Intermittent "No ADSB Pos" on Trig TT21

[applebyca]

Installed PAW with external aerials and successfully operating. But getting an intermittent error displaying on our Trig TT21 - "No ADSB Pos".

Frequently notice in the Low Level Route south of Warrington.

PAW and Trig configured on 4800 bps. Remaining Trig settings as follows :
 
GPS Input = NMEA
TIS = None
GPS Certification = Uncertified
1090mhz = No
UAT = No

Plugged into Port 1 on PAW.

Logging on PAW reveals no drops of GPS. Has anybody else had any similar experience with PAW and Trig?

[Admin]

I took a look at your ADSB track on our groundstation tracking, and the ADSB is indeed intermittent
could it be an electrical wiring issue, or a faulty USB/RS232 connector

The fact that we do not see a loss of GPS (in the track file), my guess is connectivity related
Can I ask which USB/RS232 connector you purchased.

the acid test would be to connect it to a crossover cable and run a monitor on a PC to look at the messages

Has this ever worked correctly, or has it been an issue from the first installation

Thx
Lee

[applebyca]

Hi Lee,

Quite possibly intermittent from the start as we haven't used in earnest and may not have noticed.

Purchased the original Farnell RS-232 cable as suggested and professionally installed.

Do you mean a cross-over ethernet cable to the Trig? If so, how do we capture the messages?

Regards
Charlie

[Admin]

Hi Charlie

if you have access to a second RS232/USB, I would do the following

connect the RS232/USB to a PC (or MAC or Linux if you are familiar)
Run the terminal emulator Putty
Configure Putty as a serial device at 4800 baud (so it is as if it were the transponder)

Cross over the connections from the PilotAware RS232/USB, so RX-TX / TX-RX
Then watch the putty terminal
there should be a constant stream of NMEA messages 1 / second.

if there are any gaps or corrupted characters, it would indicate a connectivity issue.
Do you think the person who fitted would be able to help with that ?

Thx
Lee

[applebyca]

OK. Not impossible but quite the task.

Familiar with Putty and serial connections.

Would the computer end need to be crimped to a D25 connector and then converted back to USB (as PC's no longer serial equipped without a Serial/USB converter).

Presumably the implication here is a short between the only two wires used - orange and black.

Would need to invest in a new RS232/USB cable, D25 connector, and USB to serial converter for PC.

Might an increase to 9600 on both sides improve or exacerbate the problem?

[Admin]

If there is a connection fault changing the baud should have no effect
I would always recommend using the highest baud which both ends could handle

Where are you based ?
Thx
Lee

[exfirepro]

Hi Charlie,

Lee forwarded your enquiry to me earlier to ask if I had any ideas, but I didn’t have any of the background information at the time to allow me to work out what is going on (and have been a bit busy today -sorry!).

I can now see from your above posts that your Mode-S/ES has obviously been transmitting, which makes determining the reason(S) more difficult. Intermittent faults are always harder to track down than straight ‘no goes’.

Looking at this logically....

Your reported configuration settings on the Trig all seem correct.

You say you are using the recommended FTDI serial (not TTL) USB to RS232 cable, purchased from Farnell, so this should be OK - I have used these for several installations and have never had a faulty one yet.

You also say the connection was installed professionally. This IMO makes Lee’s suggestion of an intermittent connection (or of course a faulty FTDI lead) the most likely explanation.

Despite the professional installation, I would check that the correct wires from the cable have been connected to the right pins on the Trig 25 pin connector. The fact that the installation appears to have been working at least at some point would tend to indicate that the wires are connected to the correct pins - i.e. Black to pin 4 and Orange to pin 5, but I know of at least one professional harness where the Yellow was connected to pin 5 by mistake instead of the Orange. At the same time, check the quality of the crimped connection to the wires at the Trig end in case there is a poor connection here. NOTE: you can’t take the pins out without the correct removal tool, but you can carefully check for a secure connection and that the pins are pushed fully home into the casing. You should also check that all other unused wires in the cable are insulated from ground and from each other.

Next check that the USB connection at the PAW end is a good tight fit and that you have the correct USB port configured to ‘Transponder Trig’. The ports are numbered....

Ethernet     Port 1     Port 3
Port            Port 2    Port 4

Again, this is unlikely to be wrong if the ADSB has been working, but worth checking.

When all is working properly, you should see a flashing RED LED showing in the FTDI connector at the PAW when position data is being transmitted to the Transponder (so about 1 flash per second).

As Lee says, it would also be worth trying reconfiguring both ends PAW and Trig to 9,600 Baud and give it another try, though this is unlikely to cure the fault if it is due to a poor connection.

If you wan’t to try the Putty test you can do this by connecting an extra USB to RS232 cable of the same type to the existing one ‘back to back’  i.e. connect black to black and orange from the PAW to yellow to the computer by disconnecting at the Trig 25 pin connector first (again carefully insulate all unused wires in the second lead).

Let us know how you get on.

Regards

Peter

[applebyca]

Many thanks gents for thorough reply.

Based near Stretton, by Warrington.

Will source additional cable (can’t get onto Farnell website tonight so will retry tomorrow).

Will report back once cable received, fitted, tested and other suggestions followed.

All the best.

C.

[applebyca]

Gents

I finally had the chance to diagnose further today. Summary as follows.

Orange and Black wires correctly terminated into pins 5 and 4 respectfully. Spare wires confirmed secured away from the pins and from each other.

