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It has been quite a few years since we have described an up-to-date, free-to-air home satellite TV system. In fact the last time we covered the subject was in May 1995 and that article sparked a huge amount of interest. But times (and satellite TV) have changed in the last few years. With the right gear, you too can watch INTERNATIONAL SATELLITE TV Part 1: by Garry Cratt* www.siliconchip.com.au December 2002  7 S ince 1995, more satellites have been launched, more free-to-air channels have become available and prices have dropped, hence our revitalised interest in the subject. And all this in the face of Pay TV which continues to have mixed success in Australia. One of the significant technological improvements that has had a major affect on home satellite systems is the introduction of MPEG broadcasting. This is a form of digital compression that allows a huge improvement in the efficient use of the satellite spectrum. As more channels can now be transmitted within a fixed bandwidth, the operating cost to broadcasters has decreased, making international satellite broadcasts an economical alternative to shortwave broadcasting. More powerful satellites now cover larger populated areas of the Earth than ever before, translating into a huge audience for broadcasters. The good news isn’t restricted to broadcasters. Consumers benefit from the mass production of digital satellite receivers, capable of producing high quality video and audio signals, at similar cost to an analog receiver a few years ago. Depending upon your (earthly!) location, there are between eight and twelve satellites visible from Australia. These satellites carry around 200 channels of international programming. While many of these are broadcast in the language of the country of origin (which is a great source for learning a language), there are enough English language channels to provide a great source of international news, documentaries and general entertainment. to illuminate specific populated parts of the world with strong signals. For example, Pay-TV services use the Ku-band because they can target areas more effectively and efficiently. In Australia, most Pay-TV operators can provide adequate signals, with some margin for rain fade, using only 65cm dishes. However, these signals are concentrated along the east coast and areas outside this “footprint” require a much larger dish for adequate reception. Rain attenuation is more severe at these frequencies, so higher power must be used to overcome this problem. But the main advantage of Ku-band remains the size of the required dish. Incidentally, the term “Ku” is used to identify a certain section of the overall band. The “Ku” band goes from 10.715.4GHz, the “K” band stretches from 15.4-27.5GHz, while the “Ka” band goes from 27.5-50GHz. What is of main interest to us here are those free-to-air international signals on the C band. How it works Most enthusiasts are familiar with the principle of geostationary satellites. But if you’re not, basically the satellite is placed about 37,000km above the equator and appears to travel at the same speed and direction as the point directly “below” it on Earth. C-band and Ku-band There are two frequency bands utilised by satellite operators, “C” band and “Ku” band. Both are in the super high frequency (SHF) region of the electromagnetic spectrum (SHF goes from 3 to 30GHz, with wavelengths between 10cm and 1cm) By international convention, C-band signals are transmitted in the 3.44.2GHz area. Unfortunately there are also some terrestrial services that operate in this region, so satellite signals do not rule exclusively here. As the amount of power able to be transmitted by a satellite is limited by the available spacecraft power supply, efficient use must be made of this limited resource. C-band signals are used for coverage of wide landmass areas because they are less affected by rain attenuation. Because they are intended for