Activating with digital voice modes?

How many of you chasers have digital VOICE capability? Especially those of you who live around the Pennines (I’m thinking of trying this on Shining Tor next year when the weather warms up)?

I’ve included a poll just to satisfy my own curiosity:-

  • I have DSTAR capability on VHF/UHF.
  • I have DSTAR capability on HF.
  • I have C4FM capability on VHF/UHF.
  • I have C4FM capability on HF.
  • I have DMR capability on UHF.
  • I have FreeDV capability on HF.
  • I cannot run any digital voice modes.

0 voters

I know that plenty of people have activated summits using digital modes. There’s plenty of videos on YouTube of people using PSK-31 & FT8 on summits & I know Tom M1EYP has done numerous FT8 activations, but has anyone tried an activation using only DIGITAL VOICE modes?

I’ve thought about giving it a go just for fun (as it’s a little different from the norm) but I’m left wondering how many chasers actually have digital voice capability, and whether it would be possible to drum up enough contacts to qualify a summit?

It also begs the question of what mode to use?


  • Yaesu C4FM:- I’m sure I’ve read other posts where this has been mentioned, so presumably a couple of people have that capability? Unfortunately I don’t currently have a radio capable of C4FM, but putting it out there as a hypothetical (I am considering upgrading/updating my handhelds, so I can’t completely rule out this mode).

  • DSTAR:- This never really took off in the UK. It had a brief burst of popularity when it first came out, then died a thousand deaths! I suspect that some people may still have some old Icom DSTAR kit laying around.

I have a Icom IC-E92D handheld which I still use in FM mode for SOTA activations on account of the fact that it’s waterproof and reasonably rugged. I also have a 2820 mobile radio in the cupboard, though I’m probably in the minority.

Obviously from my perspective this would be my preferred mode as I already have a DSTAR radio which I have with me on activations anyway, so I wouldn’t need any extra equipment.

  • DMR:- I suspect that this is the most likely to succeed as DMR has been very popular in the UK over the last couple of years, although the DMR repeaters do suddenly seem to have gone very quiet. I don’t know how many people actually use this mode (or have their radios programmed) for simplex contacts though.

On HF:-

  • C4FM:- Some of the newer rigs (Yaesu FT-991) have C4FM built in for both HF & VHF/UHF, though I don’t know how many chasers have these rigs?

  • DSTAR:- Some of the newer rigs now have DSTAR capability of HF (Icom IC-7100 & IC-9100). Again, I don’t know how many chasers actually have these rigs?

    On a side note, Icom are soon to release the IC-705 which has DSTAR on all bands. It’s a 10 watt radio which appears to be a replacement for the old IC-703. Looks like a good radio for SOTA?

  • FreeDV:- Again, not sure how many people have this mode (although anybody running FT8 or PSK should be able to run the FreeDV software on their computer). There are a few regular nets & the RSGB do the weekly new broadcast in this mode, so presumably some people are running it.

    Unfortunately it would require a computer to be carried to the summit, and would involve an added level of complexity (& chances for failure) which obviously isn’t great.

I’m swaying towards suggesting that DMR on UHF is probably the best option, closely followed by Fusion on VHF.

HF wise, I’m just not convinced that the equipment is out there (as they haven’t been on the market that long). Given another year or two as people upgrade their equipment, either DSTAR or C4FM may become more prevalent on HF. As things currently stand, I’m not sure.


Hi James,

I routinely alert for C4FM on 2m for SOTA G/LD and WOTA activations because there is an active C4FM chaser community in the north Lancashire / Cumbria area. However, even here I wouldn’t rely on getting 4 C4FM contacts to activate a SOTA summit.

regards, Andy

It does seem that most of the latest models from Yaesu now come with C4FM capability as standard, so I guess it makes sense as there are probably actually quite a few C4FM capable radios in circulation now.

How many people actually use that function is another matter of course.

I suspect that very few people routinely monitor C4FM, or any of the digital voice modes for that matter.

I think most would only bother to switch to digital if they were expecting someone to be there (if alerted for a SOTA activation or if a QSO had been pre-arranged for example).

That’s kind of what I suspected!

It will be interesting to see what the results of the poll are once a few more people have had a chance to see this post.

I also have P25 on UHF

Hi James,
Can you please update your survey - DMR is both VHF & UHF. In any case I have DMR simplex capability on 2m & 70cm but hardly ever use it over here in Germany as I tend to operate HF when I activate. I can certainly operate FreeDV from home on HF or VHF but to operate it portable would need me to take my Windows tablet along. Do-able in the dryer months but not a great idea in winter. I don’t have the FreeDV speaker Mic - which would be the more “resilient” option for portable operation.
By the way those with Flex or the Chinese RS-918 rigs have FreeDV built-in, otherwise (if not using the SM1000 FreeDV speaker Mic.) it’s extra computing hardware to be taken along to an activation (as with many of the newer digital data modes).

73 Ed.

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That’s my experience. It’s like calling CQ at random on 23cm or 2m CW. It’s a minority sport and needs to be prearranged via alerts and spots. And usually, it’s the same chasers I worked minutes earlier on FM.


