SU873429A1 - Device for measuring radio receiver frequency selectivity inter-modulation characteristic variation - Google Patents

Description

(54) DEVICE FOR MEASURING THE INTERMODULATION CHARACTERISTICS OF FREQUENCY SELECTIVITY

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The invention relates to radio engineering equipment and "" is used when measuring in the process of developing radio detectors.

A device for measuring the intermodule frequency response characteristic of a radio receiver is known, comprising a measuring signal generator connected in series and a matching unit, the second input and the output of which are connected respectively to the output of the first interference generator and to the input of the radio receiver whose output is corrected to signal / interference, the second generator ator interference and the register block 1.,

However, the measurement of the known devices in the intermodulation characteristics of the frequency selectivity of radio receivers requires a lot of time, especially with multiple measurements.

The purpose of the invention is to reduce the measurement time.

The goal is achieved by the fact that a device for measuring the intermodulation characteristic of the frequency selectivity of a radio receiver has been introduced to j Jiao4 and serially connected receivers

a comparator, a power modulator, an envelope detector, a differentiation unit, an element I, and a control unit; the output of the modulator of the marsadness is connected to the input of the first interference generator; the home of the registration unit, the control and the synchronization inputs of which are connected respectively to the output of the control unit and to the synchronization input of the interference generator,

15 connected to the synchronization output of the first generator of interference, and the second output of the differentiation unit is connected to the control input of the key, the control output of which is connected to the second input of the transmitter I.

20

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

Claims (1)

A device for measuring the interference frequency response characteristic of a radio receiver contains a measuring signal generator 1, a first and second interference generator 2 and 3, a key 4, a block 5 of the receiver, a radio receiver 6, a signal / noise ratio meter 7, a comparator of power modulator 9, a detector 10, the differentiation unit 11, the AND element 12, the control unit 13 and the registration unit 14. I The device operates as follows. The useful signal from the output of generator 1 and the interfering signal from the output of the first interference generator 2, through block 5, arrive at the input of the radio receiver 6. There, through the public key 4 and block 5, receives the interfering signal from the output of the second interference generator. The output signal of the first noise generator 2 varies in a sawtooth manner over the frequency within the measurement band of the characteristic of the radio receiver b, and its power with the help of the modulator 9 varies according to a periodic law. The transmitted signals through the radio receiver 6 are signal and interference, compared to meter 7, and the result of the comparison goes to comparator 8, which is tuned to a predetermined signal-to-noise threshold ratio. When the comparative threshold is reached, the signal from Comparative 8 is de-energized to the initial voltage of the modulator 9, and the power of the first generator of the interference 2 reaches the RMYI. enters the block 11 and from its output on the control input of the key 4. When any type of interference passes through one of the reception channels of the key 4, it is briefly closed by the first negative surge voltage from the block 11. Simultaneously from the control output to Ich 4 positive impulse is fed to the input element And 12, the second input receives a signal from the output of block 11. If there is an intermodulation-type interference at the output of the radio receiver, short-term interruption by the key 4 of the signal from the second interference generator 3. interrupts the interference to the output of radio receiver b, which leads to a positive voltage surge at the output of block 11, which coincides at the input of element I 12 in time with a positive control impulse of key 4. The impulse from the output of element And 12 starts bl to 13, the opening unit 14. In the presence of a radio receiver b interference to a nonintermodal of the local type, interruption of the signal from the second generator of interference 3 does not lead to the disappearance of interference, there is no positive ejection on the input; a.e / element I 12 coinciding with the key pulse 4, block 13 does not work, and block 14 remains closed for registration. Thus, only the intermodulation characteristic of the frequency selectivity of the radio receiver is recorded. The proposed device provides a reliable selection of intermodulation-type interference from all other interference passing to the output of the radio receiver. Automating the measurement of this technical specification of a radio receiver saves time and increases the reliability of measurement results, which is important when measurements are multiple or massive. An apparatus for measuring the intermodulation characteristic of the frequency selectivity of a radio receiver, comprising a series-connected measuring signal generator and a matching unit, the second input and output of which are connected respectively to the output of the first interference generator and to the input of the radio receiver whose output is connected to the input of the signal-to-noise ratio meter, A second generator of interference, a recording unit, characterized in that, in order to reduce the measurement time, a key N is inserted. a comparator, a power modulator, an envelope detector, a differentiation unit, an I element and a control unit; the output of the power modulator is connected to the input of the first interference generator; the second noise generator is connected to the third input of the matching unit; the output of the envelope detector is connected to the signal input of the registration unit, the control and synchronization inputs of which are connected respectively to the output of the control unit and to the synchronization input of the second interference generator connected to the sync the output of the first generator of interference, and the second output of the differentiation unit is connected to the control input of the key, the control output of which is connected to the second input of the element I. Sources of information taken into account during the examination 1. Golubev V.N, Frequency selectivity of AM radio receivers . M., Sv z, 1970, p. 185187 (prototype).