RU2244375C1 - Broadband signal search device - Google Patents

Abstract

FIELD: radio engineering; construction of radio communication, radio navigation, and control systems using broadband signals.

SUBSTANCE: proposed device depends for its operation on comparison of read-out signal with two thresholds, probability of exceeding these thresholds being enhanced during search interval with the result that search is continued. This broadband signal search device has linear part 1, matched filter 2, clock generator 19, channel selection control unit 13, inverter 12, fourth adder 15, two detectors 8, 17, two threshold comparison units 9, 18, NOT gates 16, as well as AND gate 14. Matched filter has pre-filter 3, delay line 4, n attenuators, n phase shifters, and three adders 7, 10, 11.

EFFECT: enhanced noise immunity under structural noise impact.

1 cl, 3 dwg

Description

The proposed device relates to the field of radio engineering and can find application in the construction of radio communication systems, radio navigation, control, using broadband signals.

Known devices for searching for broadband signals (see AS No. 1003372, N 04 L 7/02, 1981; No. 809619, N 04 L 7/02, 1979), which have a common disadvantage of low noise immunity search for broadband signals (SHPS) by the delay, namely, in the high probability of synchronization of search devices for structural interference.

The closest in technical essence to the proposed is the device described in the book "Noise-like signals in information transmission systems" edited by Pestryakova VB, Moscow, Sov. Radio, 1973, pp. 66-70, 195-199 , 234-240, adopted as a prototype.

Figure 1 shows a block diagram of a prototype, which shows the following notation:

1 - linear part;

2 - matched filter;

3 - preliminary filter;

4 - delay line;

5 ₁ -5 _n - first, ..., n-th attenuators;

6 ₁ -6 _n - first, ..., n-th phase shifters;

7 - adder;

8 - detector;

9 is a comparison block with a threshold.

The prototype device contains a series-connected linear part 1, the input of which is the input of the device, and a matched filter 2, consisting of a series-connected pre-filter 3 and a delay line 4, the outputs of which are connected to the inputs from the second to the n-th attenuator 5 ₂ -5 _n respectively, the outputs of which are connected respectively to the inputs from the second to the n-th phase shifter 6 ₂ -6 _n , the outputs of which are connected to the (n-1) inputs of the adder 7, respectively; the input of the delay line 4 through the first attenuator 5 ₁ and the first phase shifter 6 _{1 is} connected to the first input of the adder 7, the output of which, which is also the output of the matched filter 2, is connected through the detector 8 to the comparison unit with a threshold 9, the output of which is the output of the device.

The prototype device operates as follows.

The signal from the input of the device through block 1 is fed to the input of block 2, where through block 3 it is fed to the input of block 4. From the input of block 4 and its outputs, the signal through the corresponding series-connected blocks 5 ₁ -5 _n and blocks 6 ₁ -6 _{n is} received to the corresponding n inputs of block 7. In this case, the parameters of block 4, blocks 5 ₁ -5 _n and blocks 6 ₁ -6 _n are selected so that at the output of block 7 the signal elements are added in phase and give the value of the autocorrelation function of the useful signal, and on the output of block 8 will be the envelope value of the autocorrelation function of the useful signal Ala. Since structural interference can also come to the input of unit 1 of the device, the output of block 8 in this case will contain the envelope of the cross-correlation function for structural interference.

Thus, if only a useful signal arrives at the input of unit 1 of the device, then exceeding the threshold in block 9 leads to the correct decision on the presence of a useful signal and the search stops. If at the input of unit 1 of the device there is structural interference, then exceeding the threshold in unit 9 will lead to an erroneous decision to terminate the signal search.

The disadvantage of the prototype device is the low noise immunity when exposed to structural interference.

To eliminate this drawback, a broadband signal search device comprising a first detector and a first threshold comparison unit connected in series, a linear part connected in series, the first signal input of which is a device input, and a matched filter, which includes a pre-filter and a line connected in series delays, as well as n attenuators, n phase shifters and the first adder, the output of which is the first output of the matched filter, while the input of the line the holders through the first attenuator and the first phase shifter connected in series to the first input of the first adder, the outputs of the delay line through the (n-1) attenuators connected to the inputs of the (n-1) phase shifters, respectively, and the outputs of the second to n / 2 phase shifters connected to the second on n / 2 inputs of the first adder, respectively, a serially connected clock pulse generator and a channel switching control unit are introduced, the output of which is connected to the second control input of the linear part; the inverter, the fourth adder, the second detector, the second threshold comparison unit, the NOT element and the AND element, whose output connected to the first control input of the channel switching control unit is also an output of the device; wherein the output of the first comparison unit with the threshold is connected to the second input of the And element; the second and third adders are introduced into the matched filter, the outputs of which are respectively the second and third outputs of the matched filter, while the outputs of the phase shifters from (n / 2 + 1) -th to the n-th are connected to the first by n / 2 inputs of the second adder, respectively, the output of which is connected to the first input of the fourth adder and to the second input of the third adder, the first input of which is connected to the output of the first adder and to the inverter input.

