sign in sign up
<<
Home , Amateur radio, Amateur television

Getting started in Amateur

Whether it’s watching live from the chat room so you can join in the discussion. revival in interest. Analogue TV had International Space Station, helping produce Most groups have regular net nights previously used AM and occupied up to 6 programs for live streaming of the EME 2012 – see the table – and all welcome new MHz . In the mid 1980s, as the conference, building pre-amps and high comers to the interactive discussion. 70cms band was reduced in size and power amplifiers for the bands or became more occupied, using that amount of developing high speed data links to carry Once you have caught the bug and want to bandwidth became increasingly difficult to digital TV signals, the world of ATV has know more, the next thing to do is to join the justify. Also analogue satellite technology something to interest everyone! BATC [2] – it only costs £4 a year and gives was becoming available which enable you access to whole host of information. analogue FM TV transmissions on 23cms So what exactly is ATV? ATV is a and so interest in 70cms declined. However, fascinating area of our hobby which covers What is the BATC? Most ATV operators are all aspects of video production, editing, members of the BATC which has transmission and reception. This article is approximately 800 members, 80% of whom about Fast Scan TV which means we are in the UK. The BATC publishes a transmit and receive pictures in the same quarterly magazine called CQ-TV, runs an quality as you receive from local and national on-line shop to support home constructors TV stations such as BBC and Sky. with difficult to obtain components and sub assemblies and runs a lively members forum where you can ask questions and learn more about the hobby. It also represents the ATV community on the RSGB ETCC (Emerging TV portable contest operation Technology Co-ordination Committee) and spectrum forum and generally represents the the recent introduction of Digital ATV (DATV) interests of the ATVers around the world. has enabled operators to transmit broadcast quality pictures in a 2 MHz bandwidth and we Which band and where? Because of the are once again taking advantage of the great bandwidth required to transmit live broadcast propagation to be found on 70cm. Simplex quality pictures, Fast scan TV is transmitted activity is centred on 437 MHz and several stations in the South of England have LU9DZZ TV repeater on www.batc.tv on the higher bands and can be found on 70cms and above. recently worked several French DATV has always been at the stations. In the last BATC contest M0DTS fore front of the technology revolution. Many Repeater Time of net (UK) worked G8GTZ and G8LES at a distance of stations are now transmitting Digital pictures GB3SQ - Bournemouth Sun – 8pm over 350 Kms. GB3TM - Sun - 8pm (DATV) using the DVB broadcast standards VK2RTS - Sydney Mon – 11am and using video streaming technologies to 23cms – This is the most widely used band GB3HV – Farnham Tues – 9pm exchange pictures with ATV operators for ATV operation and there are currently 23 W6ATN - Wed – 3:30am licensed in the UK with a mixture of around the world. VK7OTC – Hobart Wed – 10:30am analogue and digital outputs between 1308 GB3NQ – St Austell Wed – 8pm and 1318 MHz and inputs on 1248 MHz. For How do I get started? The first place to start GB3BH - Watford Wed – 8pm is to go to www.batc.tv, the British Amateur GB3VL - Lincoln Fri – 7pm details of all UK TV repeaters see the ETCC Television Club’s (BATC) video streaming GB3EN - Enfield Fri – 8:30pm web site which has a full and up to date list portal[1] where you can view most of the UK Nets on batc.tv [3] along with links to repeater group TV repeaters along with those from , websites. Most repeaters are now equipped USA and South America. These are 70cms - The reduced bandwidth of digital with either DATV receive or transmit streamed live along with a live interactive transmissions compared to analogue signals capability or both and noise free pictures can means ATV on 70cms is going through a

Getting started in ATV – Copyright BATC 2013 be achieved when a digital input signal is It’s not all about ! There’s a lot more to valuable reference source of major events relayed via a digital output. ATV than transmitting and receiving – many and presentations. ATVers are also members of the local video Simplex operation takes place between 1255 club and combine the 2 hobbies. A lot of A recording of the Sunday RSGB news and 1275 MHz and broadcast quality pictures amateurs also have an interest in railways or broadcast by Roy, G8CKN, is available under using FM are regularly exchanged over planes and these tend to be favourite topics the news desk section on batc.tv is and distances in excess of 100 KM. for the transmitted on activity nights, updated each week. alongside the latest technical achievements 13cms – This band is currently home to 11 Why should I do ATV? More and more in the shack! repeaters around the UK, one of which has a amateurs are discovering how ATV can digital output. However, the recently A number of ATV operators specialise in complement their own interests and make it announced Ofcom review of the band for renovating old cameras and studio accessible to more people. amateur use means this may change, but we equipment and some even renovate Lincoln club recently are hopeful that repeaters will still be present complete Outside Broadcast vehicles[4]! on 13cms, probably with digital outputs. transmitted live pictures into GB3VL, the The BATC runs a live production desk which Lincoln TV repeater, from the their special is used to stream live events such as the event station GB70DAM from RAF Scampton annual AMSAT-UK Colloquium, microwave to commemorate the 70th anniversary of the roundtables and conferences. This gives our Dambusters raid. GB3VL is streamed live on members an opportunity to “get behind the the BATC streaming site and so attracted a camera” and be involved in production of live large number of viewers from around the TV for the batc.tv streaming video website. world to see the station behind the voice on 40 mts. The BATC team have been present at the AMSAT UK meetings for the last couple of years and provided live streaming of the lectures along with recordings which are made available for later viewing on the BATC streaming website.

