A Delay Measurement Method for Series-Fed System Based on Large-Step Frequency Source

Abstract

The present invention discloses a method for measuring the time delay of a series-fed system based on a large-step frequency source, comprising: transmitting a continuous wave signal to each channel at a first frequency from the frequency source, turning on and off the correction switch corresponding to each channel in sequence, and collecting the echo data of each channel before and after the correction switch is turned on; extracting the first pulse echo data of each channel from the echo data of each channel; measuring and compensating the coarse delay of each channel based on the first pulse echo data of each channel; after compensating the coarse delay of each channel, measuring the fine delay of each channel using a multi-frequency point deambiguation method; and calculating the total delay of each channel based on the coarse delay and fine delay of each channel. By measuring the coarse delay of each channel and performing compensation, the present invention makes the delay residual less than one sampling rate cycle, and can perform fine measurement of the delay between channels using a large-step frequency source, thereby reducing the requirements for the frequency step of the correction frequency source.

Description

Technical Field

[0001] The present invention relates to the field of radar signal technology, and in particular to a method for measuring time delay of a series-fed system based on a large-step frequency source. Background Art

[0002] Digital array radars offer agile and rapid beamforming capabilities. The performance of beamforming depends on the consistency and stability of each transmit and receive channel. For wideband signals, the aperture transit time caused by large scan angles must be considered. Furthermore, channel delay errors caused by inconsistencies in the ADC acquisition components between channels and in the RF channel must be considered. This delay error requires precise measurement and compensation.

[0003] The existing method for measuring system delay considers two aspects: signal source and correction network.

[0004] The correction network is a power splitter network that can be divided into series-fed and parallel-fed networks. The series-fed network can sequentially inject the signal into each acquisition channel by controlling the correction switch, which is used for time-sharing signal acquisition. The parallel-fed network can simultaneously inject the correction signal into each acquisition channel for simultaneous signal acquisition.

[0005] The signal source can be a calibration unit, a self-developed signal generator specifically designed for calibration. It can be connected to a DDS to generate arbitrary waveforms and produce linear frequency modulation signals according to a strict timing sequence. By compressing the pulses of the collected data from each channel, the corresponding position difference of the pulse pressure peak points is the delay difference between the channels. The signal source can also be a frequency source, which sends a sinusoidal signal with a certain frequency interval and uses a multi-frequency point method to calculate the delay difference between the channels. The frequency interval requires a small step and a large step interval method. Small steps are not ambiguous in phase, but the delay measurement accuracy is poor. Large step frequencies have high delay measurement accuracy, but the phase is ambiguous. The system delay is measured by combining small and large step frequencies. Generally, the frequency source is a standard off-the-shelf product, while the calibration unit is a self-developed device. Using a frequency source can simplify the calibration system and shorten the development cycle.

[0006] The single-unit correction device and the parallel-feed network form a correction loop. The single-unit correction device transmits a linear frequency modulation signal, and a single pulse sequence can collect samples from each channel. If a three-frequency point measurement delay is selected, the single-unit correction device transmits a point frequency signal, and three pulse sequences can collect samples from each channel. The single-unit correction device and the series-feed network form a correction loop. Because the single-unit correction device ensures the initial phase consistency of the transmitted signal, the correction channel is switched by the correction switch, ensuring that the samples collected from each channel are consistent with the correction samples of the parallel-feed network.

[0007] When using a frequency source, the frequency must be controllable, and the minimum step frequency measurement delay range must be greater than the system delay. Because the initial phases of the frequency source switching points are inconsistent, the industry often uses a parallel feed network to form a correction loop. This ensures consistent initial phases by simultaneously collecting data from all channels within a single pulse cycle.

[0008] However, for a correction network consisting of a large-step frequency source and a series-fed network, the large step frequency cannot meet the requirement that the step frequency measurement delay is greater than the system delay, and the series-fed network cannot meet the requirement for initial phase consistency at each frequency switching point. Therefore, a delay measurement method for a series-fed system based on a large-step frequency source is needed. Summary of the Invention

[0009] In order to solve the technical problems existing in the background technology, the present invention proposes a delay measurement method for a series-fed system based on a large-step frequency source.

