VK2RH ham radio

Category: Operating

  • DATV and bands in VK

    Traditionally ATV and its associated analog 7 MHz bandwidth has been restricted to UHF and microwave bands, and bandplans have reflected that. With the global emergence of DATV and RBTV (reduced bandwidth TV) experimentation is now taking place on lower bands, down as far as 10m.

    During a recent radio club meeting where there was general discussion about the new fee-less class licence system just introduced in VK (it began on 19 February 2024), I was looking at the pages on the ACMA website (the regulator in VK) and followed links to the legislation (Radiocommunications (Amateur Stations) Class Licence 2023), a relatively succinct 34 pages complement to the 483pp of Radiocommunications Act 1992.

    Alongside conditions about qualifications, licences, callsigns and electromagnetic energy exposure, there is a schedule detailing “Permitted frequencies and limits on operation” organised in terms of licence type – Foundation, Standard or Advanced.

    The main national organisation of Australian radio amateurs, the Wireless Institute of Australia last updated its detailed 32 page bandplan in September 2020.

    In contrast the recent handful of pages listing permitted frequencies and limitations indicates a light touch administration that may well enable innovation on the bands especially above 28 MHz and future proof the management of these bands. (But of course legislation and band plans are different documents with different purposes.)

    Above 52 MHz there are no bandwidth limitations on amateur transmissions.

    The limitation imposed on transmissions on 10 m is

    If a person operates an amateur station with an emission mode that has a necessary bandwidth exceeding 16 kHz, the maximum power spectral density from the station must not be greater than 1 watt per 100 kHz 
    from Tables B & C, Schedule 2
    Radiocommunications (Amateur Stations) Class Licence 2023 

    And the limitation on the 50-52 MHz segment of 6 m is

    A person must not operate an amateur station with an emission mode that has a necessary bandwidth exceeding 100 kHz 
    from Tables B & C, Schedule 2
    Radiocommunications (Amateur Stations) Class Licence 2023

    It will be interesting to see how different groups of amateur users negotiate a coordinated way to use the bands, and still maintain freedom for technical innovation for such modes as RBTV and DATV and whatever else might emerge in the future.

    I imagine anyone building a Portsdown DATV setup in Australia like I am right now, should consider bands beyond 70 cm & 23 cm. Exciting times.

  • Portsdown 4 project back on track

    I’ve been building bits and pieces of what will become a digital amateur TV capability for just on five years! I lost my momentum after building a number of components and it’s only in the last few weeks I’ve found a renewed enthusiasm to get on with it!

    One of the main prods has come from watching the weekly DATV net on VK3RTV. Anyone anywhere can watch this either live via this BATC streamer link or via Ian VK3QL’s YouTube channel. The net attracts an energetic and skilled group who easily sustain a fast paced 60 minute video conversation. It’s very smoothly presented with lots of visual variety and useful information and very few technical hiccups. The Melbourne DATV amateurs seem to have a very professional sense of time and audience interest and keep the show moving.

    My other inspiration is the weekly BATC Oscar 100 net scheduled for 8pm Thursday which is either 6am or 5am(!) on Friday morning here in eastern Australia. I’m trying to work out how I might record it off the streamer while I sleep. This international net happens over the brilliant geostationary satellite QO-100 whose footprint unfortunately doesn’t include Australia, but it does appear to have boosted interest and activity in satellite communications and DATV in Europe. If I set the alarm I can watch this BATC net via the BATC streamer .

    a block diagram to help think through the interconnections between the different components makig up the Portsdown 4 DATV transceiver.

    This is the first result of my planning the build of my Portsdown 4. I’m sure it will change over the next few weeks. It’s also to help me work out which controls and connectors might go where on the front and back of the enclosure. I actually find this thinking very enjoyable.

  • US exams at Wyong

    About midway through January, I heard via a Sunday morning WIA broadcast that a group of ARRL Volunteer Examiners was offering to hold exam sessions at the Wyong Field Day at the end of February.

    I passed my original amateur license exam here in Australia almost 40 years ago. My AOCP (Amateur Operator’s Certificate of Proficiency) says I passed a test on 21st November 1978. (That was probably the date of my second or third attempt to pass the morse at 10 wpm test.)

    For the exam, I also had to answer questions about radio regulations and to demonstrate “a knowledge of wireless telegraphy and wireless telephony and electrical principles”, I had to write a number of essays about things like neutralizing a valve (tube) power amplifier or how a superheterodyne receiver works. A lot has changed since then. New technology like software defined radio and the internet.

    After I heard that local hams were conducting US license exams here, my first resolution of the year was to pass the US exams for all three levels.

    I was surprised that I was able to do this. All the FCC required was an online registration of an FRN (an FCC Registration Number) using a US address which was easy enough to obtain without having to pay a monthly fee. Also for the US, there is no license fee and licenses have a term of ten years.

    With just on six weeks to prepare I planned to work sequentially through the three levels, spending more time on the hardest level, Extra. With no time to spare I ordered Kindle versions of the license manuals for all three levels. I also downloaded copies of the freely available complete question pools for each level. The exams are objective tests based on random selections from every part of all of the ten main exam topics – 35 questions for Technician and General, and 50 for Extra.

    The license manuals essentially re-arrange the hundreds of disparate questions into a more or less flowing narrative about how to be a modern ham radio operator.

    As I worked my way through the manuals I would mark up the questions and answers in my copies of the question pools and make notes if necessary to explain the answer.

    The information in the manuals was very well presented and manageable and digestible. I loved the way liberal amounts of ham radio wisdom about operating practice was added to the mix. It was really like having your own personal Elmer guiding you through the intricacies of aspects of the hobby that previously were unclear or were new to me.

    Best of all for me the study process demystified a lot of the mathematics of electronics and set me on a path to better understand what after all is the basis of the ‘magic’ of radio. I love the fact that the Scottish mathematician Maxwell concluded radio waves must exist, just from the maths, many years before they were actually discovered or produced by Hertz and others.

    The ARRL web pages supporting the license manuals has links to a range of other resources including a page of references that pointed me to a really brilliant site which sets out to systematically (and enjoyably) explain the advanced maths to those whose school maths didn’t quite reach those dizzy heights, like me. It’s highly recommended if you want to delve deeper.

    I’m happy to say I passed all three exams. I received an email from the FC about two weeks after the tests. There was no real need to do it, but it was a personal challenge – a little like voluntarily doing a driving test again, times three. It also turned out to be a convenient way to calibrate and update my ham radio knowledge.

    The session was well organised and afterward, one of the VEs demonstrated how he uses his US call by connecting via remoteham.com on his iPad to a contest-grade station high in the hills in New York state. Amazing and fast! At rates around US$1 a minute, this must be a good way to turn a remote location into a source of revenue to be earned from the hordes of hams living in cities with a high level of local electrical noise.