Perhaps our biggest and most successful event to date has been the EME 2012 conference held in Cambridge. For this, the 9H1VW ATV portable BATC team videoed and edited all the presentations, which were then made Project Vivat TV OB Unit under 9cms – The 3.4 GHz band has seen little available to a worldwide audience on the restoration ATV activity up to now, however with the BATC streaming site within 30 minutes of the And the amateurs involved in the High recent band plan changes it has been agreed talk finishing. that 3404 to 3410MHz should be used for Altitude Ballooning Community [5] are using DATV. This has been confirmed with Ofcom Amateur Television to transmit pictures of issuing an NoV for GB3BA near Basingstoke balloon launches back to their local repeater on 3406 MHz. This will be the first UK ATV which in turn is streamed live on batc.tv. repeater on 9cms and with 3 other applications in for approval, 9cms looks like So how do I get on air? The first thing to say becoming an important band for ATV is that transmitting and receiving ATV need operation. not be expensive or complicated.

3cms – 10 GHz has always been used by The first step is to decide which band you are ATVers as it is quite easy to make transmit going to focus on. If you already have a well and receive equipment for that band. There equipped narrow band station with a beam Figure 5: The BATC team at EME2012 are currently 7 repeaters with outputs on you are half way there! 3cms and a new application for GB3FY, near RSGB news and video library Videos of all However, as the bandwidths of digital ATV Fleetwood, on 10,425 MHz has recently been the events we have produced, including the signals are 100 times greater than a FM received. Coverage on 10 GHz is EME 2012 conference and the BATC voice signal and 6 times wider still for surprisingly good and a high performance conventions are available in the film archive analogue ATV signals, squeezing every last receive system is easy to achieve with just a section of batc.tv. This is becoming a bit of system performance is important. mini and modified LNB.

Getting started in ATV – Copyright BATC 2013

A long yagi or beam is needed to work any majority of ATV operators. These are Once modified, they are placed in line distance and in order to achieve reasonable available, ready modified for use on ATV between the mast head pre-amplifier and the results on any band it is essential to use a from a couple of suppliers [7]. standard digital STB and tuned to the up mast head pre-amplifier. The latest converted frequency. Note that the same generation of MMICs mean that a sub 1dB Even with a mast head pre-amp most digital satellite receiver can of course be noise figure and very good cross receivers will require additional gain in the used for 23cms and 70cms and just retuned performance can be achieved from very shack for optimum performance. A satellite depending on which band is being received. simple designs which are easy to build and at L-band line amplifier (available from many very low cost. Sam Jewell, G4DDK [6], does suppliers on ebay) will work in most Transmitting ATV Firstly, you need to a kit of parts for a pre-amplifier based on the circumstances and if you live in a noisy RF generate some video signals - most ATV SPF5043 which has extremely good environment, you may need to provide some operators will start with a camcorder as the performance at 70cms, 23cms and even 2.3 band pass filtering. camera in the shack and a media card GHz at a cost of only £12. reader, available for around £10, to generate For FM ATV reception, all you need to know test cards and station information slides. The pre-amp should be mounted in a is the frequency of the other station or waterproof box as close as possible to the repeater. But to be able to receive a DVB-S For analogue transmission on 23cms and antennae feed point, along with a change signal you will need to know the symbol rate 13cms most stations use the range of over relay if transmit operation is envisaged. (effectively the bit rate) and possibly the FEC Comtech modules which are available for As the system noise figure is already to set your receiver up with the correct less than £50. These generate around 20 determined by the pre-amp, and as long as parameters along with the frequency of the milliwatts but when fed in to a 2 stage power the cable run is not longer than 20 metres, transmission. Typical parameters for 70 cms amplifier will provide around 10 watts after good quality satellite TV co-ax can be used are 2Ms/s or for 23cms at 4Ms/s either at ½ filtering. to connect the pre-amp to the receiver in the or ¾ FEC. Exactly how these parameters shack and also feed DC power up to the pre- are entered and the receiver is tuned amp and antennae change over relay. depends on the make and model of STB.

