Interference Blanker for HF Receivers

Requirements exist to improve airborne receiver reception under conditions of impulse interference produced by precipitation and atmospheric static. A new approach in communication receiver interference blanker circuitry was devised which overcomes the deficiencies and limitations of previously developed blankers. The all solid state limiter-blanker circuit developed comprise an independent "black box" which can be inserted between the antenna and RF input of any typical HF receiver. The technique, which can be adapted to lower and higher frequency bands, makes use of the spectral content of impulse static in discriminating between desired signals and impulsive noise. A squelch circuit operating on signal to noise ratio rather than the conventional AGC voltage method was also developed.