SU462291A1 - Radiolini with single-band modulation - Google Patents

Description

bandwidth information. The low-frequency path of the radio transmitter is additionally equipped with locking filters 1 and 2, transmitting filters 3 and 4, amplifier-limiting stages 5 and 6, synchronized auto-oscillators 7 and 8, and summing cascade 9.

The low-frequency path of the radio receiver is additionally equipped with transmission filters 10 and 11, a frequency detector 12, a amplifier of direct current 13, controlled by a switch 14, a sawtooth generator 111 111, providing the frequency gain of the local oscillator 16 radio receiver. Filters 1 and 2, 3 and 4, 10. And 11 and auto-oscillators 7 and 8 are tuned to frequencies H and P, respectively, close to the extreme frequencies of the transmitted signal.

In the frequency transceiver path of the transmitted signal, the locking filters 1 and 2 cut out two close to the extreme frequencies FH and / U, which thus do not enter the force path. The signals of these frequencies through the permeable filters of 3 liters 4 and amplifiers-limiting 1, 5 and 6 are fed to the synchronized generators 7 and 8, respectively. In the adder 9, the transmitted signal and the output signals of the generators 7 and 8 are summed. The total signal enters the high-frequency path of the radio transmitter, where the single-band signal was generated by one of the known methods.

Radiated sigal contains as a reference frequency

/ Number: l / ,. l.

, ± F "±: F:,

where / is the carrier frequency;

L / and - instability of the carrier frequency; , AFii - frequency instabilities Fn and F “respectively.

The frequency spectrum of the emitted signal contains all the frequencies present in the transmitted message. (In this case, only amplitude distorted and distorted occur due to the instability of filters 3 and 4 of generators 7 and 8. However, even with kHz and the relative instability of the oscillation frequency of the synchronized generator 8, Rabbi

---, su.mmarna is absolute error and

This does not exceed ± 2 Hz.

In the radio receiver, due to the frequency stability of the radio transmitter exciter and the local oscillator radio frequency, the state of the propagation velocity and the Doppler effect, the low-frequency signal carrying the transmitted information may be shifted. Restored frequency of the transmitted signal is as follows.

If, due to the above reasons, the entire spectrum of the signal is shifted upwards (to the right along the frequency axis), then the output of the filter 10 of the radio receiver will not appear, and the voltage of one signal from the output of filter 1 is not enough to trigger a controlled switch 14. At In this way, the control element of the local oscillator 16 of the radio receiver, through the controlled switch 14, receives the output voltage of the sawtooth generator 15, due to which the frequency of the local oscillator of the radio receiver changes In relatively wide limits.

In this position of the controlled switch 14, an automatic frequency control (AFC) circuit, including a pass-through filter 11, a frequency detector 12

The DC amplifier 13 is disconnected from the control element of the local oscillator 16 of the radio receiver.

Due to the change in frequency of the local oscillator 16, caused by the effect on its control

the output voltage element of generator 15, the spectrum of the received xishala moves along the frequency axis. At the moment when the lower frequency of the received signal F "and the upper frequency of the received signal P3 are different

respectively, the tuning frequencies of the filters 10 and II, i.e. the frequencies F & and Fa of the transmitted signal, a voltage appears at the output of the filter 10. If there is voltage at both control inputs of the controlled switch 14, it operates by disconnecting the generator output 15 n from the control input of the local oscillator 16 and connecting the output of the DC amplifier 13 of the AFC circuit to it. In this case, the AFC system works by

the signal of the frequency detector 12, keeping such a tuning frequency of the heterodyne 16 radio receiver and Eika, which excludes the effects of the Doppler effect, inconsistencies in the speed of propagation of radio waves and instability

pathogen. At the same time, only errors remain due to the instability of the C | frequency frequencies of the filters and synchronized oscillators.

When shifting the spectrum of the signal in the direction

reduced and frequencies (to the left along the frequency axis) work is similar. In this case, there is no signal at the output of the transmission filter 11, and a single voltage from the output φ, nltra 10 is not enough to operate

controllable switch 14.

Subject invention

RadioLinn with single-band modulation, containing a single-band radio transmitter and a radio receiver, which is different from the fact that, in order to increase the reliability of the communication and reduce the frequency distortion of the transmitted

the signal, the microphone output of the radio transmitter through the amplifier is connected to the inputs of the transmissive filters and to the input of a series of connected behind-pass filters, the outputs of the transmission filters through the amplifying and limiting 1t power cascades are connected

with inputs of synchronized autogenerators, whose outputs are halls with inputs of the summing cascade, the third input of which is connected through the amplifier soydia with the output of the locking filters, and the output through the amplifier is connected to the input of the biopole signal generator of the high frequency radio transmitter unit with biband modulation, and low frequency -act of radioiryemia with o / n, but with modulation by plugging in to filters, tuned .i and frequencies, the indications of which are “limiting the frequency spectrum of the transmitted signal, and the outputs inens with control inputs of a controllable switch, the other inputs of which, respectively, are connected to the outputs of the sawtooth generator and direct current amplifier, the input of which is connected to the output of the frequency detector, and its input is connected to the output of one nz of the indicated fnlters, the output of the controlled switch is connected to the input of the control element of the local oscillator in a single-band modulation mode.

j

OM Radio Transmitter