[0010] The present invention proposes a method for measuring time delay of a series-fed system based on a large-step frequency source, comprising:

[0011] The frequency source transmits a continuous wave signal to each channel at a first frequency, the correction switch corresponding to each channel is turned on and off in sequence, and the echo data of each channel before and after the correction switch is turned on is collected;

[0012] Extract the first pulse echo data of each channel from the echo data of each channel before and after the correction switch is turned on;

[0013] Measure and compensate the coarse delay of each channel based on the first pulse echo data of each channel;

[0014] After compensating for the coarse delay of each channel, the fine delay of each channel is measured using the multi-frequency point deambiguation method;

[0015] Calculate the total delay of each channel based on the coarse delay and fine delay of each channel.

[0016] Further, the first pulse echo data includes a transition of the echo data from noise to a continuous wave.

[0017] Furthermore, the coarse delay of each channel is calculated and compensated based on the first pulse echo data of each channel, specifically including:

[0018] Taking the modulus value of the first pulse echo data of each channel to obtain the pulse signal envelope data of each channel;

[0019] Calculate the coarse delay between channels based on the pulse signal envelope data of each channel;

[0020] Compensate based on the coarse delay between channels.

[0021] Furthermore, after compensating for the coarse delay of the system, the fine delay of each channel is measured using a multi-frequency point deambiguation method, which specifically includes:

[0022] After compensating for the coarse delay of the system, the frequency source transmits a continuous wave signal to each channel at a first frequency, a second frequency, a third frequency, ..., and an nth frequency, and the correction switch corresponding to each channel is sequentially turned on and off at each frequency, and echo data of each channel before and after the correction switch is turned on at each frequency is collected; wherein the frequency step increases from small to large, and the frequency step is the minimum step of the frequency source or an integer multiple of the minimum step;

[0023] Extract the phase of each frequency point of each channel from the echo data of each frequency, and use the phase of the first frequency point of the first channel as a reference to calculate the relative phase difference of each frequency point of the remaining channels;

[0024] Calculate the fine delay of each channel based on the relative phase difference of each frequency point of each channel.

[0025] Furthermore, the number of channels is m; wherein the frequency source transmits a continuous wave signal to each channel at a preset first frequency, and the correction switch corresponding to each channel is turned on and off in sequence, specifically including:

[0026] The frequency source transmits a continuous wave signal to the kth channel at the initial frequency f0, turns on the kth correction switch, and then r The rising edge triggers the kth correction switch, and after N pulses, the kth correction switch is closed; where k = 1, 2, 3, ..., m.

[0027] Furthermore, the number of frequency points is 4; wherein the frequency source transmits a continuous wave signal to each channel at a first frequency, a second frequency, a third frequency, ..., an nth frequency, and at each frequency, the correction switch corresponding to each channel is sequentially turned on and off, and data of each channel before and after the correction switch is turned on at each frequency is collected, specifically including:

[0028] The frequency source transmits a continuous wave signal to each channel at f0, the correction switch corresponding to each channel is turned on and off in sequence, and the echo data of each channel before and after the correction switch is turned on is collected;

[0029] The frequency source transmits a continuous wave to each channel at f0+Δf, the correction switch corresponding to each channel is turned on and off in sequence, and the echo data of each channel before and after the correction switch is turned on is collected; where Δf is the minimum step of the frequency source;

[0030] The frequency source transmits a continuous wave to each channel at f0+M1×Δf, and the correction switch corresponding to each channel is turned on and off in sequence, and the echo data of each channel before and after the correction switch is turned on is collected; where M1 is an integer greater than 1;

[0031] The frequency source transmits a continuous wave to each channel at f0+M2×Δf, the correction switch corresponding to each channel is turned on and off in sequence, and the echo data of each channel before and after the correction switch is turned on is collected; where M2 is an integer greater than M1.

[0032] Furthermore, the values of M1 and M2 satisfy the requirement of unambiguous phase measurement at multiple frequency points.

[0033] Furthermore, the first frequency, the second frequency, the third frequency, ..., the nth frequency are f r An integer multiple of .

[0034] In the present invention, the proposed method for measuring the delay of a series-fed system based on a large-step frequency source detects the edges of the collected signal, measures the coarse delay of each channel and compensates for it, so that the delay residual is less than one sampling rate cycle. It can perform fine measurement of the delay between channels using a large-step frequency source, reducing the system's requirements for the frequency step of the correction frequency source. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a block diagram of a method for measuring time delay in a series-fed system based on a large-step frequency source in an embodiment of the present invention.

