BATC Forum

Hi,

I've just joined the forum to ask a couple of questions about 70cms DATV. I've still got to read through all of the topics here (I've read a few) so excuse if these are answered elsewhere.

Digital ATV would seem to me to promise the chance to get active with ATV using existing antennas. Not knowing anything (yet) about the technicalities of digital television is there a beginners guide around that introduces the subject and the equipment needed to TX - I know this is still an emerging field for kits etc, but it would be great to read a "you need A,B & C" type of article. Bear in mind that at the moment I'm not a member of BATC so not privy to the grapevine.

Also, what will be the likely frequencies for 70cm DATV, and are there any repeaters planned? If I started with just an RX what is my entry level equipment and where could I source it. Next question - is there any activity at the moment/sources of signals around.

Thanks in advance for any info.

David. G8JGO.

Hi Dave - and welcome to the wonderful world of ATV It is really one of the last niches of the hobby where people build and experiment as there is no real commercial equipment available...

Firstly on all bands ATV does use the same polarity as narrow band and so that 19 ele tonna on 70cms or 55 ele on 23cms is ideal (as long as you have a mast head pre-amp and those transverters and linear PAs can be used for the RF part of a digital transmit system...

Most ATV activity is still on 23cms with 70cms increasing in activity. On 23cms most people run FM TV with more people getting on QPSK digital due to the availability of digilite or semi commercial kit from SR systems. Most repeaters (see repeater.net to see where they are) run a mix of FM or digital out but more and more are moving to digital.

70cms is undergoing a revival due to the ability to run digital QPSK in 2 MHz centred on 437 MHz.

I am doing a series of articles for CQTV (suggest you join the BATC for just £4 per year!) on how to and have just be asked to do a getting started article for Radcom - If you PM me I'll email you a copy of the how to rx DATV article...

Re activity - not sure where you are but it is mainly centred around repeaters but with 70cms you can start to work real DX... Quite a few repeaters are getting 70cms inouts but we do not have enough bandwidth to run 70cms outputs. The real place to find activity is on batc.tv, the streaming portal. Watch G8AJN's stream (Bournemouth) on Sunday night and there's always something happening on GB3KM - unfortunately we just lost GB3IV (Isle of Wight) and GB3HV is off air at the moment.

Hopefully that will get you thinking and prompt a few more questions

Best 73

Noel - G8GTZ

Thanks for the comprehensive reply Noel. I fully intend to join BATC in due course - a bit of a "kick the tyres" exercise in progress as I research my options. I'm located in IO91XX - about 3 miles south of the GB3PI repeater at Barkway at 126m ASL. I'm in a new rented QTH where I may have the one antenna up, and I need to be mindful to be discrete. The 70cms yagi will blend in well.

Testing with a temporary 70cms colinear and monitoring 70cm FM repeaters with a UHF PMR set leads me to believe my best directions will be South/South East and due East. Have rising ground to the North towards the ridge at Barkway - but a few mins down the road for a great /P location!

Quite happy to build gear - kits preferred due to limited facilities and looking forward to learning as I go. I'll send you a PM re the article - many thanks. From what you are saying 70cms TRX and 23cm RX would cover me. I could get into the TV repater(s) on 70cms and view on 23cms (or streaming), then use simplex 70cms as conditions/activity allows.

Thanks.

David. G8JGO