SPECTRUM PROCESSING RECEIVERS FOR TELEMETRY APPLICATIONS

Abstract

When the i-f filter of a telemetry receiver is replaced by a digital processor utilizing an intermediate orthogonal transformation into either the frequency domain using Fast Fourier Transform (FFT) or sequency domain using Fast Walsh Transform (FWT), then much improvement in performance may be expected. This paper discusses both application and results of FFT and FWT processing to: 1) a signal acquisition receiver providing extremely enhanced phase lock loop (PLL) acquisition speed; 2) an adaptive i-f bandwidth receiver providing a large i-f signal to noise ratio (SNR) improvement and also immunity to undesired EMI and/or jamming signals; and, 3) a signal evaluation receiver for measurement of SNR in the range of -30 dB and up. Spectrum processor design considerations and tradeoffs are presented.