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CEENET Workshop 2001 Satellite communications Krzysztof Muchorowski NetSat Express email@example.com. Introductory remarks.
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There are (in general) three bands of spectrum available for GEO satellite communication: C, Ku, Ka.
C - 4-7 GHz (5 cm wavelength)
Ku - 10-14 GHz (2.3 cm wavelength)
Ka - 18-30 GHz (1 cm wavelength)
Following its successful launch last week, ISRO's GSAT experimental satellite a series of in orbit manoeuvres have used most, if not all, of the available fuel on the spacecraft.
Unfortunately, the GSLV launcher did not place GSAT in exactly the right orbit - the apogee achieved was 32,051 km instead of the 35,975 km expected. Also, the inclination of the orbit was 19.2° instead of the intended 19°. The reason for this slight difference has not yet been determined.
It was originally believed that the intended orbit could be achieved by a series of short thruster burns using the satellite's attitude control
thrusters at the expense of the on board fuel and hence satellite lifetime.
Unfortunately, the satellite carries two different propellant tanks, which resulted in an unequal flow of fuel. The resulting imbalance created an impulse that made the spacecraft tilt. All the remaining fuel was then used in order to stabilise the satellite. Two different tanks were used because they were available. The designers were aware of the imbalance in flow rates but did not adequately compensate for its effects.
GSAT is now in a 23 hour 2 minute orbit and is reported to be out of fuel. It is not yet known what, if any use can be made of the spacecraft.
[press release, excerpts, April 2001]
Following a perfect lift off from its launch site at Kourou, French Guiana, on Thursday Ariane 5 failed to put two comsats in the correct transfer orbit. Initial indications are that the second stage of the rocket shut down prematurely.
The two satellites were intended to be placed in a 35,853 km x 858 km transfer orbit with an inclination of 2.0°. They were actually left in a 17,528 km x 592 km orbit with an inclination of 2.9°.
Early reports are that the second stage, the Astrium manufactured Storable Propellant Stage (EPS), only generated 80% of the intended thrust and cut out 80 seconds early. It should have fired for 16 minutes 20 seconds, but this should have automatically been extended to compensate for the reduced thrust. Telemetry indicated that an anomaly occurred three seconds after ignition. Speculation is that the problem was caused by a propellant leak. The upper stage uses monomethyl hydrazine fuel and nitrogen tetroxide oxidiser, which are fed from pressurised tanks to a single Aestus motor.
In spite of these problems the second stage managed to orient itself correctly and successfully deployed the two satellites, leaving at least the possibility of recovery.
The satellites left in limbo by Ariane 510 are Artemis, an experimental European Space Agency telecommunications satellite, and BSAT-2b, a Japanese TV broadcast satellite.
Artemis, with a price tag of US$ 850 million, is ESA's most expensive satellite ever. It may carry enough fuel to allow it to reach geostationary orbit where it should be able to use ion propulsion thrusters for station keeping.
Japanese Broadcasting Satellite System's BSAT-2b may be a different story - it probably has enough fuel to reach geostationary orbit, but would be left without fuel for station keeping.
This was the tenth launch of an Ariane 5 and the third failure. Ariane 4, by comparison, which is due to be replaced by Ariane 5 in 2003 when the remaining stock of 12 launchers is used up, has had a series of 62 consecutive successful launches.
Before Thursday's launch failure, Arianespace was expecting to have three further Ariane 5 launches and three more Ariane 4 launches before the end of the year. The next Ariane 5 was scheduled to launch Atlantic Bird 2 and Insat 3C in September and the next Ariane 4 was to launch Intelsat 902 on 23 August.
An inquiry board has been appointed to investigate the cause of the launch failure. Preliminary conclusions are due at the beginning of August.
[press release from July 2001]
SATMEX PROPRIETARY INFORMATIONOther satellite issues (to close the topic)
(A short break from the main course of the lecture :)
End of break - back to main course
LNA - amplifies RF signal from the antenna and feeds it into frequency converter (typically IF of 70/140 MHz)
LNB - amplifies RF signal from the antenna and converts it to an L-band signal (950-2100 MHz)
LNA is more precise and stable but more expensive than LNB (LO stability).
Transmit power amplifiers provide amplification of signals to be transmitted to the satellite
Transceiver takes 70/140 MHz signal and amplifies it to either C or Ku-band final frequency.
Block UpConverter takes L-band signal and amplifies it to either C or Ku-band final frequency.
What is better?Receiving/transmitting devices
BW = 2048*10^3 /2 *4/3 *204/188 *1.5 = 2.2 MHz
What is Digital Video Broadcast?
SOME MULTICAST APPLICATIONS
b - Content Delivery Site hosts data for eventual playout to edge and end sitesAn Content Delivery Network Incorporating DVB
Edge Sites (ES) include: ISPs, Web Host Facilities, Cable Head Ends etc.
