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Reception of Australia National Beams
(The Optus C1 National beams project)
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C1 Vertical transponders (Note 12407 V 30000 spike) |
The Conclusion from our original findings - located HERE
When we attempted to receive Optus C1, orbital location 156 degrees east earlier this year using a 1.8m solid offset dish we were presented with several minor issues.
The offset dish used was a commercial 1.8m channel master which has its own feed horn assembly matched to the dish.
Although we modified a standard KU LNBF which provided us with our first tangible signals from C1 it was plain to see that the Horizontal beams were stronger than the verticals by at least 2 to 2.5dB. The vertical transponders that Aurora uses for its services use different FEC rates which impact upon the STB threshold “LOCK UP”.
Frequency / symbol rate / FEC/ Threshold / Beam
12407 30,000 2/3 4.2dB ANZ
12527 30,000 3/4 5.2dB NA
12728 24450 1/2 3.2dB NA
As is evident from the above, we have three different STB threshold values, and two different beam patterns.
As part one explains in detail the differences in transponder gain, this article will deal only with what type and size of dish required to provide reception which is going to be stable under most weather conditions. Given the unpredictable signal strengths of overspill ku reception, which can suffer signal fading due to weather conditions, varying uplink power levels, and atmospheric attenuation.
Received signal strengths can vary, however over the past week the variance has been 1 to 2 % points quality wise .Even under light rain conditions the lowest signal for 12527 varied 2% points from 34% to 32%.
Actual CNR’s
12407 V/ 30000M/s / FEC 2/3 = 17.6dB CNR approx signal to NZ 46/47 Dbw
12527 V/ 30000M/s / FEC 3/4 = 7.00dB CNR approx signal to NZ 33 Dbw
12728 V/ 24450M/s / FEC 1/2 = 8.4dB CNR approx signal to NZ 35 Dbw
12478 H/ 27800M/s / FEC 3/4 = 8.2dB CNR approx signal to NZ 37 Dbw
Given the threshold points of each transponder the 2.3 m solid has performed very well.
We have mated this dish with a 0.2dB universal LNBF to provide a system G/T of approximately 160K.
Whilst we would all want to own a dish which would provide larger rain fade margins, there are price considerations to take into account as well as the space required. Armed with the data we gleaned from the 1.8m tests, we felt that the next logical step was to design a cost effective system which would work just as well on C band as it would on Ku..
The results on Optus C1are beyond our expectations, no doubt there will be rain fade sooner or later it’s the nature of the beast .However we are confident that under normal operating conditions the signal has enough margin to combat light to moderate rain showers.
We encountered drizzle and we lost 2% points and the signal dropped from 34 to 32%
Transponders the 2.4m will receive:
Horizontal
(12.638, 8.2 dB) (12598, 8.00dB) (12558 7.8dB), (12518 8.9dB) (12478 8.9dB) (12438 8.9dB)
(12.358 8.7dB) (12.305 9.2dB)(12398 8.5dB) (12689 8.4dB)
Vertical
(12407 17.6dB) (12527 8.4dB) (12728 7.00dB)
Channels easily received:
12407 Channel 7, SBS One South East, SBS Perth, SBS Brisbane
12527 ABC1WA, ABC1SA, ABC1Queensland, ABC1NT, ABC1ACT
12728 GWN, WIN, Imperia, NITV
12478 H EXPO, TVSN
It would seem that the Vertical carriers for the Vast Service are very similar signal strengths to 12728 7dB please see the picture of the actual carriers.
WANT TO EXPERIMENT*?? WE HAVE A TAILORED PACKAGE
*N.B The article serves as a guide only, to experiment with "out of footprint" reception. JX does NOT condone unauthorised viewing of encrypted services
The Optus C1 National beams project - Click Here for details |
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MTI Prime Focus LNBF - $85.00 |
2.4 Meter Prime focus Dish - $580 |
Phoenix Receiver - $160 |
THE WHOLE PACKAGE IN ONE ORDER - $800