SU781715A1 - Device for measuring modulation partial products - Google Patents

Description

measure the relative level of the product MjDulitsy or signal security no more than minus 60 dB - 65 dB.

Even if it is possible to further increase the attenuation of the filter, the dynamic range of the pulse modulator will not allow the modulated signal to pass through it with a level difference between the carrier and side frequencies greater than 70 dB.

Therefore, using known devices it is not possible to measure the long-term signal security required in the order of 90 dB.,

A device is known in which, after the frequency converter and the intermediate frequency filter, a summing unit is turned on before the recording device, the second input of which supplies a signal received from a crystal oscillator tuned by the rtSa npoMe5icy frequency using a phase-locked loop, consisting of a phase detector, filter LF and block of local oscillators and shifted by 180 relative to the lib signal at the first input

A disadvantage of this device is a large level of intrinsic noise of a recording device, in which quality a conventional spectrum analyzer is used, as well as the immaturity of separate measurement of products bound by amplitude or phase moduli.

The closest in technical essence to the present invention is a device for measuring the products of multiplication, which allows to expand the dynamic range of the instrument by measuring modulation products due to the fact that the frequency converter used in it operates in the mode of a synchronous detector and provides the output power (yuiMyrnuk) lower and upper dry modulation products; In this case, the voltage of the carrier oscillation is converted into direct voltage, which is not transmitted to the hands registering device Satoru

The device allows separate measurements of the total amplitudes of the lower and upper side frequencies, either due to amplitude or phase modulation alone.

Set up the START of the frequency converter, the first input of which is fed to the input signal, the output of the converter through the amplifier and the intermediate frequency filter are connected to the first 6 input of the synchronous detector. The second input of the first frequency converter is connected to the first output of the local oscillator unit, the second and third outputs of the second-order LO oscillator unit to the input of the second frequency converter, the output of which connects the primary phase shifter and separation stage and connects the step of the combiner to the combiner, and I will have a set of 8-in. . The output of the amplifier is connected to a phase-locked frequency tuning circuit, consisting of a phase detector and a low-frequency amplifier, the output of which is connected to the input of frequency control of the local oscillator unit. Synchronous detector output Connected through a low-pass filter to the input of a low-frequency spectrum analyzer. At a zero phase shift of the phase shifter, amplitude modulation products are measured, and at a phase shift shift of 90 phase products of phase modulation 4 are measured.

The drawbacks of the device are the impossibility of separate measurement of the upper and lower frequency modulation products, as well as the limited dynamic range of the device due to the limited range of frequency converters, since the lower range is limited by its own Parasitic Modulation Products in the local oscillator voltages which are particularly strong when measuring weak b-signals modulation in the presence of a strong carrier wave signal, the upper value of the range must be at least 20 dB

0 below the key voltage of the same local oscillators.

The purpose of the invention is to increase the measurement sensitivity and the expansion

5 features.

The goal is achieved in that the device for measuring partial modulation products contains a receiving unit, a first amplifier, an output amplifier connected to a recording unit, a local oscillator whose output is connected through a series-connected phase detector, a second amplifier and a low-pass filter to controlling the input of the local oscillator; the addition unit, the modulation selection unit, two keys and the additional second local oscillator, the second phase detector, the third amplifier and the second low-pass filter are entered,

0 BEFORE the output of the second local oscillator is connected to the first input of the add-on unit and via the second key to the second input of the modulation products extraction unit, and through nOtirally connected the second phase detector, the third amplifier and the second low-pass filter, the output of the receiving unit connected to the second inputs of the addition unit and the first phase detector, the output of the first local oscillator is connected to another input of the second phase detector and through the first key to the first input. the house is block b (no modular products, the third input of which is connected through the first amplifier to the output of the addition unit, and its output is connected to the input of the output amplifier.

The block for modulation products contains an arithmetic processing unit, a quadrature signal generator and two parallel channels, each of which consists of a series-connected synchronous detector, a low-frequency amplifier and a phase detector, with the first inputs of synchronous detectors connected to the first and second inputs of the block the selection of modulation products, their second inputs are connected to the third input of the block, the quadrature signal generator is connected to the second inputs of phase detectors, the outputs ryh connected to the inputs of an arithmetic processing unit, whose output is the output of the modulation product isolation.

The introduction of a two-channel modulation product isolation unit, which allows, in addition to separate measurement of amplitude and phase modulation products, to make separate measurements of both upper and lower frequency modulation products, introducing a local oscillator that is formed using phase-locked loop which are carried out by the first and second phase detectors, by the second and third amplifiers, by the first and second low-pass filters, the signal is shifted by 90 relative to the signal at the output of the first g A second node is required for separating the upper and lower modulation products in the dual channel modulation separation module, as well as for deep suppression of the carrier oscillation at the third input of this block, insertion after the block of the adder block, in which the carrier signal is deeply suppressed. frequency signal formed in the introduced second heterodyne.

The drawing shows a diagram of the device.

