Poor 1090 connection count - resolved by reloading software

[billywmd]

I suspected the PAW on one of my aircraft was not connecting to much traffic. I also saw that my PAW grid station at home was not picking up the aircraft much. I have compared the performance against another PAW temporary plugged into the aircraft.
I used the full actual kit belonging to the test unit including the stick on antennas.
The test PAW had around 2000 connections a minute on 1090 and showed 10-12 aircraft. The PAW installed in the aircraft had around 150 connection a minute and 2 aircraft.
I have cross checked the antennas by swapping them around. The results were the same.
What else should I check?

[exfirepro]

Hi Billy,

A bit difficult to say from the limited info provided I'm afraid.

What type of aircraft are we talking about? and is the PAW a 'carry on' or semi-permanent installation? What antennas are you using with it?

The main reasons for poor 1090 reception are usually due to problems with the 1090 antenna, i.e. type/placement, obscuration by aircraft structure or something else (such as pilot or passenger bodies), or a fault with the coaxial cable or connectors. The other obvious reason would be a defective SDR dongle, but these usually either work properly or not at all.

From the Timestamps in the 'DATE' Row of each screenshot, I can see that both units were run at around the same time (though for slightly different time periods), so the same aircraft should have been 'visible' to both.

You talk about 'using the full actual kit belonging to the test unit including the stick on antennas' - do you mean PAW remote internal antennas or the ones attached to the box itself?

The figures reported in the 1090 row on the Home Screens are simply a count of the number of 1090 data packets received over the period of time that the unit has been running (- the reported UPTIME). The larger figure is the total with the smaller (in brackets) being the number of new packets received in the last 5 or 15 seconds or so (IIRC). These figures are of course dependent on the actual number of aircraft in range at the time of the tests. It would help if you could post screenshots of the Configure Screens of both units so we can compare them.

You go on to say that your PAW Grid Station at home is not picking up your aircraft much, but you don't say which mode(s) you are talking about. If you are talking about PAW transmissions from your aircraft, the two things are almost certainly unconnectedcould well be totally unconnected.

If you can post your aircraft details (Reg/HexID) - (they will be on the Configure Screen anyway, but PM them if you don't want to make them public) and I'll take a look at the database and report my findings.

Best Regards

Peter

[billywmd]

Peter, thanks for the quick reply and apologies for the abbreviated version of the issue;
The issue is on a Bulldog, G-ASAL, 4015A4. The PAW is fully installed behind the dash with with remote GPS, Neotech audio amplifier and RS232 out for ADS-B. (HOSTID ending A275 in photos)
The antennas are aviation mono-pole externally mounted on the underside of the aircraft. The 1090 reception as per image was low and at times indicated orange, not receiving any packets.
I had made the same conclusion as you about reception so decided to check the antennas. I removed the PAW from another aircraft- Jodel G-CEIS, 405122. HOSTID A048). This unit is secured on the shelf behind the rear seat and easily removed with remote GPS antenna and centre fed radio antennas fitted to the inside of the cockpit with suckers and velcro.
I placed the Jodel PAW on the seat of the Bulldog plugged the supply into the power socket and stuck the antennas on the screen with the GPS on the cowling. it was receiving as much as 180 packets on each cycle of 1090 with up to 12 targets. I swapped the antenna connection over so the Bulldog was using the Jodel centre feed stuck to the window and the Jodel PAW was using the fully installed Bulldog antenna. The results were the same, still many more packets received on the Jodel and very low on the Bulldog.
Regarding the ground station; I understand your comments but this was just an observation comparing with other local aircraft which I seem to pick up more often at the times I know they are flying. I will get a shot of the configuration later today but in the meantime you may have enough info.

[billywmd]

Peter
I have attached config file

I also tested again with GASAL showing 1 aircraft and Jodel PAW showing 21
Also exchanged antennas again with GASAL still very poor

I also noted the neither unit picked up the other directly with pilotaware connection.

ADS-B out is working on transponder and showing co-ordinates when enabled.

 

[exfirepro]

Hi Billy,

Thanks for that. The only thing I can see from your Config screenshot is that - as you say you have a transponder fitted - you should have 'Mode C/S Select' in 'Bearingless Contact Settings' set to 'Mode C/S + Filter' so the unit can filter out the 'Mode C' (altitude) transmissions from your own transponder, though I doubt this is significant to the issue you are reporting. Interestingly, you don't appear to have any of the USB Ports set to supply data for your ADSB-Out  - or does the transponder use a different GPS position source? Interestingly, I have just checked the PAW Database, which is showing P3i and MLAT reports from 4015A4 on 4th and 7th March, but no ADSB since your flight up the west coast of Scotland on 28th February.

So if I have this correct: -

You are still getting poor 1090 reception with your 'G-ASAL 'in plane' PAW  whether you are using the fitted external 1090 antenna, or the Internal One, but the other PAW (out of G-CEIS) gets good reception with it's own (stick on Internal) antenna, or the fitted external one in the Bulldog. Is that correct?

If so, the problem has to be internal to the 'Bulldog' PAW.

The 'Orange' 1090 indicator, by the way is a 'red-herring' (sorry). All that indicates is that the unit has received some 1090 data since it was powered up, just none in the last 15 seconds or something like that. It only shows green if 1090 data is currently being received, and the unit is showing no Power issues and a good GPS fix (at least for the short time covered by the test).

The first check would be to open the end cover of the Rosetta unit and check that the SDR dongle is properly seated in its USB slot - (normally lower right).

Also check that the connection between the pigtail cable and the SDR is good - if you remove it by easing it out of the connector, on the end of the SDR it should go back in with a clear click. If there is still no improvement, you could try temporarily swapping in the SDR from the other unit to see if the situation improves. If it does, you need a new SDR (they are available from the PilotAware Store at https://www.pilotaware.com/product/software-defined-radio )

Let me know how you get on.

Best Regards

Peter

p.s. I have sent you a message via the Forum Message Board.

[billywmd]

Peter
The ADS-B out is disabled at the moment until I confirm it works ok and I get a screen shot from the Jodel showing settings are ok as required by LAA.

To answer the question; Yes, that's how I crosschecked.
The orange against 1090 I was aware of. It just concerned me when one unit was going orange when the other was getting 200 or 300 connections.
I checked the USB slots but not the connection to SDR. I'll do that and also swap them as you suggest.
I had expected that GASL would have seen the Jodel through direct PAW connection.
Thanks, I'll call later.

Billy

[billywmd]

Peter

I swapped SDR on Rosetta. Still no connections. I removed SD card and reformatted the downloaded latest full software to it.
I refitted card and loaded and configured and then it worked fine with multiple connections and targets.

I assume there was a software issue on the card. I have also ordered a new card to load software in case the card has a fault.

I have also completed the connection of RS232 out to ADS-B on the transponder. I have printed a report for approval.

Thanks for your support

Billy

[exfirepro]

Hi Billy,

Thanks for updating the thread - and for the phone call.

So it was obviously a software issue - probably a glitch of some sort had corrupted the software on the card. Glad we managed to get to the bottom of what was going on by our process of elimination. That's often the only way!

It could of course go on working for long enough on the reformatted card, but probably safer to replace the card with a new one and keep the old one as a backup or repurpose it for something less critical.

I have updated the thread title to reflect the outcome.

Hopefully catch up soon.

Best Regards

Peter