SU1188898A1 - Method of determining noise immunity of radio receivers - Google Patents

Abstract

METHOD OF IDENTIFICATION. RADIO RESISTANCE OF RADIO RECEIVERS, namely, that the input of the radio receiver under test is supplied with the sum of the interference signal and the test signal, characterized in that, in order to improve accuracy, the test signal is modulated by the carrier wave signal, the test signal is delayed by the time t equal to the delay time of the interference signal and the test signal in the radio receiver under study, the reproduced signal Z (t) from the output of the radio receiver under investigation is amplified, and the delayed test signal is subtracted from it a, determine the modulus of the obtained difference corresponding to the instantaneous error value (i.) of reproduction, and the modulus of the delayed test signal S (i. + o change the amplitude of the reproduced signal Z (i) and the delay value to the minimum value of the time averaged value reproduction errors - S (t), determine the instantaneous value of the permissible error of the reproduction system MO, caused by the simultaneous action of the specified maximum permissible values of the multiplicative JU ,, and the additive fn interference, according to the formula Max M / (,) 9 (), compare the magnitude of the instantaneous. 3 the values of the reproduction error S (t) and the instantaneous values of the permissible error (t) determine the sum of the inter: time shafts At, where i is 1,2,3, .. during which the value is instant. The total value of error 6 (t) does not exceed the value of the instantaneous value of the permissible error (t), and the noise immunity of the studied radio receiver is 00. the detector is determined by the formula P z: u - / T, 00 with where P is the estimate of the total probability 00 of the correct signal reproduction; T is the measurement interval.

Description

one

The invention relates to the field of radio measurements and can be used to control the noise immunity of radio receivers during their development and production, in determining the overall likelihood of correct reception — a parameter of the electromagnetic compatibility of a radio receiver.

The purpose of the invention is to improve accuracy.

The drawing shows a structural electrical circuit diagram of a device implementing the proposed method.

The device contains a source of testing, including a signal; a signal generator 2, a carrier frequency generator 3, an adder 4, a noise generator 5, a radio receiver 6 under study, a calculator 7 of the full probability of correct reception, an adjustable delay element 8.

The calculator 7 contains an adjustable amplifier 9, a block 10 subtracting the first calculator 11 of an absolute voltage value, a voltmeter 12, a comparator 13, item 14, a ratio calculator 15, a generator of 16 clock pulses, a second calculator 17 of an absolute voltage value, an adjustable attenuator 18 adder 19 potentiometer 20.

The essence of the proposed method for determining the noise immunity of radio receivers is as follows.

As a controlled parameter of the radio receiver, the total probability of correct signal reproduction is selected. I delay the test signal 5 (i) for a time about equal to the signal delay in the radio receiver under study, calculate the modulus of the difference between the instantaneous values reproduced by the receiver (i) and the delayed 5 (its) signals, and an instantaneous value of the error 8 (i) is obtained

S (tl /; ltV6 (

Adjust the amplitude of the reproduced signal (i) and the magnitude of the delay: kn about so that the time-averaged value of the playout 8 (t) takes the minimum value

88982

w; n 8ltl min / (t) -5 (t4-t) / ,, / g (1) / gS

where -i is averaging over time.

Calculate the instantaneous value of the permissible reproduction error bf (t), due to the simultaneous action of the specified maximum permissible values of multiplicative and additive interference, while the magnitude of permissible error 8;, dg. (i) the reproduction is found as the sum of the value of the allowable additive error m and the product of the signal 5 (ivP) by the value ((Im-)

: Vm „,, / (р.-05 (1.) / 4.

0 Compare the largest instant

the values of the playback error S (i) and the permissible error 8, (1) separate the time intervals uit; correct reproduction, during which the error S (i) does not exceed the allowable values S, g, jj (i) For a given time interval T of the measurement, the sum of the time intervals of the correct reproduction is calculated, which is divided by the value T of the time of measurement. The resulting relationship. Squaring is the desired estimate of the full probability P of correct reproduction of the signal.

5P 5: ui; / T.

one

The interference immunity of the radio receiver under study is estimated by the total probability of correct signal reproduction, measured at the given parameters of the radio signal and radio interference.

The signal at the output of the radio can be represented as

 2 (t.) P (t) 5 (t) + (t), ()

where 5 (.t) is the test signal; 1i (-4) DN) - multiplicative and

additive interference;

0 - time delay of the signal in the test receiver.

The magnitude of the reproduction error is equal to

) -5 (i.l / / (((t.t). (I) / 2) The margin of error is equal to

3

8rr, a, (tl - / () 5 (iiC) / 4 (3)

where | and and - the maximum allowable

. the values of the current,. both multiplicative and additive interference.

The condition for the correct signal reproduction is the inequality

8 (i) .. W- (4) For a given time interval T, the sum of the time intervals d1 is calculated; , during which inequality (4) is fulfilled, for this purpose, the function is used

 if 8 (i) Sjnakcit),, if S8Ы8 ,, ,, aC, which can be performed using a voltage comparator. The signal U (i) is gated with clock pulses and counts the number of N d pulses that coincided with the intervals Ail, correct reception for the period T. At the same time, the total number N of clock pulses that occurred during the measurement time T is counted. The ratio Nd / N and is calculated, which is the desired match for the full probability of correct waveform reproduction.

