The signal receiver shestnadtsetirichnoe quadrature amplitude manipulation

 

The invention relates to electrical engineering and can be used at the reception signals of the quadrature amplitude-shift keying (QAM). Achievable technical result is to increase the noise immunity of receiving QAM signals by increasing the reliability of detection and elimination of false grips phase. To do this, perform the following operations on the signal from the input signal KAM restore coherent carrier frequency in the first carrier recovery block; use recovered in the first block of the recovery of the carrier frequency as a reference fluctuations in coherent demodulation of the input signal CAM in the first demodulator; use recovered in the second block recovery of the carrier frequency as a reference fluctuations in coherent demodulation of the input signal CAM in the second demodulator. 2 Il.

The invention relates to electrical engineering and can be used at the reception signals of the quadrature amplitude-shift keying (QAM).

Known demodulator shestnadtsetirichnoe quadrature amplitude manipulation, containing the first and second phase detectors, filter, generator, first and second agriseta his low immunity, associated with the presence of point a false capture phase of its discriminatory characteristic in the vicinity of the point23° (see [1, Fig.2]). The operation of the demodulator in a state of false capture phase (which in the known device cannot be detected and eliminated) leads to a complete loss of information at the output of the demodulator.

It is also known a device for the recovery of the carrier frequency signals shestnadtsetirichnoe quadrature amplitude manipulation, containing the first and second phase detectors, the first and second low pass filters, Phaser and four adder (see RF patent №2019054, IPC 5 H 04 L 27/34, publ. in BI No. 16, 30.08.94,) [2].

A disadvantage of the known device consists in its low noise immunity associated with possible loss of information due to the presence of false capture phase when23° (see [2, Fig.3]). In General, the presence of false grabs phase is the principal feature of signal receivers for amplitude-phase shift keying, which is explained by multimodality, i.e. the presence of multiple maxima of the likelihood function in the evaluation of the recovery phase carrier such signal is signal quadrature amplitude manipulation // Problems of Radioelectronics. Ser. IDW. - M.: NIEIR. - 1991. - vol.17, S. 65-76) [3].

Known technical solutions closest to the technical nature of the claimed object is the receiver of the signals quadrature amplitude manipulation, containing the first and second demodulators, the first carrier recovery block, the first and second low pass filters, first and second threshold blocks, element OR generator-sweep signal, an input connected to the OR gate's output and the output with the first input of the first carrier recovery block, the output of which is connected with the control input of the first demodulator, a signal input which is the input device and is connected with the second input of the first carrier recovery block and the signal input of the second demodulator, the outputs of the first and second low-pass filters connected respectively to the inputs of the first and second threshold units, the outputs of which are connected respectively with the first and second inputs of the OR element, the outputs of the first demodulator are the outputs of the device (see RF patent №2019053, IPC 5 H 04 L 27/34, publ. in BI No. 16, 30.08.94,) [4] is a prototype.

A disadvantage of the known device is the low reliability of the detection is a false grip and, as a consequence, low domehouse the Institute about that for certain values of the angle of phase mismatchin some selection decision on the transmitted symbol does not fit one signal point.

This assumption is true only at unrealistically high signal to noise at the input device.

When the actual signal to noise at the input device, of the order of 20-25 dB, this assumption is not always correct. In this regard, in the known device in a real working relationship signal/noise ratio, the stress values corresponding to the presence or absence of a false capture in the known device, differ slightly. Thus, the effects of noise in the known device is a high probability of not detecting a false grip or mistaken identity and address, when in fact the capture was true.

The technical result - increased robustness of reception of QAM signals by increasing the reliability of detection and elimination of false grips phase is achieved by performing the following operations on the signal:

- from the input signal KAM restore coherent carrier frequency in the first carrier recovery block;

- use restored the input signal CAM in the first demodulator;

is passed to the output obtained in the first data demodulator;

- generate a noise signal and summed with the input signal CAM, thus receiving the noisy signal KAM;

- from a noisy signal KAM restore coherent carrier frequency of the second carrier recovery block;

- use recovered in the second block recovery of the carrier frequency as a reference fluctuations in coherent demodulation of the input QAM signal of the second demodulator;

- use high-order received in the second data demodulator as a test signal, identifying a false grip, which on each step of comparing the high order bit data from the second demodulator with two older bits of data from the first demodulator;

the result of comparison of average and compared with a threshold value;

- exceeding the average of the results of the comparison threshold conclude that occurred in the first recovery block bearing false grip and trigger the sweep generator signal to output a first carrier recovery block of the state a false grip.