Receiving 23cms Receiving 23cms ATV and Note, the box MUST be able to receive free DATV is easy! This is because 23cms lies in to air broadcasts and a SKY or similar the middle of L-Band, which is the group of dedicated satellite service box will NOT tune that domestic satellite systems to the DATV parameters. use to send the signal down from the LNB, It is also possible to receive DATV signals mounted on the dish, to the Set Top Box using a PC DVB-S or S2 satellite tuner card. (STB) in your living room. Therefore any Once again the set up of the card and 70cms DATV over 350 KMs analogue satellite receiver or the very basic software will differ between products but they Free to Air (FTA) Digital STB from ebay or Digital transmission is more complex and in provide surprisingly good results. Maplin will tune 23cms without any order to reduce the cost of digital modification. Receiving 70cms. The reason why it is easy transmission, a number of amateurs have to receive 23cms ATV and DATV signals is developed a low cost system called Digilite. that the satellite boxes tune (950 – The Digilite system is designed for 2150 MHz) which includes 23cms. homebrew construction, with the hard to get However, in order to receive 437 MHz components and PCB available from the (70cms) DATV on a standard satellite STB, BATC shop, and uses a PC and video you need to up convert the signal to L band. capture card to do the video coding. Many operators are using the system to transmit Luckily there is a consumer device available DATV on both 70 and 23cms – for more in the USA which is used on cable networks details see G8AJN’s excellent website [10]. to up convert UHF signals to L Band where they are then received on a standard satellite A more complete approach is available from SR Systems in and provides a Comtech Tx and RX modules (G8CKN) box. These units are made by a company called Zinwell and known as SUP-2400. ready built digital transmit system to cover Analogue satellite receivers are becoming They are available on ebay, but only in the 70cms and 23cms. [11] hard to find, even at rallies. However, there US and they do require modification, which Linear power amplifiers from DB6NT[12] and is an alternative in the Comtech receive and involves SMD components, to work on Minikits in Australia [13] can be used for ATV transmit modules, which are actually more DATV. M0DTS [8] has documented the operation although for digital use, the drive suited to ATV operation, due to their modifications and the BATC shop [9] sells level must be reduced by up to 50% to narrower bandwidth and are used by the the unmodified units. ensure good linearity. After filtering, the Getting started in ATV – Copyright BATC 2013 average ATV station will run around 10 – 15 Areas currently under investigation by the Websearch: watts in to a low loss feeder. ATV community include the use of SDR [1] http://www.batc.tv/index.php technologies, the potential of powerful OBC [2] http://www.batc.org.uk/ Operating Because of the weak nature of systems such as Raspberry Pi and ways of [3] http://www.ukrepeater.net/repeaterlist5.htm [4] http://projectvivat.co.uk/Vivat/Home.html ATV signals, a lot of activity is centred on the generating and transmitting 3D and HD TV repeaters and the best way to get started [5] http://ukhas.org.uk/ video. [6] http://www.g4ddk.com/ is to find your local repeater group. [7] https://www.batc.org.uk/shop/3rdparty However, ATV operators do also work DX, The BATC encourages such projects with [8] http://www.m0dts.co.uk/ particularly during lift conditions and low cost digital operation a major focus for [9] https://www.batc.org.uk/shop/ distances up to 500 Km are easily the club and it has supported [10] http://www.g8ajn.tv/dlindex.html achievable. As with all microwave activities, projects by its members to produce a DATV [11] http://sr-systems.de talkback is often the challenge and a new transmission system within the reach of the [12]http://www.kuhne-electronic.de/en/home.html web based tool specifically for ATV DX average amateur. [13] http://www.minikits.com.au/ working has recently been launched at [14] www.dxspot.tv The future? Two very exciting things are [15] http://www.batc.org.uk/forum/ www.dxspot.tv [14] about to happen for the ATV community.

Most ATV stations operate from home with a Firstly, the launch of live TV from the ISS - modest outside system, particularly if they are in the coverage area of a local whilst it will be using standard DVB-S repeater. However, the BATC also organises equipment in the 13cms amateur band, due contests and a lot of operators go out to to the potentially low power of the signals operate portable stations on the local high and the orbit of the ISS, receiving it will be spots. pretty challenging but some ATV ops will be setting up equipment to receive it. For the How technical is ATV? Having said that ATV rest of us, the live pictures from several large need not be complex, it is also the one of the stations around the world will be few areas of the hobby which still supports available on the BATC streaming portal. active experimentation and developments. Secondly there is the potential release of Whilst the BATC and other groups have some bandwidth for narrow band digital ATV made entry in to the hobby easy for operation below 70cms. A number of newcomers, most people find that once they ATVers are already looking at the potential of “catch the bug” they are very soon building very narrow band DATV (sub 1 MHz) small projects and soon are experimenting operation using DVB-S2 modulation with with pre-amps and other pieces of home built MPEG4 or H265 HEVC codecs. video and RF equipment. ATV – why not? ATV is very easy to get started in and yet has plenty for everyone – take a look at the BATC forums to see what people are talking about today [15]

To find out more, your local repeater group, read the Bi-monthly ATV column in RadCom or come along to CAT13, the BATC 2013 convention to be held in October at Finningley near Doncaster.

Figure: The Digilite PCB As well as being great fun, ATV can really compliment other areas of our hobby. ATV For others, the big attraction is that there is has instant appeal as it is “multi-media” and limited commercial equipment is a valuable tool to attract young people in to available and the hobby can be as technical amateur radio as you choose with a large element of experimentation at frequencies above 1 GHz At the very least, go and have a look at the and high speed digital transmission streaming video website – but be careful, you techniques. might catch the bug!

Getting started in ATV – Copyright BATC 2013