RU1667602C - Apparatus for detecting signals - Google Patents

Abstract

The invention relates to radio engineering and can be used in bit-wise reception of discrete messages. The purpose of the invention is the detection of signals by double telegraphy frequency (DTT). A device for detecting signals with twofold relative phase shift keying comprises a generator 1. a phase shifter 2, multipliers 3-12, low-pass filters 15, 16, 13, 14, delay units 17, 18, adders 19-21, output drivers 22, 23. The goal is achieved by introducing delay units 24, 25. By combining two quadrature signals and two mutually orthogonal reference oscillations and replacing the addition in the adder 10 by subtraction, it is possible to obtain a sine or cosine component of one of the two side bands of the uncontrolled radio signal, since the components of the other side band are mutually compensated. From the delayed signals from the outputs of blocks 17, 18, 24, 25, quadrature components of respectively delayed radio signals from the same mutually orthogonal reference oscillations are formed. The multipliers 11. 12 with filters 13, 14 form a channel phase detectors. 1 ill. Ј

Description

The invention relates to radio engineering and can be used in bit-wise reception of discrete messages.

The purpose of the invention is the detection of dual frequency telegraphy (DTT) signals.

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

The device comprises a generator 1, a phase shifter 2, a first, fifth, sixth, second, seventh, third, fourth, eighth, ninth and tenth multipliers 3-12, a third, fourth, first, second low-pass filters 13-16, the first , the second delay blocks 17, 18, the first, second, third adders 19 - 21, the first, second output drivers 22, 23, the third, fourth delay blocks 24, 25.

The device operates as follows.

A radio signal is being received

S (t) Aslnfurt ± EHD), (1)

where si 2rrf is the circular average frequency, f is the average frequency value: f) is the information parameter; A is the amplitude of the signal; p is the initial phase of the signal; Q 2 / rFp is the circular spacing frequency of Fp, Fp is the spacing of adjacent frequencies of the DCT,

ABOUT

WITH

VJ oh oh

IN5

with an average frequency (ikp coming to the input of the device is converted by multipliers 3 and 4 with mutually orthogonal reference oscillations of the same frequency (Do, taken from generator 1 and split by 90 °, using phase shifter 2 by 90 °.

As a result of this correlation conversion of the received radio signal, for which the quasiharmonicity condition is fulfilled (the carrier frequency is many times greater than the frequency band occupied by the spectrum), with mutually orthogonal reference oscillations, two mutually orthogonal low-frequency convolution signals are obtained at the output of low-pass filters 13 and 14

1.5Fg + G

x (t) / S (t) slnmo t dt (2)

1,5Fg -f FM

and vW / s (t) cos r / Jcp t dt (3)

about

at a low intermediate (differential) frequency (0.5-1.5) Fp (Fp is the frequency of separation of adjacent frequency positions of the RFB) with -Ofcp. The cutoff frequency of the low-pass filters 15 and 16 is set based on the transmission of the sum of the maximum deviation of 1.5 Fp and the FM manipulation according to expressions (2) and (3).

The high-frequency conversion products that occur at the output of multipliers 3 and 4 in the form of the sum frequencies rhrnrrrr (integer type) are suppressed by filters 15 and 16 of the lower estot

Using filters 16 and 15, the proposed device performs the main frequency selection of the received signal and ensures the passage of all its useful components in the form of low-frequency convolution signals x (t) and y (t) for which the quasiharmonicity condition can be violated. Further, these signals x (t) y (t) are delayed by delay units 17 and 18 by interval T3. as a result, there is a phase incursion of 90 ° at a frequency shift, defined by the formula Tm - -gr-, and at the output of blocks 24 and 25 4g-r

delays as a result of a delay for an interval of 2 s incursion in phase ± 90 °, ± 270 °.

Then, one filtered uncontrolled common-mode CHI channel 5g „f (x) and two delayed quadrature / radio signal signal ni (t Т,) are restored

0

5

0

5

0

5

0

5

0

5

Zkv2 (1 - 2Th) of the same frequency as the frequency of the undelayed signal The delayed signals SuBi (t - T3) and SKo2 (t - 2T3) repeat the phase shift taking place, as a result of the delay of the low-frequency signals x (t) and y ( t).

