UA150132U - Counter of reference frequency of narrowband radio signals of limited duration - Google Patents

Abstract

The counter of reference frequency of narrowband radio signals of limited duration includes an amplifier-limiter of input signals and a pulse generator connected to its output on a positive difference, a calibration frequency generator, a first reference pulse counter, a reference pulse counter and a calculation module. It introduced a negative difference pulse shaper, pulse summator, lock pulse shaper, second reference pulse counter, adapting component and OR element, and the input of the negative difference pulse shaper is connected to the output of the input signal amplifier-limiter, and the output – with one of the inputs of the pulse summator, the other input of which is connected to the output of the pulse shaper by a positive difference, the output of the pulse summator is connected to one of the inputs of the adapting component, the second input of which is connected to the output of the adapting component is connected to one of the inputs of the OR element and in parallel with the control inputs of the first and second reference pulse counters, and the output of the second reference pulse counter is connected in parallel with the blocking input of the first reference pulse counter and the second input of the OR element.

Description

A useful model belongs to the field of radio measurements, in particular to devices for measuring the fill frequency of a radio signal of limited duration, and such a radio signal may have the properties of a narrowband process with phase jumps and zones with fully suppressed amplitude. Usually these are echo signals formed during the operation of acoustic, hydro and radar systems. Taking into account the narrowband, in the future we will call the filling frequency of radio signals the reference frequency.

The limited duration of signals makes it impossible to use frequency measurement devices, in which, according to the principle of operation, this process is longer than the signal itself. A device whose operation is based on "capturing" a signal with phase auto-adjustment of the frequency cannot be used to measure the frequency at short time intervals. All possible construction options are digital devices.

A well-known digital device for measuring frequency (D.V. Laptev. Measurement of the frequency of the following pulses of electrical signals by the coincidence method, - thesis for the degree of candidate of technical sciences. - Novosibirsk, 2014. - pp. 15-16, fig. 1.1, 1.2), which contains a reference frequency generator, later - a reference frequency generator, connected to a frequency divider, the output of which is connected to the control input of the key, and the other key input is connected to the output of the reference frequency pulse generator, and the key output is connected to input of the pulse counter.

The disadvantage of the device is the low accuracy of measurements, which is explained by the incoherence of the input signal and the auxiliary signal of the reference frequency generator, from which the sample time interval is formed. The error is greater, the shorter the duration of the input signal.

A further disadvantage is that the device is not suitable for frequency measurement if there are phase jumps and/or the signal contains areas with full amplitude decay, which limits functionality.

The closest analogue is a digital frequency meter (Laptev D.V. Measurement of the frequency of the following pulses of electrical signals by the coincidence method, - dissertation for the degree of candidate of technical sciences. - Novosibirsk, 2014. - pp. 18-19, fig. 1.3, 1.4) , which contains a pulse sequence shaper with a period of the reference frequency, further - an amplifier-limiter of the input signal and a shaper connected to its output

From the pulses on the positive drop, which is connected to the first pulse counter, in the future - the pulse counter of the reference frequency, the output of which is connected to the control input of the key, the second input of the key is connected to the output of the reference frequency generator, and the output of the key is connected to connected to the input of the second counter of pulses, later - of the first counter of reference pulses, which is connected to the input of the computing module.

The disadvantage of such a digital frequency meter is its lack of measurement accuracy, especially in conditions where there are phase jumps and/or the signal contains zones with complete fading of the amplitude, which limits its functionality.

The useful model is based on the task of creating a meter of the reference frequency of a narrowband radio signal of limited duration, in which, due to the introduction of new elements and their location, it is possible to avoid frequency measurement errors associated with phase jumps, and it is ensured that accumulative measurements are carried out only using high-quality signal zones and removing from this procedure zones with suppressed amplitude, which expands the functionality. Therefore, a useful model not only increases the accuracy, but also provides the possibility of such measurements in narrowband signals, which are usually characterized by the presence of phase jumps by 180" and/or zones with complete attenuation of the amplitude.

