SU1081807A1 - Device for separate receiving of digital radio signals with spectrum overlap - Google Patents

Abstract

1. A device for separately receiving digital radio signals PEREKRYVAN1TSIMISYA spectrum comprising two-phase synchronous demodulator, subtractor, whose output is connected to a first input of the copy, which Cpd nen nlchitani single input block, characterized in that, in order to increase the noise immunity , a delay element, a reference signal conditioner, a switch, a level-ratio meter and a Schmitt trigger are introduced into it, the first input of the switch, the first input of the reference signal conditioner and the input The delay elements are combined and are the input of the device, the delay element closure is connected to another input of the subtraction unit, the output of which is connected to the second input of the switch, the first output of which is connected to the third input of the switch through the first synchronous-phase demodulator, the second output of the switch through the second section The phase-phase demodulator is connected to the fourth input of the commander, the input of which is connected to the output of the Schmitt trigger, the input of which is connected to the output of the level ratio meter, the inputs of which are connected to the outputs of the reference generator, the second and third inputs of which are connected to the corresponding inputs of the switch, and the third and fourth output (; 1 switch connected to the second and third inputs of the copy generator. 2. The device according to claim 1, characterized in that the copy former consists of a series-connected synchronous detector, a direct current amplifier, a low-pass filter and a first balanced modulator, as well as a second balanced modulator, the output of which is connected to another input the first ba (Lance modulator and one input of the synchronous detector, the other input of which is the first input of the copy generator, the inputs of the second balanced modulator are the second and third inputs of the copy generator, the output of which is the output of the first balanced modulator. 3. The device according to claim 1, which is different in that the reference signal conditioner consists of x two channels, each of which contains a series-connected synchronous detector, a low frequency section generator, a dc amplifier, and a tunable the reference oscillator, the first inputs of synchronous detectors are combined and are the first input of the reference signal generator, the second and third inputs of which are the combined second inputs of synchronous detectors and are adjustable gene

Description

The horizontally supported oscillations, the outputs of the driver of the reference DC amplifier, are ignited. 1081807

