Messages

31

General Discussion / Re: NMEA out to transponder.

« on: November 20, 2015, 06:01:16 pm »

I've just checked the PAW->transponder serial output and can confirm that PAW is outputting the three sentences exactly as Less says. The position fix field in the $GPGGA sentence is 1 for my UBlox7 GPS suggesting that it's not seeing EGNOS WAAS (or at least is not setting the field correctly). The GPS antenna is indoors at the moment so it might just be not seeing the necessary satellites. I'll extend the USB outdoors tomorrow to see if things change.

BTW, Lee, I don't see a "trp" check box in the config on my 20151114 PAW. I did it the hard way via a serial port into PuTTYtel!

32

General Discussion / Re: NMEA out to transponder.

« on: November 20, 2015, 03:45:18 pm »

Indeed, very interesting analysis, Alan. Especially noteworthy is the distinction between being "WAAS capable" or "WAAS enabled" and actually setting the $GPGGA sentence correctly. That's a whole new Pandora's box of potential issues! This is a level of detail that we probably can't expect suppliers, even those as good as Mendelssohn to be able to fully resolve.

Is anyone dealing with Trig, Garmin et al to find out more about this? I am happy to have a go if no-one else is on the case.

33

General Discussion / Re: NMEA out to transponder.

« on: November 20, 2015, 01:34:05 pm »

John, have a look at this thread

Thanks Paul. I'm there now. This trial with its unusual parameter requirements has certainly forced some issues to the surface!

34

General Discussion / Re: NMEA out to transponder.

« on: November 20, 2015, 12:39:40 pm »

The TT31 installation manual says:

The TT31 GPS input can recognise the following protocols:

• Industry standard “Aviation” protocol
• NMEA 0183 protocol ($GPRMC message)
• FreeFlight and NexNav GPS proprietary protocols
• Garmin proprietary ADS-B protocols
• Trig ADS-B protocol

I think the NMEA 0183 protocol should do it.

35

General Discussion / Re: NMEA out to transponder.

« on: November 20, 2015, 11:21:46 am »

I've just received advice from Mendelssohn that the KT74 has TT31 version 3.4 firmware and that it therefore is compliant with the SIL=SDA=0 requirement. It's not clear whether this applies to all KT74s or just the current stock. I would still recommend a trial with PAW in attendance.

36

General Discussion / Re: NMEA out to transponder.

« on: November 20, 2015, 09:31:02 am »

I too far prefer the number buttons for squawk code entry, having been spoilt for it by my GTX328.

You could always get your friend to hook up a GPS and then use the latest version of PAW to see what the KT74 makes of it. If Mendelssohn's don't get an answer to the question soon (getting information out of BK is difficult) then I was going to suggest to their techy guy Dan that I take a trip up to Edinburgh with my PAW.

37

General Discussion / Re: NMEA out to transponder.

« on: November 20, 2015, 09:14:04 am »

The KT74 is essentially a Trig TT31 in drag but questions remain regarding firmware levels, etc. I am seriously considering the KT74 for my steed and the question regarding SIL/SDA settings is with Harry Mendelssohn's right now. I'll post any response that I get here.

38

General Discussion / Re: Verifying Mode S ES ADS-B Out transponder setup - Can PilotAware help?

« on: November 19, 2015, 05:35:17 pm »

Your points are all well made Steve. Trundling around the Scottish Highlands as I do gives one a slightly different perspective regarding MAC risks. There is a significant amount of (mostly) helicopter traffic in the form of Helimeds, pipeline surveys, oil rig/wind farm traffic and so on. Couple that with the lack of any radar coverage over vast tracts of lower airspace and it creates a different risk profile. Most of these aircraft come under the GA banner but they are usually equipped with TCAS and their ability to see uncertified ADS-B out would definitely be a benefit.

I completely agree that the real prize is universal, usable ADS-B out & in. I think PAW's principal contribution will, in time, be its ability to provide a useful ADS-B in capability that works with the likes of SkyDemon et al.

39

General Discussion / Re: Verifying Mode S ES ADS-B Out transponder setup - Can PilotAware help?

« on: November 19, 2015, 09:13:24 am »

Interesting comments from Ade Price. One can sense that NATS (or at least he) would prefer us to be able to use a more sensible SDA value. You can bet your house that those glider pilots in Europe won't be setting SDA=SIL=0 when they connect up their uncertified GPS.

Yes, the trial settings of SIL=SDA=0 severely limits the usefulness for in cockpit conflict awareness. That means that a safety case can be made to that effect. The CAA runs on safety cases! It seems to me that the next stage in the process is to open negotiations with CAA SARG to lift the SIL=SDA=0 restriction for safety reasons. I would like to think that this is already under way as a conclusion to the trial.

Meanwhile, it's a numbers game. The more airframes that have ADS-B out AND ADS-B in (via, for example, PAW) the better our conflict awareness will be.

40

General Discussion / Re: Verifying Mode S ES ADS-B Out transponder setup - Can PilotAware help?

« on: November 18, 2015, 12:44:43 pm »

Yes, TCAS will still interrogate your transponder (regardless of its mode). However, ADS-B, if visible to TCAs, would provide much better positional accuracy.

An ADS-B equipped transponder is actually two systems in one: a transponder that responds to interrogations from ground/airborne radars, TCAS, etc. and a broadcasting system which uses the time between interrogations to broadcast stuff like position data. To all intents and purposes they are completely independent.

I think the decision to force SIL=SDA=0 on us was necessary to get the trial under way. It will have to be reviewed in due course, as it will severely limit the usefulness of GA ADS-B. That's probably a step too far right now for the risk adverse CAA. The next steps should be to evaluate the trial results, discover (to no-one's particular surprise) that non-certified GPSs give just as accurate positional information as the certified units and therefore conclude that more useful SIL/SDA settings can be applied. It might take a while!

41

General Discussion / Re: Flyer live show - Telford.

« on: November 17, 2015, 10:26:51 pm »

I'll be there on the Saturday from 11:00 and I'm happy to bring both my PAWs along if required.

42

General Discussion / Re: NMEA out to transponder.

« on: November 11, 2015, 11:23:16 pm »

Hi Steve,

You read my mind. It would be great if the verification process could be part of the LAA (in my case) system - perhaps a squiggle from the inspector to say that he's seen the appropriate settings via PAW or some such.

I assume, notwithstanding that the NATS trial is "sort of over" the intention is that we can all continue to use our non-certified but validated systems.

Good luck with your negotiations and thanks for all you are doing on our behalf.

43

General Discussion / Re: NMEA out to transponder.

« on: November 11, 2015, 10:08:53 pm »

Great job Lee, thanks. I'm happy to wait unless it's going to be months before it gets into the release version. I still have to procure the new ES transponder (and attack piggy bank for same). It's a winter project.

44

General Discussion / Re: NMEA out to transponder.

« on: November 11, 2015, 09:55:52 pm »

Bryan, you need my new CAA/NATS/FASVIG Verification mode :-)

Will that be in a later version of PAW software, Lee? I think it would be extremely useful, especially for those of us that are outside the NATS trial area.

45

General Discussion / Re: flarm internal antenna

« on: November 11, 2015, 12:43:34 pm »

The Puck aerial claims 2.5 dBi gain. The Dipole is unknown.

A resonant dipole has 2.15dBi (isotropic) gain. Most of the system gain will come from the ability to put the dipole (or other antenna) somewhere where it has a clearer view of the sky. Antenna gain is less relevant.