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Adaptive Same Frequency Repeater (SFR) Study

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Final technical rept. 16 Apr 1974-15 Jul 1975

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This report documents the technical effort on Contract F30602-74-C- 0242. It presents the results of an investigation of Real time, non-sampling, Same Frequency Repeater SFR concepts for various types of analog and digital signals using coherent interference cancellation techniques. The report presents an analytical investigation of transmitter-to-receiver isolation achievable with a multi-channel interference cancellation system ICS when the repeater is used with a finitie bandwidth antenna in an environment which includes random ground clutter and specular reflectors. A design for a Same Frequency Repeater breadboard model is presented that incorporates the multi-channel interference cancellation system. The breadboard operates at 291 MHz with a bandwidth of 100 KHz and allows forward gain up to 120dB to be tested. The minimum input signal level is -90dBM, with a dynamic range of 60dB, for which the repeater will generate a 1 watt output using an AGC. Experimental results are presented which verify the design concepts on which the SFR breadboard is predicated. They also show areas where further work is needed to utilize the Full forward gain potential of the breadboard. In the present configuration, forward gains up to 67dB have been measured in the laboratory. With the incorporation of the suggested modifications, forward gain capability in excess of 102dB is anticipated. Further performance refinements may then be possible to push the forward gain capability to 120dB. A Follow-on effort for the breadboard improvement is being conducted. Results of this improvement effort will also be documented in a final technical report.

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  • Radio Communications

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