RU2012147C1 - Method for measuring delay of pseudorandom pulse train - Google Patents

Abstract

FIELD: radio engineering. SUBSTANCE: method involves generation of local reference signal and two local pseudorandom pulse trains which are shifted with respect to each other by interval which is same as pulse duration in train. Then two mutually correlated signals T_э are generated by means of multiplication of received pulse train and local pulse trains. These signals are stored. Then local pulse trains are shifted in time. Time interval between starts of steps of local reference signal and local pseudorandom pulse trains is measured. Additional local pseudorandom pulse train is generated. It has delay R₁ with respect to second local pseudorandom pulse train. Additional mutually correlated signal R₁ is generated by multiplying received pseudorandom pulse train and third local pseudorandom pulse train. Signals R₂, T_э and additional signal R₃ are compared. Their differences R₁ and R₂ are compared to given threshold V. Local pulse trains are shifted by R₃ until R₁-R₂ and R₃-R₂ or until R₂≅ R₁. Values of mutually correlated signals R₁-R₂> V, R₂≅ R₃ and R₃-R₂> V are computed after each shift by T_э. Correction to measured delay of pulse train is computed according to equation given in invention specification. Measured result of pulse train delay is corrected according to computed corrections R₁, R₂ and R₃. EFFECT: increased precision.

Description

 The invention relates to radio engineering and can be used in systems of radio navigation, radar and communication with pseudo-random phase manipulation.

 Known methods for measuring the delay code pseudo-random sequence (SRP) pulses. The disadvantage of these methods is that they prescribe the rules for filtering signals and generating a mismatch signal to discriminate the temporary position of the SRP pulses, but it does not include methods for counting the temporary position of the SRP signal relative to the local reference signal.

The closest technical solution to the invention is a method implemented in an airplane radio navigation indicator. The method includes the formation of a local reference signal and two local pseudorandom sequences of pulses - copies of the received SRP, offset from each other by the duration T _e of the SRP pulse, the formation and storage of cross-correlation signals (VKS) R ₁ and R ₂ by multiplying the received and local SRP pulses, subtracting the first VKS from the second, the time shift of the local SRP until the difference signal becomes equal to zero, measuring the time interval between the beginning of the cycles of the local reference signal and SRP tnoj second pulses by filling interval counting pulses with a repetition period Δ.

 The disadvantage of this method of measuring delay is that the ability to reduce the maximum instrumental error equal to the discrete Δ is limited by the maximum speed of the counters, their cost and power consumption.

In order to improve the accuracy of measuring the delay in the method, including the formation of a local reference signal and two local SRP pulses - copies of the received SRP pulses offset from each other by the interval T _e equal to the pulse width of the SRP, the formation and storage of two VKS R ₁ and R ₂ by multiplying the received SRP and local SRP pulses, the time shift of local SRP pulses, measuring the time interval between the start cycles of the local reference signal and the second local SRP, form an additional local SRP them pulses, delayed relative to the second local SRP pulses by the interval T _e , form and store additional VKS R ₃ by multiplying the received SRP pulses and the third local SRP pulses, compare the VKS R ₁ , R ₂ and R _{3 with} each other, and their difference R ₁ - R ₂ and R ₃ -R ₂ - with a given threshold V, and the time shift of local SRP pulses by the value of T _e carry out until R ₂ ≅ R ₁ and R ₁ -R ₂ > V or until R ₂ ≅ R ₃ and R ₃ -R ₂ > V, and after each shift, new VKS values are formed, the correction to the measurement result in discrete T _e and the corrector are determined cosiness is the result of measurement.

The formed third VKS R ₃ together with VKS R ₁ and R ₂ are used to analyze the position of the second SRP relative to the received one and, based on the analysis results, an amendment to the changes is formed with an accuracy of up to 1/25 of the discrete Δ.

 The delay measurement method includes the following operations.

A local reference signal is formed with a repetition cycle of the received SRP pulses and three local SRP pulses, which are copies of the received SRP, phase-shifted relative to each other by the duration T _{e of} one SRP pulse. In this case, the second PSP is late relative to the first, the third relative to the second.

Three cross-correlation signals R ₁ , R ₂ and R _{3 are} generated by, for example, multiplying the received bandwidth by local ones with the subsequent integration of the pieces.

VKS R ₁ , R ₂ and R _{3 are} compared with each other; if R _{2 is} greater than R ₁ and R ₃ , then they proceed to the next operation — the calculation of the first and second corrections; if R _{2 is} not greater than R ₁ or R ₃ , then a difference signal R ₁ -R ₂ or R ₃ -R _{2 is formed} respectively and compared with a threshold V, above which in the first case (pair R ₁ , R ₂ ) local PSP left on T _e , in the second case - right on T _e and repeat the previous and given operations; when the threshold is not exceeded, measure the interval τ ₂ between the beginning of the cycles of the received and the second local SRP.

Determine the correction to the measurement result according to the rule
Δ ₁ = R ₁ T _e / (R ₁ + R ₂ ) if R ₁ > R ₃ ;
Δ ₂ = R ₃ T _e / (R ₂ + R ₃ ) if R ₁ ≅ R ₃ .

The measurement result of τ _{2 is} corrected by adding the first correction Δ _{1 to it} or subtracting the second correction Δ ₂ .

The corrections Δ ₁ and Δ ₂ are fractions of the discrete Δ, for example, Δ / 25, so the instrumental error can be reduced by 25 or more times compared with the known technical solution.

Claims (1)

The METHOD of MEASURING THE DELAY OF A PSEUDO-RANDOM PULSE SEQUENCE, which consists in generating a local reference signal and two local pseudorandom sequences (PSP) of the copy pulse of the received PSP pulses, shifted relative to each other by the interval T _e equal to the pulse width of the PSP, form and correlation signal (VCS) R ₁ and R ₂ by multiplying a received SRP pulses and local memory bandwidth pulses carried local time offset SRP pulses measured time interval between beginning of the cycle of the local reference signal and the second local memory bandwidth pulses, characterized in that, in order to increase the accuracy of measurement of delay SRP pulses form additional local SAPs pulses retarded relative to the second local memory bandwidth pulses per interval T _e is formed and stored additional VCS R ₃ by multiplying the received pulses CAP and the third local memory bandwidth pulses compared VKS R ₁ and R ₂ and additional VCS R ₃ among themselves, and their difference R ₁ - R ₂ and R ₃ - R ₂ - a predetermined threshold V, wherein the time shift local P N pulses by the value T _e is carried out as long as R ₂ ≅ R ₁ and R ₁ - R _2> V or as long as R ₂ ≅ R ₃ and R ₃ - R _2> V, wherein after each timeslip on T _e form the values of the VKS R ₁ , R ₂ and R ₃ , determine the correction of measurements of the delay of the SRP pulses in accordance with the expressions
Δ ₁ = T _e R ₁ / (R ₁ + R ₃ ), if R ₁ > R ₃ ,
Δ ₂ = T _e R ₃ / (R ₂ + R ₃ ), if R ₁ ≅ R ₃
and adjust the measurement result of the delay of the SRP pulses by the amount of certain amendments + Δ ₁ and -Δ ₂ .