End Sites include corporate locations and SOHO sites
c - Content Delivery Site Multicasts Documents to Edge Sites and End Sites
d - Edge Sites store documents in Servers
e - End Sites store documents in local Servers or in requesting PC
3 - ES returns document
2 - ISP requests document from “closest” Edge Site
1 - Client requests document
4 - ISP returns document
a - Content Providers send web documents to Content Delivery Site
Padded or packed area
16 byte header
Modulates RF carrier; applies Reed-Solomon coding and FEC
MPEG Video Transport Stream and other multimedia
Encapsulates IP Packets within MPEG Transport Stream
Muxes MPEG program streams; encodes bit stream
Controls program entitlements; key words for encryption
Note: IRD shown in this slide is set top box; could also be PC card.
carrier with multiple streams and substreams
NOTE: IRD in this slide is depicted as set top box:
could also be card that fits in PC
Local PIDs Only
100 Base T Port
NOTE: Each PID has guaranteed bandwidth, but could burst for more, if bandwidth is available
What? Did I say voice? Voice-over-IP? Has someone rang me?
(but it may only increase possible profits :-)
This is often a ‘selling point’ so be careful!
Pushing the content to the edge of the network.
I wanted to add a few adds about Cisco Content Delivery Networks (CDN), but there is another talk tomorrow...
There are Mazdas, Porsches, Ladas, Skodas, and Daewoos. Each may carry you to your destination.
There are no free lunches - you get (at most) what you pay for!
Satellite data for: Budapest
Latitude: 48ř00'00" N
Longitude: 19ř00'00" E
Satellite Slot Azimuth Elev. Skew
Statsionsat 13 80.00 E 112.39 10.43 49.21
Gals 1/2 71.00 E 120.14 16.02 39.54
PanamSat 4 68.50 E 122.40 17.51 37.20
Intelsat 602 63.00 E 127.58 20.69 32.42
Intelsat 604 60.00 E 130.53 22.34 29.99
Intelsat 507/510 57.00 E 133.57 23.92 27.65
Statsionsat 5 54.00 E 136.70 25.43 25.41
Turksat 1B 42.00 E 150.27 30.58 17.01
Arabsat 2B 30.50 E 164.69 33.79 9.16
Kopernicus DSF2 28.50 E 167.31 34.15 7.72
Arabsat 2A&3A 26.00 E 170.62 34.50 5.85
Eutelsat I F4 25.50 E 171.28 34.56 5.47
Kopernicus DSF3 23.50 E 173.95 34.74 3.89
Astra 1/x 19.20 E 179.73 34.92 0.18
Eutelsat II F3 16.00 E 184.03 34.84 -2.65
Eutelsat II F1 13.00 E 188.05 34.61 -5.08
Hot Bird 13.00 E 188.05 34.61 -5.08
Eutelsat II F2 10.00 E 192.03 34.23 -7.35
Eutelsat II F4 7.00 E 195.96 33.70 -9.51
Sirius 1A 5.20 E 198.29 33.31 -10.77
Tele-X 5.00 E 198.55 33.26 -10.91
Telecom 2C 3.00 E 201.10 32.77 -12.28
Tv-Sat 2 0.60 W 205.60 31.73 -14.72
Thor 0.80 W 205.85 31.67 -14.85
Intelsat 702 1.00 W 206.09 31.60 -14.99
Telecom 2B 5.00 W 210.93 30.22 -17.69
Telecom 2A 8.00 W 214.44 29.04 -19.73
Statsionsat 11 11.00 W 217.84 27.77 -21.82
Orion 2 14.80 W 222.01 26.02 -24.53
Tdf 1-2 19.00 W 226.43 23.92 -27.65
New Skies 803 21.45 W 228.92 22.63 -29.55
Intelsat 601 27.50 W 234.81 19.27 -34.54
Hispasat 30.00 W 237.14 17.81 -36.75
Intelsat 603 34.50 W 241.19 15.11 -41.01
Orion F1 37.50 W 243.81 13.26 -44.09
PanamSat 3R 43.00 W 248.44 9.79 -50.45
PanamSat 1 45.00 W 250.08 8.51 -53.06
SatMex 5 116.80 W ------ Below Horizont ----Satellite positions in the sky in Budapest
Program No Satellite Pos Freq Pol Name
500 Hotbird 13E 13E 11727 V RTP
499 Hotbird 13E 13E 11489 V RTL 7
498 Eutelsat W2 16E 11095 V Algeria TV
497 Eutelsat W2 16E 11569 H Syrian TV
496 Eutelsat W1 10E 10987 H NTV
495 Eutelsat W1 10E 11621 V Samanyolu
494 Astra 19E 11494 H ARD
493 Astra 19E 11421 H MTV
492 Turksat 42E 10965 H ATV
491 Turksat 42E 11093 V TRT
490 Telecom 2C 5W 12585 H TV5
489 Telecom 2C 5W 12690 V TF1
Life will deliver its verdict, but one should not view the whole topic as satellite vs fibre war. Satellite is great at some applications, where fibre will never outperform satellites. There will be numerous applications, which will be realised over satellites for the years to come.
Thank you for your time.