Digital Voice (DV) – the new FM?

Once upon a time FM swept away AM, but DV is taking its time despite some clear advantages.

I’ve had yet another stunning 5W mobile QSO on 2m this morning on my way to work. Several miles of clear, unbroken chat, without mobile flutter. DV mode delivers good quality voice against a noiseless background. It is sometimes claimed that coverage is roughly extended by 20% due to advantages of this mode, even. I doubt this is entirely true, but an excellent quality of communication is doggedly maintained before ‘falling off’ very quickly. It is quite robust and packed with extras. Ideal for V/UHF and it’s been around for several years.

Even the 2m band-plan in the UK lists all the simplex channels as dual FM/DV. I must admit that I and my friends keep traffic to the UK DV calling frequency (144.6125 MHz) to ensure anyone equipped with DV will hear us and join. If the current FM population heard our carriers on normal working channels, they would be quick to complain about the noise the noise as QRM.

This is what DV sounds like on your FM radio:

DV mode is famous for being the common mode that binds the larger DSTAR system (Digital Smart Technology for Amateur Radio), but excels as a simplex mode too. No analogue mode will embed your callsign for display, report your GPS position, over a low speed data link – all during a normal voice QSO, rounded off with an inoffensive little beep at the end of the over. (Because there is absolutely no background noise, it’s difficult to detect when someone has released their PTT). This is why DV is such a superb candidate to network via DSTAR. This is where radio marries the internet and we are its children.

The new Icom IC-7100 even has people quirkily chatting away on 4m with DV mode, which I gather works very well.

So what is DV mode made from? Well, your voice is encoded digitally using a vocoder optimised for voice communications in the same way your mobile phone does. The device that does this is called the AMBE chip (Advance MultiBand Excitation). Some people moan that this is unfair being a proprietary device, not being open source technology. However an AMBE chip can be freely bought for just a few dollars and uses proven, reliable technology. Inmarsat have been using it for years.

The digitised voice at 3600bps combines with an additional 1200bps (which you can do anything you want with! Think file transfer, photos, messaging etc.) before being modulated. The 3600bps voice data also includes 1200bps FEC (Forward Error Correction), which sends a little extra data in case any gets lost over the air. When bits are lost, the receiver uses this extra data the plug in the gaps. The modulation scheme is GMSK (Gaussian Mode Shift Keying), which is basically a form of phase modulation. You’ll also appreciate that all new modes often save bandwidth as well as improving quality and a DV carrier will happily fit into 12.5kHz channelised plans.

So, what are we waiting for? The manufacturers! The market is caught up in adoption stalemate, with Icom having settled for DV whilst others shun compatibility. But there are also homebrew DV options out there, with modulator/codec boards that will plug into your FM radio (via the packet port or tap into the discriminator) turning your analogue radio into a dual-mode digital delight.

My home DSTAR hotspot. Comprising 2m PMR radio (underneath), GMSK modem (top) and Raspberry Pi computer (bottom).

There are other digital modes out there too, all with different strengths and weaknesses – and they are interesting. But for the sake of everyday commonality and general take-up, I think DV has it.

So is it time to catch up with modern telecommunications techniques and move away from analogue FM? Maybe there’s something in the more ‘tactile’ feel of FM: The waxing and waning, the background hiss, the heterodyne-ing. You seem to know exactly what’s happening and what’s about to happen. So many modes – enjoy the hobby!

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.

The humble HB9'

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.

My hilltop station

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.

Postscript 03 Oct. 2013: Just read EI3KD's excellent blog about this tropo opening. It coincidentally contains an audio capture of the end of my QSO with OE2XRM! Recommended reading (and listening).

"Armchair Copy"

When I was last active on HF, in 2003, I hadn’t experienced the transient pleasures of a strong 10m opening. The solar cycle was way down on the current crescendo.

For the second day running, I’ve been receiving strong, clear, frequency modulated signals from far afield that sound as if they’re just down the road. Using my FT-817 (5W) and a small Miracle Whip antenna I had a fantastic QSO into Greece. Only a little QSB here and there presented any challenge. I tuned lower in the band to hear a W2 station calling CQ using AM – well I just had to try! I’m actually quite staggered he heard my signal, but obviously not strong enough to discriminate any speech. That would have been expecting too much.

