The Aero Thread..

[s-band]

15W
1199.3285MHz LHCP
1197.4815MHz RHCP
1202.4785MHz RHCP
(with the T channels on RHCP at 1533.953 and 1534.500 (SDR VFO)

I had another look and I don't think these belong to 15W they actually peak a few degrees west of the aero. I think the 25E beacon is ok. Can anyone else see them, perhaps with a bigger dish to give a better fix?

 

[Confucian]

Thanks s-band for all the info, not had a chance to mess today been otherwise engaged and we have had sun, rain, hail, thunder, high wind and snow all in the space of a few hours.
Been at 1090mhz for a while, can track aircraft in real time up to nearly 300mile range, see file. The range rings are 50milea apart and the colours represent the different altitudes .

 

[Vipersan]

So ..its late and I'm knackered ..
This has really hurt my eyes ...
But hung the tiny 3mm TCXO chip with fine wires on stripboard ...and located a 3v supply on the SDRplay pcb ...
grounded the so called AFC pin of the osc chip ...and cap coupled (220pf) the TCXO output to the MIRIC chips osc input pin ..which previously had it's own osc crystal ...but now removed ..
It aint pretty but it IS working ..
and will be left working overnight to see if there is any drift in the morning ..?
Here are a couple of photos of the bodge up ..and a screengrab showing the Aero ACARS data coming in ...
Not an ideal temp/drift test as this can only really be done when the TCXO is properly fitted and SDRplay is located in a hot environment ..
Still it proves it works ...
and my warranty ...
errrr gone...
gnite I'm off to bed..

 

[Vipersan]

Still tired but needed to get some sort of working solution that was neater ...
So ..same basic idea ...but a tiny custom cut piece of pcb groundplane ..
cut the cross in it ..then hand drilled 4 holes with a pin vice.
An idea that came to me when I woke up this morning .
Should be able to get the lid on now ..and really test for temperature drift..
Think I might have a migraine later ...
My poor old peepers ...
rgds
VS

....forgot to mention ...
no drift at all visible at 7:30 this morning ...and bang on target again when reconnected with the mini sub pcb and tcxo re-fitted.

 

[Vipersan]

So ..the verdict fwiw ..
Still drifting when the pcb is enclosed ...ie it must get toasty inside the box.
The good news is that it doesn't drift as much ...so I guess it was worth the effort.
Really I need to check this on a more stable signal source ..
..as it may be there is _possibly_ what apppears to be drift at this frequency range ..but is actually a product of doppler shift from Inmarsat as it performs its figure 8 ?
More likely though it is indeed down to the SDRplay...and the fact that I am trying to lock such narrow signals ...and AFC cannot be used in USB mode.
It is undeniably better for having the TCXO instead of a standard crystal 'oven' ...but I guess I will have to put up with the slight drift ..which at least stabalises to a large degree once optimum temp is reached.
I am curious though ..users of dongles or Airspy ?
Just how much effort is required to maintain a stable lock on a T stream ...considering it isn't a constant signal ?
Just how much tweaking and chasing do you guys have to do ?
rgds
VS
The leftmost edge of the T stream data is now located at 1.534.718.000
whereas this morning it was at 1.534.738.000 on SDR#

 

[s-band]

I am curious though ..users of dongles or Airspy ?
Just how much effort is required to maintain a stable lock on a T stream ...considering it isn't a constant signal ?
Just how much tweaking annd chasing do you guys have to do ?
rgds
VS
The leftmost edge of the T stream data is now located at 1.534.718.000
whereas this morning it was at 1.534.738.000 on SDR#

It looks like your system is off by about 200kHz.

I suspect that the drift your are seeing is from the LNB. I have a TCXO in the LNBF. The combined drift over 24Hrs is about 2kHz which JAERO can cope with so it does not need tweaking. The widest bandwidth on the latest SDR# is 16kHz on USB which is plenty. I can relate the drift on mine to day/night temperature changes. I'm using an Airspy but was using an RTL with a 1ppm TCXO. I may lock Airspy to a GPS source but there are enough cables across the floor already.

I had quite good results with a £5 RTL stick once I took its case off. That did need tweaking after it had warmed up but its self-heating kept it steady after that. It has a surface mount xtal which may be a bit better than the large can ones.

Here's a capture showing 15W a few minutes ago. The signal in the centre is calibration at 3615.8MHz locked to GPS showing the I have an error of around 3kHz

 

[Vipersan]

It looks like your system is off by about 200kHz.

