RU2030751C1 - Method of measurement of dynamic range of radio receiver by intermodulation - Google Patents

Abstract

FIELD: radio engineering measurements. SUBSTANCE: one signal is sent in band of channel of radio receiver, second (blocking) signal tuned away from frequency is sent to stopband of first intermediate frequency filter. Signals are increased by amplitude up to value E₁ under which amplitude of first signal across output changes to level characterized by blocking factor K₁, then blocking signal is increased to value E₂ characterized by blocking factor K₂. After this ratio of these two values is checked for correspondence to permissible deviation from calculated ratio which conforms to amplitude characteristics of radio receiver. Dynamic range of intermodulation is determined by results of measurements. EFFECT: increased authenticity of measurements.

Description

 The invention relates to radio engineering measurements and can be used to measure the dynamic range of radios or any other highly linear devices.

A known method of measuring the dynamic range of a radio receiver by intermodulation, which consists in the following. An unmodulated or modulated calibration signal (EMF 1 μV) is supplied to the input of the radio receiver, respectively, in the presence or absence of the telegraph mode in the studied radio receiver, the frequency of which is equal to the tuning frequency of the radio receiver, and sets the rated voltage at its output. After that, the calibration signal is turned off, and two equal in amplitude measuring (interfering) signals, tuned in frequency to the filter delay band of the first intermediate frequency, are fed to the input of the radio receiver in the passband of the preselector. Moreover, for a signal that is located farther from the tuning frequency of the radio receiver, the frequency offset is set twice as large as for a signal that is located closer. Then the signal amplitude is increased (keeping the same) until the voltage of the intermodulation component of the form 2 f ₁ -f ₂ at the output of the radio receiver becomes equal to the nominal. The dynamic range is determined by the formula
D _2-1 [dB] = 20 log (E / 1), where E is the EMF value of each of the two signals with equal amplitude in microvolts.

 The disadvantage of this method is that upon receipt of an intermodulation component with a nominal value at the output of the radio receiver, two conditions must be met. The amplitudes of the measuring signals must be the same, and the value of the intermodulation component must correspond to the maximum, depending on the frequency of the measuring signals. Therefore, during the entire measurement process, it is necessary to change and equalize the amplitudes of the measuring signals, as well as adjust the frequency of one of them to keep the intermodulation component at the maximum value. Such operations (manipulations) during measurement can be from five to fifteen. In addition to the complexity of the measurements of the known method, it should be noted that for its implementation it is necessary to have two powerful low-noise signal generators and decoupling filters. All these facts hinder the automation of the measuring process.

 The purpose of the invention is to simplify the method of measuring the dynamic range of a radio receiver by intermodulation.

δ
(1) где γ =

, Е_{2 расч} - расчетное значение блокирующего сигнала при коэффициенте блокирования К₂, и определяют динамический диапазон по формуле
D_2-1[дБ] =

(20 lg E₁ - 10 lg K₁+3)
(2) где Е₁ - значение ЭДС блокирующего сигнала в микровольтах.This goal is achieved by supplying a calibration signal to the input of the radio receiver, the frequency of which is equal to the frequency of tuning the radio receiver (i.e., in the band of the main channel), and setting the voltage U _n equal to the rated voltage at its output, and also blocking signal tuned in frequency to the filter delay band of the filter of the first intermediate frequency (i.e., for the main channel band), determine two values of the blocking signal E ₁ and E ₂ corresponding to the values of the output signal equal to (1 + K ₁ ) U _n and (1 + K ₂₎ U _n where K ₁ and ₂ - setpoints block coefficients ratio then checked blocking signal values for valid billing evasion δ:

δ
(1) where γ =

, E _{2 calculation} - the estimated value of the blocking signal with a blocking coefficient K ₂ , and determine the dynamic range by the formula
D _2-1 [dB] =

(20 lg E ₁ - 10 lg K ₁ +3)
(2) where E ₁ is the EMF value of the blocking signal in microvolts.

= 1,29 Измеренные значения γ = 1,2-1,35. При этом уклонение, вычисленное по формуле (1), меньше 0,05.Comparative analysis shows that the inventive method differs from the prototype in that in it the complex measurement process using two measuring signals is replaced by a simple blocking measurement operation and the calculation of the dynamic range according to formula (2). If the properties of products of any type are not known, then the blocking measurement is carried out for two values of the blocking coefficient, in order to check the characteristics of the product of the third-order regularity using expression (1). According to the results of studies at K ₁ = -0.3 and K ₂ = -0.5, the calculated ratio of amplitudes
γ =

= 1.29 The measured values are γ = 1.2-1.35. In this case, the deviation calculated by the formula (1) is less than 0.05.

 When comparing the claimed method with the prototype and other technical solutions in science and technology, no method was found that would have a combination of features of the claimed technical solution. This allows us to conclude that the claimed technical solution meets the criterion of "significant differences".

 A positive effect when measured by the claimed method is as follows. The measurement process is simplified and accelerated. Instead of two powerful low-noise signal generators and two decoupling filters, one powerful generator is needed. The measurement process can be automated.

Claims (1)

 METHOD OF MIKHAILOV MEASUREMENT OF DYNAMIC RADIO OF A RADIO RECEIVER ON INTERMODULATION. A method for measuring the dynamic range of a radio receiver by intermodulation, which consists in supplying an unmodulated or modulated calibration signal to the input of the radio receiver, respectively, in the presence or absence of a telegraph mode in the studied radio receiver, the frequency of which is equal to the tuning frequency of the radio receiver, and set its output voltage U _n equal to nominal, as well as a blocking signal, the frequency of which is tuned to the filter delay band of the first intermediate frequency, set two values blocking signal E ₁ and E ₂ and the desired option is found from the measurement results, characterized in that, for the purpose of simplification, the value of a blocking signal E ₁ and E ₂ is mounted on the corresponding values of the output signal equal to (1 + K ₁₎ U _n and (1 + K ₂ ) U _n , where K ₁ and K ₂ are the set values of the blocking coefficients, according to the measurement results, check the ratio of the value of the blocking signal for compliance with the permissible deviation from the calculated δ

Where

E _{2 calculation} - the calculated value of the blocking signal with a blocking coefficient K ₂ ,
and determine the dynamic range D _{2 - 1} by the formula
D _{2 - 1} = 2/3 (20 logE ₁ - 10 logK ₁ + 3), dB,
where E ₁ is the EMF value of the blocking signal, μV.