SU879795A1 - Device for automatic selection of channels at diversity reception - Google Patents

Description

I

The invention relates to radio engineering and can be used in radio communication technology in receiving reception.

A device for automatic channel selection for communication systems with diversity reception in asynchronous demodulation methods, containing in each diversity channel, serially connected filter, demodulator and key, key outputs of all channels, is connected to the output adder, and the control inputs of all keys are connected to the unit. Comparison via decision block 1.

This device compares the frequencies of the input signals in the diversity channels and selects the channel that has the minimum frequency of the input signal, i.e. the channel containing the minimum level of the noise. However, due to; s the absence of criteria for the information content of received input signals The described device can also take a low-frequency noise at the input of one of the channels if the input noise has a higher frequency in other channels., M And, as a result, the known device has low selection accuracy channels on the "signal / noise ratio.

The closest technical solution to the image is a device for automatic selection of channels of diversity reception, containing the first adder, to each of the N inputs of which a channel filter, a demodulator and a key, a decision block and a comparison block 2 are connected in series.

However, the known device has insufficient accuracy of channel selection with a maximum signal / noise ratio due to possible loss of information.

The aim of the invention is to increase the reliability of channel selection with the highest signal-to-noise ratio.

The goal is achieved by the fact that in the device for auto-selection of channels with spaced reception, containing an adder to each of the N-inputs of which a channel filter, a demodulator and a key, a decision unit and a comparison unit are connected, the N outputs of which are connected to the corresponding inputs of the unit make decisions and control inputs of keys; a noise generator is introduced; a clock pulse generator, the output of which

connected to the clock inputs of the comparison unit and the decision unit; between the noise generator output and the auxiliary input of the comparison unit, a controlled attenuator is connected, to the control input of which a reversible counter is connected, the summing and subtracting inputs of the reversible counter are connected to the corresponding outputs of the decision unit, and a normalizer is connected between the output of each demodulator and the corresponding inputs of the comparison unit.

The comparison unit contains N circuits, each of which consists of a two-input adder connected in series, the first input of which is the corresponding input of the comparison unit, the former, the first counter and the first prohibition element, the output of which is the output of the comparison unit, between the additional input and the output of the first element the bar is turned on the second counter, the second inputs of the two-input adders are combined and are an additional input of the unit of comparison, and the other inputs of the first elements of the ban, the first and second The x counters are combined and are the clock input of the comparison unit.

The decision block is made in the form of an N-input adder connected in series, the inputs of which are the inputs of the decision module, the threshold element and the first prohibition unit, the outputs of which are the corresponding outputs of the decision block, between the output of the N-input adder and the input of the first prohibition unit is connected in series to a comparator and a second prohibition unit, the other input of which is the clock input of the decision unit.

The drawing shows a structural electrical circuit of the device for auto-selection of channels with spaced reception.

The device for auto-selection of channels with spaced reception contains an adder {, channel filters 2, demodulators 3, keys 4, decision block 5, comparison block 6, noise generator 7, clock pulse generator 8, controlled attenuator 9, reversible counter 10 normalizers 11, two-input adders 12, drivers 13, first counters 14, first interdiction elements 15, second counters 16 N-input adder 17, threshold element 18, first interdiction unit 19, comparator 20 and second interdiction unit 21.

The device works as follows.

The signal from the output of the channel filter, 2, which pre-filters the input signal, via demodulator 3 is fed to the input of the normalizer 11 and to the signal input of the key. 4. The normalizer 11 is, for example, an AGC amplifier and performs a signal-to-noise mixture normalization level in all diversity channels to UH. In the case of no. Rtvi in any channel of the information signal up to the level UH "accelerates the voltage of the input noise of the corresponding channel. Due to the normalization, the working signals in the diversity channels at the outputs of the normalizers 11 differ only in the content of the noise level. And the level

noise is inversely proportional to the signal-to-noise ratio. From the output of the normalizer 11, the signal is fed to the input of the two-input adder 12. To the other input of the two-input adder 12, the controlled attenuator 9 is supplied with the noise voltage from the generator 7. The band of the noise spectrum of the generator 7 corresponds to the band of the standard radiotelephone channel. The resulting mixture from the output of the two-input adder 12 is fed to the input of the imaging unit 13, which produces a pulse for each positive crossing of the zero line by applying the voltage of the mixture. The pulses from the output of the imaging unit 13 are fed to the counting input of the first counter 14, which accumulates them during the time determined by the period of the pulses of the ciSpea entering the zeroing input of the first counter 14 from the generator 8.

In case of overflow of the first counter 14 in time. Where, Then is the period of the reset pulses, the overflow pulse from its output enters element 15, which prohibits the passage of the reset pulses from the generator 8 to the zero input of the second counter G6. In the absence of zeroing impulses, the second counter 16 begins to accumulate the pulses arriving at its input QT of the generator 8 and corresponding to the zeroing cycles. If the second counter 16 overflows in time, which is the average duration of the natural pause of the speech signal, the overflow pulse from the output of the second counter 16, applied to the inhibition element 15, produces a voltage level at its output, which is then applied to the control input of the key 4 and translates it into a state of "Closed. In this case, the signal from the input of the corresponding channel does not pass to the output of the device. This occurs in the case when the entrance to the shaper is 13 c. a time longer than the average duration of the pause reche-. the resulting signal enters a resultant mixture consisting only of noise, or a mixture with a signal-to-noise ratio less than the threshold ratio.

When the signal-to-noise ratio at the input

shaper 13 is greater than one, frequency

3 .. the investigation of pulses from its output is

 first counter 14 does not overflow

the time between two zeroing pulses.

