Patent ID: 9634703
Date: 2017-04-25
CPC Classifications: H03K,H04B

Claim:
1. A receiver for detecting an encoded signal, having a pair of spaced predetermined frequencies, in the presence of unwanted signals having frequencies extending over the pair of spaced predetermined frequencies, the receiver comprising: three narrow band filters, a pair of the filters being tuned to the paired predetermined frequencies for receiving energy from the encoded signal and a third one of the filters being tuned to a third predetermined frequency between the pair of frequencies for receiving energy from a portion of the unwanted signals; and a detection section for indicating detection of the encoded signal as a function of the energy in the pair of filters tuned to the paired predetermined frequencies relative to the energy in the third one of the three filters, the energy in the third one of the three filters indicating a level of the unwanted signals having frequencies included over the pair of spaced predetermined frequencies.