PilotAware
British Forum => Technical Support => Topic started by: GeoffreyC on December 28, 2020, 08:34:08 pm
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Firstly thanks to all at PilotAware for the new Vector facility (and I see there’s a useful new explanation video on YouTube today https://youtu.be/VOoZPhzFNDY
Owing to bending my Quik-R in July and a long repair process I have only recently been able to try it out and see what results I got, and this was from the single post-repair check flight so it’s interesting to see the results with limited data.
PAW mounted in the front pod (on top of the battery) with the PAW antenna extended and in the front windscreen (this is actually a photo of the plane post accident, note the retractable undercarriage mod, but the antenna is back in pretty much the same position, perhaps a little more vertical):
Trig TT21 transponder, antenna underneath at the bottom back of the pod, connected to PAW for ADS-B
The PilotAware diagrams show I’ve got good 10km visibility (I was flying round the Everton base station), and some signal received at 40km. Strongest is front and left, right is good as well, a definite black-spot at about 30 degrees (which I’m guessing is the front strut attenuating the signal) and poorer behind where my body and the fuel tank are in the way.
Think I will try moving the antenna further forward to see if I can resolve the front strut issue, but I’m fairly happy with this
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(continued)
What was surprising was that Vector reports NO ADS-B traffic at all.
My transponder was on, it was connected to PAW and was receiving a GPS signal, and flightradar 24 shows my flight pretty much from when I left the circuit to when I returned back. FR24 is using ADS-B to trace my route so I am confused
Geoffrey
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Hi Geoffrey
Your flight on the 22/12/2020 you flew within 2 ground stations that were less than 10km away which were:
- PWUKBIG which doesn't have an ADS-B in
- PWEverton which does have ADS-B in but its extremely limited (the PilotAware range is 10 times better)
The 360Radar network (which feeds into the ATOM network) saw 285 ADS-B pings, however 360Radar data is not currently used in the beam graphs.
Flightradar24 saw around 40 ADS-B pings.
I am surprised that none of the other PAW groundstations saw your ADS-B, especially when PWEGBT saw your PAW at 60km.
Here are the groundstations which saw your PAW transmissions and your average distance to them.
PWEverton 3.5km
PWUKBIG 5.7km
PWUKGRL 10.6km
PWOrwell 14.1km
PWBedford 16.3km
PWOlney 27.4km
PWCambrid 30.0km
PWEGBKE 36.6km
PWEGBT 59.3km
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Hi Geoffrey
Your flight on the 22/12/2020 you flew within 2 ground stations that were less than 10km away which were:
- PWUKBIG which doesn't have an ADS-B in
- PWEverton which does have ADS-B in but its extremely limited (the PilotAware range is 10 times better)
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Thanks James, so that explains the lack of ADSB from the two most nearest ground stations, but does surprise me that there's no ADSB traffic received from anywhere else. I know I wasn't particularly high, but Gransden Lodge and Orwell should have seen me OK.
Geoffrey
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This answers a question I was about to ask, but to wander slightly off thread, how does VECTOR differentiate between ADS-B and CAP1391; aren't they both ADS-B outputs?
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This answers a question I was about to ask, but to wander slightly off thread, how does VECTOR differentiate between ADS-B and CAP1391; aren't they both ADS-B outputs?
The ADS-B packet includes 5 bits for the downlink format (DF). ADS-B is 17 and CAP1391 is 18, the groundstations decode this and store it in the database for VECTOR to query.
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Simples! Thank you.
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(continued)
What was surprising was that Vector reports NO ADS-B traffic at all.
My transponder was on, it was connected to PAW and was receiving a GPS signal, and flightradar 24 shows my flight pretty much from when I left the circuit to when I returned back. FR24 is using ADS-B to trace my route so I am confused
Geoffrey
Update: the runway had dried out enough today to get up in the air again, this time a much longer 2 hour flight around Bedford, Peterborough and towards Ely.
Looking on Vector, same/similar results.
A good set of PilotAware traces, 5676 contacts today, up to 60km away, and definite issue on front/right, caused I think by the front strut. I could move the antennae in front of the strut but then I fear I'd get no rearwards signal, I could mount it under the pod further back, but then great for planes below me, but what about above?
ADS-B does show 35 contacts, all very close range, and again FlightRadar tracks me fine, screenshot of the latter half of the flight below.
And, another strange thing, Vector is showing 869 pilotaware contacts from 9th August. They weren't there last week, I didn't fly then and in fact the plane was dismantled and PAW stripped out of it then, so unless someone else was inadvertently using my ICAO hex code, these don't make sense.
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That front strut is too close to the PAW antenna. I suspect it may be acting as a reflector and improving the signal to the left at the expense of the right.
Many microloghts and Gyros have the coms antenna on the top of the nose, as far forward as possible. Is that an option?
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Hello GeoffreyC,
I'm not so sure Flight Radar is tracking you very well.
There is a big section between Clapham and Sharnbrook where there were no tracking points.
Oundle to Peterborough looks good, but 'jumpy' between Whittlesey and Gold hill and also jumpy in the St Neots area.
Note: there are approximately 3,000 Flight radar ground stations compared to approx 200 ATOM stations so the chances that FR24 picks up your ADSB transmission is much higher because you are likely never to be far away from an FR24 station.
Flight on the 22nd shows similar big jumps.
