SU1413547A1 - Digital panoramic frequency meter - Google Patents

Abstract

The invention relates to a radio metering technique and is intended to measure signals with an extended amplitude spectrum. The digital panoramic frequency meter CPIC contains an input key 1, quadors 3, 5, 11, 13, adders 4, 12, interpolators 6, 8, blocks 9, 10 of sliding integration, extremator 14, generator 15 sync pulses, block 7 of the current coarse estimate frequency, digital analyzer 2 complex spectrum. The FDCH has the accuracy of measuring the central part of the radio spectrum. 12 il. i

Description

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The invention relates to a radio metering technique and is intended to measure signals with an extended amplitude spectrum.

The purpose of the invention is to improve the accuracy of measuring the center frequency of a radio signal spectrum having an extended amplitude spectrum.

Figure 1 shows the structural diagram of the proposed meter; 2 is a plot of a measurement error generation process in a known device when analyzing a signal with a narrow amplitude spectrum; Fig. 3 is a plot of the process of forming a measurement error in a known device when analyzing a signal with an extended amplitude spectrum; Figures 4 and 5 are diagrams of modules of discrete values X and Xg of the real and imaginary components of the complex spectrum of the signal S (t) at the output of the digital analyzer 2 of the complex spectrum; figure 6 is a plot of the signal at the output of the adder 4; figure 7 is a plot of the signal at the output of block 7 of the current coarse frequency estimate; in fig. 8 and 9 are diagrams of the real X (co) and X (oo) imaginary components of the complex spectrum of the signal S (t) at the outputs of interpolators 6 and 8, respectively; in Fig. 1, O and 11 are signal plots) and Md (-5) at the outputs of blocks 9 and 1 O of sliding integration, respectively; in fig. 1.2 - plots of signals Mg ()), Mg (), formed at the outputs of quadrants 11 and 13, respectively (a, b) and signal plot M (-5) at the output of adder 12 (c).

The meter (figure 1) contains a key circuit 1, connected to the digital analyzer 2 of the complex spectrum, the outputs of which are connected to the inputs of quadrants 3 and 5 and the first inputs of interpolators 6 and 8. The outputs of quadrants 3 and 5 are connected to the inputs of the adder 4, the output of which connected to the input of block 7 of the current coarse frequency estimate. The code of block 7 of the current roughly estimated frequency is connected to the second inputs of interpolators 6 and 8 and to the second inputs of blocks 9 and 10 of sliding integration, as well as to the second input of extremizer 14. The first inputs of blocks of sliding integration 9 and 10 are connected to the outputs of interpolators 6 and 8, respectively. The outputs of the sliding integration blocks 9 and

10connected to quad inputs

11 and 13 respectively. The outputs of quadrants I 1 and 13 are connected to the inputs of the adder 12. The output of the adder 12 is connected to the first input of the digital extremer 14. The outputs of the 15 sync pulse generator are connected by a bus (1) to the control inputs of the key circuit I and the digital analyzer 2 of the complex spectrum, via a bus (2) to the controlled inputs of the sliding integration blocks 9, 10 and via the bus (3) to the controlled input of the extremator 14.

The proposed device works as follows.

The input (1) of the key receives an additive mixture X (t) S (t) + n (t) of the radio signal S (t) with an amplitude spectrum that is constant in the Q / 2 frequency band and a broadband interference n (t) with a frequency band significantly higher than the radio frequency band. Here, -3 is the true value of the measured central frequency of the radio spectrum. Unknown center frequency of the spectrum - the radio signal takes values from the pd range, "" Key 1 is opened by a pulse at time t, which determines the start of the measurement and is generated by the generator 15 clock pulses. At the same time, this signal is fed to a digital analyzer 2 of the complex spectrum. The control pulse duration T is chosen equal to the maximum possible duration of the measured signal. As a result of the conversion of the input signal, low-frequency components in the range of 0 t SI (max-max / min) of the oscillation spectrum are selected in the digital spectrum analyzer of the complex spectrum. Further, these components are discretized in time with a step of ut and converted into digital form. By N r | jT / 2 ir signal samples The spectrum analyzer 2 generates at the outputs of two channels 2N samples of the real X (o) and imaginary X 5 (co) parts of the Fourier spectrum in the maxmax range with a pitch TO T / T. Figure 4 and fig.Z depicts an exemplary view of the modules 1Hp (s) | and IXg (co), respectively. For convenient methods for explaining the operation of the device, in FIGS. 11 and 12 the interference is not shown. The quadratures 3 and 5 form the squares of the modules of the real (and real) and imaginary Xd (o) p clock of the Fourier spectrum. Next, adder 4 forms the sum of the squares of the Fourier spectrum readout modules X (. (N) –X5 (co)), which are readings of the power spectrum of the input signal X (t) (Fig. 6). Block 7 of the current coarse frequency estimate from sequential incoming samples of the power spectrum of the radio signal produces the current rough estimate of the frequency v. The estimate is formed by iterating over the readings of the power spectrum and finding the maximum of them

1X (j)) / and specif. 5 (maxlx, (jco) |

as the spectral readings arrive. Figure 7 illustrates the maximum sample of the power spectrum signal, whose position is the current coarse frequency estimate. Block 7 of the current coarse frequency estimate can be made in the form of a digital device containing four memory locations and a comparison circuit. A number characterizing the amplitude of the first compared reference is recorded in the first memory cell, a number in the second number, a number characterizing the amplitude of the second comparative reference is written in the third memory cell, and a number in the fourth memory cell. After comparing the amplitudes, the number that characterizes the largest amplitude is entered in the first cell, and the number of this reference number in the second. As the overshoot and comparison of the power spectrum readings in the first cell, the number characterizing the maximum amplitude will be formed, and the number of the maximum counting 3 in the second memory cell. Thus, the current coarse frequency estimate is formed, which is defined as the spectral number number of the spectrum with the maximum amplitude.