[0036] Figure 2 FIG. 1 is a diagram showing the relationship between the continuous wave signal and the timing of the frequency source according to an embodiment of the present invention. DETAILED DESCRIPTION

[0037] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0038] The present invention proposes a method for measuring time delay of a series-fed system based on a large-step frequency source, comprising:

[0039] The frequency source transmits a continuous wave signal to each channel at a first frequency, the correction switch corresponding to each channel is turned on and off in sequence, and the echo data of each channel before and after the correction switch is turned on is collected;

[0040] Extract the first pulse echo data of each channel from the echo data of each channel before and after the correction switch is turned on;

[0041] Measure and compensate the coarse delay of each channel based on the first pulse echo data of each channel;

[0042] After compensating for the coarse delay of each channel, the fine delay of each channel is measured using the multi-frequency point deambiguation method;

[0043] Calculate the total delay of the system based on the coarse delay and fine delay of each channel.

[0044] The present invention detects the edges of the collected signals, measures the coarse delay of each channel and compensates for it, so that the delay residual is less than one sampling rate period. It can perform fine measurement of the inter-channel delay using a large-step frequency source, reducing the requirement for the frequency step of the correction frequency source.

[0045] It should be noted that the first pulse echo data includes the transition of the echo data from noise to continuous wave, reflecting the on / off state of the correction switch.

[0046] In this embodiment, the number of channels is m; wherein the frequency source transmits a continuous wave signal to each channel at a preset first frequency, and the correction switch corresponding to each channel is turned on and off in sequence, specifically including:

[0047] The frequency source transmits a continuous wave signal to the kth channel at the initial frequency f0, turns on the kth correction switch, and then r The rising edge triggers the kth correction switch, and after N pulses, the kth correction switch is closed; where k = 1, 2, 3, ..., m.

[0048] like Figure 1 As shown, the number of channels is 4; wherein, the frequency source transmits a continuous wave signal to each channel at a preset first frequency, and the correction switch corresponding to each channel is turned on and off in sequence; specifically including:

[0049] The frequency source transmits a continuous wave signal to the first channel at the initial frequency f0, turns on the first correction switch, and then r The rising edge triggers the first correction switch, and after N pulses, the first correction switch is closed;

[0050] The frequency source transmits a continuous wave signal to the second channel at the initial frequency f0, turns on the second correction switch, and then r The rising edge triggers the second correction switch, and after N pulses, the second correction switch is closed;

[0051] The frequency source transmits a continuous wave signal to the third channel at the initial frequency f0, turns on the third correction switch, and then r The rising edge triggers the third correction switch, and after N pulses, the third correction switch is closed;

[0052] The frequency source transmits a continuous wave signal to the fourth channel at the initial frequency f0, turns on the fourth correction switch, and then rThe rising edge triggers the fourth correction switch, and after N pulses reside, the fourth correction switch is closed.

[0053] In this embodiment, the AD is used to collect echo data of the four channels before and after the corresponding correction is turned on. The timing relationship is as follows: Figure 2 As shown, f0 is a typical value of 1MHz, f r The typical value is 1KHz, and N is 100. Figure 2 The correction switch 1 in FIG. 1 represents the first correction switch, and the correction switch 2 represents the second correction switch.

[0054] Of course, when the number of channels is other, the same can be applied.

[0055] Of course, in specific implementation, it is necessary to reasonably set the AD acquisition delay so that the first resident pulse echo data can capture the action of the correction switch being turned on.

[0056] In this embodiment, the coarse delay of the system is calculated and compensated based on the first pulse echo data of each channel, specifically including:

[0057] Taking the modulus value of the first pulse echo data of each channel to obtain the pulse signal envelope data of each channel;

[0058] Calculate the coarse delay between channels based on the pulse signal envelope data of each channel;

[0059] Compensation is performed based on the coarse delay between channels to align the signal envelopes between channels.

[0060] Specifically, the channel with the largest signal envelope delay is used as a reference, and the signals of other channels are aligned with this channel. The sampling points of each channel need to be moved in the order of K i , AD sampling rate f s , then the coarse delay T of each channel i =K i / f s , the residual delay of each channel is less than 1 / f s .

