CN103698754B - A kind of broadband time delay integration measurement method - Google Patents

Abstract

The invention discloses a kind of broadband time delay integration measurement method, adopt linear FM signal as Time delay measurement signal; Utilize high power sample rate to set up comparison tables of data, sample rate is higher, and the tables of data of foundation is meticulousr, estimation to peak value is more accurate, the impact of taking into account system noise on signal amplitude and the needs of practical application, 8 times of choosing sample rate and be actual sample rate, also can be higher. Be a kind of method that mode based on waveform comparison look-up table is estimated more accurate time delay, can measure more accurately the echo time delay of broadband system.

Description

A Broadband Delay Synthetic Measurement Method

technical field

The invention belongs to the technical field of communication, and relates to a comprehensive measurement method of broadband time delay.

Background technique

In the narrowband mode, the traditional time delay measurement mostly uses the point frequency signal of the center frequency as the test signal, but for the broadband signal, the characteristics of the center frequency can hardly replace the characteristics of the entire frequency band, so the broadband signal is used as the channel test signal. Usually, the highest point of the broadband pulse compression signal envelope is used as the position estimation of the signal. However, due to the limited sampling frequency of the data acquisition system, it has a certain influence on the accurate measurement of the broadband time delay. The measurement accuracy of the delay is the time sampling accuracy. If the sampling time interval is 4ns, the measurement accuracy of the time delay is also 4ns.

Contents of the invention

In order to overcome the defects in the prior art, the present invention provides a comprehensive measurement method of broadband time delay, which is a method for estimating a more accurate time delay based on a waveform comparison lookup table, and can more accurately measure the time delay of a broadband system. echo delay. Its technical solution is,

A broadband time delay comprehensive measurement method, comprising the following steps:

1) Generate a broadband chirp signal first, and the signal bandwidth is consistent with the actual instantaneous bandwidth of the radar;

2) The signal obtains its amplitude envelope after pulse compression;

3) Search for the maximum point and the second largest point in the signal envelope, and record the index value of the largest point and the second largest point. This value corresponds to the delay. The real delay should be at the maximum value, or between the maximum value and the maximum value. between the next largest values;

4) Use the value with the smaller index value than the value with the larger index value to obtain a ratio;

5) Establish a ratio data table using simulation data with a high sampling rate, usually 8 times the actual sampling rate;

6) Use the ratio look-up table obtained in step 4) to further accurately estimate the exact position of the signal peak, that is, the system delay.

The present invention adopts the linear frequency modulation signal as the time-delay measurement signal; utilizes the high sampling rate to establish the comparison data table, the higher the sampling rate, the finer the data table established, the more accurate the estimation of the peak value, considering the influence of the system noise on the signal amplitude and the According to the needs of practical applications, the selected sampling rate is 8 times the actual sampling rate, or higher.

Beneficial effects of the present invention:

Under the premise of not increasing the sampling rate of the system, this method can effectively double the measurement accuracy of the signal peak position by comparing the relative size of the maximum value and the second maximum value near the signal peak value, and accurately measure the system time. delay.

Description of drawings

FIG. 1 is a schematic diagram of a time delay comprehensive measurement method.

detailed description

The technical solutions of the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

As shown in FIG. 1 , the figure is a schematic diagram of the waveform of the peak part of the main lobe after the pulse compression of the broadband linear frequency modulation signal. If the time delay is an integer period, the obtained sampling value should be the value corresponding to points 1, 9, and 17, the maximum sampling value should be 9, and the next largest sampling value should be 1 or 17; if the time delay is 1/4 period, The obtained sampling value is the value corresponding to 3 and 11; if the delay is 2/4 cycle, the obtained sampling value is 5 and the value corresponding to 13; if the delay is 3/4 cycle, the obtained sampling value is 7 , the value corresponding to 15. After obtaining the maximum value and the second maximum value of the peak value after pulse compression, it can be seen from the figure that when the fractional delay is in 4 different cases, the ratio of the left value to the right value should belong to different intervals. And have single value. The time delay of its fractional cycle part can be determined by looking up the table.

Assume that the bandwidth B is 200MHz (-100MHz~100MHz), the pulse width T is 40us pulse chirp signal, the baseband data rate is 250MHz after DDC (that is, the data interval time Ts is 4ns), after pulse compression and coherent accumulation, pass The method of comparing the sequence with the sampling sequence characteristics of the SINC function is used for central estimation, that is, the time difference between the position of the peak and the position of the sampling point, that is, the delay correction value is obtained, which is accurate to 1 ns (Ts/4).

Using this method, without increasing the sampling rate, the system delay measurement accuracy is increased to 4 times of the sampling rate.

The above is only a preferred specific embodiment of the present invention, and the scope of protection of the present invention is not limited thereto. Any person familiar with the technical field within the technical scope disclosed in the present invention can obviously obtain the simplicity of the technical solution. Changes or equivalent replacements all fall within the protection scope of the present invention.

Claims (1)

1. a broadband time delay integration measurement method, is characterized in that, comprises the following steps:

1) first produce wide-band LFM signal, described signal bandwidth is consistent with the actual instant bandwidth of radar;

2) described signal obtains its amplitude envelops after by pulse compression;

3) maximum point in search signal envelope and time a little bigger numerical values recited, and record maximum point and time a little bigger index value,The corresponding time delay of this index value, true time delay should be at maximum place, or between maximum and second largest value;

4) use the larger numerical value of index value on the numeric ratio that index value is less, obtain a ratio;

5) for step 4) in ratio, adopt the emulated data of high sampling rate to set up a ratio data table, adopt for actual8 times of sample rate;

6) utilize step 5) the ratio data table that obtains, further accurately estimate the accurate location of this signal peak, i.e. systemTime delay.