Re: ISS HamTV Blank transmission report

Postby vk6mj » Mon 7 Apr 2014 07:46

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
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2,395GHz spectrum24.jpg
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Re: ISS HamTV Blank transmission report

Postby i0kpt » Mon 7 Apr 2014 12:01

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
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Re: ISS HamTV Blank transmission report

Postby vk6mj » Mon 7 Apr 2014 12:39

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
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S Band config2a.jpg
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Re: ISS HamTV Blank transmission report

Postby vk6mj » Tue 8 Apr 2014 06:52

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.
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Re: ISS HamTV Blank transmission report

Postby G4KLB » Wed 9 Apr 2014 20:23

Am also getting better results at start of pass now
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Re: ISS HamTV Blank transmission report

Postby vk6mj » Wed 9 Apr 2014 22:50

2,369GHz spectrum27.jpg
2,369GHz spectrum27.jpg (186.48 KiB) Viewed 23450 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.
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Re: ISS HamTV Blank transmission report

Postby vk6mj » Wed 9 Apr 2014 22:53

G4KLB wrote:Am also getting better results at start of pass now

Nice work Colin....Martin VK6MJ
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Re: ISS HamTV Blank transmission report

Postby F6DZP » Fri 11 Apr 2014 05:58

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
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Jean Pierre
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Re: ISS HamTV Blank transmission report

Postby zg3409 » Fri 11 Apr 2014 22:36

DishGainAndBeamwidth.jpg
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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
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Re: ISS HamTV Blank transmission report

Postby vk6mj » Fri 11 Apr 2014 23:08

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
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