[0061] In this embodiment, after compensating for the coarse delay of each channel, the fine delay of each channel is measured using a multi-frequency point deambiguation method, which specifically includes:

[0062] After compensating for the coarse delay of the system, the frequency source transmits a continuous wave signal to each channel at a first frequency, a second frequency, a third frequency, and an nth frequency, and the correction switch corresponding to each channel is sequentially turned on and off at each frequency, and echo data of each channel before and after the correction switch is turned on at each frequency is collected; wherein the frequency step increases from small to large, and the frequency step is the minimum step of the frequency source or an integer multiple of the minimum step;

[0063] Extract the phase of each frequency point of each channel from the echo data of each frequency, and use the phase of the first frequency point of the first channel as a reference to calculate the relative phase difference of each frequency point of the remaining channels;

[0064] Calculate the fine delay of each channel based on the relative phase difference of each frequency point of each channel.

[0065] This embodiment strictly controls timing relationships to ensure consistent initial phases of signals entering different channels at the same frequency. By first traversing the calibration channels, the delay measurement requirement is met when switching frequencies, even when the initial phases of the frequency source are inconsistent. Furthermore, using a frequency source to transmit multiple point-frequency signals achieves the same measurement accuracy as linear frequency modulation signals within the corresponding bandwidth, but with less collected signal data and computational complexity.

[0066] In one specific embodiment, the number of channels is 4; a frequency source transmits a continuous wave signal to each channel at a first frequency, a second frequency, a third frequency, ..., an nth frequency, and a correction switch corresponding to each channel is sequentially turned on and off at each frequency, and data of each channel before and after the correction switch is turned on at each frequency is collected, specifically including:

[0067] The frequency source transmits a continuous wave signal to each channel at f0, the correction switch corresponding to each channel is turned on and off in sequence, and the echo data of each channel before and after the correction switch is turned on is collected;

[0068] The frequency source transmits a continuous wave to each channel at f0+Δf, the correction switch corresponding to each channel is turned on and off in sequence, and the echo data of each channel before and after the correction switch is turned on is collected; where Δf is the minimum step of the frequency source;

[0069] The frequency source transmits a continuous wave to each channel at f0+M1×Δf, and the correction switch corresponding to each channel is turned on and off in sequence, and the echo data of each channel before and after the correction switch is turned on is collected; where M1 is an integer greater than 1;

[0070] The frequency source transmits a continuous wave to each channel at f0+M2×Δf, the correction switch corresponding to each channel is turned on and off in sequence, and the echo data of each channel before and after the correction switch is turned on is collected; where M2 is an integer greater than M1.

[0071] Furthermore, the values of M1 and M2 satisfy the requirement of unambiguous phase measurement at multiple frequency points.

[0072] Specifically, M1 is 4 and M2 is 8.

[0073] In this embodiment, the first frequency, the second frequency, the third frequency, ..., the nth frequency are fr Therefore, when the frequency is 4, f0, f0+Δf, f0+M1×Δf, f0+M2×Δf are f r An integer multiple of .

[0074] This embodiment requires that 1 / Δf is greater than the residual delay 1 / f s , that is, Δf must be less than the sampling rate f s .

[0075] In one specific embodiment, the phase of each frequency point of each channel is extracted from the echo data of each frequency, and the phase of the first frequency point of the first channel is used as a reference to calculate the relative phase difference of each frequency point of the remaining channels, specifically including:

[0076] From the echo data of four frequencies f0, f0+Δf, f0+M1×Δf, and f0+M2×Δf, the phase of each frequency point of each channel is extracted, and the phase of the first frequency point of the first channel is used as a reference to calculate the relative phase difference of each frequency point of the remaining channels.

[0077] Specifically, the relative phase difference of each frequency point of the remaining channels is in, represents the phase, i represents the channel number, and j represents the frequency number.

[0078] Among them, taking the delay of channel 2 relative to channel 1 as an example, according to the formula It can be seen that

[0079] The delay τ1 calculated based on the minimum step Δf is compensated for the coarse delay, and the phase difference is Within 2π, then

[0080] The 2π fuzzy number Num1 is generated by the delay τ2 calculated based on the smaller step M1×Δf after the coarse delay compensation;

[0081] but

[0082] According to the delay t2 calculated by the larger step M2×Δf, the 2π fuzzy number Num2 is generated, then

[0083] but

[0084] In this embodiment, the total delay of each channel is T i +t i ; Among them, T i Indicates the coarse delay, t i Indicates fine delay, and i indicates the channel number.

[0085] For example, the delay of channel 2 relative to channel 1 is T2+t2.

[0086] If higher delay accuracy is required, the delay measurement is not limited to four frequency points, and more frequency points can be selected for delay measurement.

