Abstract: An aircraft transponder comprises an antenna for receiving an RF signal a downconverter coupled to the antenna for downconverting the RF signal to an IF signal, an analog-to-digital converter coupled to the downconverter to digitize the IF signal to produce a digital signal, and; a processor unit coupled to the analog-to-digital converter. The processor unit is configured to: (1) generate a delayed digital signal; (2) multiply a delayed digital signal by the digital signal to produce a multiplied output; and (3) filter the multiplied output to produce a filtered output having a positive or negative sign. The transponder further includes a sign converter operable to output a one or zero based on the sign of the filtered output to recover the data component.

Abstract: An apparatus is provided for improved temperature compensation of received RF signals. An RF receiver includes receiver circuitry which receives an RF signal and demodulates it to generate an output signal. Temperature compensation circuitry is coupled to the receiver circuitry and includes a diode having diode temperature characteristics. The temperature compensation circuitry adjusts the output signal of the receiver circuitry in response to the diode temperature characteristics to provide a tighter minimum trigger level.

Abstract: An apparatus for processing pulses in ATCRBS/Mode S interrogations includes an antenna for receiving a radio frequency interrogation signal. The radio frequency interrogation signal is downconverted by a downconverter to an intermediate frequency signal. The intermediate frequency signal is converted to a digitized interrogation signal by an analog-to-digital converter. A processing unit, coupled to the analog-to-digital converter, detects a pulse peak in the digitized interrogation signal using a moving threshold to locate the peak pulse between a first fixed threshold and a second fixed threshold.

Abstract: An apparatus for processing pulses in ATCRBS/Mode S interrogations includes an antenna for receiving a radio frequency interrogation signal. The radio frequency interrogation signal is downconverted by a downconverter to an intermediate frequency signal. The intermediate frequency signal is converted to a digitized interrogation signal by an analog-to-digital converter. A processing unit, coupled to the analog-to-digital converter, detects a pulse peak in the digitized interrogation signal using a moving threshold to locate the peak pulse between a first fixed threshold and a second fixed threshold.