This invention relates to radio and may be used in radio telemetry. A device for separating two signals with an angle module is known, containing a subtraction unit, a phase shifter and the first and second synchronous-phase demodulators l., Combined by the signal inputs. However, the device does not separate two signals with matching carrier frequencies and has a low noise immunity. Closest to the present invention is a device for separate reception of digital radio signals with overlapping spectra, containing ajep two synchronous-phase demodulators, a subtractor unit, the output of which is connected to the first input of the duplicator, the output of which is connected to one input of the subtractor 2J. However, the known device has inadequate noise immunity. The purpose of the invention is to improve noise immunity. To achieve the goal, the device for separate reception of digital radio signals with overlapping spectra, containing two synchronously-phase phase demodulators, a subtractor unit, the output of which is connected to the first input of the duplicator, the output of which is connected to one input of the subtracter, a delay element is inserted, the reference generator; the signal, the switch, the meter from: the load level and the trigger; the first input is the switch, the nepBiidt input of the reference signal conditioner, and the input of the delay element are combined and are input the device, the output of the delay element is connected to another input of the subtraction unit, the output of which toe is dinane with the second input of the commander number, the first input of which is connected to the third input of the switch through the first synchronous-phase demodulator, the second output of the switch is connected through the second synchronous-phase demodulator with the fourth input of the switch, the fifth input of which is connected to the output of a Schmitt trigger, the input of which is connected to the output of a level ratio meter, whose inputs are connected to the outputs of a reference signal former, and third zhody sootvetstvugoschimi which are connected to the switch inputs of the third and fourth switch outputs are connected to second and third input of the copy. Moreover, the copy former consists of a series-connected synchronous detector, a DC amplifier, a low-pass filter and the first balanced modulator, as well as a second balanced modulator, the output of which is connected to another input of the first balanced modulator and one input of a synchronous detector, another input which is the first input of the copy former, the HO1F1-second balanced modulator is the second and third inputs of the copy former, whose output is the output of the first balanced mode l torus. The reference signal conditioner consists of two channels, each of which contains a series-connected synchronous detector, a low-pass filter, a DC amplifier and a tunable reference oscillator, the first inputs of synchronous detectors are combined and are the first input of the reference signal conditioner, the second and third inputs of which are the combined second inputs of synchronous detectors and adjustable oscillations of the opoB reference oscillations, the outputs of the dc amplifiers are the outputs that form ate a support sigpal. 3 The drawing shows a structural electrical circuit of the proposed device. The device for separate reception of digital radio signals with overlapping spectra contains a subtraction unit 1, synchronous-phase demodulators 2 and 3, a copy generator 4, a reference signal generator 5, a level ratio meter 6, a Schmitt trigger 7, a switch 8, a delay element 9. Shaper 4 consists of synchronous detector 10, amplifier 11 constant current, low pass filter 12, balanced modulators 13 and 14. Shaper 5 consists of synchronous detectors 15 and 16, low pass filters 17 and 18, amplifiers 19 and 20 constant current, adjustable oscillators 21 and 22 reference oscillations. The device works as follows. The synchronous-phase demodulator 2 receives and identifies the symbols of the signal Rj (t) of the synchronous-phase demodulator 3 of the signal 82 (t). The carrier frequencies of the signals f and f are separated by uf ig-. Both channels of the imaging unit 5 work according to the pilot signal, although they can also work according to the informational one with preliminary removal of phase keying in the input signal. In the initial state, when there are no signals at the input, the position of the switch 8 is arbitrary. The operation of the device in the presence of radio signals and the condition S S is as follows. Pilot signals are used for accurate phasing of adjusting .gx generators 21 and 22 in shaper 5. At the output of synchronous detectors 15 and 16, a useful component is allocated, proportional to the product of the input signal envelope and the oscillation amplitude of the adjustable oscillator 21 and 22. Consider the operation first channel. The voltage at the output of the synchronous detector 15 can be written as G - pj, mil ri-t P OUT42 -) (1 where is the amplitude of the input signal, the first channel; 074 oscillation amplitude of the adjustable oscillator 2 G. m - ratio: modulation ratio UjwCt) is the law of variation of the amplitude of the modulating voltage of the input signal. Since the amplitude of the pilot signal is not modulated, then U9bix, KUn, g, (2) where K is the conversion factor of the synchronous detector. Averaged in low frequency 17 and lower frequencies and amplified in the amplifier 19 direct current signal of the type I8Y) (,,,. (3) where K is the transfer coefficient of the filter 17; Kg is the transfer coefficient of the amplifier 19, goes to one input of the meter b , the other input of which receives the output voltage of the second channel of the form (3). These voltages are proportional to the levels of the pilot signals in each frequency channel. At the output of the meter 6, the voltage of the form, where C is the deposition constant, mV. Voltage ( 4) enters the controlled input of the Switch 8 through a trigger p 7 Schmitt. To prevent the switching of the inputs of synchronous-phase demodulators 2 and 3, in the case of an approximate equality of the levels of the signals of the division constant in (4.), it is chosen so as to provide the dead zone of switching of the trigger 7 of the Schmitt C. K with and., and 8bi) f2. J and H ;; p "n1 vl. h. For definiteness, let us set 2 ewxf ebixj 5 te t .e. the signal of the first channel with f is greater than the signal of the second channel with f. This case corresponds to the position of the switches of the switch 8 shown in the drawing, while the trigger 7 of the Sietttes is in a steady state. In this case, the synchronous-phase demodulator 2 performs reliable reception and identification of a strong signal Sj (t), and its information output is connected to the second input of the second balanced modulator 14, to the first shsod of which it arrives (444 from a tunable oscillator 21. At the output of the second balanced modulator 14, a copy of the received signal of the first channel is formed. To automatically adjust its amplitude, a feedback loop is used from the series-connected synchronous detector 10 of the amplifier II post This is a low current, fkptra 12 lower frequencies to the balanced modulator 13, at the output of which an az (copy) of the received strong signal is formed, which is then subtracted from: the delayed input signal - ,. . Y (t-f) -s (t-t) -s; (t-t)) S, (t-O + n (t.