This is achieved by the signal receiver quadrature amplitude manipulation is Ascot, the first and second threshold blocks, element OR generator-sweep signal, an input connected to the OR gate's output and the output with the first input of the first carrier recovery block, the output of which is connected with the control input of the first demodulator, a signal input which is the input device and is connected with the second input of the first carrier recovery block and the signal input of the second demodulator, the outputs of the first and second low-pass filters connected respectively to the inputs of the first and second threshold units, the outputs of which are connected respectively with the first and second inputs of the OR element, the outputs of the first demodulator are the outputs of the device.

According to the invention it introduced a second carrier recovery block, adder, generator noise, the four elements And the third and fourth low pass filters, third and fourth threshold blocks, and the reference input of the second demodulator connected to the output of the second carrier recovery block, the input connected to the output of the adder, a second input connected to the output of the noise generator and the first input with the input device.

The first output of the second demodulator connected to the first inputs of the first, second, third and the second inverted input of the second element, And the second output of the first demodulator is connected to a second input of the third element And the second negative input of the fourth element And the outputs of the first, second, third and fourth elements And are connected respectively to the inputs of the first, second, third and fourth low-pass filters, the outputs of the third and fourth low-pass filters connected respectively to the inputs of the third and fourth threshold units, the outputs of which are connected respectively with the third and fourth inputs of the OR element.

This allows you to perform new operations on signals: from the pre-noisy signal CAM repair coherent carrier frequency of the second carrier recovery block, it coherently to demodulate the QAM signal of the second demodulator and by comparing the demodulated data in both demodulators to identify a false grip.

In Fig.1 shows a functional diagram of the receiver CAM.

Fig.2 illustrates the principle of detection of false capture at any variants "inverse" of the demodulators.

The receiver CAM includes first and second demodulators 1 and 2, the first and second blocks 3 and 4 of the recovery of the carrier, the noise generator 5, an adder 6, the first is (PB) 15-18, the element 19 and the generator 20 sweep signal.

The input of the generator 20, the sweep signal is connected to the output element OR 19, and the output to the first input of the first block 3 recovery carrier, the output of which is connected with the control input of the first demodulator 1, a signal input which is the input device and is connected to a second input of the first unit 3 recovery of the carrier and the signal input of the second demodulator 2.

The outputs of the first and second low-pass filters 11 and 12 are connected respectively to the inputs of the first and second threshold blocks 15 and 16, the outputs of which are connected respectively with the first and second inputs of the OR element 19, the outputs of the first demodulator 1 are the outputs of the device.

The reference input of the second demodulator 2 is connected to the output of the second carrier recovery block 4, the input connected to the output of the adder 6, a second input connected to the output of the noise generator 5, and the first input with the input device, the first output of the second demodulator 2 is connected with the first inputs of the first, second, third and fourth elements And 7-10, the first output of the first demodulator 1 is connected with the second input of the first element And 7 and the second inverted input of the second element And 8, the second output of the first demodulate the first, second, third and fourth elements And 7-10 respectively connected with the inputs of the first, second, third and fourth low-pass filters 11 to 14, the outputs of the third and fourth low-pass filters 9 and 10 are connected respectively to the inputs of the third and fourth threshold blocks 17 and 18, the outputs of which are connected respectively with the third and fourth inputs of the element OR 19.

The receiver operates as follows.

In the first block 3 recovery carrier recovery is coherent carrier frequency, which through reference input signal to the first demodulator 1, which is used as a reference oscillation for coherent demodulation of the input signal CAM. Any resulting data is fed to the output of the receiver.

Likewise, it is coherent demodulation of the QAM signal from the second demodulator 2 with the difference that the recovery of the bearing block 4 is used input signal CAM, folded in the adder 6 noise signal generated by the noise generator 5. Thus, fundamentally, the operation unit 4 is different from the operation unit 3 lower signal-to-noise at its input.

The noise generator 5 generates white Housby noise across the entire bandwidth of the input signal CAM.

P is watts greatest at high signal-to-noise ratio and decreases its reduction (see, for example, [3] or A. Leclert and Vondamme P. Universal Carrier Receivery Loop for QASK and PSK Signal Sets // IEEE Transaction on Communications. - 1983. - vol. COM - 31, No. 1, R. p. 130-137 [5]).

Thus, by selecting the signal level at the output of the generator 5 of the noise is large enough, you can achieve that the second block 4 recovery carrier will never be in a state of false capture, while the first block 3 can be both true and false attacks.

This fact gives the opportunity to use the data from the output of the demodulator 2 as a test to identify the type of seizure in the demodulator 1.

