The Aero Thread..

[Vipersan]

According to Dishpointer
True Elevation For Inmarsat 3-F2 = 27.7 from my location.
This being the Elevation IF this bird was not inclined ..
So I'm going to watch the changes over a 12 hour period.


Starting at noon
I have the antenna on a 1.1m offset dish (homebrew lnb arm) ...so the size will of course employ a narrow-ish beam and since I cannot track 3-F2 I want to find the mid point and using a relatively narrow beam I am expecting dropout of signal and changes over the period of oscillation above and below the equatorial plane .
Particularly since the installation was set up at a time of day unknown in relation to this oscillation.
Frequency monitored 1.546064 ghz

My first measurement at :-
12:00 Noon local time , Elevation indicated by N2YO = +27 , Signal level = 9db approx - nominal decoding of data - occasional errors - quadrature constellation in and out of lock but mostly locked.

01:00 PM - N2YO (Inmar 3-F2 = +27.5 ) ,Signal level = 8db approx , nominal decoding of data - occasional errors - quadrature constellation in and out of lock but mostly locked

02:00 PM - N2YO (Inmar 3-F2 = +28.0 ) ,Signal level = 7db approx , nominal decoding of data - occasional errors - quadrature constellation in and out of lock but mostly locked

02:15 PM - N2YO (Inmar 3-F2 = +28.2 ) ,Signal level = 6db approx , nominal decoding of data - occasional errors - quadrature constellation in and out of lock but mostly locked
Signal levels appear to be climbing ?

02:30 PM - N2YO (Inmar 3-F2 = +28.3 ) ,Signal level = 8db approx , nominal decoding of data - no observable errors - quadrature constellation solid lock
Signal levels appear to be climbing rapidly ?

Maybe the laterall movement is playing a part now ...as 3-F2 is close to maximum Elevation cycle ? according to N2YO

Time 2:40 PM ..and the signal level just dropped a dramatic amount from 8db to just over 5db ??
back to occasional unlock of quadrature constellation and occasional data errors..?
looks like the power levels from the bird are changing ...atmospherics? or being controlled ?
Elevation +28.4

Local time 2:45 PM ...
Signal just reurned to approx 8db rapidly from about 5db ...and still climbing ?
N2YO +28.4



03:00 PM - N2YO (Inmar 3-F2 = +28.6 ) ,Signal level = 6db approx , nominal decoding of data - very occasional errors - quadrature constellation in and out of lock but mostly locked
Signal having dropped back from a max of 8db rapidly during this confusing period. ?

I'm beginning to wonder if N2YO have accurate calculated positional data ?
Time now 3:10 ...and am seeing the strongest signal level since noon at 10db
N2YO still showing Elevation of +28.6

03:30 PM - N2YO (Inmar 3-F2 = +28.8 ) ,Signal level = 9db approx , nominal decoding of data - no observable errors - quadrature constellation solid lock ...and as ususual ...just add confusian...it started raining albeit light drizzle atm..

04:00 PM - N2YO (Inmar 3-F2 = +29.0 ) ,Signal level = 8.5db approx , nominal decoding of data - very occasional errors - quadrature constellation mostly solid lock - rain a bit more intense

Rain coming down quite heavy now ...
Still maintaining good signal level and data lock for the most part ..
If nothing else this will test how well I have sealed the antenna from the weather ..
fingers crossed..

04:30 PM - N2YO (Inmar 3-F2 = +29.2 ) ,Signal level = 6.5db approx , nominal decoding of data - very occasional errors - quadrature constellation mostly solid lock - rain fairly heavy now

05:15 PM - N2YO (Inmar 3-F2 = +29.4 ) ,Signal level = 6.0db approx , nominal decoding of data - very occasional errors - quadrature constellation mostly solid lock - rain almost stopped but dish very wet

07:10 PM - N2YO (Inmar 3-F2 = +29.8 ) ,Signal level = 6.0db approx ,

Approx 7:30PM 3-F2 began its descent below the equatorial plane ...
since I have a lot of upward travel data ...I wont check it as often until it gets below the noon start point ..
ie approx midnight ..?

currently :-

08:10 PM - N2YO (Inmar 3-F2 = +29.7 ) ,Signal level = 7.5db approx

 

[Vipersan]

So ...I guess my next question is ...Does ADS-C data (1.5ghz) contain useful positional data that can be represented visually by either VR or PP ..
Certainly I have seen what 'looks' at first glance to be positional reference data in the stream ....as displayed in text by Jaero.
Do we have any Aero experts that can answer this question for me ?
I do know Cockpit data ...Text messaging and Emergency data ...can and is sent at 1.5ghz ....but does it contain data for plotting on a map ?
rgds
VS

