SU483680A1 - Device for simulating communication systems - Google Patents

Description

one

The invention relates to devices for modeling and can be used to study the characteristics of adaptive communication systems with optimal frequencies.

A device is known for simulating the operation of a communication system, i.e., its multi-channel random process generator, the outputs of which are connected to the inputs of the switch and to the comparison circuits, triggers and prohibition schemes.

However, the field of application of such a device is narrow.

The aim of the invention is to expand the field of application of the device by providing the possibility of modeling the operation of an adaptive communication system with optimal frequencies.

This goal is achieved by introducing into the device circuit a sawtooth voltage, which is connected to the second inputs of the comparison circuits, and a collecting circuit whose inputs are connected to the outputs of the corresponding comparison circuits, and the output is connected to the control input of the sawtooth generator and to the first inputs of the inhibit . The inputs of the triggers, directly and through the inhibit circuits, are connected to the outputs of the respective comparison circuits.

FIG. 1 shows a functional diagram of the device; in fig. 2 - time diagram of his work.

The device contains a multichannel random process generator 1 with outputs 2-5, the number of which corresponds to the number of operating frequencies of the system. Outputs 2-5 of the generator

I are connected to the switch 6 and to the inputs of the comparison circuits (comparators) 7-10, respectively. Switch 6 using keys 11-14 can connect one of the outputs of generator 1 to the output of device 15.

The device has a sawtooth generator 16, the output of which is connected to the second inputs of the comparison circuits 7-10. The outputs of comparison circuits 7-10 are connected to the inputs of the collecting circuit (element "OR)

17, the installation inputs of the unit of the corresponding triggers 18-21 and the prohibiting inputs of the prohibition schemes (NO elements) 22-25. The output of the circuit 17 is connected to the input of the generator 16 and through the prohibition circuit 22-25 and inputs

setting zero triggers 18-21.

The flip-flops 18-21 are associated with the keys 11-14 of the switch 6 in such a way that, when the flip-flop 18 is set to one, the AND key is closed, when the flip-flop 19 is set,

key 12, etc.

The device works as follows. Suppose that at the moment of time о the signal at the output 5 of generator 1 has a minimum (but compared with the values

signals at other outputs), trigger 21 is in a single (excited) state and, therefore, key 14 is closed. The remaining triggers 18–20 are in the zero (unexcited) state, the keys 11–13 are open, and therefore, on the device output 15, the signal comes from the output 5 of the generator 1 (minimum signal).

At the time point, a linear increase in voltage at the output of generator 16 begins. This voltage is applied simultaneously to comparison circuits 7-10, in which the signals from generator 1 are compared with the linearly increasing voltage from generator 16. First, the comparator 7 is triggered -10, which receives the minimum (compared to others) voltage from generator 1 (in this case, channel 4, comparator 9, time ti}.) The pulse from the output of comparator 9 goes to trigger 20 and translates it into one state This from the same impulse, passed through circuit 17, goes to the signal inputs of circuits 22-25. Since only circuit 24 has a single signal at the control input that covers this element, signals from the inputs of circuits 22, 23 and 25 pass to the triggers 18, 19 and 21, confirming the zero state of the triggers 18 and 19, and setting the zero state to the trigger 21.

Now instead of flip-flop 21, flip-flop 20 is in the single state, therefore the key 13 is closed and, starting from the moment ti, the output 15 receives a signal from the output 4 of the generator 1.

The pulse from the output of circuit 17 also goes to generator 16 and resets the output of this generator to zero.

Thus, at time i, the channel is changed due to the fact that the previously used channel has ceased to be extreme.

From FIG. 2 that the moment of connecting the minimum signal to the output 15 generally lags behind the time tl, when the corresponding channel becomes minimal. In this case, the lag will be the smaller, the faster the sawtooth voltage increases (relative to the rate of change of the processes at the outputs of the generator 1). However, it should be noted that it takes some time for any communication system to estimate the channel number, which will become extreme, and go to it. This delay allows to take into account the transition time, which takes place in a real communication system.

In the example considered, the best channel was the minimum, which is the case when the quality parameter is, for example, the level of interference in the system. If the best channel is the maximum (the parameter is the signal-to-noise ratio), then the generator 16 instead of the linearly increasing

must form a linearly falling voltage at its output.

Subject invention

A device for simulating a communication system, comprising a multi-channel random process generator, the outputs of which are connected to the inputs of the switch and to

The first inputs of the respective comparison circuits, triggers and prohibition circuits, characterized in that, in order to expand the scope of application, it contains a controlled saw-tooth voltage generator, which

connected to the second inputs of the comparison circuits, and a collecting circuit, the inputs of which are connected to the outputs of the respective comparison circuits, and the output to the control input of the saw-tooth generator and

the first inputs of prohibition schemes; Trigger inputs, directly and through prohibition circuits, are connected to the outputs of the respective comparison circuits.