The formation of the in-phase component of the unrestrained radio signal and the quadrature components of the delayed radio signals when reconstructing the filtered radio signals is necessary for combining the zero transition point of the phase detector characteristic as the frequency with the average frequency (ik: p of the received signal of the frequency response, i.e., using the sine form of the short-term autocorrelation functions in accordance with the formula R (r) - 0.5 A sin cor.

Filtered radio signals are reconstructed by the method of single-band modulation of mutually orthogonal reference oscillations with a frequency ftfe of the corresponding low-frequency convolution signals according to a two-phase (quadrature) phase-recombination scheme. Thus, when an uncontrolled radio signal is generated by low-frequency uncontrolled signals x (t) and y (t), the mutually orthogonal reference oscillations (multipliers 5 and 6), taken from generator 1 and split by phase shifter 2 by 90 °, are balanced. Each of the multipliers 5 and 6 at its output forms two side frequency bands (upper and lower relative to the frequency of the reference oscillation).

Thanks to the combination of two quadrature signals x (t) and y (t) and two mutually orthogonal reference oscillations and replacing the addition by the sum of 10 10 by subtraction, it is possible to obtain a sine or cosine component of 1 of one of the two side bands of an uncontrolled radio signal, since the components the other sideband is mutually compensated.

Based on the delayed signals x (t - T3) and y (t T3) from the outputs of the delay units 17 and 18, x (t - 2T3) and y (t - 2T3) from the outputs of the delay units 24 and 25, quadrature components of the delayed radio signals are respectively generated SKs (t - Т3) and Sxn (t - 2ТЭ) from the same mutually orgonal reference oscillations (Psremniteli 7, 8, adder 20 and multipliers 9, 10, adder 21).

The procedure for generating these signals is similar to restoring an undelivered radio signal (t).

From the outputs of the adders 20 and 21, the quadrature components SKoi (t - T3) and Sxe2 (t - 2Т3) are fed to the second inputs of the multipliers 11 and 12, the first inputs of which are fed unsecured radio signal 5cf (t.) From the output of the adder 19 with the same delayed frequency.

Multipliers 11 and 12 in combination with low-pass filters 13 and 14 form channel phase detectors.

Using these channel phase detectors, two values of the short-term autocorrelation function are changed at fixed delay intervals T3 and 2T3 and sign voltages proportional to the phase shifts are generated in accordance with the frequency positions of the DCB by the first output driver 22 along the first channel and the second output driver 23 on the second channel of the DCT at the output of the device.

Claims (1)

The claims A device for detecting signals with two-fold relative phase shift keying, comprising a generator whose output is connected to the first inputs of the first, second, third and fourth multipliers and through a phase shifter with the first inputs of the fifth, sixth, seventh and eighth multipliers, the second inputs of the first and fifth multipliers are the input of the device, the output of the first multiplier through the first low-pass filter is connected to the input of the first delay unit and the second input of the sixth multiplier, the output of which is union of the first input of the first adder, whose output is connected to first inputs of de in one and ten multipliers, the output of the first multiplier through the second low-pass filter is connected to the input of the second delay unit and the second input of the second multiplier, the output of which is connected to the second input of the first adder, the output of the first delay unit is connected to the second input of the seventh multiplier, the output of which connected to the first input of the second adder, the output of which is connected to the second input of the tenth multiplier, the outputs of the fourth and eighth multipliers are connected to the inputs of the third adder, the output of which is dined with the second input of the ninth multiplier, the output of which through the third low-pass filter is connected to the input of the first output driver, the output of which is the first output of the device, the output of the tenth multiplier through the fourth low-pass filter is connected to the input of the second output driver, the output of which is the second output of the device, the output of the second delay unit is connected to the second input of the third multiplier, the output of which is connected to the second input of the second adder, characterized in that, for the purpose of det ktirovani telegraphy signals twice the frequency, it introduced a third and fourth delay units, wherein the output of the first delay block through a third delay unit coupled to the second input of the eighth multiplier, a second delay unit output from the fourth delay unit coupled to a second input of the fourth multiplier. Output 2 about