Directly as the output of the entire receiver, the data output of the second demodulator 2 can not be used due to the fact that the probability of error is higher for use in demodulation of a noisy reference fluctuations.

However, since the probability of the complementary data output of the demodulator 1 error in the data at the output of the demodulator 2 is small, it gives the opportunity to use the latter as the test signals to determine the type of seizure in the demodulator 1.

For this it is enough to compare with subsequent averaging of the data at the first output of the demodulator 2 and Dunn, the inventive device is the comparison of data And2data And1,B1andin accordance with the options of "inverse" of the demodulator (see Fig.2, a - d).

While the letters a and b indicated significant bit data at the output of the demodulators, dibit pair which specifies the number of the quadrant on the signal plane, which has got received signal point. The index represents the number of the demodulator.

Then, in a state of true capture of the demodulator 1 and unit 3, the output of one of the low-pass filter 11 to 14 will be the level corresponding to the full coincidence of the sequence data at the inputs of the corresponding element And 7-10.

For example, the demodulator 1 is in a state of true engagement and at the same time option "reverse work"(see Fig.2). Then all cycles in the output of the second element And 8 will be formed signal coincidence is logical 1.

Accordingly, the output low-pass filter 12 will be level 1, the output of the LPF 11 is level 0, the outputs of the LPF LPF 13 and 14 levels of 0.5.

Each of the threshold units 15-18 arranged in such a way that the signal is a logical 1 on its the new level close to the value 1, for example 0,9.

Then in condition true capture of the demodulator 1 always exists IB (which is determined by the option "reverse work"), which has at its output a logic 1, the corresponding averaged to match the data at the inputs of one of the elements And 7-10.

In case, if in the first block 3 recovery carrier capture occurred in the state of false capture phase, then in any of the elements And 7-10 will not be sequential in time to experience the full coincidence of the signals on their inputs. This is illustrated in Fig.2 d, which shows that the signal point, really fall into one signal quadrant (as in Fig.a-g), in the case of a false capture perceived by the receiver as belonging to different quadrants. Accordingly, the outputs of all IB 15-18 will be formed to logical 0.

The generator 20, the sweep signal is triggered upon receipt of a logical 0 at its input.

Then, in a state of false capture, through the element OR 19 outputs PB 15-18 logic 0 starts the generator 20 sweep signal, which affects the block 3, bringing his state of synchronism.

Thus, the use in the inventive device operations and the corresponding signals, not with kakoi robustness of the claimed device in comparison with the prototype.

Sources of information

1. RF patent №2013018, IPC 5 H 04 L 27/22, publ. BI No. 9, 15.05.94,

2. RF patent №2019054, IPC 5 H 04 L 27/34, publ. in BI No. 16, 30.08.94,

3. Parkhomenko, N. G., Botashev B. M., Shelepin E. C. Research schemes recovery of the carrier frequency signals quadrature amplitude manipulation // radioelektroniki. Ser. IDW. - M.: NIEIR. - 1991, vol.17, S. 65-76

4. RF patent №2019053, IPC 5 H 04 L 27/34, publ. in BI No. 16, 30.08.94, prototype.

5. A. Leclert and Vondamme P. Universal Carrier Receivery Loop for QASK and PSK Signal Sets // IEEE Transaction on Communications. - 1983, - vol. COM -31, No. 1, p.p.130-137.

Claims

The signal receiver quadrature amplitude manipulation, containing the first and second demodulators, the first carrier recovery block, the first and second low pass filters, first and second threshold blocks, element OR generator-sweep signal, an input connected to the OR gate's output and the output with the first input of the first carrier recovery block, the output of which is connected with the control input of the first demodulator, a signal input which is the input device and is connected with the second input of the first carrier recovery block and the signal input of the second demodulator, the outputs of the first and second low-pass filters svenne, with the first and second inputs of the OR element, the outputs of the first demodulator are the outputs of the device, characterized in that it introduced a second carrier recovery block, adder, generator noise, the four elements And the third and fourth low pass filters, third and fourth threshold blocks, and the reference input of the second demodulator connected to the output of the second carrier recovery block, the input connected to the output of the adder, a second input connected to the output of the noise generator and the first input with the input device, the first output of the second demodulator connected to the first inputs of the first, second, the third and fourth elements And the first output of the first demodulator connected to the second input of the first element And the second inverted input of the second element And the second output of the first demodulator is connected to a second input of the third element And the second negative input of the fourth element And the outputs of the first, second, third and fourth elements And are connected, respectively, to the inputs of the first, second, third and fourth low-pass filters, the outputs of the third and fourth low-pass filters are connected, respectively, to the inputs of the third and fourth threshold units, the output is

 

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