[0087] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A method for measuring time delay of a series-fed system based on a large-step frequency source, characterized in that: include: The frequency source transmits a continuous wave signal to each channel at a first frequency, the correction switch corresponding to each channel is turned on and off in sequence, and the echo data of each channel before and after the correction switch is turned on is collected; Extract the first pulse echo data of each channel from the echo data of each channel before and after the correction switch is turned on; Measure and compensate the coarse delay of each channel based on the first pulse echo data of each channel; After compensating for the coarse delay of each channel, the fine delay of each channel is measured using the multi-frequency point deambiguation method; Calculate the total delay of each channel based on the coarse delay and fine delay of each channel.

2. The method for measuring time delay of a series-fed system based on a large-step frequency source according to claim 1, characterized in that: The first pulse echo data includes the transition of the echo data from noise to continuous wave.

3. The method for measuring time delay of a series-fed system based on a large-step frequency source according to claim 2, characterized in that: Calculate and compensate the coarse delay of each channel based on the first pulse echo data of each channel, including: Taking the modulus value of the first pulse echo data of each channel to obtain the pulse signal envelope data of each channel; Calculate the coarse delay between channels based on the pulse signal envelope data of each channel; Compensate based on the coarse delay between channels.

4. The method for measuring time delay of a series-fed system based on a large-step frequency source according to claim 1, characterized in that: After compensating for the system's coarse delay, the multi-frequency deambiguation method is used to measure the fine delay of each channel. Specifically, the following steps are performed: After compensating for the coarse delay of the system, the frequency source transmits a continuous wave signal to each channel at a first frequency, a second frequency, a third frequency, ..., and an nth frequency, and the correction switch corresponding to each channel is sequentially turned on and off at each frequency, and echo data of each channel before and after the correction switch is turned on at each frequency is collected; wherein the frequency step increases from small to large, and the frequency step is the minimum step of the frequency source or an integer multiple of the minimum step; Extract the phase of each frequency point of each channel from the echo data of each frequency, and use the phase of the first frequency point of the first channel as a reference to calculate the relative phase difference of each frequency point of the remaining channels; Calculate the fine delay of each channel based on the relative phase difference of each frequency point of each channel.

5. The method for measuring time delay of a series-fed system based on a large-step frequency source according to any one of claims 1 to 4, characterized in that: The number of channels is m; wherein the frequency source transmits a continuous wave signal to each channel at a preset first frequency, and the correction switch corresponding to each channel is turned on and off in sequence, specifically including: The frequency source transmits a continuous wave signal to the kth channel at the initial frequency f0, turns on the kth correction switch, and then r The rising edge triggers the kth correction switch, and after N pulses, the kth correction switch is closed; where k = 1, 2, 3, ..., m.

6. The method for measuring time delay of a series-fed system based on a large-step frequency source according to claim 5, characterized in that: The number of frequency points is 4; the frequency source transmits a continuous wave signal to each channel at a first frequency, a second frequency, a third frequency, ..., an nth frequency, and the correction switch corresponding to each channel is turned on and off in sequence at each frequency, and data of each channel before and after the correction switch is turned on at each frequency is collected, specifically including: The frequency source transmits a continuous wave signal to each channel at f0, the correction switch corresponding to each channel is turned on and off in sequence, and the echo data of each channel before and after the correction switch is turned on is collected; The frequency source transmits a continuous wave to each channel at f0+Δf, the correction switch corresponding to each channel is turned on and off in sequence, and the echo data of each channel before and after the correction switch is turned on is collected; where Δf is the minimum step of the frequency source; The frequency source transmits a continuous wave to each channel at f0+M1×Δf, and the correction switch corresponding to each channel is turned on and off in sequence, and the echo data of each channel before and after the correction switch is turned on is collected; where M1 is an integer greater than 1; The frequency source transmits a continuous wave to each channel at f0+M2×Δf, the correction switch corresponding to each channel is turned on and off in sequence, and the echo data of each channel before and after the correction switch is turned on is collected; where M2 is an integer greater than M1.

7. The method for measuring time delay of a series-fed system based on a large-step frequency source according to claim 6, characterized in that: The values of M1 and M2 satisfy the requirement of unambiguous phase measurement at multiple frequency points.

8. The method for measuring time delay of a series-fed system based on a large-step frequency source according to claim 6, characterized in that: The first frequency, the second frequency, the third frequency, ..., the nth frequency is f r An integer multiple of .

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