I suspect that the drift your are seeing is from the LNB. I have a TCXO in the LNBF. The combined drift over 24Hrs is about 2kHz which JAERO can cope with so it does not need tweaking. The widest bandwidth on the latest SDR# is 16kHz on USB which is plenty. I can relate the drift on mine to day/night temperature changes. I'm using an Airspy but was using an RTL with a 1ppm TCXO. I may lock Airspy to a GPS source but there are enough cables across the floor already.

I had quite good results with a £5 RTL stick once I took its case off. That did need tweaking after it had warmed up but its self-heating kept it steady after that. It has a surface mount xtal which may be a bit better than the large can ones.

Hmm ..I figured that the Titanium PLLs were less prone to drift ...certainly it is better than the ESX lnb I previously tried.
Did you retrofit the TCXO in your lnb ?
If so perhaps I too should do this ?
If so..did you document the procedure ?

My system is certainly not stable enough to be left unattended for more than a couple of hours ...it then requires tweaking of SDR#

..I am also limited to an earlier version of SDR# on account SDR# stopped supporting SDRplay in more recent versions..
rgds
VS

I have a couple of GPS patch antennas on order ...but because I cant use a later version of SDR# ...I dont have access to a second VXO ....so unlikely I can use the GPS lock method.

 

[spacedish]

Now back after 2 weeks away so hopefully I can help with a few of the issues.

First...keep everything as simple as possible
Use a PLL C band lnb such as the Titanium series
Inmarsat is used whilst crossing the OCEANS.When in 1090mhz range normal ADS-B is used , which Planeplotter can track to give "joined up" coverage.
Planeplotter is now also incorporating PiReps { pilot reports} for Oceanic Traffic which means more plots including mil traffic.

Its a lot to ask , I know but for anyone prepared to dedicate their system to feeding PlanePlotter at C band full time , I have a small number of free licences available. I would especially like to hear from anyone who can see the outer limits of the arc...or anyone based in the US who may be reading this thread.

Drift.....it has been noticed that around 0800 GMT and 1600GMT the Inmarsat frequencies shift about 5khz
...otherwise signals on 15 west are pretty stable. On 25E the increased inclination can cause some loss of signal at times but a carefully centred dish up to 1.8m will maintain a useable signal all day without adjustment.

Its pretty busy in the Atlantic at present!

 

[s-band]

Did you retrofit the TCXO in your lnb ?
If so perhaps I too should do this ?
If so..did you document the procedure ?

Yes.
It's worth it.
Not yet - I have some reservations about the levels into the downconverter IC. I'll add something here www.satellites.co.uk/forums/threads/titanium-pll-c-band-lnbs.168071/ soon

 

[Vipersan]

Now back after 2 weeks away so hopefully I can help with a few of the issues.

First...keep everything as simple as possible
Use a PLL C band lnb such as the Titanium series
Inmarsat is used whilst crossing the OCEANS.When in 1090mhz range normal ADS-B is used , which Planeplotter can track to give "joined up" coverage.
Planeplotter is now also incorporating PiReps { pilot reports} for Oceanic Traffic which means more plots including mil traffic.

Its a lot to ask , I know but for anyone prepared to dedicate their system to feeding PlanePlotter at C band full time , I have a small number of free licences available. I would especially like to hear from anyone who can see the outer limits of the arc...or anyone based in the US who may be reading this thread.

Drift.....it has been noticed that around 0800 GMT and 1600GMT the Inmarsat frequencies shift about 5khz
...otherwise signals on 15 west are pretty stable. On 25E the increased inclination can cause some loss of signal at times but a carefully centred dish up to 1.8m will maintain a useable signal all day without adjustment.

Its pretty busy in the Atlantic at present!

Much as I'd like to feed PP ....I see little point dedicating a system/dish to this unless I can solve the drift issue...
I can't be here 24/7
;)
Is that what those triangles are that appear instead of planes ...? Military Traffic ?

 

[s-band]

Its a lot to ask , I know but for anyone prepared to dedicate their system to feeding PlanePlotter at C band full time

Drift.....it has been noticed that around 0800 GMT and 1600GMT the Inmarsat frequencies shift about 5khz

Sorry but I can't dedicate a dish and a PC.
Is that real drift from Inmarsat and or the planes? Does the satellite use a regenerative repeater or is it just linear?

Here's my plot from 15W at about the same time. The heap around London is from my ADSB RX which is sitting on the window sill.

