PCM-NRZ/FM Telemetry 시스템에서 Bit 오차확률에 관한 분석

Analysis for the Bit Error Probability in the PCM-NRZ/FM Telemetry System

PCM符號가 NRZ-L인 binary data를 5次 Bessel low-pass filter를 通하여 傳送하는 telemetry systemn에 對하여 FM方式으로 RF link를 構成하고 liniter-discriminator로 複調하였을 경우에 digital通信system의 性能評價에 重要한 bit誤差確率을 SNR에 對하여 解析的으로 檢討하였다. 實際로 設計에 적용한 telemetry system에서 bit rate를 140kHz, 變調前 filter의 f를 100kHz, 送信機의 最大周波數編移 2f를 300kHz로 設計하였을 때 f0T=0.7 및 h=2ft=2이며 SNR이 10dB일 때 bit誤差確率은 10으로 計算되었다.

PCM-NRZ/FM Telemetry system is constructed on the basis of RF link with FM modulatedand NRZ-L binary coded PCM data are assumed to transmit through 5th-order Bessel filter. Upon demodulated by the limiter-discriminator at the receiver, the probability of bit error, which is important for performance estimation of digital system, is analyzed against SNR. The analysis based on the following parameters, that is bit rate 140kHz, frequency of pre-modulation filter f-100kHz, maximum frequency deviation of transmitter 2f=300kHz, was performed. As a result, when the telemetry system with the parameters above is designed, the probability of bit error is obtained as 10 along with fT=0.7 and h=2, T=2.