However, flights in July show a good signal being picked up, so has a connector been disturbed or something else changed?
I'd be looking at the ADSB antenna / cabling installation, FR24 (and Vector) are indicating a possible range problem.
Deker.
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That front strut is too close to the PAW antenna. I suspect it may be acting as a reflector and improving the signal to the left at the expense of the right.
Many microlights and Gyros have the comms antenna on the top of the nose, as far forward as possible. Is that an option?
Thanks Ian, I suspected that the front strut was causing problems to the right and Vector certainly shows it up in a very visible way. Hadn't thought that the strut might be improving the left side as well as impacting the right.
Putting the antenna on the front of the nosecone is an option, my pod had its radio antenna originally there and I know that Brian Montilla has his PAW one mounted on the front in the hole. Following my accident I had a new pod made by Albatross (and they've done a good job of the fabrication), so would have to be drilling a hole in the virgin fibreglass :(
Its not a position I favour because we store our trikes with the wings de-rigged and so have to drop the base bar over the nose of the trike every time we put the plane away and vice-versa to re-rig it. I've caught the antenna with the bar on a previous trike and ripped the fibreglass as a result, so would prefer not to introduce that risk.
Having said that, it does make logical sense that this would maximise my front visibility, doubtless at some impact to rearwards.
Will look at Brian's traces and see how his PAW visibility compares to mine.
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Hello GeoffreyC,
I'm not so sure Flight Radar is tracking you very well.
There is a big section between Clapham and Sharnbrook where there were no tracking points.
Oundle to Peterborough looks good, but 'jumpy' between Whittlesey and Gold hill and also jumpy in the St Neots area.
Note: there are approximately 3,000 Flight radar ground stations compared to approx 200 ATOM stations so the chances that FR24 picks up your ADSB transmission is much higher because you are likely never to be far away from an FR24 station.
Flight on the 22nd shows similar big jumps.
However, flights in July show a good signal being picked up, so has a connector been disturbed or something else changed?
I'd be looking at the ADSB antenna / cabling installation, FR24 (and Vector) are indicating a possible range problem.
Deker.
Thanks Deker.
The transponder cable did get shortened and a new plug fitted on it post accident as the old cable was always too long (bent around the pod bag) and in fact it came off when I was dismantling the plane. I am sure I checked there were no shorts when I put the new plug on it, but I'll check again.
Suspect some of the jumpiness on the FR24 track is the PAW GPS losing signal. The GPS mouse trail prior to July was on the top of the pod, to the right of the front strut. Post-accident reassembly it got installed on top of the base tube at the bottom of the front strut. On the flight of the 22nd I noticed a couple of GPS dropouts and planned to relocate the GPS mouse, so I'll do that first. It doesn't explain a potentially poor range on ADS-B though.
Geoffrey
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That front strut is too close to the PAW antenna. I suspect it may be acting as a reflector and improving the signal to the left at the expense of the right.
Many microloghts and Gyros have the coms antenna on the top of the nose, as far forward as possible. Is that an option?
Hi Geoffrey / Ian,
Sorry, I’m playing catch-up on the Forum.
I agree, the PAW polar diagram appears to show significant obscuration to the front right, but with the antenna in its 'new' position as shown in the most recent photo, I would be surprised if the front strut alone would cause such a significant area of shadow to the right side of the plane - as the greater part the antenna is now above / in front of the strut. I must admit, however, that I'm at a loss to think what else in the plane would be obstructing your PAW signal to the front right to such a broad extent, so maybe there is more to this (as Ian suggests) than at first appears likely. The 'gap' might of course just have been poor line-of-sight to the Ground Station antenna(s) at whatever range and heading you were when being received by them. Blocking of your PAW signal to the right rear, however, will almost certainly have been due to a combination of the front strut, plus (to a varying degree, particularly bearing in mind that the receiving stations are predominantly below), the front fork and wheel assembly, battery, instruments in the panel, plus (presumably) your phone or tablet - as well as Pilot / Passenger / engine and rear suspension as you alluded to earlier (as well as potential line-of-sight issues to the Ground Station antenna(s)).
I was about to suggest moving your existing antenna to just inside the outer edge of the upper windscreen - as high up as you can manage, which would clear the immediate (close) obstructions, and help to reduce obstruction to the right rear due to Pilot, Passenger, Pylon and Engine, etc., but have just seen your recent post about dropping the wing for storage, which would make this awkward (though not impossible - it would just involve disconnecting the cable from the antenna before removing the upper screen).
And Yes Ian, it would be 'possible' to fit a PAW antenna externally on the upper front of the pod, but very difficult to align it vertically (if using a standard Rohan 'external antenna') and, as the front strut goes on down through to a bracket at the front of the base tube, it would still be right behind the antenna, so could actually make coverage to the rear worse. As you say, Geoffrey - worth checking results with Brian M first. :)
WRT fitting an external antenna further back below the pod, that's the option I have settled on after considerable trials. Mine is fitted just in front of the fuel tank with a flexible ground-plane on the inside (my Txpdr antenna is mounted through the rear skirt on a separate aluminium sheet ground plane, earthed to the base tube). I have now been using this setup for over a year, with excellent results, though from the attached diagram I still seem to be seeing some obscuration from the rear undercarriage and to the front by the front wheel and suspension, though I currently only have the one polar diagram from one single (approx 1hr 30) flight past 3 ATOM Ground Stations on Christmas Eve, two of which were at fairly long range (my most recent previous flight was well in excess of 30 days prior to the introduction of the Vector Tool due to the Scottish travel restrictions).
