March 1967 | NTIA Technical Memo IER TM ITSA
Monitoring techniques for evaluating useful frequencies for HF telecommunication circuits
James C. Blair
Abstract: Significant channel characteristics of HF communication circuits are reviewed, with particular emphasis on their importance in the evaluation and selection of useful operating frequencies. Various theoretical and experimental results from several sources are analyzed and a number of techniques for determining channel characteristics are identified and analyzed. The best circuit monitoring system for many applications would include the oblique sounder supplemented by on-circuit CW measurements of Doppler spread and signal intensity, together with independent noise and interference monitoring by spectrum analyzer methods. For some applications, especially the broadcast service, backscatter sounding can be extremely valuable for determining frequency coverage.
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