Digital Voice (DV) – the new FM?
|My home DSTAR hotspot. Comprising 2m PMR radio (underneath), GMSK modem (top) and Raspberry Pi computer (bottom).|
2m – a Band of Two Parts
Like the incoming tide washing away a beautifully constructed and elegant sandcastle, bit by bit, this week’s tropospheric ducting crumbled away with equal inevitability.
At its height, this radio superhighway, formed by different layers of air density and temperature, ‘hotwired’ parts of Europe together on 2m and above like they were connected with RG45 coax itself.
The opening was heralded, accurately, by William Hepburn’s tropospheric ducting forecast (see http://www.dxinfocentre.com/). This site also explains various propagation modes on VHF and above, in a clear and informative manner.
Let me tell you a little about my 2m station here in North Wales. I have a lovely Icom IC-910HX and my antenna is an HB9CV. Yes, you heard right, a peashooter. Two small elements phased together and put up on a pole on the side of the house. You see, I’m starting modestly because our national culture demands that we never do things the easy way. Added to the equation of difficulty, I have a range of 3000ft mountains not too far away from me. Did I mention the HB9CV was fixed? It points plaintively towards the south-east in cold, metallic expectation of flux. It points towards the long, golden beaches of the low countries, the rolling fields of northern France, the great cities of Western Europe and finally, the snow-capped Alps and beyond. But it also has a ‘heart’, a cardiod footprint in fact. The characteristics of the HB9CV trade-off a modest gain with quite a wide beam-width, with a sharp null behind it, giving it its heart shape.
You need good hearing. The receive gain is lacking for weak-signal work, but work it does. And this week I worked a station (OE2XRM) in Salzburg, Austria. 5,5 both ways! The pure magic of hearing a man who may be wearing lederhosen over what is normally a line-of-sight form of communication, is thrilling! A couple of stations from Bavaria followed and I was then content to listen as the chatter of stations from France and the Netherlands filled the band.
Later in the afternoon, fuelled by electromagnetic excitement, I ventured onto a local hill (178m/584ft.) with my lovely FT-817 and a 9-element 2m yagi. I also took along a 70cm yagi for fun. A quick scan through the beacons bought in HB9HB in Switzerland! The Alps, the chocolate and cuckoo clocks! Unleashing my 5W on Europe didn’t produce much, unfortunately – just a couple of cheery calls from the UK, so I thought I’d swing the beam round to Spain. Now, the DX cluster was not showing any propagation in this direction and I wasn’t hearing any of the beacons on the north Spanish coast. But suddenly, out of nowhere, and at 5,9+, came a signal booming in. Danny, EB1LA, on the northern Spanish coast was stunned to hear me at 5,9 with my humble five Watts. What a result! I can only conclude that the beacons may have been situated too high to ‘tap in’ to the duct. How many people in the UK and Ireland must have been beaming away from Spain that day having assumed that no beacon = no path? I wonder. A quick scan on 70cm revealed no traffic, but I did receive the Netherlands beacon PI7CIS. Quite a trip for UHF.
The two metre band can be sublime, but comes in two parts. The FM part of it is like an amateur ‘pub’. It seems the place where people gather in the evening to discuss their day and engage in chat (For example, one QSO I heard earlier this year was despairingly on the subject of “my favourite biscuits”). But the lower portion of the band has the elegance and sophistication of a Grand Cru. It’s as if it’s optimised in terms of antenna size, required power and number of users to give you a fighting chance of achieving glory in the aether. And I did.
A Quick RoIP Experiment
RoIP stands for Radio over the Internet Protocol and you can use this technology to connect remote radios over any distance, easily.
Above: Zello VOX settings on PC and Zello GUI on Windows XP
Now I know that Ham Radio Deluxe can be established to give full remote control over my rig, but that’s for another day. This is one solution to automatically link two radios that anyone can do.
More of a Shout than a Whisper…..
|FT-817 and Signalink USB Interface|
|WSPR Control Software|
|10 mins on 17m!|
|10 mins on 20m!|
More of a Shout than a Whisper
|FT-817 and Signalink USB Interface|
|WSPR Control Software|
A WSPR in your ear.
|Screenshot of WSPR.net Map Page|
A WSPR in your ear*
*This article is copied from my regular blog page – I apologise to any readers of AmateurRadio.com who may be dismayed at too many articles on this subject at the minute. Thanks for your indulgence!
Like many of us, I am still amazed by the amount of radio spectrum we have to freely play with. Shots are being fired and eyes are being gouged by companies for small slices of precious bandwidth. Multiply our many electric playgrounds by the number of games (or modes) available and the permutations are enough to overload your front end.
I’ve decided to catch up with WSPR, a mode well known to many but new to me. I’m going to give it a go – the difficult way. Julian, G4ILO has an excellent article on the system here.
WSPR stands for Weak Signal Propagation Reporting and is a computer programme that runs your VHF/HF transceiver automatically in order to receive others running the same system. Successful contacts, one or two-way, are reported automatically to a website. It’s like having a worldwide net of propagation beacons for every band available at your fingertips and the results appear quickly after automatic contact confirmation. What a great thing to leave your equipment running overnight or during the day when you’re otherwise occupied!
The best thing is that WSPR works below the noise threshold and you can use very low power. I was staggered the other day to see that Tim, G4VXE had hit Australia on 40m with just 1W! One Watt! So I’m going to give it a go with 1W and just an indoor Miracle Whip antenna. I know many QRP CW experts may cracked this one before – but I’m new and excited. I’ll try 40m and work my way up to 2m and see what happens!
I’ll use my FT-817. A CAT lead arrived this week from Hong Kong but it seems I’ll also need an audio interface between the transceiver packet port and computer sound card to make it all work. Another option is to buy an external interface that has a sound card and interfaces to the computer with a USB. It’s not quite going to be a ‘plug and play’ job, I’m afraid to report.