 

[Confucian]

So ...I guess my next question is ...Does ADS-C data (1.5ghz) contain useful positional data that can be represented visually by either VR or PP ..
Certainly I have seen what 'looks' at first glance to be positional reference data in the stream ....as displayed in text by Jaero.
Do we have any Aero experts that can answer this question for me ?
I do know Cockpit data ...Text messaging and Emergency data ...can and is sent at 1.5ghz ....but does it contain data for plotting on a map ?
rgds
VS

No, have only ever read of current position data being available in C-Band. :-(

 

[Confucian]

No, have only ever read of current position data being available in C-Band. :-(

But a move to Iridium is on the cards in the neat future.

 

[Vipersan]

Gone midnight ...and signal levels down around 5db ...but then ...I have changed a few things in the win 7 OS ...so ...
enough monitoring for tonight as this is exactly as it was last night after 11:30 pm ..
Will leave it all running and see if I get a lock and data flowing tomorrow..

fwiw I had almost 12 hours of operation.
rgds
VS

 

[Vipersan]

Ordered on of these from the US ...
cost around £35 inc postage ...
My intention is to use it to supply power to C band LNBs ...working like a bias T ...allowing just the RF to reach the RTL device(s)

It requires external psu power ..so I dont have to use the US psu ...which is the wrong mains voltage ..
I'll report on this when it arrives ..and I get hands on ..
rgds
VS
Sonora HRPID1422A Power Inserter With 24V Power Supply DTV DBS Satellite Directv | eBay

 

[Confucian]

Grrrrrr SDR# keeps crashing ! Has anyone any experience with another Sdr program that has multiple VFO's and can have more than one instance running concurrently ?

 

[Vipersan]

Sorry Confucian ...
Not aware of anything that fits the bill ..
doh!

Been and cast my vote this morning ...then attacked my next extension to the Helical problem..
I want to fit both a C band lnb (C1PLL) at the focus of the MAXX dish ...
..but also the Helical antenna ...so that both look at 15W ..
Problem is of course that ..theoretically ...there can be only one ..
But with some juggling of the offset position of the Helical ..which is less critical than Cband ...it might be possible to get enough signal for L band as well as sufficient signal for the C1PLL ..
When it arrives (currently on order) ..
I Left the dish as was ..unmoved ...and temporarily mounted the Helical about 10 inches to the west side laterally ...and am still getting about 6db at 1.5ghz ..
So ..some tweaking to do later ..with the lappy outdoors so I can see whats going on..
Looks promising tho' ..
rgds
VS

 

[Vipersan]

So ...looks like this might actually work ... not as an offset ..
but stacked vertically ...
I won't know for sure until I have the new C1PLL mounted and targeted at Inmarsat ..
but ...am getting about 7db with the config in the photo ..
Poor pic of the data ..but certainly still there and likely useable..
rgds
VS

If you are wondering about the Titanium lnb already mounted ..
It is a faulty narrow band version ..so unlikely to be useful even if it were not faulty..
;)

 

[Vipersan]

So ..
Today I am currently cable testing regarding the capability of RG58 to connect to Titanium Cband lnbs ..
..and so far is looking good ..
Since the ability to receive higher frequencies and picture data isn't needed ...IF frequency needed for RTL/SDR only being in the 1.5ghz range ...
I wondered how RG58 would perform ..
Fine it would appear ..
currently looking at 54W and have 8 planes on the PP screen ..data collected from the TD110 at height ..

Confucian ..
could you make a list for me of all T channel frequencies you use at 25E , 15W and 54W ..
So I can test reception of all frequencies and all Inmarsats in our arc using the TD110 which is steerable (usals)
rgds
VS

 

[s-band]

There is a frequency list buried in an earlier thread here: Inmarsat .. something different

 

[Vipersan]

There is a frequency list buried in an earlier thread here: Inmarsat .. something different

Thanks SB ...must have missed that ..
very helpful list ..
rgds
VS

...problem is I guess ...A list is only as accurate as the dongle or indeed the Xtal in the LNB

For example there is no mention in that list of the channel I am currently getting my positional data from on 54W ..
which is 1.534.277.000 approx

perhaps I should start my own list ??
lol

 

[Vipersan]

So ..started my list which I will add to in due course

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Data received on Triax TD110 with Titanium C1PLL and Version 2 RTL Dongle with TCXO
Data read in USB thus the frequencies listed are the lower than the mid point.

