SU1190283A1 - Digital spectrum analyser - Google Patents

Abstract

A DIGITAL SPECTRUM ANALYZER containing two sign converters, harmonic and auxiliary signal generators, a matching unit whose input is connected to the analyzer input, and an output to the first inputs of both sign converters, the second inputs of which are connected respectively to the first and second harmonic signal generator outputs, the third and fourth inputs - respectively with the first and second outputs of the generator auxiliary. PPS signals, the generator of counting pulses connected to the first input of the key, you Which is connected to the first input of a reversible counter, characterized in that, in order to spread the dynamic range, a comparator and an OR connected in series and a second reversible counter are entered into it, the comparator input connected to the first output of the auxiliary signal generator, the second input OR is connected to the second output of the first signed converter, the output of the NIC is connected to the second input of the key, the first input of the second reversible counter is connected to the output of the key, and the second input The odes of the first and second reversible counters are connected respectively to the outputs of the first and second: about sign transducers. uh uh u

Description

The invention of measurement technology can be used for spectral analysis of deterministic and real-time learning signals. The aim of the invention is to expand the dynamic range of the spectrum analyzer. The drawing shows a structural diagram of a spectrum analyzer. The digital spectrum analyzer contains a matching unit 1, a generator of 2 harmonic signals, a Comparato 3, the output of which is connected to the input of the sign converter 4, a generator of 5 auxiliary signals, the outputs of which are connected to the inputs of sign converters 4 and 6, the OR element 7, the output connected to the input of the key 8, the generator 9 of the counting pulses connected to the second input of the key 8, and reversible meters 10.1 and 10.2, the first inputs of which are connected to the output of the key 8, and the second to the outputs of the sign converters .4 and 6, the third inputs cat The first ones are connected to the matching unit 1, and the fourth ones to the outputs of the generator 2. The sign converters 4 and 6 contain comparators, the outputs of which are connected to the inputs of the character multiplication unit. The output of the sign converter is the output of the character multiplication unit, the second output of the sign converter 4 is one of the outputs of its comparator. Block 1 matching is an AC amplifier; block 3 is a comparator, the first input of which is the input of the block and the second input is connected to the common bus of the device, and the signal at the output of block 3 is equal to 1 if BXOAHoif signal is greater than zero, and logical About otherwise. The element OR 7 violated the signal of logical 1 when the levels of logical signals at its inputs did not match (ie, at one of the inputs - the level of logical 1, and on the other - the level of logical O and logical O otherwise. The generator 2 of harmonic signals generates a sinusoidal and Cosinusoidal (quadrature) signals of the reference frequency at which the spectrum of the input signal is analyzed. Auxiliary signal generator 5 generates independent random signals with a uniform distribution, the boundary of which covers a range measuring zones input and reference signals. The spectrum analyzer works in the following way. For simplicity, consider the operation of only one quadrature channel, since the second channel works in a similar way. . In block 1, the input signal is centered and scaled, after which it enters the first input of sign converter 4, the second input of which receives a cosine signal from generator 2. In converter 4, these signals are mixed with the corresponding auxiliary signals from generator 5 (these signals are independent of one of the signal under study, have uniform density of distribution, the boundaries of which cover the main range of the signal under study), their sum is quantized into two levels, and the output Nakova D converter formed piecewise constant signal. The positive value of the piece-wise sig “ala corresponds to the logic level 1, and to the negative one - the logic level O. The mathematical expectation of the signal with an accuracy of the proportionality coefficient is equal to the product of the input signal To the harmonic reference signal. Due to this, the operation of multiplying analog signals is reduced to the operation of multiplying characters, which is easily implemented on the digital elements, and also allows replacing the analog integrators with reversible counters. Integrating the result of multiplying the input signal into the harmonic reference signal is carried out by a reversible counter 10.1, the direction control input of the account of which is connected to the output of the sign converter 4. At the counting input of the reversible counter 10.1, counting impulses 9 are fed through the switch 8 to the analyzer the range of additional noise that narrows its dynamic range, weak signals may be below the residual level of auxiliary signals by Exit by reversing tors 10.1 and 10.2. To broaden the dynamic range of the analyzer, the influence of the auxiliary signal on the analysis result is reduced, which is achieved by compensating for this signal. Compensation of the auxiliary signal is performed as follows. The auxiliary signal from the output of the generator 5 is fed to the input of the comparator 3, at the output of which a piecewise constant signal is formed. At the additional output of the sign converter 4, a piecewise constant signal is also formed. These signals are fed to the inputs of the element OR 7, at the output of which the logical level 1 is formed when the input signals are not equal. This level opens the key 8, allowing the passage of counting pulses from the generator 9 to the counting inputs of the reversing counters 10.1 and 10.2. When these input signals are equivalent (in particular, if there is no input signal), the logic level O, which closes the key 8, is formed at the output of the element OR 7, while the counting pulses at the inputs of the reversible counters 10..1 and 10.2. do not come. The indicated prohibition of counting and compensation of the auxiliary signal is carried out and, consequently, a decrease in its effect on the result of spectral analysis, which leads to an expansion of the dynamic range of the analyzer (the compensation does not affect the average value of the useful signal). The introduction of an auxiliary signal compensation is an effective means of expanding the dynamic range, ensuring reliable detection of weak signals. The second channel of the spectrum analyzer works similarly to the first one, but uses the sinusoidal signal of generator 2 as the reference. Since the outputs of the comparators of both sign converters form the same signals (the first inputs of the comparators receive an input signal and the second signal auxiliary signal), the action compensation of the auxiliary signal is distributed to the second channel of the analyzer. “Since the spectrum analyzer channels use quadrature harmonic signals as reference signals, the digital codes at the outputs of the reversing counters 10.1 and 10.2 correspond to the quadrature components of the input signal and thus represent its complex spectrum. The use of auxiliary signal compensation is especially effective in the spectral analysis of pulse signals. In this case, the signal at the analyzer's input is different only in short periods of time. Using the auxiliary signal compensation completely eliminates its effect on the result of spectral analysis — while the input signal is zero, otherwise the effect at that time of the auxiliary signal on reversible counters would distort the analysis result.

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Claims (1)

A DIGITAL SPECTRA ANALYZER containing two sign converters, harmonic and auxiliary signal generators, a matching unit whose input is connected to the analyzer input and the output to the first inputs of both sign converters, the second inputs of which are connected respectively to the first and second outputs of the harmonic signal generator, third and fourth inputs - respectively, with the first and second outputs of the auxiliary signal generator, a counting pulse generator connected to the first input of the key, the output of which It is connected to the first input of a reversible counter, characterized in that, in order to expand the dynamic range, a comparator and an OR element are connected in series and a second reversible counter, while the input of the comparator is connected to the first output of the auxiliary signal generator, the second input of the element OR is connected to the second output of the first sign converter, the output of the OR element is connected to the second input of the key, the first input of the second reverse counter is connected to the output of the key, and the second inputs of the first and w cerned soott reversible counters are connected respectively to the outputs of the first and second sign inverters.