I have done many 2m C4FM activations, quite a number of them with >= 4 QSOs in that digital voice mode.

Here are some “SOTA life hacks” for improving your chances of getting C4FM contacts while activating: (Most of them pretty obvious, but still included here for ‘completeness’).

  1. Alert - and publicise. Add a reply to this thread along the lines of “Tomorrow morning I’ll be calling on 144.6125MHz C4FM from Shining Tor G/SP-004…” etc.

  2. Self-spot from the summit when you are about to call.

  3. Have all the local C4FM repeaters programmed into your radio. Scan through from the summit and call into any active nets. Ask the net if anyone can hear you simplex, and if so to QSY to 144.6125MHz (for instance) for a simplex QSO.

  4. Coincide your activation with the Stockport Radio Society C4FM Fusion Digital Net - Monday evenings, 7.30pm, on 145.375MHz C4FM. Everyone on there will be more than happy to welcome a SOTA station onto the net and allow them to work down everyone else on frequency.

  5. Call CQ on 2m FM analogue, as usual, on S20 (145.500MHz FM) but keep mentioning that you are available on C4FM if anyone is interested. I’ve had quite a few come back to me on S20 that have then QSYd down to 144.6125MHz C4FM with me. The simple fact is that many more Fusion-enabled stations will be monitoring 145.500MHz FM than monitoring that actual DV calling frequency!

  6. Plan to do some activations March 1st-7th 2020 and October 1st-7th 2020. These are the Digital Voice “Flavours” of the SOTA 2020 Challenge, so should hopefully see a concentration of both activator and chaser activity on DV modes.

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Hi Tom, I think your reply was meant to answer questions from James @M0GQC rather than myself - my comments were more around FreeDV and DMR and none around C4FM.

Just a general reply to the thread.

I just tried to change the poll, but it won’t let me.

To be perfectly honest, I left it off because (in the UK at least) the majority of DMR activity happens on UHF. In the early days of DMR, most people were using re-purposed PMR equipment. A lot of people (myself included) still are using PMR equipment on DMR, which generally seems to be mono-band.

The DMR world seems to have settled predominantly on UHF repeaters.

There are literally only a few DMR repeaters in the UK running on VHF (so few that I could probably count them on one hand) verses a significantly higher number of UHF DMR repeaters.

You are quite correct that DMR can also happen on VHF. I note that with the more recent introduction of some of the Chinese duel-band DMR radios, VHF DMR may become more common. As things currently stand, I suspect that most people with DMR radios could do UHF, but fewer could do VHF.

That said, I only have UHF DMR capability. At the risk of upsetting the DMR crowd, I note that the repeaters are significantly quieter than they were a couple of years ago. It feels to me like DMR is in decline as people move onto the next craze.

I believe that there is still a lot of DMR & DSTAR activity from people using their own personal hotspots which connect via wifi. Frankly, that just doesn’t float my boat.

For that reason I don’t intend to spend money another DMR radio to use VHF, so from my perspective a DMR activation using VHF is completely out of the question.

I therefore didn’t really see it as being relevant.

So I know this isn’t particularly scientific, and it’s only a very small sample of the SOTA fraturnity (23 voters at the time of this post) but a quick scan through the results so far brings me to the following conclusions:-

  • A significantly higher percentage of people than I expected have C4FM on VHF/UHF. I guess Yaesu are pushing this mode quite hard as it comes as standard on most of the more recent Yaesu radios, so I probably shouldn’t be that surprised.

  • A much lower percentage than I expected have DMR. This is a bit of a surprise to me as I thought DMR would win the poll due to the fact that DMR has been quite popular over the past few years and there is a lot of equipment on the market at comparitively low prices.

  • DSTAR on VHF & UHF did much better than I expected, matching DMR. This was something that I didn’t expect as I thought that DSTAR activity had died spectacularly a few years ago in the UK. Presumably a lot of people (myself included) bought the radios when they first came out but now only use them on FM.

  • The number of people saying that they cannot run any digital voice modes at all doesn’t really come as a surprise. I actually thought that this number might be a bit higher.

Specifically on HF:-

  • DSTAR came out on top, which was a bit of a surprise. I suppose that the IC-7100 is a popular radio which has been out for a while now, so there are probably quite a few of these radios in use. My guess is that this is the rig that most people who clicked this option have?

  • FreeDV polled lower than I expected. Given that it is free to download, and requires very little to get it going if you are already running other digital modes like FT8 & PSK-31, I’m a liitle surprised that it didn’t do better. That said, I’m not sure how practical a proposition this is from an activators perspective. As people have already said, it would require a laptop or tablet computer with a separate soundcard (unless you have one of the adaptors). As Ed has already said…maybe a possibility in the summer months, probably not a great idea in the winter months.

  • I thought a few more people would have C4FM on HF, although as far as I’m aware, the only C4FM capable rig on HF is the FT-991, which I don’t think has been out that long.

I think for the purposes of activating summits on digital voice between now & next year, I think the conclusion has to be that C4FM is the most likely mode on VHF/UHF, so I should look for this if I decide to upgrade or buy another handheld.