Inmarsat 54 W
1.534.240.000 T channel
1.534.255.000 R/RT chanel
1.534.270.000 T channel
1.534.285.000 R/RT channel

1.534.790.000 R/RT channel
1.534.805.000 R/RT channel


....................................................

Inmarsat 15W
1.534.235.000 R/RT channel
1.534.250.000 R/RT channel
1.534.265.000 T channel
1.534.280.000 R/RT channel


1.534.780.000 R/RT channel
1.534.795.000 R/RT channel
1.534.810.000 T channel

Inmarsat 25E

1.526.365.000 ???
1.526.380.000 ???
1.526.395.000 ???
1.526.410.000 ???

1.526.600.000 ???
1.526.615.000 ???
1.526.630.000 ???

 

[Vipersan]

I suspect 25E will be an issue for me as it is so much weaker and the TD110 may well be too small ..
I can see the data streams between
1.526.335.000 and 1.526.675.000 approx ..but not currently possible to resolve data with this setup..
I have had data in the past with Carl (1.5m ) and thought back then this would be the minimum required size..
But certainly it is possible to track planes with a 1.1m dish from 15 and 54 west
rgds
VS

 

[Confucian]

So ..
Confucian ..
could you make a list for me of all T channel frequencies you use at 25E , 15W and 54W ..
So I can test reception of all frequencies and all Inmarsats in our arc using the TD110 which is steerable (usals)
rgds
VS

These are the frequencies I monitor according to my SDR#'s.all "T" channels. Forgive me for not being a "purist" I have made no attempt to calibrate my system so they will not "real" frequencies.
15W 1533935 1534483
25E 1526108 1526138
54W 1533796 1533766
Mick

 

[Vipersan]

Cheers Mick
Yep 'tis confusing for anyone trying to find the T channels cos we can only use approximate frequencies ..
Yours for example are different to mine ..which in turn are different again from Paul (aceBs) list ..
I can only conclude ..variations in LNBs or SDR dongles ...
We can only really rely on our own lists ..

btw ...do you also find the signals from 25E to be weaker than t'other 2 Inmarsats ..thus requiring the largest dish ?
..also ..
no possiblity of tracking at 54W this late in the evening ..on the TD110
I'm guessing this is down to the bird being inclined ( the wobble factor)
This Inmarsat fleet has been in service since the 90s ..
fingers crossed they get replaced at some point in the near future..
rgds
Evan

 

[Confucian]

Cheers Mick
Yep 'tis confusing for anyone trying to find the T channels cos we can only use approximate frequencies ..
Yours for example are different to mine ..which in turn are different again from Paul (aceBs) list ..
I can only conclude ..variations in LNBs or SDR dongles ...
We can only really rely on our own lists ..

btw ...do you also find the signals from 25E to be weaker than t'other 2 Inmarsats ..thus requiring the largest dish ?
..also ..
no possiblity of tracking at 54W this late in the evening ..on the TD110
I'm guessing this is down to the bird being inclined ( the wobble factor)
This Inmarsat fleet has been in service since the 90s ..
fingers crossed they get replaced at some point in the near future..
rgds
Evan

Its difficult to say for sure as I have a 1.8m prime dish on 25E and 1.4m offset on the other two. I'm struggling with 54W at the moment, I was getting good signals at one time but they have drooped off recently.
I have swapped the lnb and dongle without much affect and had a go at re aligning the dish. I need to find out what time of day the bird is in the middle of ist wobble and have a go at re setting the dish then and see if that helps.

 

[Vipersan]

Well Mick ..
fwiw I get best results on the TD110 morning till noon atm ...54W
..and hopefully the usals motor is on the arc ..
assuming it is ..then this is probably in the ballpark for mid wobble ..
rgds
VS

 

[Confucian]

Its difficult to say for sure as I have a 1.8m prime dish on 25E and 1.4m offset on the other two. I'm struggling with 54W at the moment, I was getting good signals at one time but they have drooped off recently.
I have swapped the lnb and dongle without much affect and had a go at re aligning the dish. I need to find out what time of day the bird is in the middle of ist wobble and have a go at re setting the dish then and see if that helps.

I have even "Pruned" the trees to ensure a clean view, had fun with a chain saw up a ladder, wife checked insurance policy ! lol, made a right mess very quickly and still clearing it up.

 

[Vipersan]

Just to let you know Mick ..
T channels at 54W were strong at 7:30AM this morning when I woke ...and still are ..
at least 6 or seven planes evident on PP although some bad RT packets now evident ..
I expect much like yesterday my reception will degrade as the day progresses..
rgds
VS