Figure 2 shows a block diagram of the proposed device, which shows the following notation:

1 - linear part;

2 - matched filter;

3 - preliminary filter;

4 - delay line;

5 ₁ -5 _n - first, ..., n-th attenuators;

6 ₁ -6 _n - first, ..., n-th phase shifters;

7, 10, 11, 15 - the first, second, third and fourth adders;

8, 17 - the first and second detectors;

9 and 18 - the first and second blocks of comparison with the threshold;

12 - inverter;

13 - channel switching control unit;

19 is a clock generator.

The proposed device contains a series-connected linear part 1, the first, the signal input of which is the input of the device, and a matched filter 2; serially connected clock generator 19 and channel switching control unit 13, the output of which is connected to the second control input of the linear part 1; the inverter 12, the fourth adder 15, the second detector 17, the second comparison unit with the threshold 18, the element 16 and the element And 14, the output of which, which is the output of the device, is connected to the first control input of the channel switching control unit 13; connected in series with the first detector 8 and the first unit of comparison with the threshold 9, the output of which is connected to the second input of the element And 14.

The matched filter 2 contains a pre-filter 3 connected in series, the input of which is also the input of the matched filter 2, and a delay line 4, as well as n attenuators 5 ₁ -5 _n and n phase shifters 6 ₁ -6 _n , the first 7, the second 10 and the third 11 adders, the outputs of which are respectively the first, second and third outputs of the matched filter 2. In this case, the input of the delay line 4 through the first attenuator 5 ₁ and the first phase shifter 6 ₁ connected in series to the first input of the first adder 7, and the outputs of the delay line 4 are dined with inputs from the second to the n-th attenuator 5 ₂ -5 _n respectively, the outputs of which are connected to the inputs from the second to the n-th phase shifters 6 ₂ -6 _n, respectively, the outputs of which are connected to the second to n / 2 inputs of the first adder 7, respectively and from the first to n / 2 inputs of the second adder 10, respectively. In addition, the output of the first adder 7 is connected to the first input of the third adder 11 and to the input of the inverter 12; the output of the second adder 10 is connected to the second input of the third adder 11 and the first input of the fourth adder 15; the output of the third adder 11 is connected to the input of the first detector 8.

The proposed device operates as follows. A signal, structural noise, or a mixture thereof may be input to the device.

Consider the case when the first signal input of block 1, which is the input of the device, receives only a useful signal. From the output of block 1, the signal enters the input of block 2, where through block 3 it enters the input of block 4. From the input of block 4 and from its n / 2-1 outputs, the signals are transmitted through the corresponding blocks 5 ₁ -5 _{n / 2} , and then through the blocks 6 ₁ -6 _{n / 2} enter the inputs of block 7, respectively. From the remaining n / 2 outputs of block 4, the signal through the corresponding blocks 5 _{n / 2 + 1} -5 _n , and then through blocks 6 _{n / 2 + 1} -6 _n are supplied to the inputs of block 10, respectively. The signals from the outputs of blocks 7 and 10 are respectively supplied to the first and second inputs of block 11. The parameters of block 4, blocks 5 ₁ -5 _n and blocks 6 ₁ -6 _n are selected so that at the output of block 11, the signal elements add up in phase and give the value of the autocorrelation function of the useful signal, which is output from the output of block 11 to the input of block 8. From the output of block 8, the envelope value of the autocorrelation function of the useful signal is fed to the input of block 9, where the comparison with the threshold value occurs. Exceeding the threshold in block 9 leads to the fact that the logical unit is supplied from the output of block 9 to the second input of block 14.

At the same time, from the output of block 10, the signal goes to the first input of block 15, and from the output of block 7 through block 12, the signal goes to the second input of block 15. This leads to the fact that at the time when in block 11 all the elements from the outputs of blocks 7 and 10 are added in phase, in block 15 the elements from the output of block 10 are added with antiphase elements coming from block 7 through block 12, i.e. the value of the autocorrelation function of the signal at the output of block 15 will be close to zero. From the output of block 15, the value of the autocorrelation function of the useful signal is fed to the input of block 17. From the output of block 17, the envelope of the function of the autocorrelation of the useful signal is fed to the input of block 18, where a comparison with a threshold value occurs. In this case, the threshold in block 18 will not be exceeded, and from its output to the input of block 16 a logical zero will be received, while from the output of block 16 to the first input of block 14 a logical unit will arrive. Therefore, the logical unit will exit the output of block 14 and go to the first control input of block 13, which will fix this channel, since the output of the logical unit from the output of block 14 means that the signal is found and the search is finished.