I did, however carry out a fairly short local flight immediately prior to the test flight shown, involving a 'circuit' of the area around my local airfield at up to about 5 miles range from the ground station, with several fairly tight 'orbits' at various points in the flight while still well away from the station (to ensure 360 degree visibility to the station antennas). I then checked the Vector track immediately after landing and prior to the main test flight. The initial report showed pretty effective 360 degree coverage, though of course with a maximum range of 5 miles, but unfortunately I omitted to take screenshots as I was pushed for time to get the main flight in before dark, so this is incorporated in the main report. In view of the relatively short flight and relatively long range from two of the 3 Ground stations reported during my main test flight, and my previous ‘good results’ from other evaluation tools, I suspect the 'gaps' in the Polar Diagram may be due to ground obscuration at or near the Ground Stations or simply my heading in relation to them during this single test flight rather than simply obscuration at the plane. I need to do some further testing once the travel restrictions are relaxed to confirm this.
If you do decide on the option to add a PAW antenna below the pod, I wouldn't worry about 'missing' aircraft above you. We did lots of testing for this in early PilotAware trials and found that it was almost impossible for a plane to approach from above (or vice versa with a top mounted antenna) without it being seen well before it got above us (or below as appropriate). IMO below is a much better option for external antennas, especially if you want to receive Ground Station uplinks reliably.
In closing, I’m not sure why your Vector search is bringing up your PAW results from your flight from 9th August - Vector is only 'supposed' to report on flights from the past 30 days (though I have seen a few flights listed on other ICAOs from ‘30 + a few’ days)..
WRT your ADSB issues, it definitely looks like a fault to me. Loss of GPS to the Txpdr - would prevent Mode-S/ES transmission, but would also affect PAW transmissions and would be reported as gaps on your Nav System and PilotAware Tracks, so relatively easy to check. Please let us know how you get on.
Best Regards
Peter
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Vector is an excellent function – well done PilotAware team, thanks :D :D!
FYI attached are the plots from my RV-7 (external antennas under cockpit) from 5 flights in Nov-Dec last year. The first shows all EC and the second is just ADSB. Looking at the data overall there were 14154 contacts over the 5 days, but ADSB only had 2738 contacts on 4 out of these 5 days. I guess there wasn't much ADSB equipped traffic flying in the area on those days, however at least it confirmed that ADSB was being picked up with my PilotAware installation.
Chris Y
G-RVAH
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Hi Chris
The PilotAware transmission polar diagram is stunning and shows a great installation well done.
When you say that this proves that you were picking up ADSB with your PilotAware installation, unfortunately, it does not. The polar diagram is of the ADSB transmission out of your aircraft and being picked up by the ground stations.
Regards
Keith
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Thanks Keith - that's helped my understanding of the Vector plots.
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That front strut is too close to the PAW antenna. I suspect it may be acting as a reflector and improving the signal to the left at the expense of the right.
Many microloghts and Gyros have the coms antenna on the top of the nose, as far forward as possible. Is that an option?
I was about to suggest moving your existing antenna to just inside the outer edge of the upper windscreen - as high up as you can manage, which would clear the immediate (close) obstructions, and help to reduce obstruction to the right rear due to Pilot, Passenger, Pylon and Engine, etc., but have just seen your recent post about dropping the wing for storage, which would make this awkward (though not impossible - it would just involve disconnecting the cable from the antenna before removing the upper screen).
...
WRT your ADSB issues, it definitely looks like a fault to me. Loss of GPS to the Txpdr - would prevent Mode-S/ES transmission, but would also affect PAW transmissions and would be reported as gaps on your Nav System and PilotAware Tracks, so relatively easy to check. Please let us know how you get on.
Best Regards
Peter
An update on my PAW and ADSB results from the flight I managed to get in on 2nd January, probably the last for a while >:(
I moved the PAW ADSB antennae up as high as I could on the lower windscreen, so it was half on the bottom windscreen and half on the upper. PAW Vector was near identical to prior flights. Having looked at Brian Montilla's trace, his trace doesn't show the right hand 'blind spot' mine does, but his Rosetta is mounted underneath the lower windscreen so has antennae in almost identical position to mine. This makes me think that its not the front strut that is shielding the signal, I am wondering whether it is the USB cigarette socket converter for my ipad which is on the opposite side of the front strut from the PAW antennae.
I'll try flights with no power converter plugged in or a different one in use, somehow I have misplaced the Ankher I was using.
ADSB, no positive progress. Moved the GPS mouse to above the coaming and didn't see any GPS dropouts on my Trig or Skydemon in flight. The Vector plot is non existent again, and looking at Flightradar 24 and ADSB Exchange, they both show a patchy flight trace.
Have ordered replacement plug to makeup a new antennae cable for my transponder as first option before I change the transponder antennae.
But next stage of testing these will depend on ability to fly again :-(
Geoffrey
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Hi Geoffrey,
Thanks for the feedback.