R & 1, / T Md / He,. (five)

Thus, the process of measuring the total probability of correct reproduction of a signal is reduced to hardware computation of the relative time of the condition (4) when the signal is input to the receiver of the signal and interference with specified properties.

A device that implements the proposed method works as follows.

The signal generator 2 modulates the carrier oscillation of the generator 3, forming a test radio signal having a frequency band equal to the main channel band of the radio receiver under study 6. The input of the radio receiver 6 under study is fed into the sum of the test radio signal and radio interference. Radio 6 demodulates the radio signal, and the reproduced signal from the radio output is 8898,. four

the receiver 6 is fed to one input of the calculator 7 of the full probability of correct reception. The output from the regulating element 8 of the delay 5 is fed to the second input of the calculator 7 of the full probability of correct reception, which calculates the ratio (5).

The calculator 7 of the full probability of 10 correct reception works as follows.

The signal (t.) From the output of the radio receiver 6 is fed through an adjustable amplifier 9 to the input of the unit 10,

15 where the calculation of the reproduction error 8 (t) is carried out, and its module / ((t) / is obtained at the output of the calculator 11. The average value of the / S (t) / module of the reproduction error is recorded by a voltmeter 12, Signal Stt) from the output of the adjustable element 8 the delays are fed to the second input of the block 10 and through the second calculator 17 of the absolute value

5 voltage and adjustable attenuator 18, having a transfer coefficient of 4H / jUf - (/, is applied to one input of the adder 19, to the second input of which a voltage equal to the value of y is applied from the output of the potentiometer 20. The voltage at the output of the adder 19 equal to the maximum allowed playback error

SMaKcitl - / (pm -) (,

The value of the error S (t) and the permissible error of doo (, (t) are compared by comparator 13. When the condition is satisfied. "(1 | 7 5 (t at the output of the comparator 13 is a logical one; figure 1, which opens the access clock pulses of the generator 16 at the input A of the calculator 15 are ratios, at the input B of which the clock pulses of the generator 16 are fed.

5 performs the operation of calculating the ratio of the number Kd of pulses transmitted to input A during the total time of correct reproduction to the number of Ng pulses transmitted to input B

0 during the measurement time T.- Obtained

Therefore, it is the desired estimate of the overall probability of correct reproduction of a signal.

The measurement is made as follows.

5 way.

The modulation method of the carrier oscillation is selected depending on the method of demodulation in the studied radio receiver 6. The amplitude of the radio signal is set equal to the sensitivity, and the frequency equal to the frequency of the radio receiver 6. The level of the radio interference of the generator 5 is set to the predicted level of total radio interference, under the action of which the operation of the radio receiver is expected 6. The value of the maximum permissible multiplicative interference is chosen from the interval 1 - 1.3, hence the transfer coefficient re the attenuator 18 is set in the interval O - 0.3. The value of the maximum allowable additive interference is chosen from the condition

(5 (t) /

 g

where g is 0-0.3

The measurement time T is chosen to be longer than the maximum correlation interval of process 5 (i) or from the condition

T 1 / Fg

where Fg is the width of the signal spectrum S (t). The delay 2 of the adjustable element 8 delay and the gain of the adjustable amplifier 9 is adjusted so that the reading of the voltmeter 12 is minimal. The measurement result is counted from a digital scoreboard of the ratio calculator 15.

The delay T and the gain of the adjustable amplifier 9 must be adjusted after each change in the interference or signal parameters.

Claims (1)

METHOD OF DEFINITION. INTERFERENCE OF RADIO RECEIVERS, which consists in the fact that the sum of the interference signal and the test signal are fed to the input of the studied radio receiver, characterized in that, in order to improve accuracy, the signal of the carrier oscillations is modulated with a test signal, the test signal is delayed by a time ί equal to the delay time of the sum of the interference signal and the test signal in the studied radio receiver, the reproduced signal 2 (t) from the output of the studied radio receiver is amplified, the delayed test signal is subtracted from it, divide the obtained difference module corresponding to the instantaneous value of the playback error 8 (t), and the delayed test signal module 5 (4 + о), change the amplitude of the reproduced signal 2 (£) and the delay value Ί) to the minimum value of the time-averaged value of the playback error δ (t)>, determine the instantaneous value of the permissible playback error, due to. simultaneous action of the given maximum permissible values of the multiplicative [Um and additive interference, according to the formula ° Max ^ ~ / (+ c) / + _; compare in magnitude instant. the error values S (t) of the reproduction and the instantaneous values of the permissible error (t) determine the sum of the time intervals, where i = 1,2,3, .., during which the instantaneous value of the error δ (() does not exceed the instantaneous value of the permissible errors _e (t), and the noise immunity of the studied radio receiver is determined by the formula where P is the estimate of the total probability of correct signal reproduction; T is the measurement interval. oo oo oo oo>