The task is solved by the fact that the meter of the reference frequency of a narrowband radio signal of limited duration, which contains an amplifier-limiter of the input signal and a pulse generator connected to its output, a reference frequency generator, a first counter of reference pulses, a counter of reference frequency pulses and a computing module, according to a useful model, a negative-drop pulse shaper, a pulse adder, a blocking pulse shaper, a second counter of reference pulses, a coincidence element and an OR element are introduced, and the input of the negative-drop pulse shaper is connected to the output of the amplifier- limiter of the input signal, and the output is connected to one of the inputs of the pulse adder, the other input of which is connected to the output of the pulse shaper on a positive gradient, the output of the pulse adder is connected to one of the inputs of the matching element, the second input of which is connected to the output of the pulse adder via block pulse shaper, the output of the matching element is connected with one of the inputs of the OR element and in parallel with the control inputs of the first and second counters of reference pulses, and the output of the second counter of reference pulses is connected in parallel with the blocking input of the first counter of reference pulses and the second input of the OR element.

The function and principle of operation of the narrowband radio signal reference frequency meter of limited duration are explained in the figures. In fig. 1 shows the structural diagram of the meter. In fig. 2 shows the radio signal in the phase jump zone on an enlarged scale; in fig. 2a shows the high-frequency filling of the radio signal in the zone of the change of sign of the contour; in fig. 26 shows a sequence of pulses with a period of reference frequency M; in fig. 2c is a sequence of pulses corresponding to the boundaries of the half-periods of the reference frequency Mt. In fig. C represents the radio signal in the fading zone; in fig. For - high-frequency filling of the radio signal in the zone of its fading; in fig. 3b shows a sequence of pulses of the reference frequency M without a fading zone; in fig. Zv - a sequence of pulses corresponding to the boundaries of the half-periods of the reference frequency Mlplp, with the calculated pulse; in fig. Zg is a sequence of pulses of the reference frequency n, which is formed on the interval of existence of half periods of the reference frequency.

The meter of the reference frequency of a narrowband radio signal of limited duration (Fig. 1), contains: 1 - amplifier-limiter of the input signal; 2 - pulse shaper with a positive gradient; C - pulse shaper on the negative gradient; 4 - pulse adder; 5 - reference frequency generator; 6 blocking pulse generator; 7 - the second counter of reference pulses; 8 - matching element; 9 - the first counter of reference pulses; 10 - OR element; 11 reference frequency pulse counter; 12 - computing module.

The meter of the reference frequency of a narrowband radio signal of limited duration works as follows.

The narrowband signal is fed to the amplifier-limiter of the input signal 1, which converts it into a "meander" type signal. The "meander" arrives simultaneously at the pulse shaper along the positive 2 and negative Z drops, at the outputs of which sequences of pulses tied to the positive and negative drops of the "meander" are created, respectively. The pulse adder 4 combines the received sequences into a single sequence, which actually reflects the boundaries of the half-periods of the reference frequency. In fig. 2c shows such a sequence with preservation of the integrity of the half-periods of the reference frequency, which makes it possible to avoid frequency measurement errors in the presence of phase jumps. In the "meander" "crushing" of the fronts can be observed, therefore false triggering of the pulse generators on the positive 2 and negative Z differences is possible. As a result, the sequence at the output of pulse adder 4 may turn out to be "unclean", so it

From the diagram, fig. 1, marked Maya. The clearing of this sequence is provided by the blocking pulse shaper b, which operates in the standby multivibrator mode, triggered by the pulses of the sequence Moya, forming pulses with a duration approximately equal to a quarter of the period of the reference frequency (To/4). The matching element 8 works in such a way that during the blocking pulse, pulses of the reference frequency sequence do not pass to its output.

