I have a Trig TT21 and include below the section from the Installation Manual which details the requirements for GPS input. It looks as though it can accept a number of different protocols but the NATS Non Certified GPS Trial information document states the following requirements for the GPS:
"As a minimum, any GPS that outputs
NMEA 0183 sentences over an RS-232
link."
It looks as though using the NMEA protocol sets the required SIL and SDA values for the trial on many transponders.
Mike
*****Extract from Trigg TT21/TT22 Installation Manual*****
5.6.9 GPS Position Input
The GPS position input is required to support ADS-B functionality. The GPS
position input is an RS232 input to the transponder. The ADS-B features are
optional – no GPS is required for normal Mode S Elementary Surveillance.
The TT21/TT22 GPS input can recognise the following protocols:
Industry standard “Aviation” protocol
NMEA 0183 protocol
Freeflight and Accord NexNav GPS proprietary protocols
Garmin ADS-B protocol, including ADS-B plus
Trig ADS-B protocol
C199 TABS compliant GPS using NMEA protocol
The interface speed can be selected between 4800, 9600, 19200 and 38400
bps.
Hi Mike,
Can you try and find out which NMEA messages it is looking for ?
I am trying to keep the data to a minimum to not overload the transponders
Thx
Lee
Lee,
I've just been looking for the info required there is nothing in the Trig Manuals but I did find this from a Q&A Sheet
"Q: Can the Trig transponders receive NMEA GPS data from any GPS receiver?
A: Yes, you can connect any NMEA GPS position source to a Trig transponder, and with the correct configuration the
transponder will broadcast ADS-B position squitters. However there are limitations with the NMEA data. The NMEA
messages do not include Receiver Autonomous Integrity Monitoring (RAIM) information, which means that the position
transmitted by the Trig transponder will be indentified as "low quality" on most traffic information systems. Please note
that this type of NMEA GPS/transponder configuration will not meet forthcoming FAA ADS-B requirements, but in the end
it will be rather beneficial for use in flight tracking and traffic avoidance."
http://www.sea-aviation-parts.com/documents/SEA_TRIG_FAQ.pdfIt may be no use.... But it says "Any NMEA will provide"