RU163281U1 - 180 ° SIGNAL DETECTOR WITH ABSOLUTE PHASE MANIPULATION - Google Patents

Abstract

A signal detector with 180 ° absolute phase shift keying, consisting of a phase detector, a pulse regenerator, a 180 ° phase shift key, and also a reference oscillator, through which the information input of the phase detector is connected to its reference input and the second input of the phase shift key, characterized in that it is equipped with a standard frequency demodulator and a time integrator connected to the output of the phase manipulator in the indicated sequence.

Description

“The technical field to which the utility model belongs”

The utility model relates to the reception of radio signals.

"Prior art"

Known signal detectors with absolute phase shift keying (QPS) at 180 °, disclosed in the following sources of information: patent of the Russian Federation for No. 124461 for utility model “Coherent signal detector with phase shift keying at 180 °”, authors - Alekseev VM, Volkov A.A., Alekseev D.V., priority from 07/06/2012 .; Gorelov. G.V., Volkov A.A., Shelukhin V.I. "Channel-forming devices of railway telemechanics and communications." - M.: GOI 2007. - C 228-228.

By technical nature, the signal detector closest to this utility model is described in the first source, which for this reason is taken as its prototype. The second source describes an analogue of a utility model.

The prototype detector consists of a phase detector (PD1) sequentially connected, a pulse regenerator (P), a 180 ° phase manipulator (PSK), PD2, and also from a reference oscillation driver (PSF), through which the PD1 information input is connected to its reference input and with the second input of the PSK. The FOC block consists of a sequentially connected quadrator, a second harmonic filter, a 2-fold frequency divider, a first harmonic filter - a reference oscillation. It can be seen that the reference oscillation is filtered by narrow-band filters twice: once for the second harmonic, and second time for the first harmonic obtained from the second. So the reference oscillation is without interference. But such a reference oscillation under the influence of interference at the detector input has spontaneous (random) phase jumps of 180 °, which is why the detected low-frequency signal at the output of PD1 is adopted on the contrary: units are zeros and zeros are units. Therefore, this phenomenon is called the reverse operation of the signal detector with an absolute QPSK of 180 °, which disrupts communication and therefore an absolute QPSK of 180 °, which provides the maximum possible noise immunity of the communication, is not used in practice. The detected signal at the output of PD1 is broadband, and therefore it is impossible to filter it out so carefully as a reference oscillation. In addition, this signal is distorted by noise. The regenerator restores the original undistorted transmitted signal from it and without interference. When it is multiplied in the PSK block with the reference oscillation, an undistorted PSK by 180 ° is obtained without interference, which is fed to the input of PD2. Since there is no interference at its input, reverse operation of this detector is not expected.

. Знаки ± равновероятны, поэтому обратная работа может быть вызвана не только помехами на входе детектора, но и другими процессами в приемнике. Именно поэтому считается, что обратная работа во всех когерентных детекторах сигналов с абсолютной ФМ на 180° неустранима, почему и была разработана относительная фазовая манипуляция (ОФМн) на 180° вместо абсолютной ФМн на 180°. Но ОФМн обеспечивает помехоустойчивость приема в два раза меньше, чем абсолютная ФМн, и не обеспечивает передачу и прием сигналов по клиппированному речевому сигналу, так как его импульсы имеют случайную длительность.But the reverse operation of the detector is determined not only by interference at its input, but also by the principle of operation of the FOC. It follows from the foregoing that in the FOC the input signal is first squared to eliminate the QPS by 180 ° and obtain the second harmonic, from which the first one is the reference oscillation, which is equivalent to extracting the square root of the square of the input signal. But the square root has a sign

. The signs ± are equally probable, therefore, reverse operation can be caused not only by interference at the detector input, but also by other processes in the receiver. That is why it is believed that the reverse operation in all coherent signal detectors with an absolute FM at 180 ° is not removable, which is why the relative phase shift keying (OFMn) of 180 ° was developed instead of the absolute FMN of 180 °. But OFMn provides noise immunity of reception half as much as absolute FMN, and does not provide transmission and reception of signals by a clipped speech signal, since its pulses have a random duration.

The main disadvantage of the prototype is the likelihood of reverse work in it, eliminating the practical use of an absolute FMN of 180 °, which provides the maximum possible noise immunity of the reception.

