Long Marston Test 17 October

[falcoguy]

We also undertook some testing yesterday based near March.

Our results were max 3 nm in air.  Our ground monitoring station managed only 1000m range!  Our best airborne aerial was the whip aerial mounted externally on a Streak Shadow.  We think even this was being shadowed by the airframe, since the signal would go and then come back for no reason.  We are using 2.5amp mains power supply and juicybits cable for the ground monitor, and Charge 2 with juicybits power cable in the air stations.  We don't believe we have power issues.  Our range could be similar or marginally worse than you demonstrated.  There appear to be many variables when undertaking live testing.  We keep getting differing results for no apparent reason!  Oh and our ARF's have onboard SMA connector.  Although to be fair we can detect no obvious difference in range whether with pigtails or direct SMA connection.  Again because of the spread of results.

The range we are demonstrating with the ARF as a P3i transceiver is not currently enough for us, we are all GA types with a collision approach speed of between 200 and 300 kts.  We are hopeful that an alternative and higher power transceiver will become available to all, and incorporated in the standard build.  We have measured a few of our ARF transmitting outputs and they all measure 89-90 mW and nowhere near the 500mW maximum allowed for under the terms of the licence free rules.  We think from Lee's state of the nation address he may be considering the apparent range problem, currently experienced with the ARF, and hope he may look at an alternative with a higher output.  However, Our experience with ADSB is very good. 

Regards

dave

[ianfallon]

I think we were getting a bit more during our air to air tests at Long Marston. Subject to me solving another curiosity, perhaps a lot more. I wouldn't write the ARF off just yet.

[Paul_Sengupta]

CaptChaos and I also went up to play yesterday.

He had two units, I had one. I could see his one unit from 5 miles or more away, definitely beyond visual range! He swapped units and his other unit wasn't quite so good, I had to get closer to see him. However, he couldn't see me at all.

We landed and had a walk around. He could get the signal from my unit when close up, but lost it when 30-40 yards away. From his weaker unit, it continued to be picked up half way across the airfield, maybe 300 yards away. Still not that far.

So something's going wrong. I measured the voltage on mine which didn't seem to transmit much at all (but I assume the aerial is fine as it was with that unit I was picking up at 5 miles) and it was 4.9V. I think my ARF transmit may be duff. Don't know if JCurtis has any sort of scheme to send these things back?

We then went flying with me using his other unit, the one which had been received on the ground from 300 yards away. Anyway, similar thing, I could see him from 3 miles away or more, but he could only see me when we got within reasonably close visual range.

Anyway, if these things are only outputting 80-90mW even when they're working as suggested in another post, we might be able to do better.

[scsirob]

Fully agree, the ARF is still a good option. 5 miles is obtainable using proper antenna setup. I would think that using a metal housing for the RPi and the 868MHz antenna centered on top might already give enough ground plane to be effective.

Air-to-ground is cute, but for safety it is more important to have good coverage in the horizontal direction you're flying in, plus or minus 1000 ft or so. Transmissions to the ground is power wasted...

[JCurtis]

Don't know if JCurtis has any sort of scheme to send these things back?

I have contacted those who have already placed orders for ARFs to be absolutely sure they want to continue with their order.  I'm not taking any more orders for the ARF modules.

If the ARF heartbeat is flashing then the module is up and active, bar plugging one into an RF Power meter there is little you can do to test them.  The PAW box doesn't start to transmit on the ARF until it gets a GPS fix, so when testing after a power up always ensure you either have a GPS unit attached or CollisionAware active.

The shield is still available, as it gives the Barometric sensor for those who want an easy option to fit one of those.

Anyway, if these things are only outputting 80-90mW even when they're working as suggested in another post, we might be able to do better.

Doing better is an option as 500mW rated, fully certified, packet radio modules are available for a very similar price point and physical size, downside is they won't talk to the existing ARFs.

[Mig29fuk]

I'm giving a PAW UNit to some Radio Ham boys who are very knowledgeable on getting the best out of low power, higher frequency communications.
They will measure output with various aerials I have tried and then start tuning through aerial design and ground plane combinations knowing that gain shouldn't exceed 500mW.
It's worth a try to utilise the ARF route which looks good except for range.
G

[Paul_Sengupta]

If the ARF heartbeat is flashing then the module is up and active, bar plugging one into an RF Power meter there is little you can do to test them.  The PAW box doesn't start to transmit on the ARF until it gets a GPS fix, so when testing after a power up always ensure you either have a GPS unit attached or CollisionAware active.

After poor RF performance, we sited two Awares near each other and started walking. As mentioned, the signal was lost for mine after 30 or 40 yards or so. Can we send the things back to the manufacturer for replacement? Out of the three we had, lt looked like one transmitted 30 or 40 yards, another 300 yards, and the third about 5 miles!