wide area coverage, the average signal level is far less than the spot beams used to cover smaller, populated areas. Ku-band signals are transmitted (at least for our part of the world) in the 12.25-12.75GHz region and are generally used by satellite operators 8  Silicon Chip A 2.3m C-band mesh dish mounted in a suburban backyard. Note the heavyduty steel mounting pipe: this is set in concrete another 1.5m into the ground to prevent the dish moving in high winds. The mesh construction also assists this. www.siliconchip.com.au Of course, the satellite travels very much faster through space than the point on Earth moves. But the important point is that it moves at a speed which keeps it in the same relative position as that point on the ground. The Earth’s gravity constantly tries to pull the satellite out of orbit but at roughly 37,000km the centripetal force of the moving satellite exactly balances the pull of the earth’s gravity. So the satellite neither falls to Earth nor spins out into space. Therefore, the satellite appears to be in a fixed position. In practice, it’s not quite that simple – regular “adjustment” firings of the satellite’s rocket motors are required to keep it in geostationary orbit. When the limited amount of rocket fuel on board eventually runs out, the satellite will fall and probably burn up on re-entry. This fixed position simplifies things significantly, because a fixed dish can now be used as there is no need to move the dish to follow, or “track” a moving By way of contrast, a 3m C-band solid dish in a commercial installation. This satellite. This is quite different to LEO required a crane to lift it into position and very extensive anchoring to the flat satellites (low earth orbiting) such as roof. Windage can be a real problem with solid dishes, especially up high. those used by GPS and weather satellite services. panels. This reflector is mounted on a support ring, which The only reason to change the position of the dish is to in turn sits on top of a mounting post. lock onto the signal from another satellite. Commercial dishes are often one piece spun aluminium Satellites can be launched from a number of sites around construction, making transport and mounting a far more the world, using multi-stage launchers to propel the satel- difficult proposition. lite to the final orbit. By contrast, the USA’s Space Shuttle Due to the mesh construction, the reflector is semi transcan take the satellite to an altitude of 200 Km, where an parent, and hence not nearly as instrusive as a solid dish. “apogee” kick motor boosts the satellite into the final orbit. That’s important when it comes to satisfying neighbours There are now commercial launch sites in Russia, China, and local councils. India, Japan, USA, French Guiana and from the Boeing “Sea Launch” platform in the Atlantic Ocean. A consor- Size does matter! tium is also reported to be currently trying to put together The dish shape is a parabola. The unbelievably tiny a commercial site in Australia using the now-largely- signals which arrive at the dish’s surface bounce off it and, disused Woomera research centre in South Australia. because of the parabolic shape, concentrate at the dish’s focal point. What you need The lower the signal levels, the larger the dish required. Basically an international satellite TV reception system It’s not so much that C-band signals require a large dish comprises a dish of suitable size, an LNB (low noise block because they are longer wavelength (even though that is down converter), a feedhorn, a digital satellite receiver and true!), it’s because they are invariably much lower in level connecting cables. In some cases, a multi-system video than Ku-band signals. standards converter may be required. The further away from the satellite you are (ie, the higher The simplest implementation is a system designed to your latitude), the less signal you will receive . Again, the look at one satellite. The dish is simply pointed in the larger