-range measuring unit are implemented by programmable logic devices.

6. The delay stability control device for spread spectrum signal transmission equipment according to claim 4, characterized in that: The Farrow filter includes FIR filter 1, FIR filter 2, FIR filter 3, FIR filter 4, multiplier 1, multiplier 2, multiplier 3, adder 1, adder 2 and adder 3; the ranging baseband spread spectrum signal is input into FIR filter 1, FIR filter 2, FIR filter 3 and FIR filter 4 respectively; the output end of FIR filter 1 is connected to multiplier 1, the output end of FIR filter 2 is connected to adder 1, the output end of FIR filter 3 is connected to adder 2, and the output end of FIR filter 4 is connected to adder 3; the delay control code is input into multiplier 1, multiplier 2 and multiplier 3 respectively; multiplier 1, adder 1, multiplier 2, adder 2, multiplier 3 and adder 3 are connected in sequence.

7. The delay stability control device for spread spectrum signal transmission equipment according to claim 6, characterized in that: The FIR filter 1, FIR filter 2, FIR filter 3 and FIR filter 4 are all fourth-order FIR filters.

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