Activating with digital voice modes?

I can’t speak for C4FM (as I’ve never actually used it). Though my observation from using both DMR & also experimenting with DSTAR (in the early days when it was first released) are…

They generally both seem to fail at around the same point as FM, although digital often holds up better (is obviously cleaner & less noisy) up until the point of failure.

As Andy says, I have seen occasions where you can work an FM signal after the digital mode has failed (albeit that the signal is very noisy, harsh on the ear & unpleasent to listen to).

Then again, I was listening to a couple of stations testing FreeDV against SSB on HF a few evenings ago. One of them was a struggle on SSB, the other station I couldn’t even hear.

When they switched to digital (700D mode if I remember correctly) I could clearly hear the station which was difficult without any lost packets. The other station (which was unreadable on SSB) I could make out most of what he was saying. He turned into R2D2 for some of the overs as the QSB kicked in but I got about 90% of what he was saying.

That said, when a strong SSB station popped up just above them, they both became totally unreadable.

As Tom said, it can work both ways.

They’ve recently released another mode in FreeDV called 2020. I’ve not had a chance to try it yet, but I believe that it is apparently supposed to be even better (if you believe the hype). I think we will eventually get to a point where digital modes will out perform SSB.

I think a lot of people are put off by the “robotic” sound that seems to accompany digital voice communications, and I would accept that it takes a bit of getting used to.

We have a Motorola DMR system for our communications at work, so maybe I’ve just got used to it over the past few years.

As I did some experimentation with freeDV in the early days in Australia, one fact I found was readability at the other end was directly related to the quality of microphone and audio settings in the PC on the sending end. Many PC Microphones are “tinny” and these (in my experience) do not work well with FreeDV. I am not saying that you need to use a studio quality microphone (but if you already have one - go for it), just that some PC microphones are a LOT better that some others for FreeDV. NEVER try to use the built-in microphone in a laptop for FreeDV transmissions for example (because the room noise it picks up will kill the transmission).

As the FreeDV software can also switch into “analogue mode” you can easily test microphones (and audio settings) out by transmitting in analogue mode and listening to yourself via a WebSDR receiver before switching to digital. This is also useful to let the station know, who just started calling CQ on top of you, that you are not electrical interference rather that you are using the frequency…

73 Ed.

Quite correct! Guess how I figured that one out!!!

That was exactly what I also noticed when switching between digital & analogue.

FreeDV sounds like static if you are on SSB.

Strong signals would probably be passed off as local QRM/interferance by most ops (which might be enough to deter them from using your frequency).

If you are a weaker signal to them, it would probably just blend into the background static noise and not be noticed by a lot of ops.

I am waiting for that day. My understanding is that there are several current digital modes, each with their commercial backing by different manufacturers, each with their adherents, with none of them sufficiently superior to the others to become the standard. Furthermore none of them seem to have a clear superiority to legacy modes. Frankly, to me this looks more like chaos than progress and I am staying with legacy modes until the situation stabilises. A great time to be an experimenter, perhaps, but not an attractive situation for a user.

Yep, long live the spark gap!!

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Well even SSB is ~90 years old now! (Actually the patent goes back to 1915!)

The problem with digital voice modes when at the point the error correction fails is that we humans cannot understand the partially decoded audio. Whereas with SSB/AM/FM etc. the years and years of speech recognition learned by our brains helps us fill in the bits of audio we missed.

There’s lots of reasons for using digital voice comms but weak signal dx isn’t one of them unless you are able to get the two stations into a mode where they repeat and retry and slow the data rate down till the data is decoded. Then it’s not real time.

Or you can be very lucky and get a diamond.

My son Liam records his weekly local FM radio show using an ancient PC mic we found at the bottom of a junk box - and it sounds really good, almost as though he’s in the broadcast studios - as opposed to the PC under the stairs in our front hall!

I can’t imagine there’s any kind of science to this - just luck. This is a really scruffy obsolete looking thing. We’ve bought much more up-to-date and nicer looking PC mics but they don’t come near to the one he uses.

Listen for yourself from around 2215 UTC tonight on 102.8MHz FM in East Cheshire, or online via

Or if you can’t wait that long, his past shows are available “On Demand” from his website -

I don’t really think about advantages and disadvantages of DV for activating. i just think of it as another mode to play with to add some interest.

Completely agree.

That was my thinking when starting this post.

It’s not about which mode is better or worse. I simply wanted to see which mode most people had (in other words, what was most likely to succeed).

Based on the survey, I think that’s going to be C4FM.

I am a little surprised how many people have DSTAR though. I thought that DSTAR was as dead as a Dodo in the UK! I don’t know how many of those people that voted are from outside the UK though. I believe that DSTAR has a bit more of a following in the USA.

The overriding point was that we see plenty of FM, SSB & CW activations. I wanted to do something a little different just to “spice things up a little”.

James, I’m not suggesting you post another poll here but after your DV capability survey, it would be interesting to know people’s usage of the DV mode(s) they have.

Something like … “Do you QSO by {DV mode} about once a day , once a week ., once a month , once a year , every blue moon , …”

Not really much point because that will all change in the first week of March anyway.

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What happens in the first week of March? What am I missing here?

Tom, I doubt if it will change much in the long term (sorry for being an Old Sceptic).

You’re talking about a special event where people (myself included) will come out of the woodwork because they know it’s an occasion where their favourite lesser-used mode will get used a lot.

Maybe participating in such an event will encourage some people to use those modes more often at other (common or garden, non-event) times. But it’s not going to make much difference spread across an association or region.

So back to DV: if DV has few advantages over AV then fewer activators will stick with DV for very long simply out of interest. What’s more, if alerting and spotting DV raises few or no chasers over a number of activations that’s a further disincentive to persist with DV when FM gets you the contacts. Don’t like to negative but I can’t see an obvious solution.

You’re not looking at the correct advantages DV systems have.

Hint: it’s nothing to do with amateur radio.

The level of use of 12m for activating after the 12m Challenge is significantly higher than before the 12m Challenge. Nothing like as high as actually during the Challenge obviously, but it’s had a quantifiable significant positive impact.

Anyway, even if the boost in activity is just for those Challenge flavour weeks, that in itself is worthwhile is it not?

I recognise the advantage to some parties of promoting new modes, new features and new models. Andy, you and I already discussed this principle w.r.t. Yaesu’s replacement models for my FT-1D.

Having worked for commercial electronics companies most of my life, I understand why manufacturers do this and need to do it. But for this reflector and this topic I’m looking only from an end-user’s point of view.

Oh definitely Tom, hence the reference to my participation.

AFAIC the only advantages that DV could have lies in what it can do for me that earlier modes can not do. It appears that these advantages are minor or illusory. At present. I am no Luddite, when that changes so will I.

Will be activating on 2m C4FM in ten minutes…