Messages

16

General Discussion / Re: Transceiver Interference

« on: March 08, 2016, 10:58:46 pm »

Lee  - it’s a white noise effect, and  it was a USAMS twin port charger, one of these:

http://www.ebay.co.uk/itm/NEW-TWIN-USB-USAMS-DUAL-2-PORT-3-1-AMPS-UNIVERSAL-CIGARETTE-SOCKET-CAR-CHARGER-/121911798279?hash=item1c62826a07:g:NFIAAOSwYlJW1uxJ

We have only connected the PAW to this one which I bought because of the higher current requirement.
I will try sorting out a battery supply to check that out too. We also have 2 12v sockets in the aeroplane, and have another (different) usb charger in the other one which drives an Aware gps. What I should have done is to switch the chargers, and see if the USAMS one causes the same interference when connected to the Aware. I will check this out the next time I fly!

Do you have a recommendation for a good USB charging socket?

Thanks
Rick

http://www.ebay.co.uk/itm/Adjustable-DC-DC-Boost-Step-up-Power-Converter-Module-XL6009-Replace-LM2577-/272041588474?hash=item3f56f136fa:g:68gAAOSwiwVWRUaf

These work pretty well, but you have to wire them in (don't forget a fuse).. adding extra capacitor also helps keep the noise down.  You need to use a multimeter to set the output voltage to 5V (or just a little higher, say 5.25V), then it's best to glue up the potentiometer with cyano so it doesn't readjust itself with any vibrations.


Cheaper than a £100+ power supply.

17

General Discussion / Re: Mode A and Mode C

« on: March 07, 2016, 10:58:09 pm »

Cool.  Are they still flying the Tiger Moth?

18

General Discussion / Re: Mode A and Mode C

« on: March 07, 2016, 01:57:56 pm »

....I suspect the RAF would be quite happy to try low cost means of preventing their multi million pound assets from hitting puddle jumpers.

Mil need tough vibration performance, so while a good idea in concept it would struggle to meet their specs.  Reference oscillator needs to be tolerant to high vibration, which is usually a fairly high cost item. 

It would need to be ruggedised, but do-able of course.

19

General Discussion / Re: Mode A and Mode C

« on: March 03, 2016, 09:27:32 pm »

If you are watching for Ext Squit on say FR24, how do you tell if they are either Mode C, Mode S or ES returns ?

John

The non Mode S are "MLAT" returns.  MLAT stands for multilateration and they estimate these positions based on triangulation from all available ground stations.

20

General Discussion / Re: How do you know if you are squittering ?

« on: February 22, 2016, 08:04:58 pm »

Aha -  thats what it was, I had used port 3 but  configured port 1 for the Txpdr.

So it appears to work on the ground reporting my own txpdr at my position at 0feet.

Couldn't see myself on FR24, but then I was in a metal hangar with the doors shut. So next thing is a flight test when the 50hr is finished.

Do you know if you can look at FR24 or suchlike for a flight you have just made or is it only realtime flight tracking.

Thanks for everones help.

John

hi John,

Yes you can look on FR24 retrospectively.  There's a menu option at the top of the webpage where you can type in your a/c reg.

I found the trace only hangs around for a few days (maybe a week or so).

Cheers
Andy

21

General Discussion / Re: Mode A and Mode C

« on: February 20, 2016, 08:20:13 pm »

Ok I can take a hint 

I know where I fly there will be mode C all over the place, so it'll be a case of lookout or lookout!

22

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

« on: February 19, 2016, 09:28:57 pm »

does FTDI not work with the standard RPi style linux OS, then?  I thought it did....

Here are the drivers...?
http://www.ftdichip.com/Drivers/D2XX.htm

23

General Discussion / Re: Mode A and Mode C

« on: February 19, 2016, 09:11:56 pm »

Yes indeed.  like I say not trying to kill it off, but like to add some practical angle :-)  The naysayers would be worse, believe me :-)

I had thought about timing etc off the radar heads, but I'm not sure this would work because it's probably not possible to correlate the Mode C response to the radar interrogations?.. so you'd loose the timing reference in order to make the calculation... AFAIK Mode C doesn't have a field in its return transmission which describes the radar head it's responding to (unlike Mode S where reduction of "FRUIT" is one of the main advantages, so is more controlled by the radar head itself).

In any case the current PAW implementation uses the standard widely available DUMP1090 program to decode transponder squawks, so a "DUMP1030" would be required, including the associated algorithms etc.  Not impossible, but quite an undertaking. in addition you need a lot of MIPS in the DSP to be able to discriminate very small difference in the arrival time of the received signals.  Timing resolution could be a challenge, so perhaps not suitable for our low cost RPi solution.