I'd be very surprised if the USB socket and adaptor on their own, or even with the attached cable, were causing such a big gap in transmission to the front right from where your antenna is positioned, but I suppose when combined with the front strut and front wheel (depending on your height/distance from the ground station(s)), between them all they could be. If so the only viable option is to move your antenna higher up on the windscreen or fit an external one below the pod or rear skirt.
Getting back to your original (and possibly more important issue), however - why we are seeing no ADSB from your Trig TT21 transponder.
You are obviously transmitting P3i from your PAW, which means it definitely has a GPS fix (or it wouldn't transmit).
That means the reason for 'No ADSB' has to be down to one of the following: -
1. Transponder is not not transmitting due to a fault.
But you were tracked on FR24 so that can't be the case - though I suspect the tracking was probably from your Mode-S via MLAT.
I am seeing faint signs of a very weak transmission on your ADSB Vector charts - which is probably the TT21 auto-transmitting its Hex ID.
Both of which show that the transponder IS transmitting.
2. Transponder is not receiving GPS Data from PilotAware.
We have already determined that the PilotAware is producing GPS data, and it's very easy to check if this data is being received by the Transponder (you can do this on the ground).
First power up both PilotAware and the Transponder (set the Transponder to 'ALT').
Next, login to the PilotAware Home Screen and check that it has a GPS fix. If it has, press the 'FN' (Function) Button on the Transponder Control Head Twice. This should bring up the ADS-B position monitor screen - which will display local lat/long co-ordinates on screen if the transponder is receiving GPS position data. If they don't appear, or just show 'dashes', there is a problem with one or more of the following. (Note: it's easiest to check the settings first, before starting to take connectors apart).
3. Fault in USB to RS232 cable or settings.
These are likely to be one or more of: -
(i) Faulty Cable (You are presumably using the recommended FTDI USB to RS232 Serial Cable ?), if so, the only cabling fault can be wrong wires used, or the correct wires but connected to the wrong pins in the Trig 25-way connector. The correct wiring is Black Wire (Ground) connected to Pin 4 and Orange Wire (Data Out - From the PilotAware) connected to Pin 5 (these are on the 13 pin row (the other row has only 12 pins) and if you are at the correct end, Pin 1 will have a connection, then Pins 2 and 3 won't - if they do, you're at the wrong end! The most common mistake I find is the Yellow (Data In) wire connected to pin 5 instead of the Orange one.
(ii) Wrong Setup at the PilotAware End.
This can be one of two errors - either the wrong USB port has been set up, or the wrong Baud Rate has been set. Looking at the USB end of the PAW, with the Ethernet Port to the Left of the USB Ports, the USB ports are numbered from the left, 1 then 3 on the top row, and 2 then 4 on the lower row. If you have the standard Classic setup, the 'spare' port which the USB lead to the transponder will most likely be plugged into will be Top Left, which is Port 1. On the Configure Screen, Port 1 should be set to 'Transponder Trig' and 9600 Baud. If it isn't in Port 1, you must identify and then configure the CORRECT USB Port.
(iii) Wrong Setup in the Transponder.
To get to Setup, Hold in the 'FN' button in while switching the Transponder ON. Once the transponder has turned on, release the 'FN' button. Each further press of the 'FN' button moves the unit to the next setting position in sequence. If you don't need to change the setting, simply press the 'FN' button again to move on to the next option. The critical ones you need to find and check are GPS Input - which should be set to NMEA 0183, and GPS/TIS Line Speed - which must be set to the same as you set in PAW - namely 9600 Baud. Once you have checked or reset these correctly, simply switch the transponder OFF then ON again (back to 'ALT') and re-press 'FN' twice to see if the Position Co-ordinates are now showing. If they are then 'Bingo' you have won the prize.
If it's still not working get back to me.
Best Regards
Peter
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Thanks Peter for your advice on checking the transponder and Pilotaware connection.
Went briefly to the airfield yesterday evening, the transponder head is showing the GPS coordinates from PilotAware when you press FN several times, as I thought it was.
I have removed the transponder body to antennae cable and took it home with the plan to make up a new cable with the plugs I've ordered. Testing it last night, it appears to have good continuity both on the outside shielding and the inside pin, so thought it might be due to degradation of the shielding over time that was causing the poor transmission quality.
This morning I thought to test the continuity of the inside pin to the shielding, and I can report that that's showing great continuity as well, barely any resistance at all !
Think I now know the source of the ADSB transmission quality. I'm sure i was careful to not get any braiding trapped when I shortened the cable, but clearly I must have done somehow. Will see if I can find and fix it, otherwise will continue with plan A of making up a new cable.
Thanks for all your help and advice
Geoffrey
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This morning I thought to test the continuity of the inside pin to the shielding, and I can report that that's showing great continuity as well, barely any resistance at all !
Yikes!
I hope that has not damaged the power output amplifiers by shorting, might be worth consulting the manufacturer
On a related note, I am happy that the VECTOR service helped identify the issue - even if that is not its main intention!
Thx
Lee
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This morning I thought to test the continuity of the inside pin to the shielding, and I can report that that's showing great continuity as well, barely any resistance at all !
Yikes!
I hope that has not damaged the power output amplifiers by shorting, might be worth consulting the manufacturer
On a related note, I am happy that the VECTOR service helped identify the issue - even if that is not its main intention!
Thx
Lee
It did indeed thanks Lee, I would probably have been none the wiser on this issue other than perhaps some ATC's reporting poor visibility of my transponder.
