New ATOM Ground station SDR Detection Issues

[exfirepro]

Hi Kevin,

POE cable running next to good quality (well screened) coax should cause no issues. I also echo Lee's comment about the 'In Range / Out of Range' figures - this refers to GSM signals available and used for calibration and has no relation to traffic or effective receive range.

Out of interest, what's in the box under the Flarm antenna?

Regards

Peter

[kevkdg]

Hi,

All the Coax cable we used (1090/Pi3/FLARM) is the HDF400, so I believe that is good quality low loss and is the stuff Keith supplies.  So should be well insulated.

The FLARM antenna we have is not one we ordered from Keith, it was one we had already from our OGN Ground Station.  A Gliding club member is a lecturer at a University in the area of radio, comms, antennas, electronics etc and so fine tuned this antenna at the uni.  It has a small SMA Male Connector at the end, this is housed inside the waterproof box at the base of the antenna.  We purchased an HDF400 SMA Female Crimp Connector which connects the Coax directly to the SMA connector at the base of the antenna (all housed in the small box).

Cheers
Kevin

[exfirepro]

Hi Kevin,

Thanks for the quick reply. As I said earlier, I wouldn’t expect interaction between your POE cable and the good quality coax you have used.

I take it the photo is of the connector on the bottom of the tuned ‘homebrew’ antenna? (not the end of the coax feed).

OK on the box being used to protect the SMA connectors. I was concerned that it might contain a filter/preamp (often used in OGN installations in an attempt to boost range). I had one of these fitted originally at my home station, but experience has shown that these can preclude (or at best seriously skew) the GSM Scan, so mine has since been removed. That was why I asked.

Hopefully all will now be good.

Best Regards

Peter

[kevkdg]

Hi peter,

Yes it's an sma connector at base of antenna in the photo.

Fingers crossed all will be well now.

Kevin

[exfirepro]

Thanks Kevin,

It certainly seems to be working ok now thanks to your hard work. Good to know that we have helped to get it sorted out.

I’ve just had a look at the PWUKRUF coverage via the PilotAware data site (I have access via the admin network) and it’s showing good levels of traffic at fairly impressive range, though probably not surprisingly a little bit ‘sparse’ on the FLARM side at the moment due to lack of recent activity. That should of course build again once we get back out of Lockdown and into better weather. I know I’m certainly experiencing withdrawal symptoms as I haven’t flown since before Christmas. Hopefully not too long now. 

Best Regards

Peter

[kevkdg]

Thanks Pete,

There has been some FLARM traffic today at Rufforth as the Gliding Instructors have been taking currency flights (as permitted by the DFT and BGA).

What tools are you using to determine coverage?

Kevin

[kevkdg]

One thing I've noticed is that PWUKRUF has a couple of stickys on the Throttled report....

I'm not sure what the "stickys" represent.... do they mean the station has experienced those issues, if so how long does a "sticky" flag remain in place if the ground station is now operating OK

[steveu]

What tools are you using to determine coverage?

If you are the ground station maintainer you will have had an e-mail (to the address attached to your station) a while back with a URL + password for your ground station for remote access, and in one of the menus from the home page there is a coverage menu.

Some info here:

https://www.youtube.com/watch?v=VOoZPhzFNDY

Thread here:

http://forum.pilotaware.com/index.php/topic,1998.0.html

[Admin]

One thing I've noticed is that PWUKRUF has a couple of stickys on the Throttled report....

I'm not sure what the "stickys" represent.... do they mean the station has experienced those issues, if so how long does a "sticky" flag remain in place if the ground station is now operating OK

Sticky’s remain until the next reboot
I presume these are voltage issues?
Thx
Lee

[kevkdg]

I'm not aware of any issues.

So am wondering went the stickys.

[exfirepro]

Kev / Lee,

PWUKRUF is showing UVS and THS on the Database Throttled Screen, so both at some point since the unit was last rebooted, but not at the present time. Kev, as it seems to be working ok at the moment, I’d suggest just monitoring for a period and see what happens, or do a hard reboot to reset the report which will make it easier to see if it happens again.

I used the ‘Coverage’ tool which is accessed at the bottom of the ‘Status’ Dropdown on the ‘PilotAware Data’ Maintainer screen referred to by Steve above (rather than the Vector tab which is more for aircraft reports). You can then easily select the desired coverage type and if appropriate narrow the time period by selecting specific dates from the drop down calendar at the top right of the Coverage screen. Remember that ADSB reports are limited to a maximum of 60Km to control the level of data.

Regards

Peter

[kevkdg]

Thanks Chaps,

I did a remote "sudo reboot" over the weekend, but guess that does not reset the report.  I assume I need to switch it off then on again.

It had been running for a while without the FLARM antenna or RTLSDR, maybe that had some bearing?

Regards

Kevin

[Admin]

Hi Kev
What is the power supply being used ?
Can you provide a link to where it was acquired?

I understand you are using POE ?
Thx
Lee

[kevkdg]

Hi,

PoE reference was due to a ethernet cable being used to power an external wi-fi antenna routing next to the FLARM Coax, not as a power supply to the ground station Pi.

The Raspberry Pi3 is being powered by the same AC/DC Adaptor that was used when it was just an OGN station.  This is 5v 3amp (Model JCY-0530) micro USB.

However, we are showing sticky's rather than current voltage/throttling issues.  Is there a log of when these voltage/throttling issues occurred?

I have just done a remote sudo reboot, this has indeed cleared UKRUF from the Throttled report.  But if there was a voltage/throttling issue, why would it not be consistent if it was due to the power supply.  What would cause intermittent voltage issues?

Kevin

[Admin]

Hi Kevin

The circuitry on the RPI which measures the voltage levels has a threshold, when this is crossed, the Flags are set both sticky and now
if the threshold is exited the sticky remains but the now is cleared

During different operations the RPI will draw different levels of power depending upon the processing which is happening.
The heaviest load is from the ogn-rf/ogn-decode processes, when there is a lot of FLARM data to decode, this can take processing upto 100%, this generates cpu load, and draws current, drawing current can cause the voltage to drop, triggering the flags in question

When the station was run as a pure OGN, this would not have been checked - there is nothing for you to observe if the  voltage is dropping below the threshold, it could have been happening and you would have no feedback to tell you

I googled the power supply (Model JCY-0530), and could only find this reference
https://www.supremegamegear.com/products/5v3a-power-supply-us-plug
which shows it as a $1.75 power supply 
is that for real ?

I think the Official Pi power supply would be a better choice - but lets monitor how you get on with yours

Alternately, if you want an official supply, here is the reference.
https://shop.pimoroni.com/products/raspberry-pi-universal-power-supply

Thx
Lee