A replacement cable was sourced from Farnell and piggy-backed onto existing connection. Undisturbed output as follows :

$GPGGA,131831,5320.493,N,00231.888,W,1,09,1.1,74.5,M,48.8,M,,*60
$GPVTG,000.0,T,,,0.00,N,0.00,K*2D
$GPRMC,131832,A,5320.493,N,00231.888,W,0.000,0,190120,,,A*7F
$GPGGA,131832,5320.493,N,00231.888,W,1,09,1.1,74.3,M,48.8,M,,*65
$GPVTG,000.0,T,,,0.00,N,0.00,K*2D
$GPRMC,131833,A,5320.493,N,00231.888,W,0.000,0,190120,,,A*7E
$GPGGA,131833,5320.493,N,00231.888,W,1,09,1.1,74.1,M,48.8,M,,*66
$GPVTG,000.0,T,,,0.00,N,0.00,K*2D
$GPRMC,131834,A,5320.493,N,00231.888,W,0.000,0,190120,,,A*79
$GPGGA,131834,5320.493,N,00231.888,W,1,09,1.1,74.2,M,48.8,M,,*62
$GPVTG,000.0,T,,,0.00,N,0.00,K*2D
$GPRMC,131835,A,5320.493,N,00231.888,W,0.000,0,190120,,,A*78
$GPGGA,131835,5320.493,N,00231.888,W,1,09,1.1,74.1,M,48.8,M,,*60
$GPVTG,000.0,T,,,0.00,N,0.00,K*2D
$GPRMC,131836,A,5320.493,N,00231.888,W,0.000,0,190120,,,A*7B
$GPGGA,131836,5320.493,N,00231.888,W,1,09,1.1,74.0,M,48.8,M,,*62
$GPVTG,000.0,T,,,0.00,N,0.00,K*2D
$GPRMC,131837,A,5320.493,N,00231.888,W,0.000,0,190120,,,A*7A
$GPGGA,131837,5320.493,N,00231.888,W,1,09,1.1,73.9,M,48.8,M,,*6D
$GPVTG,000.0,T,,,0.00,N,0.00,K*2D
$GPRMC,131838,A,5320.493,N,00231.888,W,0.000,0,190120,,,A*75
$GPGGA,131838,5320.493,N,00231.888,W,1,09,1.1,73.7,M,48.8,M,,*6C
$GPVTG,000.0,T,,,0.00,N,0.00,K*2D
$GPRMC,131839,A,5320.493,N,00231.888,W,0.000,0,190120,,,A*74
$GPGGA,131839,5320.493,N,00231.888,W,1,09,1.1,73.6,M,48.8,M,,*6C
$GPVTG,000.0,T,,,0.00,N,0.00,K*2D
$GPRMC,131840,A,5320.493,N,00231.888,W,0.000,0,190120,,,A*7A
$GPGGA,131840,5320.493,N,00231.888,W,1,09,1.1,73.6,M,48.8,M,,*62
$GPVTG,000.0,T,,,0.00,N,0.00,K*2D
$GPRMC,131841,A,5320.493,N,00231.888,W,0.000,0,190120,,,A*7B
$GPGGA,131841,5320.493,N,00231.888,W,1,09,1.1,73.5,M,48.8,M,,*60
$GPVTG,000.0,T,,,0.00,N,0.00,K*2D
$GPRMC,131842,A,5320.493,N,00231.888,W,0.000,0,190120,,,A*78
$GPGGA,131842,5320.493,N,00231.888,W,1,09,1.1,73.5,M,48.8,M,,*63
$GPVTG,000.0,T,,,0.00,N,0.00,K*2D
$GPRMC,131843,A,5320.493,N,00231.888,W,0.000,0,190120,,,A*79
$GPGGA,131843,5320.493,N,00231.888,W,1,09,1.1,73.5,M,48.8,M,,*62
$GPVTG,000.0,T,,,0.00,N,0.00,K*2D
$GPRMC,131844,A,5320.493,N,00231.888,W,0.000,0,190120,,,A*7E
$GPGGA,131844,5320.493,N,00231.888,W,1,09,1.1,73.4,M,48.8,M,,*64
$GPVTG,000.0,T,,,0.00,N,0.00,K*2D
$GPRMC,131845,A,5320.493,N,00231.888,W,0.000,0,190120,,,A*7F
$GPGGA,131845,5320.493,N,00231.888,W,1,09,1.1,73.3,M,48.8,M,,*62
$GPVTG,000.0,T,,,0.00,N,0.00,K*2D
$GPRMC,131846,A,5320.493,N,00231.888,W,0.000,0,190120,,,A*7C
$GPGGA,131846,5320.493,N,00231.888,W,1,09,1.1,73.3,M,48.8,M,,*61
$GPVTG,000.0,T,,,0.00,N,0.00,K*2D

No visible garbage anyway in the output.

Having not detected anything unusual in the output, I've left the existent cable in situ but swapped the USB onto port 2 and increased speeds on both sides to 9600. Transponder correctly picked up GPS position.

We will flight test on the new port and report any further anomalies.

Regards
Charlie

[exfirepro]

Hi Charlie,

Good work and very useful feedback!

I don’t know if you saw my post on the other ‘Trig ADSB Out’ thread, where I managed to get a colleague’s setup running properly today on 4800 Baud (both ends). It will be interesting to see how both systems perform over a reasonable period as this may give us a better appreciation of the optimal setup (if there is one). Comments from any other users with expertise or experience in this area will also be gratefully received.

Please keep us informed and I’ll ask Bob to do likewise.

Best Regards

Peter

[applebyca]

Hi Peter,

Glad to contribute. If it doesn't always help me, it's useful notes for others to follow under similar challenges.

Sadly the test flight today was flawed with a new problem on the radio; which diverted attention to diagnosing that. Once I can clear that problem, I can return to the PAW.

Having spent many of my earlier years in IT sending code to programmable keyboards for a large chain of pizza restaurants, I concur with your thoughts in the other thread about using lowest baud rate in the event of issues. Will leave ours on 9600 for the moment and report back with more feedback.

Regards
Charlie