the dish you will need. right direction and a single coaxial cable runs inside to The same applies to satellites located further around the satellite receiver and TV set. the equator from your location. Satellites located on your A more comprehensive (and complex) system is one longitude will require a certain sized dish, while satellites that has been fitted with a motor, allowing access to all on distant longitudes will require larger dishes. visible satellites. Ultimately, where the satellite is located below the hoThis system relies on a particular type of dish mount rizon from your location, no dish, not even a monster the called a “polar” mount. This achieves polar tracking of the size of the Parkes radio telescope, will be able to receive geostationary arc using only one motor. signals from that satellite because there is a little barrier The most obvious component of the system is the dish. called the Earth in the way. Typically, for domestic use, the reflector is constructed from Therefore, when you hear people talking about watchexpanded aluminium mesh, supplied as four pre-assembled ing programs from domestic USA or European satellites, www.siliconchip.com.au December 2002  9 A C-band Low Noise Block Downconverter/Filter (LNBF) together with its associated feed horn. These devices are made to very tight tolerances due to the extremely high frequencies involved. they are talking through their hats (or should that be through their Earth?). Undoubtedly, what they are watching is a USA or European program received by a much closer earth station and re-transmitted on one of the satellites you can see from Australia! It can be shown mathematically that at best (ie, an unobstructed path) you cannot view a satellite more than 81° from your longitude. As Sydney, for example, is at 151°E, that limits you to satellites located from 70°E to 128°W. To adequately capture C-band signals at latitudes between, say, Brisbane and Melbourne, a dish of around 2.3m minimum diameter is required. Further south, you might need a 3m dish, or even larger. Further north, you might get away with 1.5m or so. Again, these sizes assume your satellite is reasonably close to your longitude. So why do TV stations and satellite earth stations have such enormous (10m+) dishes? They are there to capture every last femtovolt of signal to ensure rock-solid reception, good enough for commercial applications. And they may also be looking at satellites close to the horizon. of signal anyway). And it must be able to convert a whole “block” of frequencies to lower frequencies which (a) are within the range of the receiver and (b) won’t be as severely attenuated by the length of coaxial cable between it and the receiver. (There will always be some attenuation of the signal along the coax and the higher the frequency, the greater the attenuation). Remember that the incoming signal is within the frequency band of 3.4-4.2GHz, so we need to convert the signal to a more manageable frequency to run down a piece of coax, if we are to have any hope of getting the signal to the receiver! The LNBF has an internal local oscillator at 5150MHz, and this mixes with the incoming signal to produce a block of intermediate frequencies (IF) from 950-1450MHz. That’s a far more manageable range! For maximum spectrum efficiency, most satellites transmit signals of both polarities (horizontal and vertical), so the LNB has two probes (one for each polarity) that can be remotely selected by the satellite receiver. By convention, cables used in satellite TV are 75 ohm and it is important that a good quality cable is used to connect the LNBF to the receiver. For best results RG-6/U quad shield coax is recommended. The quad shielding ensures that any adjacent RF field (generated by 2-way radio, mobile and cordless phones, etc) does not interfere with the satellite IF signal being fed down the cable. The dynamic range of most satellite receivers allows signals to be received anywhere between –20dBm