[ianfallon]

If the ARF heartbeat is flashing then the module is up and active, bar plugging one into an RF Power meter there is little you can do to test them.  The PAW box doesn't start to transmit on the ARF until it gets a GPS fix, so when testing after a power up always ensure you either have a GPS unit attached or CollisionAware active.

After poor RF performance, we sited two Awares near each other and started walking. As mentioned, the signal was lost for mine after 30 or 40 yards or so. Can we send the things back to the manufacturer for replacement? Out of the three we had, lt looked like one transmitted 30 or 40 yards, another 300 yards, and the third about 5 miles!

A few questions:

- Do they all have the same hardware construction technique ?
- Do they all have the same antennas / antenna connectors (SMA soldered vs pigtail etc)
- Are they all soldered as well as each other 

AFAIK ground - ground even in clear air will not be as good as air - air (in clear air).

btw do you know about the master / slave test mode ? You can put one in each mode via the Configuration web interface and then the logging will show power levels. Would be interested to see the values you get.

[Paul_Sengupta]

A few questions:

- Do they all have the same hardware construction technique ?
- Do they all have the same antennas / antenna connectors (SMA soldered vs pigtail etc)
- Are they all soldered as well as each other 

Two of them used the JCurtis module, including mine which didn't appear to transmit much at all. I can't comment on the quality of the soldering! But my unit which wasn't transmitting for toffee could still receive from 5 miles away, so I don't think it's the antenna or connection. Two of the units have the large antenna, the third has a GSM type antenna, but for the final test we swapped antennae and went flying again but it made little difference.

Air to air range was similar to ground range in that the 300 yard one was picked up from about 300 yards away in the air, and my one was only just picked up when in close formation.

btw do you know about the master / slave test mode ? You can put one in each mode via the Configuration web interface and then the logging will show power levels. Would be interested to see the values you get.

Forgot about that. I'll maybe give that a go next time.

Ah, more info in this thread:

http://forum.pilotaware.com/index.php/topic,160.msg2400.html

[JCurtis]

Two of them used the JCurtis module, including mine which didn't appear to transmit much at all. I can't comment on the quality of the soldering!

Well, it was soldered with additional flux to ensure good wetting on the joints.  The Rx would't have got through if it was too bad, the signal would have been very low at 5nm and a bad joint would have made that much worse.  I'll pop it onto a power meter if you would like, but I suspect it will be the same ~90mW as the rest.


Edit: Correct units from dB to mW...

[ianfallon]

Sorry - please don't interpret that post as being rude about your soldering am sure it's better than mine by far!

[JCurtis]

Sorry - please don't interpret that post as being rude about your soldering am sure it's better than mine by far!

No problem there , a connector issue won't resolve the problems with the ARF.

[JCurtis]

I'll pop it onto a power meter if you would like, but I suspect it will be the same ~90dBm as the rest.

1 megawatt seems a bit excessive 90 mW?

Yep, should be ~90mW, spent to much time flipping between units today.  I'll nip back and edit that!

[Pete]

Hi.

Just want to reiterate a few things.
I had a measurement done on the PA Box -89mW was recorded. I have tested on the ground and in the air all 3 types of build.
Build 1 - The original self build with Digole Regulator board and home brewed wiring using 40 pin IDC block..
Build 2-  Jeremy's shield board with Baro and myself soldering another ARF unit to it.
Build 3-  Jeremy's  shield board with Baro and ARF as the plug and play no soldering option using pigtail and direct SMA for comparison. No difference observed.


The most range I ever had from these units was 4.7nm line of sight to a unit on the ground from 1000'. I have not done an air to air  test and flying at 150kts wouldn't want to get anywhere near a potential target either. One aircraft used during testing, had the Aerial mounted externally for testing with a 70Kts airspeed.
More tests are planned at lower airspeeds. Same observations  as most of this topic thread indicates-, nothing has been consistent.

[captchaos]

A few questions:

- Do they all have the same hardware construction technique ?
- Do they all have the same antennas / antenna connectors (SMA soldered vs pigtail etc)
- Are they all soldered as well as each other 

AFAIK ground - ground even in clear air will not be as good as air - air (in clear air).

Ian the construction techniques are detailed in my air testing post. However, briefly one of mine is soldered by me using Digole reg and the other is the full Jeremy shield presoldered option with on board SMA. The soldered one uses two pig tails, one for the ARF and one for the DVB dongle so I can mount on the case for spiral GSM type aerial. The other one has standard long aerial on the SMA and standard DVB aerial.

The one I soldered (but not for that reason) is detectable at the greatest range. But I could only detect Paul's unit and one of mine when Paul took it in his aircraft when very close. Therefore I wondered if power source was a factor, or blanking or may be both my units don't receive well. It would be good to work through each potential issue to reach a conclusion.

Hope that helps answer your question.