Peter's useful guide to checking the PAW to Transponder connection, and then mine to check the continuity (or not) of the cable might be worth writing up somewhere.
I'll makeup a new cable and will have to wait until can fly to try it out. Don't think at the moment I can make provision for this as urgent flight safety, maybe when lockdown starts easing.
Thanks again all
Geoffrey
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Hi all,
I have a couple of related questions regarding the new Vector tool.
1. Does selecting "PilotAware" from the Type pulldown show the polar diagram for transmissions from my aircraft to ground stations using the 869.5MHz PilotAware antenna?
2. Does selecting "ADS-B" from the Type pulldown show the polar diagram for transmissions from my aircraft to ground stations using my existing transponder's 1090MHz ADS-B out antenna?
I'm interested because from the Vector plots I can see much better performance with 1. compared with 2. Whereas when I look at my reception performance (using track files) I see much better 1090MHz reception (albeit this would be using the PilotAware ADS-B in antenna) compared with 869.5MHz reception from ground station uplink.
I'm not an expert, but trying to understand since it seems counter-intuitive to me.
Thanks,
Chris.
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Hi all,
I have a couple of related questions regarding the new Vector tool.
1. Does selecting "PilotAware" from the Type pulldown show the polar diagram for transmissions from my aircraft to ground stations using the 869.5MHz PilotAware antenna?
Yes Chris, that is correct. Provided you have selected your own aircraft by its ICAO Hex ID, the VECTOR report shows the transmission performance of the selected Mode from your aircraft as received by PAW ATOM-GRID Ground Stations along your route* from data gathered from however many flights you have made over the previous 30 days.
*Providing you have flown within range of at least one of these stations on each flight.
2. Does selecting "ADS-B" from the Type pulldown show the polar diagram for transmissions from my aircraft to ground stations using my existing transponder's 1090MHz ADS-B out antenna?
Again, yes that is correct, providing you have ADSB out enabled via a GPS feed into your transponder. Those using a CAP1391 Device (such as SkyEcho2) to provide ADSB instead of via a transponder need to select CAP1391 as the desired Mode.
I'm interested because from the Vector plots I can see much better performance with 1. compared with 2. Whereas when I look at my reception performance (using track files) I see much better 1090MHz reception (albeit this would be using the PilotAware ADS-B in antenna) compared with 869.5MHz reception from ground station uplink.
I'm not an expert, but trying to understand since it seems counter-intuitive to me.
Thanks,
Chris.
Chris,
Assuming we are talking about RVAH, I agree - the plots do appear to indicate significantly better transmission coverage from your PilotAware than from your transponder.
Remember, however, that what is shown always depends on your installation - in particular the position in your aircraft of your devices and antennas # and - especially with a low flight density - on how 'visible' you were to the Ground Stations along your route. Apart from the setup in your aircraft, this can also be dependent on your flying height and ground topography. Remember also that ADSB range reporting is deliberately limited to 60Km to limit the amount of data which has to be processed to generate the reports. The most important thing to determine is whether we are achieving good all round cover through 360 degrees. Unless extremely poor, range is initially of far less significance.
# Again assuming we are talking about RVAH, I have seen your installation video and can't see any issues which would reflect poor indicated coverage to the RH side of your aircraft, though we need to look specifically to see what stations you were reported from (I am aware that you have posted data on another thread which I will take a look at to see if there is anything obvious).
Regards meantime
Peter
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Thanks Peter that's helpful and it's great that Vector is helping me to understand and fine tune EC performance of my aircraft RVAH,
I think there are two issues which I'm exploring:
1. ADSB-out from my transponder is a bit uneven (better to left than right) and the range is not as good as the PilotAware-out.
2. PilotAware-in directly from ADSB contacts is significantly better than PilotAware-in via uplink which appears to be intermittently / short range.
I'm more worried about issue 2 (which I've raised on the other thread "OGN-R uplink typical range") since I fly from a gliding airfield and don't want to be missing glider traffic.
Regards,
Chris.
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Hi Chris,
I have just had another look at your PAW install pics and video on the RV thread (very neat installation BTW - which undoubtedly accounts for your excellent PilotAware transmission performance). The pics and video however also confirm my suspicion that your transponder/ADSB Out antenna (the Narco blade-type one) is IMO poorly positioned just inboard of your right-hand undercarriage leg, where it will be significantly screened to the right-hand side by the leg, fairing and wing and also to the front-left by the exhaust/cowling (as borne out by your 1090MHz Vector plots).
WRT your PilotAware Uplink issues, I concur with Lee’s posts on the other thread that this is much more due to lack of traffic and distance/bearing from the Ground Stations you have flown past than any problem with your installation. I would certainly expect you to see gliders locally on your way in and out of Bidford as it has it’s own ATOM Station, though Vector shows a significant gap in its PilotAware coverage to the north (from about 300 to 080 degrees), though this may again be due (at least in part) to lack of recent traffic.
Hope this helps.
Best Regards
Peter
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Thanks Peter,
I think you are correct on the position of the 1090MHz Narco antenna from my transponder. That would explain the worse performance to the right.
Also understood on the uplink issues, I will re-analyse some of my track files in and out of Bidford to make sure I was getting good uplinks of glider traffic within 10km.