The reference frequency generator 5 forms a sequence that enters the counting inputs of the first 9 and the second 7 reference pulse counters. The first counter of reference pulses 9 performs the calculation of the number of pulses of the reference frequency n, which is subsequently used in the calculations of the reference frequency. Its capacity should be more pulses for the largest measurement interval. This counter is set to the zero (initial) state by a reset pulse that arrives synchronously with the next emitted radio pulse. It is triggered by the first pulse of the adjusted sequence M i (i.e. from the output of the matching element 8), from this moment it calculates the reference pulses and does not react to the following pulses from the output of the matching element 8 until it is blocked by the calculation pulse. Resumption of counting by this counter occurs with the appearance after the calculation pulse following it, which is applied to start. So, as a result, the first counter of reference pulses 9 counts those pulses of the reference frequency that coincide in time with the "active" half-periods of the reference frequency. This can be seen in fig. According to

The second counter of reference pulses 7 ensures the formation of a calculated pulse.

It is characterized by the modulus of the Klee count - Pl, that is, the counter returns to its initial state after the arrival of Pt reference pulses, where Pl is the number of reference pulses within the half-period of the reference frequency. This value is calculated in advance using the formula:

AND,

Pp prCHICHNY 2. Lv 0) where: l. frequency of the reference generator; ext. the smallest value of the reference frequency determined by the purpose of the system.

The calculated pulse is formed when, due to the fading of the signal, the formation of a real pulse does not occur, and the second counter of reference pulses 7 will complete the counting of Pplp pulses. Provided that the input signal is of good quality, the real pulse will be formed before such a calculation is completed. Within the duration of the echo signal, there may be no cases of formation of calculated pulses, but there may be several of them.

The second counter of reference pulses 7 "starts" always from the moment the start pulse is supplied from the output of the coincidence element 8, regardless of the state in which it is, that is, its counting of reference pulses begins from the moment of arrival of each pulse of the sequence M i,

The calculation pulse formed by it is simultaneously sent to the blocking input of the first counter of reference pulses 9 and to one of the inputs of the OR element 10. Blocking the operation of the first counter of reference pulses 9 allows you to avoid counting reference pulses in the zone of no signal, fig. Zg, and the operation of the OR element 10 ensures the input to the appropriate time position in the formed sequence M i of the calculated pulse and, thus, the final formation of the sequence of pulses of the reference frequency Mlp, fig. Zv.

The finally formed sequence of pulses Mppl is received at the counting input of the pulse counter of the reference frequency 11. This counter should determine the actual total number of half-periods of the reference frequency, if the signal had fading zones, or simply the number of half-periods for the case when no fading zones were observed during the duration of the radio pulse.

The result of the calculation from the output of the counter in the form of a binary number Mpp is fed to the computing module 12.

The computing module 12 receives a binary number n from the output of the first counter of reference pulses 9 - the number of periods of the reference frequency in the interval of half-periods of the reference frequency. This means that the first reference pulse counter 9, as well as the reference frequency pulse counter 11, works on the principle of accumulating the number of pulses if the signal had fading zones. Thus, the number of periods of the reference frequency and half-periods of the reference frequency, which are received by the computing module 12, must belong to the same measurement interval within the input radio pulse.

Computing module 12 calculates the value of the reference frequency according to the formula: it - M Y I,

Ko) where: ю - reference frequency; Mpp - the number of half-periods of the reference frequency; It is the frequency of the reference generator; n - the number of periods of the reference frequency in the interval of existence of half periods of the reference frequency.

Claims (1)

USEFUL MODEL FORMULA The meter of the reference frequency of a narrowband radio signal of limited duration, containing an amplifier-limiter of the input signal and connected to its output a pulse shaper on a positive gradient, a reference frequency generator, a first counter of reference pulses, a counter of reference frequency pulses and a computing module, which is distinguished by the fact that it has a negative-drop pulse shaper, a pulse adder, a blocking pulse shaper, a second counter of reference pulses, a matching element and an OR element, and the input of the negative-drop pulse shaper is connected to the output of the amplifier-limiter of the input signal, and output - with one of the inputs of the pulse adder, the other input of which is connected to the output of the pulse shaper on a positive gradient, the output of the pulse adder is connected to one of the inputs of the matching element, the second input of which is connected to the output of the pulse adder through the blocking pulse shaper, the output of the matching element is connected to one of the inputs of the OR element and in parallel with the control inputs of the first and second reference pulse counters, and the output of the second reference pulse counter is connected in parallel with the blocking input of the first reference pulse counter and the second input of the OR element.