If a mixture of a useful signal and powerful structural noise arrives at the first signal input of block 1, then, as in the case of only a useful signal, exceeding the threshold by the sum of the envelopes of the signal autocorrelation functions and the cross-correlation function of interference in block 9 will lead to the input to the second block input 14 logical units. The probability that at the same moment the value of the cross-correlation function does not exceed the threshold in block 18 is quite small. That is, the output of block 16 to the first input of block 14 receives a logical zero.

Therefore, from the output of block 14 to the first control input of block 13, a logical zero will arrive, meaning that the signal has not been found, and the search for the useful signal will continue on other channels.

If a powerful structural noise arrives at the first, signal input of block 1, then the probability that the threshold at both the block 9 and block 18 is exceeded is high enough. This means that the first input of block 14 will receive a logical zero, and the second input of block 14 will receive a logical unit. From the output of block 14 to the first, control input of block 13, a logical zero will be received and the search for the signal will continue on other channels.

The block diagram of block 13 is shown in figure 3, which shows the following notation:

131 - binary counter;

132 - fixed number counter;

133 - shaper;

134 - channel switch;

135 - tunable generator,

136 is the key.

Block 13 contains a serially connected key 136, a fixed number counter 132, a shaper 133, a channel switch 134, and a tunable generator 135, the output of which is the output of block 13; and also contains a binary counter 131, the input of which is also the first controlling input of block 13, and the output of the binary counter 131 is connected to the first input of key 136, the second input of which is also the second, synchronizing input of block 13.

Block 13 operates as follows.

The signals from the output of block 19 go to the second input of block 136, which is also the second, synchronized input of block 13. From the output of block 136, the signals go to the input of block 132, which is designed for a certain number of clock pulses. This number is determined by the time during which the search device will detect a useful signal on this channel. If a signal for a certain time has not been detected, then a signal will be output from the output of block 132 to the input of block 133. Under the action of this signal, a pulse will be output from the output of block 133, which will be fed to the input of block 134. From the output of block 134, a signal will be transmitted to the input of block 135, which will enable the transition to the selected channel. From the output of block 135, which is also the output of block 13, the signal goes to the second, control input of block 1.

If the search device has detected a useful signal, then from the output of block 14 to the input of block 131 a logical unit will arrive and transfer it to another state. From the output of block 131, a signal will arrive at the first input of block 136, which will lead to the closure of block 136. This will ensure reception on this channel. Before starting work, block 13 is reset.

Structural diagrams of blocks 134 and 135 and a description of their operation are given in the application of the UK No. 1473608.

Blocks 14, 18, 12 and 19 are widely used. A description of the structure and principles of constructing such block diagrams can be found, for example, in M. Mandle's book "200 Selected Electronics Circuits", trans. from English edited by Yitzhoka Ya.S., Moscow: Mir, 1980:

block 12 - p. 32-34, fig. 1.13;

blocks 14, 18 - p. 176 - 181, fig. 8.3 (b), 8.6 (b).

Block 19 can be made on the basis of various types of generators, for example, on the basis of a quartz oscillator (Mandle M. "200 Selected Electronics Circuits", M .: Mir, 1980, pp. 86-87, Fig. 4.5), or based on blocking generator (ibid., pp. 94-96, Fig. 4.9).

In the prototype, the effect of structural interference leads to a high probability of exceeding the threshold of the envelope of the cross-correlation function of the interference. This will cause false synchronization to interfere.

In the inventive device, the effect of structural interference can be significantly reduced due to the high probability of exceeding the thresholds in blocks 9 and 18 at the time of reference, which leads to the continuation of the search signal. That is, the introduction of additional blocks in the claimed device reduces the likelihood of false synchronization compared with the prototype.

Claims (1)

A broadband signal search device comprising a first detector and a first threshold comparison unit connected in series, a linear part connected in series, the first signal input of which is the device input, and a matched filter, which includes a series-connected pre-filter and a delay line, as well as n attenuators, n phase shifters and a first adder, the output of which is the first output of the matched filter, while the input of the delay line is connected in series through the first attenuator and the first phase shifter are connected to the first input of the first adder, and the outputs of the delay line through (n-1) attenuators are connected to the inputs (n-1) of the phase shifters, respectively, and the outputs of the second phase shifters to n / 2 are connected to the second to n / 2 inputs of the first adder, respectively, characterized in that a series-connected clock pulse generator and a channel switching control unit are introduced, the output of which is connected to the second, control input of the linear part, inverted p, fourth adder, second detector, second threshold comparison unit, NOT element and AND element, the output of which, connected to the first control input of the channel switching control unit, is also the output of the device, while the output of the first comparison unit with the threshold is connected to the second input element AND; the second and third adders are inserted into the matched filter, the outputs of which are the second and third outputs of the matched filter, respectively, while the outputs of the phase shifters from (n / 2 + 1) through n are connected to the first through n / 2 inputs of the second adder, respectively the output of which is connected to the first input of the fourth adder and to the second input of the third adder, the first input of which is connected to the output of the first adder and to the inverter input.

Images