SU951730A1 - Device for checking intermodulation and side channels in radio receivers - Google Patents

Description

one

The invention relates to the technical diagnostics of radio receivers and can be used to detect and measure intermodulation and side channels in monitoring and testing to assess the non-linearity and efficiency of the selectivity of high-frequency paths of radio receivers.

A device for measuring interference frequency channels is known, comprising first and second sawtooth generators, first and second controlled oscillators, first and second variable attenuators, first and second adders, a logarithmic amplifier, electron beam indicator and clock generator, and the output of the first sawtooth generator voltage is connected to one input of the first adder, the input of the horizontal deflection of the indicator beam and the input of the clock generator

pulses, the output of which is connected to the input of the second generator of the sawtooth voltage, the output of which is connected to the input of the vertical deflection of the indicator beam, the input of the second controlled generator and the second input of the first adder, the output of which is connected to the input of the first control generator, the output of which through the first attenuator is connected

10 with the input of the second adder, wherein the output of the second controlled generator is connected via a second attenuator to the second input of the second adder, the output of which is connected to.

ts by the input section of the tested radio receiver, the output of which through a logarithmic amplifier is connected to the input of the intensity modulation of the beam of the p j indicator.

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However, the known device has insufficient accuracy for quantifying the level of intermodulation channels and can use 3951

to detect intermodulation and side channels of the radio receiver.

The purpose of the invention is to improve the control accuracy when extending the range of monitored frequencies of signals by separating detection and measurement functions, and introducing a threshold to the output signal of a radio receiver.

The goal is achieved by the fact that the device for controlling intermodulation and side channels in radio receivers, containing serially connected clock generator, sawtooth generator, first test signal generator, first attenuator and first adder, successively connected second, test signal generator and the second attenuator, the output of which is connected to another input of the first adder, an electron-beam indicator and a logarithmic amplifier, has been introduced a step-by-step generator voltage generator, the reference voltage generator, the second and third adders, the amplitude detector, the threshold element., the third, fourth and fifth attenuators and the first and second switches, while the output of the clock generator is connected through series-connected step voltage generator and The first switch to the input of the second test signal generator and through the third attenuator to one of the inputs of the second adder, and through the fourth attenuator to one of the inputs of the third adder, the other input of which is connected with the output of the first adder and through serially connected fifth attenuator, radio receiver, amplitude detector, logarithmic amplifier, the input of which is connected to the input of the threshold element, and a second switch, another input of which is connected to the output of the threshold element, the output of the sawtooth voltage generator is connected to another the input of the second adder, the output of which is connected to the input of the horizontal deviation of the electron-beam indicator, the input of the vertical deviation of which is connected to the output of the third adder.

FIG. 1 shows a block diagram of a device for controlling intermodulation and side channels in

.four

radio receivers; in fig. 2 - time diagrams of the device; in fig. 3 and i depict the receiver channels on the screen of the electro-radiation indicator of the device in the detection mode (Fig. 3) and in the measurement mode (Fig.).

The device comprises a clock pulse generator 1, a step voltage generator 2, a sawtooth voltage generator 3, the first test signal generator k, the first attenuator 5 the first adder 6, the second test signal generator 7,

the second attenuator 8, the first switch 9j the third and fourth attenuators 10 and 11, the second adder 12, the electron-beam indicator 13, the third adder Il, the fifth attenuator 15, the radio receiver 16, the amplitude detector 17, the logarithmic amplifier 18, the threshold element of the device 19. the second switch 20 and a reference load generator 21.

The device works as follows.

Clock pulses U-j. (Fig. 2) of the period T of the generator 1 ensure the start of the generator 3 of the saw-tooth voltage and the period T- (Fig. 26) and the formation of the next voltage step AUi. with the period U. (Fig. 2c) of the generator 2 of the step voltage. The voltages U and U2 are used to control the oscillators A and 7 of the test signals and to form the ZOX plane of the three-dimensional space (Fig. 3) on the display of the indicator 13 using n lines of the scanning beam. With

this shift of the beam along the axis OX respectively, I

determines the change in generator h

OTfj t to fyyicjy (2g). The formation of each next step and U. voltage U of generator 2 corresponds to the offset of each new line

along the axis OZ by the value of D2 (Fig. 3) and the change in the frequency of the generator 7 by the value of L f.2 (Fig. 2e). Thus, a point on the plane OX corresponds to a certain combination of two

frequencies f and f of generator A and 7, whose signals through attenuators 5 and 8, adder 6 and attenuator 15 are fed to the input section of the radio receiver 16. From the output section of the radio receiver 16, the signal goes to the amplitude detector 17, to the output of which is connected a logarithmic amplifier 18, compressing the dynamic range of the responses of the various channels of the radio receiver 16 to conveniently represent the screen of the indicator 13, since they can differ in amplitude by more than 100 dB. The threshold element 19 is turned on in the Measurement mode instead of the log amplifier 18

