SU982204A2 - Device for automatic selection of channels in space-deversity reception - Google Patents

Description

one

The invention relates to radio engineering and can be used in remote reception systems based on the principle of auto-selection of the channel with the highest signal-to-noise ratio.

According to the main author. St. No. 879795, a device for automatic selection of channels with spaced reception is known, containing an adder, to each of the N inputs of which a channel filter is connected in series, a demodule, a torus H key, a decision unit and a comparison unit, the N outputs of which are connected to the corresponding inputs of a received block These solutions and control inputs of the keys, as well as containing a generator and a generator of clock pulses, the output of which is connected to the clock inputs of the decision block and the comparison block between the output of the noise generator and additional The input of the comparator unit is enabled with an equal- ity attenuator, to the control input of which is connected, a reversible counter, summing and zeroing inputs of the reversible 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 Norm is enabled.

Comparison block contains N circuits, each of which consists of a connecting two-input accumulator | I, the first input of which is the corresponding input of the comparison block, forming the first counter and the first prohibition element, the output of which is the output of the comparison block, between the additional input and the output of the first the inhibitor is turned on the second counter, the second inputs of the two-input adders are combined and are an additional input of the comparison unit, and the other inputs of the first elements of the ban of the first and second counters The ticks 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 block, the threshold element and the first block, the outputs of which are cooTBeTCTByroinHN ™; the outputs of the decision block, the output of the N-input adder and the additional input of the fifth block, includes a sequential comparator and a second block, the other input of which is The clock input of the peuiemiHfij block is received. In the known device, the accuracy of channel selection with respect to the signal-to-noise ratio is determined by the number of bits of the controlled attenuator connected to the reversible counter, and the speed is determined by the frequency of the control pulses of the clock generator. Since the average frequency of the signal-to-noise mixture at the outputs of the adders included in the comparison unit is a random value, to average it the time period of the TO clock pulses (necessary for periodically zeroing the number of periods included in the block comparison) should be several tens of milliseconds (almost TO 40 ms). The above-mentioned clock pulses are simultaneously controlling pulses of a reversible counter connected to a controlled attenuator. Consequently, the maximum possible channel selection time with the highest signal-to-noise ratio is determined by the expression: Tg () TO, where n is the number of detuned attenuator (for n 8 and TQ. 40 ms, Tg is about 10 s) time, equal to Tg, at the device output, the input signal is the sum of signals from all the diversity channels that are not currently disconnected, which reduces the noise immunity of the device by the time of channel selection. Another disadvantage of the known device is as follows. If, for example, at the output of the NJ channel there is an information signal from Uj, / U 10 and at the output of the NJ .. channel, there is an information signal from Uc / Urn 8, then when normalizing the mixture, the output of the normalizer is at the level equal to 3 V, to disable Nj. a channel with U (, / U 8, it is necessary to introduce at least 2.34 V of additional noise voltage into the comparison unit from the output of the controlled attenuator. Further, suppose that, due to the change in radio reception conditions, the signal-to-noise ratio in all the diversity channels deteriorates This means that in order for the device to select the NJ channel with the current value of Up (Uf 5, it is necessary to reduce the level of the additional noise at the output of the controlled attenuator to a value of 1.98 V. At n 8 and TO 40 ms of the level adjustment glama, w of this example takes about 1.2 s and at this time in the description A loss of information occurs in the device. Thus, the known device has insufficient speed. The purpose of the inventors is to increase the speed. The goal is achieved by having a demodule to the device for selecting channels with diversity reception, containing an adder, to each of the N inputs of which are connected in series a torus and a key, a decision block and a comparison block, the N outputs of which are connected to the corresponding inputs of the decision block and the control inputs of the keys, as well as containing A noise generator and a clock pulse generator, the output of which is connected to the clock inputs of the comparison unit and the decision unit, between the generator outputs of the chum and the auxiliary input of the comparison unit, a controlled attenuator is connected, to the control input of which a reversible counter is connected, summing and inverting inputs the reverse counter is connected to the corresponding outputs of the decision block, and a normalizer is connected between the output of each demodulator and the corresponding inputs of the comparison block, between the first The additional output of the decision unit and the control input of the clock pulse generator includes an additional key, the control input of which is connected to the second auxiliary output of the ruyusha reception unit, the output of the noise generator is connected to the input of the controlled attenuator via a tunable bandwidth filter, the control input which is connected to the output of an additional key, and the zeroing and subtracting inputs of the reversible counter are combined. The decision block is made in the form of an N-input adder connected in series, the inputs of which are the inputs, and the output is the first additional output of the decision block, the comparator whose output is the second additional output of the decision block, and the prohibition element, another the input of which is the clock input of the decision block, the threshold element is connected to the output of the N-input adder, and the output of the prohibition element and the threshold element is the corresponding outputs of the decision block . The drawing shows a structural electrical circuit of the proposed device. The device for auto-selection of channels with spaced reception contains an adder I, channel filters 2. demodulators 3, keys 4, normalizers 5, block 6 compare unit 7 to make a decision, noise generator 8, filter 9 with adjustable bandwidth, controlled attenuator 10, reversible counter 11, - an additional key 12, a generator of 13 clock pulses, an N-input adder 14, a threshold element 15, a comparator 16 and an element 17 of the prohibition. The device for automatic selection of channels when receiving diversity works as follows. i The signal from the output of the channel filter 2, pre-filtering the input signal, is fed to the input of the demodulator 3, from the output of which the low-frequency signal is fed to the signal input of the key 4 and to the input of the normalizer 5. The normalizer 5 is an AGC system and produces the normalization level signal-to-noise mixture. Thus, at the outputs of the normalizers 5, the diversity channel signals are distinguished by the content of the level of the noise in the mixture, and the noise level in the signal-to-noise mixture at the output of the normalizer is inversely proportional to the signal-to-noise ratio. The signals from the outputs of the normalizers 5 are fed to the signal inputs of the comparison unit 6, the clock input of which receives pulses from the output of the generator 13. The additional noise voltage from the output of the noise generator 8 through the filter 9 and the control attenuator 10 is fed to the control input of the comparison unit 6. As the level of additional noise at the output of the controlled attenuator 10 increases, comparison unit 6 sequentially generates voltage levels at its outputs equal to logic zero levels, with the first logic zero level appearing at that output of comparison unit 6, which corresponds to the channel with the smallest signal / noise ratio. The logical zero level from the output of the comparison unit 6, arriving at the control input of the corresponding key 4, disables the passage of the - signal from this channel to the output of the adder 1. At the same time, the voltage from the output of the comparison unit 6 goes to the inputs of the decision block 7. Each level corresponding to a logical unit, from the output of the comparison unit 6, increases the voltage level at the output of the input adder 1 by the value D. The voltage from the output of the N-input adder 14 is fed to the inputs of the threshold element 15 and the comparator 16. The comparator 16 is a dual comparator with a tolerance zone of the input signal equal to 0.8-1.2 Di. If the output voltage level of the N-input adder 14 is in the specified tolerance zone of the comparator 16, which corresponds to one enabled channel, a voltage level is generated at the output of the comparator 16, which closes the auxiliary key 12 n simultaneously prevents the clock pulse from passing through counter input of the reversible counter 11. If in the selected communication channel the signal / noise ratio decreases below the level determined by the level of the noise input entered in comparison block 6, then at the outputs of the N-input sum torus 14 and threshold element 15 level output voltage is close to zero. The level of logical zero from the output of the threshold element 15 enters the resetting of the reversing counter of Ik. When the reversing counter is zeroed out, the output of the shuma is close to zero at the output of the controlled attenuator 10. . At the same time, at the outputs of the comparison unit 6 levels of logical units appear corresponding to the diversity channels in which the signal-to-noise ratio exceeds the threshold sensitivity of the device to the signal-to-noise ratio. At the output of the N-input adder 14, the voltage level is determined by the expression UcyMM M-Di, where M is the number of channels, the signal-to-sound ratio in which exceeds the threshold sensitivity of the device to the signal-to-noise ratio. With Ugy, the logic unit level appears at the output of the threshold element 15. At the same time, a control voltage level is generated at the output of the comparator 16, allowing passage of the reverse counter II of pulses from the output of the generator 13 through the element 17 prohibiting the counting input and opening an additional key 12. In this case, the follow up and Ivms of the generator 13 That / Kg, where Kj is the steepness of the control of the generator 13; the period of the pulse generator 13 in the absence of control voltage. Each pulse arriving at the counting input of the reversing counter I increases the noise level by one output of the controlled attenuator 10 connected to the comparison unit 6, which leads to the sequential shutdown of the diversity channels. Thus, the voltage level at the output of the N-input adder 14 is discretely reduced by the magnitude di. Simultaneously with a decrease in the voltage at the output of the N-BXonoBoro adder 14 back to the pro.