Today on 29.620 the New York repeater, KQ2H, was booming in at 5/9+, of course. European stations a few hundred miles or less apart, were talking to each other via a lengthy transatlantic trip. The FM capture effect ensured that my QRP signal wasn’t fully heard, though I suspect I accessed the repeater more than once.

I’ll look forward to a little more 10m FM while it lasts. Congratulations if you’ve enjoyed a DX ‘armchair copy’ this week.

Cracking the Whip....

The Miracle Whip, that is.

I only acquired my fantastic Yaesu FT-817 to give me 5W of SSB on V/UHF from windswept Welsh hilltops. I couldn’t resist a second-hand bargain of a Miracle Whip to see what I could achieve with QRP on the HF bands.

The '817 and Miracle Whip

It’s a classic Fred-and-Ginger combination that has been blogged, reviewed and You-Tubed extensively along with other rig/telescopic antenna double-acts. Yes, it’s only 57” of radiating metal with a rather good tuner at the base, but thanks to the current propagation conditions it at least enables you to experience the miraculous. Its advantage lies also in its simplicity. It means you’ll use it because it connects, extends and tunes in seconds. I like that! Connect. Extend. Tune.

I’ve been having fun with the ‘817 on my lap, indoors, running off its own batteries (=2.5W max) and chatting to stations on the higher bands in places such as St. Petersburg and the Ukraine with 5/9 reports. You simply can’t get this thrill with a big station. It’s reconnecting to the magic of radio – which is a real miracle every time a contact comes out of the ether. I’m even moved to ‘Tweet’ a new QSO with excitement! (@MW0DNK).

I’ve started at 10m, sliding my way down the bands as the challenge rises. Using 5W (external battery) I managed a QSO with Algeria yesterday on 15m, 4/3. I finally cracked 20m with a shorter, brief contact to Spain. I had a 5m counterpoise wire connected this time.

Connect. Extend. Tune.

On 40m I’m simply not heard, at least not yet. This is where I need to start learning some CW skills. This will open up the lower bands for me. Until then, living on the Isle of Anglesey, I might head to a beach and try getting some salt water under my portable station to see if I can crack the ‘40m SSB phono challenge.’ Listen out for me.

On 2m the antenna is a ¾ wave. I’ve no idea what the radiation pattern is for this length, but it seems to work very well. Unfortunately the antenna is just short of a ¼ wavelength at 6m, so perhaps a wire clip-on extension is the answer.

It was with sadness that on visiting the Miracle Antennas website I saw an announcement about the passing of the company founder and product inventor, Robert Victor, this year. It seems he’s left us a wonderful legacy. Vy 73, OM.

Mic Clickers: Easy 3-Point Guide.

And I’m not talking about the clicking of computer mice here. I’m talking about the highly vexatious and irritating habit of jamming people, mainly on 2m FM by others. Sometimes this escalates to music-playing and verbal abuse. They are here and here to stay. Thankfully there aren’t many of them, but we’ve nearly all heard one from time to time. What to do?

Don’t worry! I’ve compiled a quick, easy and memorable 3-point guide on what to do if you encounter any wireless abuse. Feel free to print this out and place it above your rig:

1. DO NOT acknowledge any interference
2. DO NOT acknowledge any interference
3. DO NOT acknowledge any interference

Clear enough? Self-evident? One would blooming think so. However, I’ve regularly heard some less-than-fully-brain-QRV amateurs :

1. Acknowledge the interference, repeatedly
2. Provide the abuser with a useful and accurate signal report
3. Articulate ‘entertaining’ anger and frustration to encourage further abuse

Once you can grasp the simple, blinding reality that these abusers only do this to elicit a response – provide them with that response and they will continue, satisfied and emboldened. Deny them that response and they will, eventually, cease and desist. I promise you.

In my beloved country of Wales, we have a legend that the entire army of Owain Glyndŵr, rebel leader and last (Welsh) Prince of Wales (1400 – 1415 AD) lies sleeping in a hidden cave in the mountains, waiting for the call to defend the country once more. I have heard amateurs say on-air ‘that a group of detecting stations’ was out-and-about and would quickly track down the offender with their accurate yagis and Jedi-like triangulation skills. Oh. Would this mythical radio foxhunting elite be the band of 2m septuagenarians who only exit their shacks to eat, make tea and perform vital bodily functions, would it?