BTW interested that Vector could be used to review the transmission pattern from an ATOM station. What do you type into the ICAO code to get this? I tried PWBidford and it obviously did not work!
Regards,
Chris.
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Hi Chris,
Ah.. That's because at the moment the Ground Station Analysis is only available to Station Maintainers through their secure login (and of course to the Development Team).
I have attached a PilotAware coverage screenshot for PWBidford taken just now but which only includes data from a total of 7 days between 11/11/20 and 05/01/21. Happy to take a look at any other specific stations for you.
Best Regards
Peter
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Thanks Peter - that's interesting.
For such Vector plots for an ATOM station does the pattern represent transmissions picked up by other ground stations or other PAW units on aircraft? If it is the latter then I would expect more contacts to the South of Bidford since the circuit pattern is on this side.
Regards,
Chris.
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For such Vector plots for an ATOM station does the pattern represent transmissions picked up by other ground stations or other PAW units on aircraft? If it is the latter then I would expect more contacts to the South of Bidford since the circuit pattern is on this side.
Hi Chris,
I wasn't going to put up any Vector plots before PAW HQ say I can, but you can see rough coverage in the public domain for all aircraft into a ground station in a nice pretty picture. Use gliderradar and pull up the PAW side of the ground station and ask for coverage in the sub menu that pops up.
In the attached the red line is the runway at Headcorn.
https://www.gliderradar.com/center/51.12464,0.53833/zoom/10/time/15 (https://www.gliderradar.com/center/51.12464,0.53833/zoom/10/time/15)
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One of the non obvious issues is airspace
You see blank areas to the north of Bidford and Turweston, due to Birmingham airspace
Thx
Lee
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Thanks Steve - that's a great tool and gives a good picture of the ground station coverage.
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One of the non obvious issues is airspace
You see blank areas to the north of Bidford and Turweston, due to Birmingham airspace
Thx
Lee
For the avoidance of doubt or confusion, when I commented on Bidford’s Radiation Pattern above, I was well aware of the proximity of Birmingham airspace to the North East of Bidford and agree that would obviously limit the range of expected PAW traffic in that direction, but under ‘normal’ circumstances I would expect to see a fair density of PAW traffic routing through the obvious ‘gap’ between Bidford and Birmingham whilst avoiding controlled airspace en route to and from Wales and the North West and the East Midlands / South and East. I have personally used this route in both directions on several occasions in the past.
That’s why I took care to advise that the chart is based on a small number of records from only 7 flying days in the middle of a pandemic, so on this occasion almost certainly only illustrative rather than truly representative.
Best Regards
Peter
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Thanks Peter for your advice on checking the transponder and Pilotaware connection.
Went briefly to the airfield yesterday evening, the transponder head is showing the GPS coordinates from PilotAware when you press FN several times, as I thought it was.
I have removed the transponder body to antennae cable and took it home with the plan to make up a new cable with the plugs I've ordered. Testing it last night, it appears to have good continuity both on the outside shielding and the inside pin, so thought it might be due to degradation of the shielding over time that was causing the poor transmission quality.
This morning I thought to test the continuity of the inside pin to the shielding, and I can report that that's showing great continuity as well, barely any resistance at all !
Think I now know the source of the ADSB transmission quality. I'm sure i was careful to not get any braiding trapped when I shortened the cable, but clearly I must have done somehow. Will see if I can find and fix it, otherwise will continue with plan A of making up a new cable.
Thanks for all your help and advice
Geoffrey
Hi Geoffrey,
I had a long chat on the phone to one of my contacts in Trig Technical Support this afternoon. She confirmed that the output of the TT21 is protected, so hopefully all will be well once you fit your new cable.
Best Regards
Peter
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This morning I thought to test the continuity of the inside pin to the shielding, and I can report that that's showing great continuity as well, barely any resistance at all !
Think I now know the source of the ADSB transmission quality. I'm sure i was careful to not get any braiding trapped when I shortened the cable, but clearly I must have done somehow. Will see if I can find and fix it, otherwise will continue with plan A of making up a new cable.
Thanks for all your help and advice
Geoffrey
Hi Geoffrey,
I had a long chat on the phone to one of my contacts in Trig Technical Support this afternoon. She confirmed that the output of the TT21 is protected, so hopefully all will be well once you fit your new cable.
Best Regards
Peter
Thanks Peter, that's useful to know. Good old Trig.
I think I know the source of the original problem which was fitment of the BNC cable onto the existing antennae cable, the outer shield was crimped onto the outer rubber sleeving and not the wire braid inside, so when the BNC was plugged in it could push the pin backwards partly out of the plug and cause it to short on the outer shielding.
Although I could re-make this one to be more secure I've made up a whole new cable and thoroughly tested it for continuity in the right and wrong places. Its waiting in the car boot to take it and fit back to my plane.
Miserable foggy weather today so not like I'm missing anything, but yesterday was clear and I heard the sonic boom from the Typhoon jet from Coningsby as it rushed to intercept an errant German pilot that had lost comms. We should check their Vector plot !
Cheers, Geoffrey
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I think I know the source of the original problem which was fitment of the BNC cable onto the existing antennae cable, the outer shield was crimped onto the outer rubber sleeving and not the wire braid inside, so when the BNC was plugged in it could push the pin backwards partly out of the plug and cause it to short on the outer shielding.