The first prohibition element 15 in this case allows the passage of reset pulses from the output of the generator 8 to zeroing the second counter 16. At the same time, the first prohibition element 15 switches the key 4 of the corresponding channel to the “Enabled” position. In this case, the input signal passes to the output of the device. During the natural pauses of a speech signal with a duration less than Tfi, the first prohibition element 15 maintains key 4 in the On state. This is because, during Tb, the second counter 16 does not overflow, and after the end of the speech pause, it is again zeroed by impulses arriving at its zero input from the generator 8 through the first prohibition element 15. . The decision block 5 is designed to control the voltage level of the noise that is active in two-way adders 12. If at the inputs of several diversity channels there are simultaneously information signals, the signal-to-noise ratio of which exceeds the current value of the threshold signal-to-noise ratio, then the outputs of the first elements 15 the prohibition of the corresponding channels there are voltage levels, which, entering the control inputs of the keys 4, transfer them to QOC that is “Enabled. These voltage levels from the outputs of the inhibition elements 15 are fed to the inputs N of the input sum) of the atom 17. Each such voltage level, entering the input N of the input adder 17, increases the voltage level at its output by the value of D U. The maximum voltage level at the output of the weight adder, the value can be: - NA and. The voltage level from the output of the input adder 17 is fed to the comparator 20 and to the input of the threshold element 18. The comparator 20 is a dual comparator with a tolerance zone of the input signal equal to 0.8-1.2AU. If the voltage level at the output N of the input adder 17 is in the specified tolerance zone, which corresponds to only one "switched on channel, then at the output of the comparator 20 there is a voltage level which, acting on the second block 21, prohibits impulses passing through it from the generator 8 on the first block 19 of the ban. If the DC voltage level at the output of the N-input adder 17 is 0.8D U Uebix, uy "if1.2LHJ, then the output of the comparator 20 has a voltage level that permits the passage of the second prohibition block 21 through the second block 21 . In turn, the threshold element 18, if the level of voltage at the output of the N-way adder 17 is ll..jj. 1.24 and, which corresponds to several (a smaller measure of two) “w. Loaded ka. On its output, a voltage level is generated at its output, which, entering the first prohibition block 19, sends incoming pulses to the input of the “Addition of a reversible counter 10. Each pulse entering the input of the“ Addition of a reversible counter 10 increases the level by one step noise voltage at the output of the controlled attenuator 9, the signal input of which receives the noise voltage from the noise generator 7. An increase in the Noise level at the output of the controlled attenuator 9 leads to a decrease in the signal-to-noise ratio at the outputs of the two-input adders 12, which leads to an alternate "deactivation of the diversity channels." The disconnection of the next channel leads to a decrease in the DC voltage level at the output of the N-input adder 17. The output voltage level of the N-input adder 17 will decrease until it falls within the tolerance zone; comparator 20. The comparator 20 will prohibit the passage of 21 pulses through the second prohibition block to control the noise voltage level, and the channel selection process is terminated. Thus, the last remaining enabled channel has a minimum level of input noise (at the output of the normalizer 11), i.e., the highest signal-to-noise ratio at the input. If in this selected channel the signal / noise ratio decreases below the current threshold ratio, then at the output of the first prohibition element 15 the voltage level locking key 4 is output and the voltage level at the output of the N-input adder 17 to zero, i.e., it will leave the tolerance zone of the comparator 20, which at the same time allows the passage of pulses through the second block 21 of the ban on the first block L9 of the ban. The threshold element 18, at the output voltage level of the N-input adder 17 Ivnh, sum "0.8iMJ, produces at its output a control level, which, arriving at the first, block 19, sends the pulses of the generator 8 to the input B1 reading of the reversible counter 10 Every impulse, fasting. .,. ".". "" "" Subtracting the annular power counter 10 by one step reduces the noise voltage level at the output of the controlled attenuator 9. This leads to an increase in the signal-to-noise ratio of the resulting mixture at the outputs of the two-input adders 12 and, ultimately, the " enable the diversity channel having the most signal-to-noise ratio at the time. Compared with the prototype, the proposed device improves the accuracy of the selection of the diversity channel with the highest signal-to-noise ratio by eliminating loss of inform tion. 3jo is achieved by

Claims (3)

The claims ^1S 1. A device for automatic channel selection with diversity reception, comprising an adder, a channel filter, 20 a demodulator and a key, a decision block and a comparison block, N outputs of which are connected to the corresponding inputs of the decision block and the control inputs of the keys to each of N inputs characterized in that, in order to increase the reliability of the choice of ²⁵ channels with the maximum signal to noise ratio, a noise generator and a clock generator are inserted into it, the output of which is connected to the clock inputs and a comparison unit and a decision unit, between the output of the noise generator and the additional input of the comparison unit a controlled attenuator is connected, to the control input of which a reversible counter is connected, summing and subtracting the inputs of the reversing counter are connected to the corresponding outputs of the decision unit, and between the output of each demodulator and the corresponding inputs of the comparison unit included normalizer. 2. The device according to π. 1, characterized in that the comparator contains N circuits, each of which consists of a two-input adder connected in series, the first input of which is the corresponding input of the comparator, former, first counter and the first inhibit element, the output of which is the output of the comparator, between the additional input and the second counter is turned on by the output of the first inhibit element, the second inputs of the two-input adders are combined and are additional inputs of the comparison unit, and the other inputs of the first elements are pre, the first and second counters are combined and are the clock input of the comparison unit. 3. The device according to π. 1, characterized in that the decision block is made in the form of an N-bx input adder connected in series, the inputs of which are the inputs of the decision block, the threshold element and the first prohibition block, the outputs of which are the corresponding outputs of the decision block, between the output of the N-input adder and the comparator and the second prohibition block, the other input of which is the clock input of the decision block, are connected in series with the additional input of the first prohibition block.