Owain Glyndŵr,
detection genius.

It’s equally remarkable and disturbing how some people even enter into one-sided psychological games with their abusers, labouring under the misconception that they are cleverer than the offenders who must be naturally stupid. They are not. Threats of ‘I know who you are’ (when you don’t), reports to government agencies (who don’t care or are too busy), Owain Glyndŵr’s sleeping detection-army – I’ve heard it all. Don’t rely on the fact that you’ve passed a foundation exam that a five year-old girl passed last month will guarantee you intellectual superiority in this case. The same goes for intermediate and advanced licence holders for that matter.

Break any of my 3-point guide rules and you’ve lost before you’ve begun.

In my next blog: How to deal with pesky competition stations…….

Icom IC-E92D – Why This Is My ‘Staple’ Handheld

Every ham has a handheld in their collection of transceivers. I have one normal rig in my collection of handhelds. Nearly all the equipment I have can be held in my hand, chucked in the car, operated ‘portable’ or temporarily connected at home. It’s the capability that would suit a cold war double agent who has to move between a series of safe-houses at short notice. Everything I have, I can pick up and run with. Just as well I don’t have an HF vertical that looks like a porcupine then.

I’ve had my beloved Icom IC-E92D for a couple of years now and I spend more time talking though this than any other piece of equipment. Two years ago there was no DV (Digital Voice) or D-STAR activity in my area, but I wanted a dual band handheld that would be, to some extent, future-proof.

And before the rival Yaesu C4FM digital system is mooted, let me say that D-STAR is so firmly established, that a lot of infrastructure would be needed to better the existing system. Great advances have been made lately with the advent of the German DV-RPTR (‘DV Repeater’) boards as well as the new DCS reflectors. Having said that, I’m always keen to try any new digital modes. 

I’m not going to dwell heavily on specification and features because this is not a newly launched product – there are plenty of excellent resources and reviews already available. But here are some things that have pleased me about both the radio and the technology behind it.

Icom IC-E92D

Let’s put the digital stuff to one side for the time being. I think the E92D is just an excellent FM transceiver in its own right. Its construction is solid and feels good in the hand. Used outdoors, it’s comforting to know that it’s waterproof. I live in Wales, after all. The send/receive audio quality is very good in all modes and the microphone doesn’t suffer from the aforementioned weather-proofing that blights some other units. It seems XYL’s sewing kits have been raided worldwide for needles to pierce microphone membranes.

I love using low power when I can. In DV mode you either get a R5 copy or rapidly nothing. Why not see how low you can go? The E92D will go down to 100mW and oddly enough I use this more than any other power setting. It’s also all you need for your home D-STAR hotspot, isn’t it? A group of three of us had a 2m net with a distance of 20 miles between the furthest stations. We all used DV mode and 100mW (external antennas, of course) for a full lock and quality audio output. Compare this with the FM mindset of achieving ‘full quietening’ in many local nets. Admit it - a small swell of pride is taken in how many dB’s ‘over’ are registered. With DV it is how few. Back to the E92D: If things get marginal and stressed then the next increments are 500mW, 1W and 2.5W. Unleash the whole 5W if it’s a national holiday or you’re feeling reckless. In common with many handheld owners, I also have an aftermarket antenna to add a little more gain when needed.

Built for the outdoor life - with HM-175
GPS Speaker-Mic 

I have, and recommend, the RS232C remote cable and bundled programming software. There are enough people now who have kindly uploaded their files (called .icf files) to the internet with repeater and node settings for entire countries. You can enter or edit data manually from the front panel, but as with most radios a computer will save you time you can otherwise spend chatting idly. Seeing how the channels and banks are organised on-screen helps you properly exploit the memory capacity. Apart from the usual, I have also stored AMSAT, marine band, PMR and SWL channels. I travel a lot so it’s good to have repeaters stored by region too.

Dislikes? Only a couple and they’re not going to jaundice my high regard for this pleasure-giving, grown-up gadget. Most E92D owners acknowledge that although the battery life is good, there is little warning given before the battery dies. A bit like a pet hamster. Again, with four power settings you should optimise your battery life. Secondly, I don’t think many consumers would eagerly vote for an SMA antenna connector over a BNC, but we have to live with that. The main problem can be a snapped pin from an over-stressed SMA to SO239 adaptor, for example. This happens easily, frequently and on one occasion to me. I sent my unit back to Icom UK for repair, as the stuck pin could not be extracted. I must add that their support and service was fantastic. The repair was carried out quickly and was not costly. Chastened, I made a pigtail adaptor for use in the car, shown below.