“Disclosure of a utility model”

The technical result of the utility model is the realization of the maximum possible noise immunity of receiving signals with an absolute QPSK of 180 ° due to the complete exclusion of the detector reverse operation in it.

The essence of the utility model is that in a signal detector with absolute phase shift keying (QPSK) at 180 °, consisting of a phase detector PD in series, a pulse regenerator P, a phase shift keyer at 180 °, and also from a reference oscillator (FOK), through which the information input (PD) is connected to its reference input and the second input of the PSK, it is equipped with a standard frequency demodulator (SSD) and a time integrator connected to the output of the PSK in the specified sequence.

A significant difference of the invention is the standard frequency demodulator (RDS) and the time integrator additionally introduced into it, connected to the output of the PSK by 180 °. Since the reference oscillation is not used in the SDH, the reverse operation of the detector is, in principle, excluded.

"Brief Description of the Drawings"

The utility model is illustrated by drawings. In FIG. 1 is a structural diagram of a developed signal detector with an absolute QPS of 180 °, and FIG. 2 is a timing chart explaining its operation.

"Implementation of a utility model"

In FIG. 1 is indicated: 1 - phase detector, 2 - Pistalcorse reference oscillation driver, 3 - pulse regenerator, 4 - 180 ° phase manipulator, 5 - standard frequency demodulator (RDS), 6 - time integrator. The newly introduced (distinctive) elements are outlined by a dotted line.

The operation of the circuit is as follows.

A signal with absolute phase shift keying (QPSK) at 180 ° U _FM (t) = U _m cos {ω _pr t + 90 ° [γ (t) -1]}, where γ (t) = ± 1 is the transmitted information signal, arrives at the information input of the phase detector ФД 1 and in parallel to the driver of the reference oscillation ФОК 2. Phase detector 1 consists of a multiplier of signals from the low-pass filter at its output, and ФОК 2 consists of a series-connected quadrator, a second harmonic filter, a 2-fold frequency divider, a filter the first harmonic is the reference oscillation u ₀ (t) = U ₀ cosω (t). In phase detector 1, these oscillations are multiplied among themselves, resulting in a signal

, то есть фронт и срез прямоугольного импульса (Фиг. 2). В интеграторе по времени 6 по фронту и срезу восстанавливаются неискаженные импульсы γ(t) (Фиг. 2). Элементы 1-4 тщательно фильтруют от помех ФМн колебание, устраняют искажения импульсов в нем, отчего СЧД 5 и интегратор по времени 6 точно воспроизводят переданный сигнал.The low-pass filter of phase detector 1 eliminates high-frequency (HF) oscillation and only the transmitted square-wave signal γ (t) shown in FIG. 2. For γ (t) = + 1, there is a positive impulse (+1), and for γ (t) = - 1, a negative impulse (-1). This alternating signal is really distorted by interference, restores its rectangular shape and is freed from interference in the pulse generator 3, after which it enters the information input of the phase manipulator at 180 ° 4, which is a signal multiplier. The second input of the pulse generator 3 receives a harmonic reference signal, freed from interference by the two narrow-band filters indicated above. As a result of multiplication at the output of the pulse generator 3, there is a signal with absolute phase shift keying 180 °, completely cleared of interference and distortion. This signal is fed to the input of the frequency control system of type 5 fractional detector. Since its input circuit is tuned to the reference frequency, then at the output of the power supply system 5 there will be a time derivative of the phase of the PSK signal:

, that is, the front and slice of a rectangular pulse (Fig. 2). In the time integrator 6, undistorted pulses γ (t) are restored along the front and the slice (Fig. 2). Elements 1-4 carefully filter the FMN oscillation from interference, eliminate the distortion of pulses in it, which is why RDS 5 and the time integrator 6 accurately reproduce the transmitted signal.

The technical and economic effect of the utility model is to exclude in principle the reverse operation of the signal detector with an absolute PSK by 180 °, which allows its practical use to increase the noise immunity of signal reception by 2 times compared to the PSK and makes it possible to transmit using the absolute PSK by 180 ° clipped speech signal.

Claims (1)

A signal detector with 180 ° absolute phase shift keying, consisting of a phase detector, a pulse regenerator, a 180 ° phase shift key, and also a reference oscillator, through which the information input of the phase detector is connected to its reference input and the second input of the phase shift key, characterized in that it is equipped with a standard frequency demodulator and a time integrator connected to the output of the phase manipulator in the indicated sequence.

Images