An idea I thought of which might work is the use of multilateration, based on lots of ground based PAWs that could broadcast Mode C positions using a special format over the P3I channel.  Each of these ground stations use GPS timing for triangulation of the mode C reception, they then coordinate the measurements to calculate position.. I could envisage a ground network broadcasting P3I based packets to airborne PAW systems, which could give a more reliable Mode C detection method..... It's one hell of a lot of effort though!  I suppose you could take MLAT outputs from FR24 and broadcast on P3I.. only issue there is that FR24 adds too much delay, so we'd get the data too late!

24

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

« on: February 19, 2016, 03:28:23 pm »

Software drivers cannot be loaded in into the PAw. What is needed is a standalone hardware solution, i.e usb to 232 protocol + level shifting.

John

The operating system running on the PI needs to know about the USB<>RS232 converter chip that you are connecting to your USB port, so it does need to support the chipset you are using.. FTDI is a very common one, so it should work..

25

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

« on: February 19, 2016, 03:25:00 pm »

Just be careful which RS232/USB you buy, and what your transponder requires.
RS232 or RS232-TTL

RS232 is +/- 12v (inverted logic)
RS232 is 0v/5v

They are totally incompatible

Thx
Lee

Yes, there are different types.. The one I linked to above is for RS232 +/-12V, not TTL (3V3 or 5V) ... you can get the TTL version if desired.. I figured that the Transponder wanted to see genuine RS232 level signalling (+/-12V)

26

General Discussion / Re: Mode A and Mode C

« on: February 19, 2016, 02:17:21 pm »

Hello Paul,

I'm not trying to be deliberately argumentative here, merely challenging the thought processes :-)  From very early discussion about PAW, much of the feedback was "I don't want another bloody gadget that is going to distract me", which is after all a valid point of view... And to be fair, many of the gadgets we use can be quite a distraction.

The argument of being fixated on something which isn't actually a risk, while being completely oblivious to something else which is a significantly higher risk (i.e. "more important matters" - it could be anything) is a known attribute of human factors...  it is also a well documented and understood psychology which is manipulated by illusionists and marketers alike!

I'm not saying one or the other is right or wrong (and I do accept that a Mode C detection scheme would be very useful).. what I'm saying is the system should not be designed to include more distractions leading to a loss in "improved" safety, over and above its main intention, which was to give a reliable and accurate traffic data feedback to the pilot - without increasing cockpit workload.

By the way I was looking for that bloody lion all morning.. couldn't find it... and didn't get any of my other work done which was %^&*£"$ urgent.  Turned out the BBC got it wrong and it was actually Mr Miggins's cat seen through a telescope (they didn't mention that).  I wish I would have known that, since I wasted my entire morning and could have been much more constructive doing something more important... ;-)

Rgds
Andy

27

General Discussion / Re: Mode A and Mode C

« on: February 19, 2016, 11:58:26 am »

I do take your point, believe me :-)

One of the major 'issues' (if you call it that) and criticisms of these type of systems is that if the data isn't spot on reliable without introducing pilot workload, then there is an argument that this is a negative safety benefit.

So you spot a ModeC return on your screen... instead of being confident of its location (like you would a mode s return), a proportion of pilot workload time is taken trying to verify the position of the Mode C return... when this was originally conceived one of the big things from feedback was that you need untainted pilot assistance to detect traffic WITHOUT increasing pilot workload.

Mode S returns are reliable and alarms can be created based upon accurate position data, which means that pilot workload is not hindered, more that the system is offering genuine assistance and only takes your attention when it really is required..

Adding into the mix an unreliable Mode C return and now the pilot has to take cockpit time to verify the accuracy of this information (very time consuming!).  Now we have a system that is arguably not helping, more that it is increasing your workload with unreliable data.
Spend time trying to verify this and you may be victim of using a percentage of your workload time being unnecessarily distracted on something where there could be more important matters to be thinking about.

The naysayers would have a field day on this one..... Is this an assistance device where no pilot workload is used looking at the screen (which was what we were aiming at), or is it something which given a mode C return actually distracts you from what you should be doing?

It is important not to invent technology just for the sake of it "because we can".

28

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

« on: February 18, 2016, 05:22:40 pm »

It would depend if the FTDI chipset is supported by the SW drivers...

29

General Discussion / Re: Mode A and Mode C

« on: February 18, 2016, 05:21:20 pm »

How do you know it's any good?

30

General Discussion / Re: Mode A and Mode C

« on: February 18, 2016, 12:33:39 am »

There are too many variable for this to be any use, if you ask me....
Results will be unreliable and possibly more useless than no result at all! :-)