SMA - SO239 adaptor

As far as accessories go, I have the HM-175 GPS speaker microphone. The embedded data channel in DV is something we’re only just starting to fully explore. GPS position and distance reporting between simplex users or posts on APRS.fi via a repeater are fun. I also have a two-pin mic/headset adaptor for mobile work.

Just download an electronic manual and have a look at the level of specification and configurability! You'll find a new feature every day for the first few months. There are now the lower-cost IC-E80D and 70cm-only IC-ID31E to supplement the range, of course.

So, after two years I think the big test for any bit of equipment would be “If it was damaged/stolen/confiscated by vexed YL/XYL, what would I replace it with?” For me, an exact replacement, no less. It’s a much of a staple as the King Edward potato. 

The Man Who Fishes For DX

I live on Anglesey, a mystical Celtic island steeped in the legends of the Druids and lapped by the misty waters of the Irish Sea. There was whispered talk amongst the old people of an elusive man who fished for DX and caught specimens from Borneo, Antarctica and other strange lands.

Actually, it’s only Dave.

Dave, GW4JKR, has an antenna system that you can’t buy from any supplier. He uses a carbon-fibre fishing pole on a metal spike and several acres of saltmarsh. The system is blindingly simple, takes minutes to erect and is devastatingly effective.

“I set up on the 20m band and all was quiet. I put out my first call (SSB) and you know what? I worked Borneo 5/9. Because he was an English ex-pat, I thought he was local until he gave his callsign for the second time! Other local stations here couldn’t even hear him.”

In a similar vein, Dave related how he’s had a 5/9 chat with a chap with a German accent. Only turned out he was on holiday in Guadalcanal. “You’re the only station in Europe I can hear,” he said from his sunny patio.

One of Dave's many QSL cards

The DX takes the bait each time. Reports come in from the Pacific islands, China, Japan, Korea, Antarctica and New Zealand. I think Dave’s witnessed more pile-ups than the M6 motorway.

The antenna system comprises two ultra-efficient parts, making it a genuine ‘killer’ setup. For the antenna, Dave uses a carbon-fibre fishing pole, also known as a ‘roach pole’. He specifies the better quality versions that use high modulus carbon for optimum conductivity. The pole is approximately 12m in length, coming in seven sections. It is featherweight at under a kilogram. The base of the pole mates to a large ‘agricultural’ steel earth spike, which is actually a brutal pummelling device for digging holes in rocky ground. A plastic sleeve insulates the two components. Coax is easily attached by jubilee and croc clips. The second part of the antenna system is the saltmarsh on the edge of an expansive tidal sandy bay. The saltwater saturation, even at low tide, is high. Ask the shellfish.

Red Wharf Bay, Anglesey

Like a latter day St. George, Dave holds the spike aloft and plunges it deep into the salty mud where it stands at the ready. If there’s a small pool of salty water nearby, all the better – in it goes. Wet, sandy beaches work, but not nearly as well as dark, oozing mud it seems. Lovely.

Clearly the vertical radiator, wide open aspect, perfect electrical ground and ultra-low angle of radiation give the best start a radio signal could ever want in in its sinusoidal life. It’s as electrically quiet as a library down on the beach which makes for reception most of us can only dream of.

Base section of carbon fibre
vertical in situ

Follow Dave’s simple formula and you too can become a fisher of men and the stuff of legend.

SAFETY: Dave would like to warn all readers to exercise care when handling a carbon fibre pole in the open. Do NOT venture anywhere near power lines. You may render yourself permanently QRT.

More photos available on Dave’s Flickr site.

DCS: Also Reflecting Our National Traits

Sometimes I find how we use new technology is as interesting as the technology itself. You may not know or care what DCS reflectors are, but the way they’re developing tells us a little about ourselves, I think.

DCS reflectors are basically a new generation of servers or chat rooms we use with digital amateur radio to link repeaters, nodes and individuals together. They were developed recently by some very clever enthusiasts in Germany and are growing in an organic way. A bit like dandelions.