and –50dBm, so some cable attenuation can be tolerated. Typically RG6, the coax most used for satellite receivers, has 25dB attenuation per 33m (100ft) at 1000MHz, so this is a about the maximum length we can use without amplification. The use of a 20dB line amplifier can extend this considerably. Coming indoors The only indoors component for the system (apart from the bit of coax that enters the building!) is the satellite receiver. The receiver takes the IF input and processes this digital stream to produce composite video and audio signals. The digital receiver connects like any other audio/video Feedhorn and LNBF Mounted at the focal point of the dish, supported by three or four arms, is an assembly called the feedhorn and LNBF (low noise block downconverter/filter). The feedhorn “looks” at the reflector surface, and collects the signal reflected from the surface of the dish, concentrating the signal into a piece of waveguide to which the LNBF is connected. The parts of the LNBFs name are significant. It must have very low electrical noise (so it doesn’t introduce any significant noise of its own to what is a very tiny amount 10  Silicon Chip A typical digital receiver for C-band TV. MPEG-2 digital DVB compliant, his one retails for around $495 and has 4000 channel capability. www.siliconchip.com.au Receiving Pay-TV and other encrypted services This map of Asiasat II’s (100.5°E) “footprint” gives a good idea of the size of dish required for various areas. Note that the footprints are not circular – combinations of satellite transmitters and antennas are used to achieve the best footprint over populated areas. component in a home entertainment system: composite video and/or SVHS video output, stereo line audio outputs, and RF (generally UHF) modulated output. Most receivers have at least two sets of A/V outputs for routing to VCR, TV, etc. OK, so now that we have all these components in place, just what is there to see ? There are really two reasons why free to air satellite TV signals exist. Either they are an extension of international shortwave broadcasting, or they are “fortuitous”. Over the last few years, satellite TV has taken over from the more traditional shortwave broadcasting. For example, the BBC no longer transmits on shortwave but they do produce a satellite TV channel, BBC World. Other examples of government-operated satellite channels include Deutsche Welle (Germany), Worldnet (USA), NHK (Japan) and our own ABC Asia to name a few. These are deliberately set up to promote the culture, lifestyle and customs of the country of origin. These signals are of great interest to tourists, expatriates living overseas, schools, universities, and hotels. Such broadcasters normally produce a satellite “TV Guide” which can be accessed through their internet web sie. The second type of free-to-air satellite TV signals encountered, are those that are “fortuitous” – another word for lucky! Many of these are not specifically intended for public consumption (for example, a broadcaster’s link between one country and another) but suitably equipped satellite enthusiasts can view these signals. Every now and then you can see a real gem – like a movie transfer. All such signals are subject to copyright which is designed to prevent commercial use being made from these signals. SC * Garry Cratt is Technical Director of Av-comm Pty Ltd, suppliers of satellite TV equipment and peripherals. While this article has concentrated on C-band, free-toair services which can be received and viewed by anyone with a suitable dish and receiver, there has been a lot of discussion over whether it is possible to receive Ku-band signals, such as those from Pay-TV service providers, and whether having your own dish and receiver is legal. Of course, technically speaking Ku-band signals can be received with suitable equipment, otherwise satellite Pay-TV wouldn’t be possible. But it’s not quite as simple as pointing your dish in the right direction and tuning