The device also has a Cross-section mode when the output of the generator 21 of the reference voltage is connected through a switch 9 to the inputs of the third attenuator 10, the fourth attenuator 11 and the input of the second generator 7. This mode allows you to record and randomly change the frequency fj of the second generator 7 and the row position sweep in the ZOX plane, which makes it possible to observe the cross section of a complex surface, depicting a set of frequency channels of the radio receiver and making frequency readings fj, on a scale of the reference voltage generator 21.

The measurement is performed in the following sequence. Switches 9 and 20 are set to position 1, corresponding to the Detection mode. The average frequency of the generators t and 7 using the appropriate adjustments set near the tuning frequency of the radio 16. With attenuators 10, 11 and 15 get the image (Fig.) On the screen of the indicator 13, similar to the image in FIG. 3 and making it possible to observe the intermodulation, side and main channels of the radio receiver 16 simultaneously. Switch 20 is then set in Measurement mode and the maximum attenuation of the test signal is introduced by attenuator 15. In this case, the marks of all channels should disappear. Further, the attenuator 15 increases the test signal until the main channel is received and the first reading is made on the scale of the fifth attenuator 15. calibrated in decibels relative to one microvolt. This count, expressed in microvolts, is the sensitivity of the radio receiver 16. Then the test signal is increased to obtain marks from the intermodulation channel of interest in a given frequency range. The reading of the scale of the fifth attenuator 15 corresponds to the sensitivity of the given intermodulation channel at the edge of this frequency range. The difference between the first and second samples is the level of the given intermodulation channel with respect to the main channel of the radio receiver 16.

Thus, by increasing the accuracy and using a more informative three-dimensional image, the invention controls the sensitivity of the intermodulation, side and main channels of the radio receiver, distinguishes individual intermodulation and side channels, reveals the most dangerous of them, and generally increases the efficiency of monitoring radio receivers. .

Claims (1)

Invention Formula 20 A device for controlling intermodulation and side channels in radio receivers containing serially connected clock pulses, a sawtooth generator, the first test signal generator, the first attenuator and the first adder, the second test signal generator in series, and the second attenuator whose output is connected to another the input of the first adder, the electron beam indicator and a logarithmic amplifier, characterized 5 in order to increase accuracy. control when expanding the range. monitored signal frequencies, a step voltage generator, a reference voltage generator, 0 second and third adders, amplitude detector, threshold element, third, fourth and fifth attenuators, and the first and second switches, while the output of the clock generator is connected via a sequentially connected stepwise generator and the first switch to the input of the second test signal generator and through the third Q attenuator - to one of the inputs of the second adder and through the fourth attenuator - to one of the inputs of the third adder, the other input of which is connected to the output of the first sum- of the oscillator through a series-connected fifth attenuator, radio receiver, amplitude detector, logarithmic amplifier, whose input connected to the input of the threshold element. and the second switch, another input which is connected to the output of the threshold element, the output of the sawtooth generator is connected to another input of the second adder, the output of which is connected to the horizontal deviation input of the electron-beam indicator, input 95173 5 with the output of the third sum is connected to a torus. . Sources of information taken into account in the examination 1. USSR author's certificate in application No. 2868007 / 18-21, cl. G 01 R 27/28, 08.01.80. UT. Ui / i u one I f I I1 F F 15 12 YU / J / " --n one JJ - W . t (2 .one L, / trm Fm.2 ylLvG Ug-l-l dl-ch A, l-l chl-ll tfi-l / h 3frZf, - / H JW-JW-A at   V- .JL "..", DD PG lg-t g-ygl g: vrz:, / / L V g, l l l d / g-s-l. l.- /