Each DCS reflector has modules from A to Z, which are a blank canvas. The way in which these are being filled is like a group of sugar drink-fuelled children scrambling to choose their bunk-beds in a large dormitory at summer camp.

Let me explain: The first two DCS reflectors, DCS001 and DCS002 were hosted by the Germans. They had neatly and orderly divided up the entire globe into modules. It was a good start. For their own country they had a national module of course, with additional modules for north, south, east and west Germany respectively. But anyone who knows a little about Germany should not be surprised to see that Bavaria has broken away and formed its own module. The states of Hessen and Baden-Wuettenberg followed suit, of course. The states of the former East remain quiet for the moment, it seems.

There are now nine DCS reflectors at the time of writing, all now hosted by different countries who wanted their own national servers. The Dutch are fastidious in their egalitarianism. They’ve gone and divided their reflector into nation-wide, north, mid and south Netherlands as well as – wait for it - thirteen different regions including the colonies of the Dutch Antilles. The inhabitants of Flevoland must be ecstatic.

The Swiss, however, have no national module at all. No, they’ve divided their piece of DCS cake in language-slices: German, French and Italian. I’m also sure it will be the most reliable DCS reflector ever known to man.

The Italians seem a little less self-assured. They have a record number of four test channels, just in case.

The US reflector is well-ordered, with a couple of the noisier states, like Texas, having their own module. Even the Canadians are accommodated.

And as for my lot, the Brits? Well, we would have to be a little bit different, wouldn’t we? At the time of writing there is a national UK module, with a Northern Ireland, Wales & West, Midlands and South module. No Scotland so far. Maybe it’s the expense. And uniquely in the new DCS community, the city of London has decided that it is elevated enough among the great and good capitals of the world to merit its very own module.

I think we can rightly take most pride in the four inconspicuous modules simply labelled as ‘chat’. You can transfer to these modules for your one-to-one conversation without tying up the repeaters of an entire small country. I have heard less-than-scintillating conversations occupy worldwide reflectors for some considerable periods.

The pace of development is astonishing. An idea whispered in the ear of a developer is often embodied overnight. And we’re just one month into the story…..

UK DCS005 shown on he excellent (German) DV-RPTR
Control Centre software

FT-790R, 1W of Forlorn Hope?

“One Watt! One Watt! What on earth bl***y use is that to you?! I don’t know… (sigh)” exclaimed one local straight-talking OM on 2m FM yesterday.

His response to my acquisition of a rather dated Yaesu FT-790R ‘portable’ transceiver was less than encouraging. It’s just as well I’m an optimist then. With a maximum output of one Watt on one band (70cm) I think I’ll need to maintain an upward outlook.

But here’s the thing – I always find myself drawn to obtaining the more elusive QSO. You need a certain amount of eccentricity and tendency to self-harm to stand on a hilltop for hours calling out on 23cm FM QRP, for example. I was the first in the area to start calling CQ on DV mode on 2m. It took months before my first simplex QSO and then very little since.

The higher bands and modes have their rewards in spades, however. The rush of excitement when you finally make that new or distant contact. The perceived camaraderie knowing someone has gone to the same quirky lengths as you to operate on a lesser used band/mode or from an unusual location. You feel you have made a meaningful and personal connection, at least for the duration of the QSO. Oh, it’s such a far cry from exchanging reports of 5/9 with the fiftieth Italian station running 1kW on 20m you’ve spoken to in one morning. Better still, no QSL cards.

Any why the FT-790? Well, at just over £100 it’s one of the few portable internal battery-powered transceivers you come across before taking the small fiscal leap to an FT-817, for example. Either way, it will hold its value if my 2m friend’s prophecy becomes true.

Anyway, so far so good. It’s powered up and seems to be fully serviceable. I’ve even managed a short-distance QSO with John GW4ZPL over the Menai Strait in the Caernarfon direction, just a few miles away.

I’ll be out and about when the weather improves and will post my experiences here. Will it be too futile, or with a bit of luck will I make that elusive QSO I’m after? Will my single sidebanded plaintive cries of CQ reach a caring ear?

Maybe I’ll be happily shouting “One Watt! One Watt!” from a heathery Welsh hilltop.

FT-790, forlorn hope?