The device contains serially connected receiving unit 1, adding unit 2, first amplifier 3, block 4 for modulation products, output amplifier 5, recording unit b. The device has the first and second local oscillators 7 and 8, the outputs of which are connected respectively to the first and second phase detectors 9 and 10, the outputs of which through the second and third amplifiers 11 and 12, the first and second filters 13 and 14 of the lower frequencies are connected to the inputs of the local oscillators 7 and 8. The outputs of the local oscillators 7 and 8 over the corresponding keys 15 and 16 are connected to the inputs of the synchronous detectors 17 and 18 that are included in the block 4 of the selection modulation products. Outputs of synchronous detectors 17 and 18

through the corresponding amplifiers 19 and 20 of low frequency connected to the inputs of the third and fourth phase detectors 21 and 22, the outputs of which are connected to the block 23 arithmetic processing. Other inputs of the phase detectors 21 and 22 are connected to the quadrature signal generator 24. In addition, the output of the receiving unit 1 is connected to another input of the first phase detector 9, the output of the first

o the local oscillator 7 is connected to another input of the second phase detector 10, the output of the second local oscillator 8 is connected to another input of the addition unit 2.: The device works as follows

Signal through the receiving unit 1 enters the input of the adding unit 2, as well as using the first phase-locked loop (phase detector 9,

Q amplifier 11, low pass filter 13) adjusts the frequency of the local oscillator 7 to the frequency of the received signal, with a phase shift between the voltages at the first and second inputs of the phase

detector equal to 90

Hetero25 frequency

Home 8 is captured by the frequency of the local oscillator 7 using the second ring of phase locked loop consisting of phase detector 10, amplifier 12 and low pass filter 14.

30 Phase shift (between the voltages at the inputs of the phase detector 10 is also equal to 90. Two hundred automatic tuning of the frequency1 and the presence of phase shifts 90 between the voltages at the inputs

The 35 phase detectors provide a phase shift of 180® between the voltages across the inputs of the adding unit 2 at equal frequencies, which leads to a deep suppression of the carrier oscillation on de block 4 of the modulation products.

The modulation product isolation unit consists of two synchronous detectors 17 and 18, to the second inputs of which, via switches 15 and 16, the voltage of the local oscillators 7 and 8, the low-frequency amplifiers 19 and 20, the phase detectors 21 and 22, the generator 24. Quadrature signals, the quadrature voltages of which are supplied to the second inputs of the phase detectors 21 and 22, the arithmetic processing unit 23, in which the quadratic law signals from the phase detectors 21 and 22 are measured. rms or lower, or top-modulation products resulting from changing the signs of one of the components (a simple dip-switch). When the key 15 is opened, the total upper and lower products of phase modulation are measured, and when the key 16 is opened, the total upper and lower products of amplitude modulation are measured.

When the frequency of the quadrature signal generator is changed, the partial products of the different frequency oscillations are measured. Over the 5th output is set to 5, the separate signal goes to the recording device b,

The proposed device is easy to operate, does not require subtle adjustment operations in the measurement, does not require adjustment to the part of the adjustment. switching to the measurement of the top or bottom product: phase or amplitude modulation is performed by switching the switches.

Claims (4)

1. Device To measure partial modulation products, containing a receiving unit, a first amplifier, an output amplifier connected to a recording unit, a local oscillator, the output of which is connected through a series-connected phase detector, a second amplifier and a lower 4at: TOTCoe Diode filter with the local oscillator control input, characterized in that, in order to increase the sensitivity of measuring and expanding the functionality, a block, a modulation product extraction unit, two keys and an additional second local oscillator are introduced into it, the second phase detector, the third amplifier and the second low-pass filter, the output of the second local oscillator is connected to the first input of the adder unit and through the second key to the second input of the coder’s modulation products, and through the second phase connected in series eight the detector, the third amplifier and the second low-pass filter with the control input of the second local oscillator; the output of the receiving unit is connected to the second inputs of the adder unit and the first phase detector Ktopa; the first local oscillator is connected to another input of the second phase detector and through the first key with the first input of the B14 block, the Modulation products division, the third input of which connected via the first amplifier to the course of the add-on unit, and its output is connected to the input of the output amplifier. 2. The device according to claim 1, wherein the block in the section for modulation products contains a block 5 arithmetic processing, a generator of quadrature signals and two parallel channels, each of which consists of a series-connected synxporio detector, a low frequency amplifier and a phase detector, the first inputs of synchronous detectors connected to the first and second inputs of the modulus of the modulation products, the second ones The inputs are connected to the third input of the unit, the quadrature signal generator is connected to the second inputs of phase detectors, the outputs of which are connected to the inputs of the arithmetic processing unit whose output is the output of the modulation output module. Sources of information taken into account in the examination 1. Author's certificate of the USSR 5 No. 26596, c. 01 R 29/06. 2. USSR author's certificate №520522, cl. G 01 R 29/06. 3.fernme dtechnik 4, 1977, p. 144, FIG. 2 (O Zelbis CAT, Leipzig). 0 4.Fernnie dtechnik No. 4, 1977, p. 144, fig. 3 (On Zeibis KOT.Leipzig).