in. Nor, apparently, is it now legal. For a start, Pay-TV services are encrypted (with the exception of one channel – TV Shopping Network). So they have to be decrypted before you can watch them (that’s one of the things the Pay-TV set-top-box does!). Second, Pay-TV providers don’t take kindly to people watching their service for free. That’s why the set-topbox is provided with a smart card, a digital “key” which unlocks the box. This key is periodically changed by a signal from the satellite which turns the box off if you haven’t paid your bill or it is unauthorised. All you’ll see on your TV set is a message such as “unknown service” or “this channel is encrypted”. There are a number of ways the service providers do this but the most usual is to periodically change the “country code” (or coco) after a message from the satellite tells the decoder that it is about to be changed. If the coco being transmitted and the coco stored on the card don’t match, your signal disappears. So stolen set-top-boxes and cards only work for a short time. (That’s one reason that there isn’t a huge market in stolen boxes). Finally, there is now legislation designed to stop you receiving Pay-TV signals without paying for them, even if you work out how to decrypt the signals yourself. Owning, buying and selling satellite dishes and receivers is not illegal but trading in the smart cards designed to make those receivers decrypt signals definitely is. And even if you are particularly clever and are able to program your own smart card, since March 2002 there has been legislation to prevent you obtaining the benefit of a received Pay-TV satellite signal unless it is with the authorisation of the provider – ie, you’ve paid for it! Unless you pay for it, don’t hold your breath for authorisation! (In fact, it’s rarely, if ever, given – they come and install their own equipment even if you have your own.) And finally, a tale: in the US, service providers have been known to broadcast “stings” – offers so good they’re impossible to resist. But they are also specifically coded so that legitimate viewers don’t even see them. When people respond to these amazingly good offers, they know they’ve caught themselves some pirates! Aaaaarrrrrr, me hearties . . . NEXT MONTH: Putting together your own satellite TV system (including a special system discount offer – exclusive to SILICON CHIP readers). www.siliconchip.com.au OVERLEAF: Currently available C-band digital f-t-a services December 2002  11 C-BAND FREE-TO-AIR DIGITAL CHANNEL LIST FREQ USER SR FEC Video Polarity PAL PAL PAL PAL Vertical Vertical Horizontal Vertical 5.150 LO 5.700 LO Origin 1445 MHz 1354 MHz 1302 MHz 1174 MHz 1995 MHz 1904 MHz 1852 MHz 1724 MHz China India Hong Kong Thailand (symbol (forward error rate) correction) APSTAR 2R<at>76.5° E 3705 3796 3848 3976 Channel News Asia DD NE TVB8 I Cable 6111 2500 13280 5000 3/4 3/4 3/4 3/4 THAICOM 3 <at>78.5° E 3424 3448 3551 3600 3666 3671 Korean Central TV 3366 2/3 NTSC Horizontal 1726 MHz 2276 MHz N Korea TV Cambodia 6312 1/2 NTSC Horizontal 1702 MHz 2252 MHz Cambodia TRT 13330 3/4 PAL Horizontal 1599 MHz 2149 MHz Turkey Thai TV 5 26667 3/4 PAL Horizontal 1500 MHz 2100 MHz Thailand VTV 4 Vietnam ATN Bangla India ETC Punjabi CMM Music Test pattern India MR TV 4442 2/3 PAL Horizontal 1484 MHz 2034 MHz Burma MR TV 13330 3/4 NTSC Horizontal 1479 MHz 2029 MHz Cambodia INSAT 2E<at> 83° E 3683 3831 3911 4005 Asianet DD1 National DD2 Metro ETV bouquet 4340 4998 4998 27000 3/4 3/4 3/4 3/4 PAL PAL PAL PAL Vertical Vertical Vertical Vertical 1467 MHz 1319 MHz 1239 MHz 1145 MHz 2017 MHz 1869 MHz 1789 MHz 1695 MHz China India India India ASIASAT 2 <at> 100.5° E 3660 Saudi TV 1 27500 3/4 PAL Vertical 1490 MHz 2039 MHz Saudi Muslim TV Saudi Kuwait Space Channel Kuwait Jame-Jam Network Iran IRIB 3 Saudi 3705 Satlink adhoc 5632 3/4 PAL Vertical 1445 MHz 1995 MHz Europe 3706 Henan TV China 4418 3/4 PAL Horizontal 1444 MHz 1994 MHz China 3714 Satlink adhoc 5632 3/4 PAL Vertical 1436 MHz 1986 