User's Manual

Multiple synthesizers are controlled by the RTC CCA. First is the transmitter synthesizer located on the LP
amplifier that is serially loaded based on the backplane frequency select switches. Second is the receiver
synthesizer that is loaded to provide an IF frequency of 125MHz. Output frequencies of both these
synthesizers are checked by the Monitor CCA.
When operating as a TACAN the North, Aux, and Ident trigger signals from the TACAN antenna
controller are converted to TTL signals using comparators located on the RTC CCA. These TTL signals
are used by the FPGA hardware to transmit the North and Auxiliary burst sequences after a short delay.
This delay will be configurable in order to support remote shifting of the azimuth angle as required for
flight check operations. Both the trigger signals and the delayed triggers will be sent to the monitor for
integrity alarm processing.
In addition to the LVDS gate and Gaussian modulation pulses, each power amplifier provides VSWR fault
and long pulse fault signals to the RTC CCA. For the LP amplifier connection a synthesizer lock signal is
also sampled. All of these signals are sent to the RMS where a maintenance alert is generated and detailed
status can be displayed on the PMDT.
Morse code identification is controlled by the RTC CCA primarily by the RTC software. Identification
keying can be sourced into the RTC from external equipment such as a VOR, Localizer, or Glideslope.
Identification is fully configurable from the PMDT to allow such things as window keying, inverted input
keying contacts, interlock-off upon external keying loss, etc. The RTC can even operate in a master mode
where keying is output to external equipment.
Front panel test points are provided for inspection of the large and small signal IF waveforms after the
signals leave the Receiver RF CCA. A BNC connector provides the transmitter trigger signal that can be
used to trigger an external oscilloscope for inspection of the detected transmissions. LEDs on the front of
the RTC CCA shown that the power supplies and RTC software are operating properly as well as indicate
whenever the receiver has reduced the sensitivity due to traffic overloading or detection of CW.
On the board test points are available to inspect the Gaussian modulation pulses for each power amplifier.
These modulation pulses are also multiplexed back into the sampling ADC for diagnostics purposes.