SU655087A1 - Adaptive device for selecting phase-manipulated signals - Google Patents

Description

one

The invention relates to a pulse technique and can be used in communication channels in which other signals, such as television picture signals, are also transmitted along with phase-shifted ones.

A device for selecting phase-shifted signals is known, comprising a first delay line with taps and inverters, a subtraction unit connected via a second delay line with taps and inverters to a weighting factor block whose outputs are connected to the inputs of the adder, as well as serially connected coincidence unit, delayed gate driver , key stage and integrator {.

However, this device makes it possible to select only one narrow central lobe of the autocorrelation function, regardless of the correlation properties of the selectable phase-shift keyed signal at the nominal duration of its each element.

The purpose of the invention is to improve the noise immunity in the range of mismatch.

To do this, in an adaptive device for the selection of phase-shift keyed signals,

containing a first delay line with taps and inverters, a subtraction unit connected via a second delay line with taps and inverters with a weight unit, whose outputs are connected to the inputs of the adder, as well as serially connected coincidence unit, delayed gate driver, key stage and integrator, are entered the logic element, the error indication block and the reference pulse shaper, the first delay line through the taps and inverters connected to the inputs of the match block, and the last withdrawal

also connected to the input of the subtraction unit and through an inverter with the input of a logic element, the output of which is connected to the first input of the error indication block, the second and third inputs of which are connected

respectively, with the output of the reference pulse shaper and the output of the coincidence unit connected to the input of the reference pulse shaper, while the outputs of the error indication block are connected to the corresponding inputs of the weighting factor block, and the output of the adder is connected to another input of the key stage. The drawing shows a structural electrical circuit of the proposed device.

The adaptive device for the selection of phase-shift keyed signals contains the first line of the delay 1 with taps and inverters 2, the subtraction unit 3, the second delay line 4 with the taps and inverters 5, the weighting unit 6, the adder 7, the coincidence unit, the delayed coder 9, key stage 10, an integrator 11, a logic element 12, a discrepancy indication unit 13, and a reference pulse driver 14.

The predol; enno device works as follows.

The input signal, for example, a signal manipulated in phase in accordance with the eleven-digit Barker code, is fed to the input of the first delay line 1. At that moment, when all the inputs of block 8 match, there are positive polarity pulses, which is possible if the device under consideration has phase-shifted the signals of only one particular structure, at its output a resultant positive pulse is produced. The presence of positive pulses that overlap with each other, at least as much as possible at the same time at all inputs of the block 8 coincidence, is a necessary condition for generating a resultant pulse. The same factor limits the range of possible mismatch.

With matched digital filtering, the duration of the resulting pulse is TO. In case of a mismatch, when the duration of one element of a complex phase-shifted signal differs from the nominal value TO by some value b, and the delay between every two adjacent taps of the delay line 1 (4) remains equal to TO, the resulting pulse shifts to the right relative to the nominal number by value () 5, and at TO-b, remaining in the nominal position, decreases in duration by the same amount. These features make it easy to indicate the presence and sign of a mismatch. For this, in display unit 13, three signals are compared in relation to each other and the duration: resulting from the output of block 8 matches, the delayed input phase-shifting signal, taken to equalize the delays from the logic element 12, and the reference pulse of the nominal duration TO, produced by driver 14, representing for example, a waiting multivibrator that is triggered by a positive edge of the resulting pulse.

When the durations of the resulting and reference pulses coincide, and when the positive fronts of the resultant pulse and the first element of the delayed phase-mapped signal coincide, the display unit 13 detects the absence of a mismatch and produces an appropriate control pulse, which is then fed to the weight factor 6. If the resultant coincides with the positive fronts (its pulse and the first element of the delayed phase-shift signal, the resulting pulse duration is shorter than the reference pulse, another control impulse corresponding to the TO-B mismatch is generated for supplying weight 6 to the block 6. If the positive front of the resulting pulse is delayed relative to the positive front of the first element of the delayed phase-shift keyed signal, in block 6

coefficients, a third control pulse is applied, corresponding to the To-f-b mismatch.

Influenced on block 6 weights, the corresponding control

impulse translates it into one of three positions, conventionally designated as “TO-b,“ TO, “That + b. In addition, each input and the corresponding output of the block 6 weights, connecting it with the line

delay 4 and adder 7 are switched simultaneously.

Thus, during the passage of the phase-manipulated signal through the subtraction unit 3, in block 6 weighting coefficients, the side lobes are zero in the gating area in each particular case.

After passing block 3 subtraction

the phase-shift keyed signal is fed to the second delay line 4. The delay lines 4 removed from the taps of the delay 4 after each TO in the desired polarity, the signals arrive at block 6 of weighting coefficients and then -

Adder 7, where the sum is combined with different weights, forms the response, which in turn is fed to the input of the key stage 10. Pa another input of the key stage 10

a strobe is supplied, the duration of which A is chosen from these considerations so that fluctuations of its fronts, which increase as the signal-to-sound ratio deteriorates, do not affect the accuracy of the selection of the central lobe of the autocorrelation

phase shift key functions

both with matched filtering and

at a mismatch.

The components of the response of the adder 7, forming in the strobe zone only the central lobe of the autocorrelation function, in the case of matched filtering ("TO), should be located in the middle of the gated portion. This is necessary so that in the remaining two cases ("TO-6," then + b), the components of the response of the adder 7, which form in the strobe zone the central lobes of the autocorrelation function that are somewhat deformed (due to mismatch), the maxima of which are shifted respectively to the left and to the right of the nominal position, would not go beyond the strobe's limits. In order to comply with this condition, the strobe should start affecting the key cascade 10 earlier at its second input the components of the central lobe of the autocorrelation function at matched filtering for a time (or the same thing after the appearance of the resulting pulse at the output of block 8 AG 7VTo-Dt L to-Zbg.

Both operations — delaying the onset of strobe formation by AT and forming the required duration of the strobe D — are carried out in shaper 9, for example, using two waiting multivibrators, the first of which is triggered by a positive front of the resulting pulse, forming a delay time equal to DG.

Gated in the key stage 10, the components of the response of the adder 7 are fed to the integrator AND, where only the central lobe of the autocorrelation function is formed, both in case of matched filtering and in case of mismatch.

The introduction of new units allows to increase the noise immunity in the error range.

6 Forms u. 1 a and 3 o b e te n u

An adaptive device for the selection of phase-shift keyed signals comprising

a first delay line with taps and inverters, a subtraction unit connected via a second delay line with taps and inverters with a weight block, whose outputs are connected to the inputs of the adder, as well as series-connected matching unit, delayed gate driver, key stage and integrator, distinguished by that, in order to increase the noise immunity in the error range, a logic element, a mismatch indication unit and a reference pulse former are introduced into it, the first line being delays through taps and inverters are connected to the inputs of the matching unit, and the last tap is also connected to the input of the subtracting unit and through an inverter to the input of the logic element whose output is connected to the first input of the display unit

the error, the second and third inputs of which are connected respectively to the output of the onor pulse generator and the output of the coincidence unit, connected to the input of the reference pulse generator,

the outputs of the error indication block are connected to the corresponding inputs of the weighting factor block, and the output of the adder is connected to another input of the key stage.

Information sources,

taken into account during the examination 1. USSR Copyright Certificate M 481998, cl. H OZK 5/18, 1973.