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International Ham Radio News & Opinion

Digital Voice (DV) – the new FM?

7 October 2013 | by Rob MW0DNK | Leave a Comment (2)

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!

Rob Law, MW0DNK, is a regular contributor to AmateurRadio.com and writes from Anglesey, Wales. Contact him at [email protected].

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Coronal Mass Ejection (CME) on 2013/09/29

6 October 2013 | by Tomas NW7US | Leave a Comment (1)

A magnificent eruption ejected a massive cloud of solar plasma out away from the Sun, into interplanetary space on September 29th (2013/09/29). A long filament of plasma hovered above the photosphere, captured by the magnetism in the Sun’s northern hemisphere. Then, it erupted in spectacular energy as seen by the Solar Dynamics Observatory, and by Stereo and SOHO spacecraft. This plasma eruption produced a stunningly beautiful coronal mass ejection (CME).

Coronal mass ejections are often associated with solar activity such as solar flares, but a causal relationship has not been established. A coronal mass ejection is also produced when a plasma filament (or prominence) breaks away from the magnetic clutch of the Sun, escaping the gravitational pull. While many plasma ejections originate from active regions on the Sun’s surface, such as groupings of sunspots associated with frequent flares, any plasma formation could break away. Near solar maxima, the Sun produces about three CMEs every day, whereas near solar minima, there is about one CME every five days or even less frequently.

When a CME passes Earth (not all CMEs are directed toward the Earth), it could cause geomagnetic disturbances, triggering aurora and causing disruption of shortwave radio communications.

Although this CME was not aimed at Earth, it passed by the Earth with a glancing blow from the plasma cloud on October 2-3 2013. This caused a geomagnetic storm (minor level), which lowered the Maximum Usable Frequency (MUF) over many ionospheric radio-wave propagation paths on shortwave radio. This lowing of the MUF is often regarded as a
degradation of shortwave radio conditions. Some aurora is also produced, though this event did not cause much significant aurora.

Here’s a video showing the magnificent plasma eruption and CME:

Credit: SOHO/Stereo/SDO/NASA

More info: http://SunSpotWatch.com and on Facebook at
https://www.facebook.com/spacewx.hfradio

Aurora Watch: http://Aurora.SunSpotWatch.com

Visit, subscribe: NW7US Radio Communications and Propagation YouTube Channel

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The West Virginia Chapter of the NAQCC Club

6 October 2013 | by John N8ZYA | Leave a Comment (0)

I’ve reached a peak in this QRP radio hobby where I have a deep desire to share my enthusiasm for Morse Code and QRP radio with those in my home state of West Virginia. The announcement of the West Virginia Chapter of the North American QRP CW Club is in the current newsletter of the NAQCC club this month.

I’ve included a link to our “West Virginia Chapter” page on the right side of this blog, so be sure to check it for the latest information on activities and feel free to drop your comments and suggestions for our NAQCC WV Chapter on this site.

West Virginia is a beautiful place to live and we’re known as the “Mountain State” for good reasons. There are more than one hundred “mountain tops” at more than 4,000 ft elevation. West Virginia is also a “rural” state where electrical noise is nearly “zero” in many places. This makes an “excellent” venue for low power Morse Code radio operations.

This local chapter is for the CW QRP operators in West Virginia. I’ve discovered around 40 NAQCC members on their national membership list. I find around 20 are “radio active” in our state. I hope to hear from and meet many of them as soon as possible.

Listen for our chapter on the standard QRP frequencies of all bands. Check the NAQCC WV Chapter for our future activities.

If you’re a WV QRP CW radio operator, and not on the NAQCC membership roles; drop me a line and I’ll be more than happy to include you on their (and our) e-mail list. Membership is absolutely and unconditionally “free”.

John Smithson, Jr., N8ZYA, is a regular contributor to AmateurRadio.com and writes from West Virginia, USA. Contact him at [email protected].

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ICQ Podcast S06 E20 – Using PC as test Equipment (06 October 2013)

6 October 2013 | by Colin M6BOY | Leave a Comment (0)

Series Six Episode Twenty of the ICQ Amateur / Ham Radio Podcast has been released. The latest news and Martin, M1MRB & W9ICQ discusses using a PC as test equipment.

•VK amateurs win reprieve for 2300-2302 MHz
•FCC dismisses 'Encryption' petition
•YL Activity Week
•Guantanamo Bay
•School to launch 434 MHz balloon
•The question is: .... "Explain amateur radio?"
•Amateur Radio well underway in Kosovo
•Turkish Special Event
•Swedish Radio Hams on 472 kHz
•White House recognizes Radio Ham as 'Champion of Change'

Colin Butler, M6BOY, is the host of the ICQ Podcast, a weekly radio show about Amateur Radio. Contact him at [email protected].

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ICQ Podcast S06 E20 – Using PC as test Equipment (06 October 2013)

6 October 2013 | by Colin M6BOY | Leave a Comment (0)

Series Six Episode Twenty of the ICQ Amateur / Ham Radio Podcast has been released. The latest news and Martin, M1MRB & W9ICQ discusses using a PC as test equipment.

Colin Butler, M6BOY, is the host of the ICQ Podcast, a weekly radio show about Amateur Radio. Contact him at [email protected].

» Leave a Comment (0)

Series Six Episode Twenty – Use PC as Test Equipment

6 October 2013 | by Colin M6BOY | Leave a Comment (0)

Series Six Episode Twenty of the ICQ Amateur / Ham Radio Podcast has been released. The latest news and Martin, M1MRB & W9ICQ discusses using a PC as test equipment.

Colin Butler, M6BOY, is the host of the ICQ Podcast, a weekly radio show about Amateur Radio. Contact him at [email protected].

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When the kids leave….you down size but what about the shack!!

5 October 2013 | by Mike VE9KK | Leave a Comment (6)

As I sit here in the "shack", "radio room" "man cave" it's hard to fathom downsizing also includes the radio room. So what kind of changes am I in for....? The "I love me wall" with all the paper is now going to become the "I love me book", as there is no wall space. The operating desk with 3 monitors and the rigs and "stuff" all spread out is moving to a roll top desk with much less space. My attic fan dipole ( which is down and sold) is now changing to..........well I'm not sure yet. There is the other part of the hobby I love, the kit building. I have an Elecraft K2 on the go and as I look over my shoulder at my setup for kit building that is going to have to go. I am going to have to use the roll top for double duty. So one may wonder if I am a depressed ham.......NOT AT ALL. It's exciting times here at VE3WDM for sure and I look forward to the challenge!

You know what folks, me and my family have our health which is HUGE to me! Overall we are not doing bad at all so the real big picture is not what is going to happen to ham radio..... that will always be there just in a different way. Each night I watch the news and peoples lives change in ways I could never imagine or handle. As for me my little world it's just a change in ham radio and that is just plane old peanuts!

Mike Weir, VE9KK, is a regular contributor to AmateurRadio.com and writes from New Brunswick, Canada. Contact him at [email protected].

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