periodically, the period follows the clock pulses of the generator 13 and the cutoff frequency of the filter 9 is directly proportionally changed in order to adjust the noise band for discharge, the condition

T fmcp const,

where f pp is the average frequency of the noise at the output of the filter 9.

Enforcement of this is necessary so that with a varying period of following clock pulses, the average number of zero-line crosses by noise during the time between the two-clock pulses of two clock pulses remained constant.

The voltage level at the output of the N-input adder 14 is reduced until it reaches the tolerance zone of the comparator 16, which at the same time prohibits the passage of clock pulses through the inhibit element 17 and puts the additional key 12 in the closed state. This completes the channel selection process with the highest signal-to-sound ratio.

The technical and economic effect of the present invention is to increase the speed of the device in the channel selection process.

In the prototype device, the maximum possible channel selection time is TB (- 1) TO and with n 8 and TO 40-10-3 s, IB W c.

In the proposed device, the channel selection time is determined by the expression

. .f:.% b.

at

N Cr-li-H1 1

when n 8, N 5, K.- 7.5 Hz / V, TO 40-10-3 s, li 1B, TB 2.8 s. (In the above formula. For the time of channel selection in the proposed device, for simplicity, it is assumed that the channel spacing is evenly distributed over the whole range of variation of the signal-to-noise ratio).

In the proposed device, as compared with the prototype device, due to a change in the algorithm of the operation of the block to decide: 1 the information was lost for the time of channel selection.

Claims (2)

1. Device for automatic selection of channels with spaced reception on aut. St. 879795, differing from the fact that, in order to increase speed, between the first additional output of the decision block and the control input of the clock pulse generator includes an additional key, the control input of which is connected to the second additional output of the decision unit, the output of the noise generator is connected to the input of the controlled attenuator through a tunable passband filter, the control input of which is connected to the output of the additional key , and the zero and subtract inputs of the reversible counter are combined. 2. The device according to claim 1, wherein the decision block is executed in the form of an N-input adder connected in series, the inputs of which are inputs and the output is the first additional output of the reception block the solution, the comparator, the output of which is the second additional input of the decision block and the prohibition element, the other input of which is the clock input of the decision block, is connected to the output of the N-input adder threshold element, and the outputs of the prohibition element and the threshold element are are the relevant outputs of the decision block. Sources of information taken into account during the examination 1. USSR Copyright Certificate №879795, cl. H 04 B 7/02, 1981. CTB "about F if I G 3511 CNI t