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Re: ISS HamTV Blank transmission report

PostPosted: Mon 7 Apr 2014 07:46
by vk6mj
WOW !!
8 minutes of continuous video lock. Yes the ISS seems to be flying backward giving early reception on approach. I did get broken video almost to the horizon when it was leaving and heading away.

73 from a very happy Martin

Re: ISS HamTV Blank transmission report

PostPosted: Mon 7 Apr 2014 12:01
by i0kpt
Hi Martin,
this is really a wonderful result!! Congratulations!! Could you remind me which is your setup (antenna size, rotator, tracking SW, any Sun noise measurement, etc.).

Best 73

Piero, I0KPT

Re: ISS HamTV Blank transmission report

PostPosted: Mon 7 Apr 2014 12:39
by vk6mj
Hi Piero

Thankyou for your kind comments.

My setup is :

1.2 mtr prime focus dish
homebrew patch antenna (LHCP)
Kuhne 25 TM LNC
Yaesu G-5500 combo az/el rotator
Yaesu GS-232b controller
SatPC32 tracking software
S2-1600 HDTV tuner card
Tutioune Software V0.5b ISS
Windows 7 32 bit OS
Intel Core i3-4130 CPU @ 3.40 GHz
vcam
Adobe Flash Media Live Encoder 3.2

I think that is about everything.

The best frequencies for my station are 2.395 GHz and 2.369 GHz as these are both free from QRM. It would seem from this pass that config 5 performs best so far. 2.422 GHz and 2.437 suffer badly from local wifi interference.

This pass was very high and nearly directly overhead. I was surprised to receive the signal so early in the pass.

Good luck with your testing.

73 Martin VK6MJ

Re: ISS HamTV Blank transmission report

PostPosted: Tue 8 Apr 2014 06:52
by vk6mj
This was a lower pass at max elevation of 43 degrees. 7 minutes of video lock. The ISS is once again flying backwards according to the radiation pattern. Video lock (AOT) occurred at 2 degrees elevation on approach and LOT at 21.5 degrees heading away.

Re: ISS HamTV Blank transmission report

PostPosted: Wed 9 Apr 2014 20:23
by G4KLB
Am also getting better results at start of pass now

Re: ISS HamTV Blank transmission report

PostPosted: Wed 9 Apr 2014 22:50
by vk6mj
2,369GHz spectrum27.jpg
2,369GHz spectrum27.jpg (186.48 KiB) Viewed 24854 times
8 minutes of video lock with a slight dropout as the ISS went behind trees to my NW.
First video lock was at 2.5 degrees elevation. Max Elevation at 83 degrees.

Re: ISS HamTV Blank transmission report

PostPosted: Wed 9 Apr 2014 22:53
by vk6mj
G4KLB wrote:Am also getting better results at start of pass now

Nice work Colin....Martin VK6MJ

Re: ISS HamTV Blank transmission report

PostPosted: Fri 11 Apr 2014 05:58
by F6DZP
Last night:

First AOT began with 4.1° elevation( 1960 km). At such low elevation, I have some neighbour houses that cut the stream at the beginning.
Without them, I could receive 8mn also. But they are there... That let me about 6mn of usable TS.
LOT was done at 8.4° elevation (1600 km)
I did not thought we could receive such far range.

F6DZP_TiouneData_11_04_2014_0h03UTC.jpg
F6DZP_TiouneData_11_04_2014_0h03UTC.jpg (186.81 KiB) Viewed 24808 times


Jean Pierre

Re: ISS HamTV Blank transmission report

PostPosted: Fri 11 Apr 2014 22:36
by zg3409
DishGainAndBeamwidth.jpg
DishGainAndBeamwidth.jpg (18.31 KiB) Viewed 24778 times


Reports at 2.5 and 4 degrees show the signal can be picked up above 1000KM

Based on the calculations in this document
http://www.amsat.it/Amsat-Italia_HamTV.pdf

The link system was designed for 1000KM range.(with 7dB margin at this range)

However the dish size used was 90cm and downconverter gain was put as 35dB,

In reality the recommended system ends up with:
Dish 90cm=24.3dB --> 1.2M (120cm) 26.6dB = +2.3dB
Pre-amp 35dB --> 48dB(my unit typically 40dB) = +13dB (also interference amplified)

With no interference we may have 2.3+13=15.3dB more signal than calculated. We also have the 7dB margin,
meaning at 1000Km we should be 23.3dB above link budget. Reports of signal picked up with an omni directional antenna on a high pass would confirm with low interference noise, the signal is quite strong.

Those calcultions do not take into account things like
-Interference from Wifi or other signals (detected myself up to 60dB above noise)
-Losses from pointing innacuracies, rotator not tracking 100%.
The dish 3dB beamwidth is 8.4 Degrees so we need to point very accurately (+/- 4 degrees total error)
-Cable/connector losses

Re: ISS HamTV Blank transmission report

PostPosted: Fri 11 Apr 2014 23:08
by vk6mj
Thankyou for the previous calculations. I will have a good look at those.
My low angle access to the ISS HAMTV signal is also aided by my location which has very little to block my reception with the exception of 3 trees to my north west. My antenna has this view from the south west to north west. I live on the coast of the Indian Ocean.
Regards Martin