MHz Europe 3717 Quinghai TV 4418 3/4 PAL Horizontal 1433 MHz 1983 MHz China 3720 Fujian TV China 4418 3/4 PAL Horizontal 1430 MHz 1980 MHz China 3727 Jiangxi TV China 4418 3/4 PAL Horizontal 1423 MHz 1973 MHz China 3734 Liaoning TV China 4418 3/4 PAL Horizontal 1416 MHz 1966 MHz China 3799 APTN news feeds 5632 3/4 PAL Horizontal 1351 MHz 1901 MHz Europe 3806 GX TV 4418 3/4 PAL Vertical 1344 MHz 1894 MHz China 3813 Shaanxi TV China 4418 3/4 PAL Vertical 1337 MHz 1887 MHz China 3820 AH TV 4418 3/4 PAL Vertical 1330 MHz 1880 MHz China 3827 Jiangsu TV 8410 3/4 PAL Horizontal 1323 MHz 1873 MHz Mongolia 3827 JSTV 4418 3/4 PAL Vertical 1323 MHz 1873 MHz China 3830 Northern Mongolia TV2 8410 3/4 PAL Horizontal 1320 MHz 1870 MHz Mongolia 3834 Hei Long Jiang TV 4418 3/4 PAL Vertical 1316 MHz 1866 MHz China 3840 Guangdong TV 4418 3/4 PAL Horizontal 1310 MHz 1860 MHz China 3847 Hunan TV China 4418 3/4 PAL Horizontal 1303 MHz 1853 MHz China 3854 Hubei TV China 4418 3/4 PAL Horizontal 1296 MHz 1846 MHz China 3872 Jilin Satellite Channel 4418 3/4 PAL Vertical 1278 MHz 1828 MHz China 3880 Worldnet USA 20400 3/4 PAL Horizontal 1270 MHz 1820 MHz USA 4000 Deutsche Welle 28125 3/4 PAL Horizontal 1150 MHz 1700 MHz Germany RAI Italy TV5 France TVe1 Spain RTPi Portugal 4020 Dubai Sports 27500 3/4 PAL Vertical 1130 MHz 1680 MHz UAE Dubai Business Dubai EDTV Europe 12  Silicon Chip www.siliconchip.com.au ASIASAT 3 <at>° 105.5° E 3700 3714 3742 3755 3760 3820 3900 4000 4095 4129 Bharathi TV 27500 3/4 PAL Vertical 1450 MHz 2000 MHz India Kaveri TV India MS TV 5868 3/4 PAL Horizontal 1436 MHz 1986 MHz China SABe 3300 3/4 PAL Vertical 1408 MHz 1958 MHz India Arirang TV 4418 7/8 PAL Vertical 1395 MHz 1945 MHz Korea Now TV 26000 7/8 PAL Horizontal 1290 MHz 1940 MHz USA Bloomberg Asia Splash TV S/S Music Speedcast TV 27500 3/4 PAL Vertical 1330 MHz 1880 MHz China Indus TV 27900 7/8 PAL Vertical 1250 MHz 1800 MHz India Phoenix I 26850 7/8 NTSC Horizontal 1150 MHz 1700 MHz China Xing Kong Phoenix C Channel V Sun TV 5555 3/4 PAL Horizontal 1055 MHz 1605 MHz China CCTV 3,4,9 13240 3/4 PAL Horizontal 1021 MHz 1571 MHz China PALAPA C2 <at> 113° E 3473 4000 4080 4184 RCTI Channel News Asia Swara TV Quick TV Anteve Global TV Metro TV TPI digital 8000 26085 28125 3/4 3/4 3/4 PAL PAL PAL Horizontal Horizontal Horizontal 1677 MHz 1150 MHz 1070 MHz 2227 MHz 1700 MHz 1620 MHz Indonesia Taiwan Indonesia 6700 3/4 PAL Vertical 966 MHz 1516 MHz Indonesia PAS-8 <at> 166° E 3740 3852 3829 3880 3900 3940 4020 4060 4180 MTV China 27500 3/4 PAL Horizontal 1410 MHz 1960 MHz China Tzu Chi TV 28000 5/6 NTSC Horizontal 1298 MHz 1848 MHz Taiwan Hai Hua Satellite TV Taiwan 29 radio services Power TV Taiwan CCTV 4,3,9 13240 3/4 PAL Horizontal 1321 MHz 1871 MHz China Lakbay TV 28694 3/4 PAL Vertical 1270 MHz 1820 MHz Philippines CNBC 27500 3/4 PAL Horizontal 1250 MHz 1800 MHz USA EWTN 27690 7/8 NTSC Horizontal 1210 MHz 1760 MHz USA Fox News feed USA BBC UK ESPN 26470 3/4 NTSC Horizontal 1130 MHz 1680 MHz USA++ NHK World 26470 3/4 NTSC Horizontal 1090 MHz 1640 MHz Japan Channel J Japan NIME TV Japan ABC Asia 27500 3/4 PAL Horizontal 970 MHz 1520 MHz Australia Radio Australia PAS-2<at> 169° E 3743 3771 3837 BBC World (Singapore) 21800 3/4 NTSC Vertical 1407 MHz 1957 MHz UK YTN Korea 11574 3/4 NTSC Horizontal 1382 MHz 1932 MHz Korea RAI Australia 13331 3/4 PAL Vertical 1372 MHz 1922 MHz Italy RAI Radio Italy 3903 CBS/ Adhoc feeds 30800 3/4 NTSC Horizontal 1249 MHz 1797 MHz USA Bloomberg TV USA BloombergRadio ABC Asia Radio Australia 3992 Fox MUX 26470 7/8 NTSC Vertical 1158 MHz 1708 MHz USA 3940 Napa feeds 7498 2/3 PAL Vertical 1210 MHz 1760 MHz 3942 Napa feeds 6620 2/3 NTSC Horizontal 1208 MHz 1758 MHz 4026 TVBSUSA 22000 3/4 NTSC Vertical 1124 MHz 1674 MHz Taiwan INTELSAT 701 <at> 180°E 3769 3886 TBN Worldnet 20000 25000 7/8 3/4 PAL PAL RHCP RHCP 1381MHz 1264MHz 1931MHz 1814MHz USA USA + = audio only    * = 0900-1800UTC    $ = 1800-0900UTC    LAST UPDATE: 6/9/02 www.siliconchip.com.au December 2002  13