 

[Vipersan]

Only showing a couple of planes on my radar atm ..
But then I'm not connected to the network ...so only showing my own captured data
..and I have to keep correcting if there is any drift..
;)

 

[Vipersan]

Suddenly got quite busy here on Cband ...
All my data ...still no network connection ..
Not bad for an offset 1.5m
;)

 

[Confucian]

Confucian, I forgot to say that, on my set-up, 25E is LHCP and 15W RHCP. I checked polarisations based on Arabsat 20E and other TV but am only getting 15dB X polar rejection. It is worth tweaking the position of the plate fore/aft in the feed as I found I could get 1.5dB improvement moving it out a little from the end stop.

I think I've found the beacons and it is easier to peak the antenna on them than the aero stuff. The beacons have sidebands out to about +/-150kHz. CW frequencies at IF and within about 1kHz:
15W
1199.3285MHz LHCP
1197.4815MHz RHCP
1202.4785MHz RHCP
(with the T channels on RHCP at 1533.953 and 1534.500 (SDR VFO)
25E
1198.9975MHz LHCP
(T channels 1526.078 and 1526.108MHz also LHCP)

Had a quick fiddle this morning, peaked dish on a signal I found close to 1198.9975
Still nothing seen on "T" channels
got plenty of activity higher up the band so still not sure I'm looking at 25e.

 

[s-band]

Had a quick fiddle this morning, peaked dish on a signal I found close to 1198.9975
got plenty of activity higher up the band so still not sure I'm looking at 25e.
[/ATTACH]

That may be the beacon, it looks similar. The beacon is quite strong here relative to the aero signals. I can't see anything that looks like your 2nd pic.
Attached are pics of the beacon (I think) and the Aero sigs. The T channels are at the markers and there are some R channels around 1526.3MHz.
The effective sample rate is 1.25Ms/s & FFT setting is 131072. You could replicate the settings to get an idea of relative s/n in a known bandwidth. I think you can set 1Mbps?

I realised why the s/n I get on 25E is worse than 15w - I'm looking through trees that weren't that big 20 years ago when the dish was installed - doh! I'm getting about 4-5dB xs noise. The Aero s/n is 2-5dB which ties in with the 6-13dB on 15W

 

[s-band]

got plenty of activity higher up the band so still not sure I'm looking at 25e.

I don't know why I didn't see it the first time but those signals peak at the same point as the beacon and aero but they are RHCP. I guess they are BGAN or other Inmarsat voice/data. Aero sigs are a 5-10dB lower.


I'm also not convinced that my xs noise was from the trees. Looking in a wider span the beacon is sitting on a pedestal of noise. Playing more I think it is data from BADR6 Badr-6 - Arabsat which doesn't appear to carry any permanent TV. The beacon from BADR6 is quite strong on 3701.1 (1448.9 IF) LHCP. That peaks with the noise humps and is slightly to the east of Inmarsat.

I think BADR6 is reducing the s/n of the aero signals for me

 

[s-band]

I think BADR6 is reducing the s/n of the aero signals for me

Ignore that - it's only affecting the Inmarsat beacon, BADR doesn't seem to go below 3700, the aero being ~3623.9

 

[Confucian]

That may be the beacon, it looks similar. The beacon is quite strong here relative to the aero signals. I can't see anything that looks like your 2nd pic.
Attached are pics of the beacon (I think) and the Aero sigs. The T channels are at the markers and there are some R channels around 1526.3MHz.
The effective sample rate is 1.25Ms/s & FFT setting is 131072. You could replicate the settings to get an idea of relative s/n in a known bandwidth. I think you can set 1Mbps?

I realised why the s/n I get on 25E is worse than 15w - I'm looking through trees that weren't that big 20 years ago when the dish was installed - doh! I'm getting about 4-5dB xs noise. The Aero s/n is 2-5dB which ties in with the 6-13dB on 15W
View attachment 92254 View attachment 92255

Way Hay , cracked the problem what I thought was LHCP was RHCP
Whole thing needs a lot of refining but it works (ish). Advice needed on Jaero settings as I have been working on "poke & hope" just to get something on the screen. Also being able to hear the signal would be very helpful, must read back I seem to remember something about that earlier in one of the threads.

 

[Confucian]

....... I may lock Airspy to a GPS source but there are enough cables across the floor already.
........... The signal in the centre is calibration at 3615.8MHz locked to GPS showing the I have an error of around 3kHz

Ok so as an "amateur" how do I accomplish "locking my receiver to a GPS source"

 

[Vipersan]

Ok so as an "amateur" how do I accomplish "locking my receiver to a GPS source"

Sorry buddy ...
I hope you get an answer ..cos I too want to know how .
;)