Interpolators 6 and 8, using the value 4 measured in block 7 of the current coarse frequency estimate, as well as the information contained in the amplitudes of the samples of the real Xj. (JQ) and imaginary Xg (JQ) parts of the discrete Fourier spectrum, reproduced in the frequency band - $ th, + IJ form of these functions (Fig.8 for Xj (ci) and Fig. 9 for Xd (co)) for input signal of the radio signal and broadband interference n (t). Thus, interpolators

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6 and 8 restore the shape of the real X (i) (Fig.8) and POWERFUL) (Fig.9) parts of the Fourier spectrum in the –fZ, 5-Sl frequency band, since the Fourier sampling of the spectrum with a spacing of WSE WT is possible —the formation of the spectrum in the interval between the calculated spectral readings with the help of Kotelnikov's series.

The 5oe discretization step of the interpolated spectral components at the output of Interpolto1 1a is significantly lower than in the digital complex spectrum analyzer 2, i.e. S U loz.

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The reconstructed real and imaginary parts of the Fourier spectrum are further processed in blocks 9 and 10 of sliding integration, arriving at their first inputs. Blocks 9 and 10 sliding integration form

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the signals Mj (-) Jl. (u) d (o and

+ fj / 7

 X (co) dto (fig. 10) for

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X. () 5 -h / 7 values of 5 in the frequency band

 - P / 2, N h-2-J These blocks implement numerically linear filters matched with a square pulse, which is a function of frequency, the length of which in the frequency domain is equal to the width of the spectrum of the useful signal. A sliding integration unit is a linear filter with a rectangular transient function, considered as a function of the current frequency. In discrete form, the sliding integration unit performs operations

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 where Uc (j S co) is a digital signal at the output of the interpolator that corresponds to Xj. (co) or X5 ((o) (Figures 8 and 9); the value of i varies within (-} - S2 / 2) / i Q to

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(+ -r-J / UQ; the value of k is defined as 0

is the width of the S1 band, i.e. k

. The discretization step Q is given by interpolators 6 and 8 as 5 minimally possible with the element base (LO) used. The limits of changing the value of 1Tmg1m Wwc in blocks 9 and 10 of sliding integration are corrected by the information signal from block 7 of the current coarse frequency estimate.

Digital signals M () (M (i)) and MgC) (M (i)), formed in blocks of sliding integration, are fed to the inputs of quadrants 11 and 13, respectively. Pi quadrants

13 form the signals MRO) (Fig. 12a) and) (Fig.126), which then go to the inputs of the adder 12. The adder 12 generates a signal M () Mj () + M (0) (Fig.12v), which is fed to the input extremer 14. The extremer 14, by enumerating the incoming numbers (characterizing the amplitudes M (i) of the spectrum readings), determines the position - (- the absolute maximum M (-O), which is an estimate of the unknown radio frequency of the radio signal. At the moment of time corresponding to the end of the measurement, the measured frequency (reference number) of the radio signal spectrum is indicated at the output of the accelerator Ala with the highest accuracy ("). The control of the continuous formation of the largest counting and its number is carried out by the generator of 15 sync pulses on the bus (3). Information about the value of the coarse estimate of the frequency N is fed from the output of block 7 to blocks 9, 10 and

14 in order to limit the integration interval Xj, (o), Xgtco)

and search for the extremum of the signal M (5). As a result, the time required to obtain an estimate, YI, of an unknown frequency -Op of a radio signal is reduced.

When measuring the carrier frequency of a radio signal that has an extended carnal frequency amplitude spectrum peak, the accuracy of the frequency estimate by a known device drops significantly.

The proposed device in these conditions provides the maximum attainable accuracy of the estimate (estimate of the maximum likelihood) of the carrier frequency of the radio signal and provides

more accurate estimate compared to the known.

Claims (1)

g Formula of invention Digital panoramic frequency meter auth.St. No. 569961, characterized in that, in order to increase the accuracy of measuring the center frequency of a radio signal spectrum with an extended amplitude spectrum, an input key is inserted in it, the first additional quadrant in series and the first additional adder, the interpolator connected in series, the first sliding integration unit , the second additional quad, the second additional adder and the extremator, are connected in series the second block of the sliding integration and the third complement A quadrant as well as a sync pulse generator, the outputs of which are connected to the second extremator input, the second inputs of the sliding integration blocks, the control input of the digital analyzer of the complex spectrum, and through the input key with the signal input of the digital analyzer of the complex spectrum, the first input of which is connected to the input the first additional quadr and the first input of the additional interpolator, the output of the first additional adder is connected to the input of the coarse frequency evaluation unit, the second inputs and terpol tori are connected to third inputs of blocks sliding integration, to the output of a rough estimate chastoty.i ekstrematora to the third input, the squarer output is connected to the second input of the first additional adder, the first input of the second slide block Integration is connected to the interpolator output, and the second input of the second additional adder is connected to the output of the third additional quad. / v. x   / BUT H sk / fMJ Xs {(i)} liB.S one up BUT. p-i + Q d i P ) d - i 0 0+ ar. 12 t lf V