Although I could re-make this one to be more secure I've made up a whole new cable and thoroughly tested it for continuity in the right and wrong places. Its waiting in the car boot to take it and fit back to my plane.
Some BNC connectors have inner pins that locate with a positive click in the housing. There isn't a lot of force on the inner pin when inserted into the socket AIUI.
It's worth using a template when trimming the various insulation layers and the inner and outer conductor for a crimp connection BNC. These may be provided by the manufacturer and consist of measurements to strip to.
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Hi Chris,
I have just had another look at your PAW install pics and video on the RV thread (very neat installation BTW - which undoubtedly accounts for your excellent PilotAware transmission performance). The pics and video however also confirm my suspicion that your transponder/ADSB Out antenna (the Narco blade-type one) is IMO poorly positioned just inboard of your right-hand undercarriage leg, where it will be significantly screened to the right-hand side by the leg, fairing and wing and also to the front-left by the exhaust/cowling (as borne out by your 1090MHz Vector plots).
Best Regards
Peter
Hi Chaps, just reading this thread and was interested in any recommendation you could make on what to do with my Transponder antenna position. I read the comment above ref the positioning of the Narco antenna and that is exactly where I have mine, also seeing some blanking from what I assumew is the U/C legs/wings.
Where on a metal low wing aircraft (mines an RV9) is the best place to permanently install the antennas?
I have the three underneath, PAW in and out are currently in a temporary position in the wing root fairings, TXP in the 'standard' RV position.
Thanks Regards, Clive
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Hi Clive,
Antenna fit positions on aircraft are often a compromise between the ideal and what is physically achievable.
With a low wing aircraft with fixed undercarriage like an RV, I'd suggest ideally as far back on the belly as possible away from the undercarriage legs, so that the angle(s) obscured by the legs, etc. are as narrow as possible - especially towards the front of the aircraft, but not so far back that the body of the aircraft itself becomes a significant obstruction towards the front - such as might be the case with a high-wing aircraft like a Cessna or Foxbat, where the antenna(s) need to be mounted on the lowest part of the belly, not the slope up towards the empennage - even though this may require a compromise in relation to the undercarriage. Remember also that most RADAR or other receiving stations we are interested in will be below us. Don't worry too much about aircraft flying in from above. Signals between you both will normally be detected well before obscuration by the aircraft bodywork becomes a problem.
Having said all that, of course the position chosen has to be accessible to facilitate the antenna installation. For each potential mounting site, you need to envisage how much will be obscured through 360 degrees from that point. I would also suggest discussing your chosen 'potential' options with your inspector before going ahead with a fit. Compromise is usually necessary in most cases.
Oh, and if the chosen position requires long cable runs, remember to use high quality coax matched to the signal frequency to minimise losses.
Hope this helps.
Best Regards
Peter
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I think I know the source of the original problem which was fitment of the BNC cable onto the existing antennae cable, the outer shield was crimped onto the outer rubber sleeving and not the wire braid inside, so when the BNC was plugged in it could push the pin backwards partly out of the plug and cause it to short on the outer shielding.
Although I could re-make this one to be more secure I've made up a whole new cable and thoroughly tested it for continuity in the right and wrong places. Its waiting in the car boot to take it and fit back to my plane.
...
Cheers, Geoffrey
First flight today after lockdown, unfortunately I missed the good weather as I was away earlier in the week, so it was decidedly lively for my check flight today.
To try to isolate the cause of the front RHS blind spot on PAW I tried flying without the Anker plugged into the USB socket by the front strut.
Looking at the Vector diagrams after what was a very local 30 minute flight it does seem to still have the front right gap, so suggesting its the front strut rather than the Anker. Most traces from 10km away but encouragingly some traces up to 40km. When I get the chance for longer flights I'll see if this bears out.
And I now have ADS-B working now and appearing on Vector as well, and on https://globe.adsbexchange.com/?icao=405f7f&lat=52.148&lon=-0.311&zoom=12.9&showTrace=2021-04-01 (https://globe.adsbexchange.com/?icao=405f7f&lat=52.148&lon=-0.311&zoom=12.9&showTrace=2021-04-01) the trace is absolutely rock solid, no gaps or faint lines at all, so the new Transponder to Antenna cable did the trick.
Cheers, Geoffrey
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Flew yesterday with my new Sky Echo 2 as well as PAW; 3 flights Garston Fm-Devizes-Lyneham-GF, up to 4000', to compare different positions of the SE2. Vector plots of the 3 flights combined given below for PAW and SE2. Very impressed by PAW coverage (though there's room for improvement in some sectors): 8 stations in total (Wadswick, Shirenewton, Calne, Clench, Kemble, Oxford, EGVL, Enstone, with at least 4 most of the time. SE2 results significantly thinner. Referring back to earlier messages on the thread, is this because quite a few of these ATOM stations don't have ADS-B In capability (is this listed anywhere?), or should I be wondering about the performance of my SE2?
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On the SE 2 web page, this is the claim:
With 20W transmit power, your 1090MHz ADS-B signal can be received up to 40NM away.
So, the limit seems to be 40NM, or 74km.
You're getting some pings up to 40km,and the occasional towards 50km, looking at your diagram?
You don't say if your PAW is using the integral, internal or external aerials, or what sort of aircraft it is, metal, wood or rag & tube?
