Author Topic: New Stations Added  (Read 94532 times)

Keithvinning

Re: New Stations Added
« Reply #15 on: September 09, 2017, 11:09:30 am »
Hi Rob

Thanks for your support in extending the network. I look forward to seeing traffic

Moffrestorer

Re: New Stations Added
« Reply #16 on: September 24, 2017, 02:00:33 pm »
Hi all,

PW Kingstone, SW of Hereford now fully operational with antennae mounted on top of my house on a 3 metre mast. Thanks for your help Keith in supplying the system and initial set-up.

I repeated the set-up yesterday after erecting the aerials. Not sure if that was necessary. It gives the same message as seen by another new station in an other thread, that results are inconsistent. Is this likely to be a problem?

Not much traffic around this weekend but did get acknowledgement from OGN for seeing an RAF Tutor aircraft NE of Shobdon (presumably PowerFlarm equipped), so range not bad on that direction.

Chris

exfirepro

Re: New Stations Added
« Reply #17 on: September 24, 2017, 02:48:37 pm »
Hi Chris,

Well done. Milfield (nr. Berwick on Tweed) also went live on Thursday.

The 'inconsistent results' message refers to the gsm scan, though this 'could' I understand reflect other issues. I ignored it and mine (OGN-R PWBalerno) works fine.

Regards

Peter

Admin

Re: New Stations Added
« Reply #18 on: September 24, 2017, 03:09:16 pm »
Hi Chris

What sdr dongle are you using, and what was the reported crystal error in ppm

Thx
Lee

Moffrestorer

Re: New Stations Added
« Reply #19 on: September 24, 2017, 07:49:21 pm »
Hi Lee,

The SDR is the NooElec NESDL Dongle as supplied by Keith Vinning. In fact Keith supplied the complete system last week with software pre- loaded.

Yesterday's  gsm scan concluded with a receiver crystal correction of +1.040 (0.335) 71 ppm

"Warning: measurements appear inconsistent:please retry with better initial estimate or with lower gain to reduce distortions. Note when the receiver warms up the Xtal may drift 5-10ppm". In fact the system was powered up for approx 4 hrs before redoing the set-up which was mainly done to change the password, as recommended. I'm not sure what "initial estimate" refers to, is it the Station Lat/long which we obtained from the Shellenberg site?

The Summary of the set-up was as follows;
Station SDR PPM is 1
Station SDR Gain is 50
Station SDR Freq Centre is 957.400

Thx,

 Chris

exfirepro

Re: New Stations Added
« Reply #20 on: September 25, 2017, 08:33:22 am »
Hi Chris,

The 'Initial Estimate' referred to is the ./gsm_scan --ppm 50 --gain 20 that you put in to get things started. The starting point of 50 parts per million for frequency drift is designed to cope with 'cheaper', less technical SDR dongles (like the standard PilotAware ones), where the frequency can drift considerably with temperature. With the Temperature Controlled Crystal Oscillators used in the NooElec TCXO dongles (other makes are available) which we are using for the OGN-R relay stations, we expect to see virtually no frequency drift, so the start point of 50ppm for the gsm scan (which is designed to measure the drift of each individual dongle) is far too high. Best results are obtained by starting the gsm scan at ./gsm_scan --ppm 0 --gain 20.

The 'inconsistency' report relates to significant variations in the figures achieved during the scan, for the range of gsm frequencies compared, which 'should' apparently all report within +/- 1ppm or so of each other. This could result in an inaccurate figure being applied to compensate for 'non-existent' frequency drift.

An 'expected' result for a TCXO dongle should apparently be in the region of RF crystal correction +/- O.1 with an RF gain of somewhere around 30dB, though there are several factors which combine to influence the actual result.

There is an excellent explanation of this on the OGN forum at 

https://groups.google.com/forum/m/#!forum/openglidernetwork

though you need to sign up to the group via the OGN wiki page to read this, see....

http://wiki.glidernet.org/subscribing

Regards

Peter
« Last Edit: September 25, 2017, 08:46:01 am by exfirepro »

Moffrestorer

Re: New Stations Added
« Reply #21 on: September 25, 2017, 09:59:43 am »
Thanks Peter, very informative.

The results of my gsm scan were generally within +/- 1ppm with the only exceptions being +82 ppm at 957.0 Mhz, +7ppm at 957.8, and +150 at 958.8 Mhz. I'm guessing these latter readings are unlikely to be significant in the overall picture.

