Digital solution to mitigate pulse stretching in iff receivers

摘要

At higher power levels logarithmic amplifiers used in IFF receivers stretches the received coded pulses. It is difficult to resolve same range targets with receiver pulse stretch. Pulse stretching also limits usage of spurious free dynamic range of analog IFF receiver in dense air traffic conditions. Recovery time of analog logarithmic amplifier is main cause of pulse stretching for repetitive coded pulsed wave forms in analog receivers. The logarithmic amplifiers and nonlinear RF components are implemented in digital domain with usage of high speed FPGA and wide band ADCs. Direct sampling of RF signals from Antenna allows implementation of RF blocks in digital domain. This paper discusses cause for pulse stretching in analog receivers and solution.