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... Referring back to earlier messages on the thread, is this because quite a few of these ATOM stations don't have ADS-B In capability (is this listed anywhere?)...?
I thought all ATOM stations had ADSB in? Some early OGN-R stations may not and this needs to be addressed if possible.
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On the SE 2 web page, this is the claim:
With 20W transmit power, your 1090MHz ADS-B signal can be received up to 40NM away.
So, the limit seems to be 40NM, or 74km.
You're getting some pings up to 40km,and the occasional towards 50km, looking at your diagram?
You don't say if your PAW is using the integral, internal or external aerials, or what sort of aircraft it is, metal, wood or rag & tube?
Low wing, wood and fabric. Classic PAW, internal aerials, central on the coaming. SE2 in 3 positions: coaming RHS, central behind me near canopy, canopy RHS low. (to keep it vertical). On PAW playback grid, not a lot of difference between the SE2 playback for the 3 positions, but some breaks compared with PAW. On FR24 the addition of SE2 shows tracking to a much lower height on take-off/landing compared with previous Mode S only. Of the 8 PAW stations which tracked me (for at least some of the time), 5 were within 22nm the whole time, the other 3 never more than 43nm. Hence my question about whether some ATOM stations are not receiving ADS-B In. Does any one else have PAW/SE2 comparison for their flights? And I recognise that this is air-to-ground, not air-to-air.
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Hi Smaragd / Ian,
Not all ATOM Stations have 1090 Rx yet - including some which were upgraded from original OGN only - though most of the newer ones do and we are trying to encourage those that don't to add it. All it needs is a 1090MHz antenna, co-ax and an additional SDR.
Of the 8 stations listed above, I can see no evidence of 1090 ADSB or CAP1391 (SkyEcho) reception at either PWCalne or PWOxford. All the others listed are showing definite recent results for both ADSB and CAP1391.
Hope this helps.
Regards
Peter
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Thanks Peter. I'll see how the picture fills up with a few more varied flights.
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Hi Geoffrey
Just looking at your post. I seem to have a similar problem and set up too yours. I have a PAW Rosetta, recently installed SE2 and mode s Garmin 328. Good results with PAW but none ADSB. SE2 also not brilliant. My aeroplane is metal low wing (PA28). Hex code 401C1B. Check my vector pole results over 3 flights. Pete is helping me this problem under another thread.
Regards Dave
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I have a slightly different issue and request please:
RV-8 (G-RUVE 405F9B) with PAW, ADSB(out) via FUNKE txpdr, PowerFLARM Portable with all incoming tracks concentrated by PAW and displayed via wifi to SKD. All tx & rx via external mounted antennae.
Checked radiation patterns using the impressive Vector tool which shows good cover for PAW and ADSB but zilch for FLARM.
The internal IGC tool records a polar diagram of received FLARM traffic via the FLARM SD card but it does not measure tx.
PowerFLARM unit was removed and tested by LX which confirmed tx operating but signal strength not measured. Either I put it back in the aircraft or send it to Switzerland for investigation.
Question - does the lack of FLARM data on Vector give a reasonable assurance that there is indeed a fault in my FLARM device tx?
John
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Stupid question on my part but is the licence in the unit up to date? Some of the PG mob have been caught out with forgetting to renew?
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Hi John,
I’ve just checked the PAW Database, and while there are loads (probably hundreds) of reports from your aircraft, over the period since 25th February 2021, from a significant range of PAW ATOM Ground Stations, I can’t find one single report of a FLARM transmission from that Hex ID.
This clearly indicates that either your Flarm device isn’t transmitting OR that it is transmitting a different ID (such as its default FLARM ID) from your aircraft (hence it won’t show up on a Vector (or database) search using the aircraft HexID).
Worth checking that your FLARM Firmware has been updated in the last 12 months (as per Steve’s post above - certainly not a stupid question Steve) and that it is configured to transmit your Aircraft ID, NOT the default FLARM one before you even think of sending it back to Switzerland.
Please let us know what you find.
Best Regards
Peter
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Hello Peter,
The FLARM firmware is current and the LX ground test showed it was transmitting FLARM signals of at least sufficient strength for a bench test. The HEX ID checked as correct.
I tried to test the FLARM using K Trax (see attached) but although their website talks all about FLARM, their data appears to come from the OGN so suspect that plot may be produced from PAW or ADSB data.
Next plan is to put the FLARM in the aircraft, deselect the ADSB(out) and turn off the USB power to disable integrated PAW and try again. I will also try replacing the antenna cables and maybe try fitting an antenna direct to the PFLARM unit.
Vector does give us a window on what is really going on in our conspicuity effectiveness! Just been comparing installed coverage to some new carry-on devices in our club aircraft and the differences are significant, VMT
John
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Hi John,
Sorry, I’m struggling to get my head round what is going on here (hence why it’s taken me so long to reply).
I also use K trax regularly. Although their data may be collected via the OGN network, the report will be based solely on FLARM data - which makes it even more surprising that I could find no reports of Flarm transmissions from that HexID on the PAW database. The K trax plot thereforecertainly shows that your FLARM has been transmitting during the period of the report.
You mention ‘deselecting the ADSB(out)’ and turn off the USB power to disable integrated PAW. Do you just mean ‘turn off your PilotAware’ or is there some more complicated link or setting that we need to know about?
Regards
Peter