SIGNAL/NOISE RATIO ASSESSMENT METHOD BASED ON RESULTS OF IONOSPHERE SOUNDING WITH CHIRPED SIGNALS Russian patent published in 2014 - IPC G01R29/26 

FIELD: radio engineering, communication.

SUBSTANCE: method involves of signal/noise ratio assessment within the frequency range of ΔF_S based on the data of linear frequency modulation of ionosphere sounding. The latter comprises irradiation of continuous chirped signal by transmitter with power of P_{trn son}, processing the signal in the receiver, heterodyning the signal using a converter and preliminary filtration in the frequency range from -ΔF_pr/2 to ΔF_pr/2, then the signal undergoes filtering with differential frequency filter, in the range from -ΔF_fr/2 to ΔF_fr/2. Afterwards, FFT is calculated, additionally, the output signal of converter is filtered using noise filter. After that, output of differential frequency filter is aligned by time to output of noise filter, using alignment device. Then output data of the latter and noise filter is transferred to the inputs of assessment device, which calculates the value of signal/noise ratio for frequency of analysis f_a and FFT k output as per the following formula

$$h_k^2\left(f_a\right)=\frac{K_{trn}}{2{\displaystyle \sum _{m=0}^{N_c-1}{S}_{c0}^2\left(f_m-f_a\right)}}\frac{{\displaystyle \sum _{m=0}^{N_c-1}\frac{S_{c0}^2\left(f_m-f_a\right)}{S_s^2\left(f_m\right)}{S}_{recsk}^2\left(f_m\right)}}{P_n\left(f_a\right)},$$

where K_{trn s}/P_{trn son}; P_{trn s} is power of transmitter, radiating the connection signal, $$S_{c0}^2\left(f\right)$$ - energy spectrum module of the radiated connection signal; $$S_s^2\left(f\right)$$ - energy spectrum module of the radiated sounding signal; $$S_{recsk}^2\left(f\right)$$ - energy spectrum of the received sounding signal, calculated per FFT k output, N_s - the number of radiated connection signal spectrum components; f_m - frequency of m-component of the radiated connection signal spectrum, P_n(f) - power of noise at the receiver input, calculated per output voltage of noise filter.

EFFECT: better assessment validity due to taking into account the individual features of communication channel.

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