The Aero Thread..

[Channel Hopper]

View attachment 92122
...not sure what I did ..but selected the 'satellite' image ...and zoomed out ...and the home location appears to have corrected itself ...

Still laughing at the 'coast of Cornwall' bit.

 

[Vipersan]

Well I think I've found the needed 24mhz TCXO ...and would certainly consider adapting it ...but damned if I can find a spec sheet or pdf for it ..so no way to know the VCC supply voltage ...ground pin or indeed output pin ..
Nor can I determine its physical size...
This is the device ..
NDK 24MHz TCXO SMD ENA3291A
if anyone has more luck than me let me know.
doh!

 

[Vipersan]

Gave up trying to find the pdf for the above ...but found this one at Farnell
..and since I had to order somw chip quik anyway for work ...added a couple at about £1 each
rgds
VS
TXC 7Q-24.000MBN-T TCXO, GPS, 24MHZ, 3.2 X 2.5MM, CLIPPED SINE

 

[Vipersan]

Finally got hold of accurate dimensions for a large-ish homebrew patch antenna for 1.5 ghz ..
and ordered a nice sheet of 24swg brass to cut it from..
looks to be a straightforward build ..and although 0.2 inch balsa was used for the patch/reflector spacing in the original design ...this I will replace with something more weather friendly.
Guess what is just the right thickness ..?
Those c band dielectric plates that come with every c band lnb ..
It will require an lna at the head end ..which will require power which is something of a pita ...on account Bias Tees are so fffing expensive for power-insertion-into-coax.
The build will use sma connections as far as the lna ..but standard 50 ohm coax back to the SDR .

Just as an aside ..I have invested in a long leverage metal plate hand guillotine ...
Got one of fleabay for about £35 delivered ...250 mm blade.
Time I had one of these ..on account I find it difficult these days cutting sheet metal ...and hand sheers always make it curl anyhoo ..
;)

Not sure how well it will perform when used to receive inmarsat ..but what is important imo ...is that unlike a satellite dish which is highly direcional ...the patch _should_ accomodate an inclined bird better..
Yes it is still somewhat directional ..but not _as_ critical as a dish....behaving more like a GPS antenna/receiver.

 

[battenfan]

It will require an lna at the head end ..which will require power which is something of a pita ...on account Bias Tees are so fffing expensive for power-insertion-into-coax.

I'm tempted to order one of these:

http://lna4all.blogspot.se/

Can't the sat card power the lna? Those expensive bias tees are for people that use their rig for transmission as well, aren't they? I'm a noob so I'm just guessing, asking.

 

[Vipersan]

I'm tempted to order one of these:

http://lna4all.blogspot.se/

Can't the sat card power the lna? Those expensive bias tees are for people that use their rig for transmission as well, aren't they? I'm a noob so I'm just guessing, asking.

I wouldn't buddy ..(power from a sat card that is)
the voltage might well be excessive ..
Some Low noise amps draw their power down the coax ..some dont ...
but usually about 3 to 5 volts ...not 13 to 19volts as with a sat card ..
..but then again ..I would not be using a sat card or lnb for the patch antenna ...so would be a seperate coax 50 ohm ...not sat connected at all..
Bias Tees are basically just a method of in line power insertion to the coax without affecting the RF signal ...and using a low pass filter (ie cap and inductor in its simplest form ...to isolate the injected DC supply from the RF line without influencing the signal.
They are usually frequency or band specific and imo ..grossly overpriced for the job they do..
I have 2 LNAs ...one which has a choice of external power ...3 to 5v ...(similar to the one you linked to) ...and a more expensive WorldSpace one ...which has NO way of externally powering it ...and takes its supply down the coax at 2.3volts ..
rgds
VS

 

[Confucian]

Hi All sorry for the cross post but .............
Has anyone in the UK/Ireland had any joy on Inmarsat 25E ? I get plenty of signals higher up the band but zilch where the Aero Signals are supposed to be. :-(

 

[Vipersan]

Hi All sorry for the cross post but .............
Has anyone in the UK/Ireland had any joy on Inmarsat 25W ? I get plenty of signals higher up the band but zilch where the Aero Signals are supposed to be. :-(

I've already answered your post in the inmarsat thread ..
..think you mean 25E ?