With W | Osoda block 1 subtraction signal type.

y (t-i:) - s; (t -) - t-S (t -) + n (t), (5) where is the length of the character in

radio links KHM, 4tf; $ (t-t) - uncompensated remainder of the signal;

n (t) is an additive white ohm, arrives at the input of the second siphon-phase demodulator 3, where it is pushed.

With this, it is necessary to spit the following conditions.

Since the recognized symbol at the output of the synchronous-phase demodulator appears through a time interval equal to the symbol duration tg, the input signal y (t) needs to be delayed by from fTf one ration by the delay-9 element 9. -

In addition, in order to automatically adjust the amplitude of the formed copy of the signal, it is necessary to go only beyond the uncompensated remainder fi (t-tj.) And not to go ina following the signal level S (t-bg). This is accomplished by the elimination of the residue S (t-Cc) from the mixture

(5) by its frequency basis. For this purpose, the synchronous detector 10 receives the frequency f from the output of the balanced modulator 14 as a reference signal.

Similarly, the operation of the device takes place at. In this case, the Schmitt trigger 7 goes to another stable position and switches the switch 8. With this, a copy of the signal Sl is formed and the input of the balanced modulator 14 oscillates at a frequency f, from the output of the adjustable oscillator 22, and the input of the synchronous-phase demodulator 2 is connected to the output of block 1 subtraction. The rest of the device is similar to the considered. In both cases, when an approximate equality of signal amplitudes is reached, channel switching does not occur, as there is a dead zone.

Thus, at any ratio of received signal levels, a strong signal is always received, a copy is formed and subtracted from the input signal mix, while the output of the subtraction unit is always connected to the input of the synchronous-phase demodulator that detects a weak signal. The greater the amplitude of one of the signals, the more confident its reception and identification and the more accurate the formation of its copy. Consequently, the device performs separate reception of 1-SHF radio signals with overlapping spectra with an arbitrary ratio of radio signal levels, which increases the noise immunity of the reception. With a minimum frequency separation uf, taking into account the real instabilities of unsaturated frequencies, inaccuracies in synchronization and other destabilizing factors, the known receivers are practically inoperable even if the amplitude input signals are equal.

Claims (3)

1. DEVICE FOR SEPARATELY RECEIVING DIGITAL RADIO SIGNALS WITH OVERLAPPING SPECTRA, comprising two synchronously-phase demodulators, a subtraction unit, the output of which is connected to the first input of the copy generator, the output of which is connected to one input of the subtraction unit, characterized in that it is immunity to increase the immunity a delay element, a reference signal driver, a switch, a level ratio meter and a Schmitt trigger are introduced into it, the first input of the switch, I the first input of the reference signal generator and the input The delays are combined and are the input of the device, the output of the delay element is connected to another input of the subtraction unit, the output of which is connected to the second input of the switch, the first output of which is connected to the third input of the switch through the first synchronous-phase demodulator, and the second output of the switch is through the second sync-phase the demodulator is connected to the fourth input of the switch, the fifth input of which is connected to the output of the Schmitt trigger, the input of which is connected to the output of the level ratio meter, the inputs of which are connected to the output odes of the reference signal driver, the second and third inputs of which are connected to the corresponding inputs of the switch, and the third and fourth outputs of the switch are connected to the second and third inputs of the copy driver. 2. The device according to π. 1, characterized in that the copy former consists of a series-connected synchronous detector, a DC amplifier, a low-pass filter and a first balanced modulator, as well as a second balanced modulator, the output of which is connected to another input of the first balanced modulator and one input of a synchronous detector , the other input of which is the first input of the copy former, the inputs of the second in the balanced modulator are the second and third inputs of the copy former, the output of which is the output of the first balance modulator. 3. The device according to π. 1, characterized in that the reference signal shaper consists of two channels, each of which contains a synchronous detector, a low-pass filter, a DC amplifier and a tunable reference oscillator, the first inputs of synchronous detectors are combined and are the first input of the reference signal shaper, the second and third inputs of which are the combined second inputs of synchronous detectors and tunable generators of reference oscillations, outputs, direct current amplifiers are output from the reference driver.