The OGN forum posting by Nick Bonniere seems to outline an approach for estimating initial ppm and gain for the scan test but it would also seem that the ognpaw software does this automatically in a series of steps to set the SDR crystal correction and Tuner gain. So I'm assuming there is not a lot one can do to improve on these figures?

Thx,

Chris


exfirepro

Re: New Stations Added
« Reply #22 on: September 25, 2017, 09:53:14 pm »
Hi again Chris,

I wouldn't worry too much about a couple of slightly 'out of range' results. The purpose of the exercise is simply to calculate the frequency 'error' of the particular dongle, by measuring the reported frequency of 'known frequency' gsm signals, so that the software can then tune the receiver to the correct receive frequency. With the TCXO dongles we are using for OGN-R, frequency error and drift are generally extremely low at around +/- 0.1ppm. The actual figure derived from your setup is reported on (ognpaw.local):8080 as RTL-SDR device / Frequency correction...... If this is reporting a significantly greater figure than the above it might be worth rechecking the scan, but otherwise things should be just fine.

You are correct by the way, Lee has already 'automated' the OGNPAW setup, including the gsm scan to save non technical users having to worry about all this, so this shouldn't normally be an issue. It certainly took me a while to get my head round it all with the early 'manual' setups.

In extreme cases, the figure can if necessary be adjusted manually within the 'config' file, by those who have the required knowledge / expertise.

Best regards

Peter


exfirepro

Re: New Stations Added
« Reply #23 on: October 21, 2017, 02:40:18 pm »
Hi All,

Just had word from Rob Tatlow, that PWUKKir is now 'live' at Kirton (UKKir) - just south of Scunthorpe.

No sign of PAW traffic yet, so feel free to fly by and help populate the heat map if you are flying in the area (once the winds die down a bit).

Regards

Peter

PaulRuskin

Re: New Stations Added
« Reply #24 on: November 19, 2017, 04:30:39 pm »
There's now an OGN-R station at Orwell - about 15km west of Cambridge.  It's sitting alongside the Orwell OGN station.  Antennas mounted high and outside on a chimney.

Good results for OGN traffic, but still working on getting PAW traffic.

Paul

ridders

Re: New Stations Added
« Reply #25 on: November 19, 2017, 06:04:14 pm »
PWDeanlan (Deanland) has been online for about a week, once I finally got a pair of brackets to mount the two aerials to a 2 and quarter inch mast. Ive seen gliders detected on the OGN site that were some considerable distance away, the site has good line of sight and  the tug and gliders from Parham were occasionally detected by it this afternoon, when I was looking.  Being in close proximity to ringmer I hope that we may see OGN-UP from any local Flarm equipt gliders/Aircraft.
The views I express here are entirely my own and are not intended to represent my employer.

paulshutt

Re: New Stations Added
« Reply #26 on: December 04, 2017, 07:42:27 pm »
New Station now online.

Just converted our OGN station to an OGN-R station over the weekend at the Longmynd (Midland Gliding Club - PWMynd) between Shrewsbury and Ludlow in Shropshire.
The station is 1500ft above sea level so should get some good results, I just need to get the setup back into the proper position as I had to locate it in a temporary position whilst we had our new building built, once it is in the final position it should get 100 - 150 km range and will reach well into Wales.

Cheers

Paul.
There are 10 types of people in the world, those who understand binary and those who don't.

grahambaker

Re: New Stations Added
« Reply #27 on: December 04, 2017, 09:31:30 pm »
New Station now online.

Just converted our OGN station to an OGN-R station over the weekend at the Longmynd (Midland Gliding Club - PWMynd) between Shrewsbury and Ludlow in Shropshire.
The station is 1500ft above sea level so should get some good results, I just need to get the setup back into the proper position as I had to locate it in a temporary position whilst we had our new building built, once it is in the final position it should get 100 - 150 km range and will reach well into Wales.

As a power pilot PAW user based at Welshpool, that's brilliant news!

Deker

Re: New Stations Added
« Reply #28 on: December 05, 2017, 03:19:34 pm »
Turweston, EGBT is now up.

In testing phase with antennas slightly below roof level, once all OK these will be permanently installed on top at 45m above ground.
Currently getting about 40KM range which should improve once the antennas have clear 360deg sight of the horizon.
ATB
Deker.

Keithvinning

Re: New Stations Added
« Reply #29 on: December 06, 2017, 09:24:07 pm »
Quote

As a power pilot PAW user based at Welshpool, that's brilliant news!

What do we need to do to get one at Welshpool?
There is one also at Foel

Keith