 

[Vipersan]

Could just be that it's friday and the air traffic is heavier ..
Could just be that Inmarsat is on the ARC (no idea atm)
Or ..it could be the higher quality link pigtail coax I ordered...and just fitted.
Certainly I hope it's the latter.
Probably the most traffic in the air I've had from my setup ..
Still suffering drift ..but I have my TCXO on order and will retrofit it when it arrives ..
Said it was in stock at Farnell when I ordered ...
They lied..
doh!

 

[aceb]

25e is very busy, there's a single T channel I can hear but it handles a lot of traffic over Africa. I think there's another channel but it's too weak to decode atm. I normally have about 90 AC after an hour of decoding on 25e.

 

[Confucian]

25e is very busy, there's a single T channel I can hear but it handles a lot of traffic over Africa. I think there's another channel but it's too weak to decode atm. I normally have about 90 AC after an hour of decoding on 25e.

Thanks for the info, I was beginning to think I was flogging the proverbial dead horse. If it ever stops raining (here in Ireland) I will persevere.

 

[s-band]

Thanks for the info, I was beginning to think I was flogging the proverbial dead horse. If it ever stops raining (here in Ireland) I will persevere.

I have been getting T channels on IF frequencies of 1526.078 and 1526.108MHz +/-1kHz (SDR# VFO, not centre) which decoded reasonably well at Eb/No of 3-5dB compared to 8-13dB on 15W. I'm using a 1.5m PF with feed offset & tit C1W lite LNBF.

 

[Vipersan]

I have been getting T channels on IF frequencies of 1526.078 and 1526.108MHz +/-1kHz (SDR# VFO, not centre) which decoded reasonably well at Eb/No of 3-5dB compared to 8-13dB on 15W. I'm using a 1.5m PF with feed offset & tit C1W lite LNBF.

Well ..fwiw I hope to be going after Inmarsat(s) with a patch antenna soon ...which of course will be less directionally critical ....and will mean I dont have to tie up my 1.5m dish 24/7
Have any of you guys tried this yet ?

 

[Channel Hopper]

Well ..fwiw I hope to be going after Inmarsat(s) with a patch antenna soon ...which of course will be less directionally critical ....an will mean I dont have to tie up my 1.5m dish 24/7
Have any of you guys tried this yet ?

You need a toroidal antenna, just by chance I have one in the shed.........................

I'll add it to the box.

 

[Confucian]

I have been getting T channels on IF frequencies of 1526.078 and 1526.108MHz +/-1kHz (SDR# VFO, not centre) which decoded reasonably well at Eb/No of 3-5dB compared to 8-13dB on 15W. I'm using a 1.5m PF with feed offset & tit C1W lite LNBF.

Thats encouraging looking at your set up I should have a chance. I'm using a C1W-PLL Wideband LNB which a 1.4m offset dish all to itself feeding a 1ppm TCXO R820T2 dongle. I got to the stage of finding Astra 28.2 and 19.2 then came between them, swooped lnb and nudged the inclination, can see signals higher in the band but nothing around 152x 153x. I need to get the screen out near the dish so I can see whats going on while i'm ferckeling it and it to stop raining and blowing a gail. lol
Thanks for your input, most appreciated.

 

[aceb]

Well ..fwiw I hope to be going after Inmarsat(s) with a patch antenna soon ...which of course will be less directionally critical ....an will mean I dont have to tie up my 1.5m dish 24/7
Have any of you guys tried this yet ?

Not sure what you're going for on L band but I'm pretty sure there's no a\c positioning data on it, John or Jonti can confirm.

 

[Vipersan]

Not sure what you're going for on L band but I'm pretty sure there's no a\c positioning data on it, John or Jonti can confirm.

I know a/c data is available in L band ..but didn't know the positioning data had been stripped ..
That 's a dissappointment..

 

[Vipersan]

So what about 1090 mhz ...sounds from the reading that positioning data is available there ??

How to receive and decode ADS-B and ACARS GPS signals from aircraft with RTL-SDR | F1JXQ

 

[s-band]

I know a/c data is available in L band ..but didn't know the positioning data had been stripped ..
That 's a dissappointment..

I thought that the L band was ground station to aircraft and C band aircraft to ground?

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)

 

[s-band]

So what about 1090 mhz ...sounds from the reading that positioning data is available there ??

How to receive and decode ADS-B and ACARS GPS signals from aircraft with RTL-SDR | F1JXQ

Yes, it is. Get ADSB# or similar and stick a bit of wire (~70mm) in the SDR input and you should see something from nearby aircraft on 1090MHz.