On HF, DSTAR seems to be the winner as things currently stand (and the IC-705 does look like a really nice portable radio if I decide to go for an upgrade).

That said, if Yaesu push C4FM on all of their new HF rigs in the same way that they have with their VHF/UHF rigs, then it may start to catch up over the next couple of years.

I’ll leave the poll for a few more days before I close it to give a few more people a chance to vote.

Perhaps that because some people have already voted ??

Yes, I appreciate that in the UK, most DMR repeaters are on 70cm (possibly as there are more frequency slots available than on 2m in the UK). In both Germany and the US, there are 2m DMR repeaters as well as 70cm. DMR simplex is rare as far as I can see in all the areas I’ve been to.
As you say, there are more and more dual-band DMR HTs now - but in the majority of cases, I suspect the 2m side is mainly used for analogue FM.

Your survey, I believe is targetted at UK activators, so I won’t vote in it. Comparing the number of views to the number of votes a lot of people don’t seem to have voted as yet.

The last time it was surveyed 50% of all DMR contacts happened via personal hotspots rather than over repeaters and that figure is trending upwards, hence the lack of activity on DMR repeaters. I suspect the same is happening for D-Star and C4FM.
In Germany you will have problems finding a D-star repeater these days - the majority have switched to DMR and as the DV hotspots or add-on boards for RPi are becoming cheaper and cheaper, I suspect the number of repeaters, in general, will soon start to drop.

I suspect the only C4FM repeaters in Germany are the ones set-up to operate as either analogue or C4FM not only in DV mode. In the UK, Yaesu seem to have got a larger market share.

Your comment about D-Star on HF surprised me a little. I thought D-star was only allowed on 10m (which OK is HF) not the HF other bands becuase of its bandwidth being something like 7kHz wide - perhaps that’s only in “FM mode” not “SSB mode”? I’ve never heard of people running D-Star for example on 40m or 20m.

I believe the big three consider digital voice primarily a mode for VHF & UHF, not HF. Given however that FreeDV in 700D mode is now capable of making voice contacts when normal SSB is down in the noise, it’ll be interesting to see if digital voice can bring the same advantages that weak signal digital data modes have brought to HF?

73 Ed.

I believe the UK repeater coordinators declared 2m repeater frequencies full sometime back. Now it’s a case of 1 out - 1 in. So either a repeater has to close down before a new one is licenced or an existing repeater needs to decide to change mode. If the existing operators are happy with their setup, they wont change.

n.b. In the UK a special licence is needed to operate a repeater.

Isn’t that the case everywhere?

OK on all 2m slots are full. I presume you are at 12.5kHz spacing already?

In any case, As I said, with more and more personal DV Hotspots, I think the demand for Digital voice repeaters will die down. Of course a hot spot and TG/Room/reflectors cant replace a local repeater for local club / emcomms usage.

73 Ed.

Nupe. There is an entire world out there beyond the UK.

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This might set the cat among the pigeons. Although I use C4FM regularly on 2m, I have seen few advantages over FM on VHF at least.

I usually work chasers on C4FM shortly after having worked them on FM (so I doubt propagation conditions would have changed). So, I get to compare C4FM vs FM a lot.

C4FM doesn’t seem to increase or decrease the usable distance from the other station. In fact, based admittedly on only a few QSOs with more distant stations, I could still hear a weak (and noisy) FM station but not work them on C4FM (presumably because the software decided the CODEC error rate was too high).

The voice quality with C4FM (at least on my FT-1D) is not as pleasant as listening to FM due to the digital quantization needed on a single channel (it sounds fine if you use both channels). The ‘dead silence’ behind the voice is nice but can be a bit disquieting until the other person starts talking.

The callsign display and distance calculation (with GPS) are nice features.

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Yes but for example in VK2 - we had to have special repeater licences for VK2RAG & VK2RTG at the CCARC. I’m pretty sure here in DL a repeater needs a specific licence as well. You can’t run it under your normal licence.

73 Ed DD5LP (VK2JI).

You can in the USA. There are repeaters that have coordinated frequencies and those that don’t.

I tend to agree with your observations Andy @G8CPZ.

I have found it can work both ways. As you say, sometimes a weak analogue signal is workable, but the digital version is not there - error rate too high as you suggest.

On the other hand, there have been plenty of occasions when there is a mediocre analogue signal, but the digital signal does make it - and because it makes it, it is perfect!

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To some degree I would agree with that statement, with but with a caveat…

If attempting an activation on HF (say 20m, 40m or 80m) using FreeDV or with the small number of radios on the market which can do DSTAR or C4FM on the HF bands, it is quite conceivable (and likely) that I would be chased by a station outside the UK.

The survey was partly to get a feel for what people have on VHF/UHF in the UK. I think I’ve already got that answer. The general concencus seems to be that C4FM is probably the best mode for VHF/UHF in that particular region because a couple of people who live in the region that I’m looking at have stated that they regularly use C4FM for activations.

However it will still be interesting to see what other stations outside of the UK can run on HF (particularly around Europe) as this could still be very relevent if attempting an HF activation.

What I’m trying to say is don’t feel excluded from voting.