Goodbye FM, welcome DMR

Since I left the Netherlands in 2010 the situation on VHF/UHF there has changed considerably. The Dutch telecom regulator (Agentschap Telecom, or AT for short) revised their repeater policy which resulted in some well known repeaters not getting their licence renewed. On the other hand it opened up opportunities for new experiments like the Coversity network in the north of the country, inter regional repeaters PI3UTR and even the world’s first intercontinental repeater PI2NOS with an access point on the Caribbean island of Curaçao (PJ2NOS). If you want to listen in you can visit the 70 cm webSDR at http://websdr.pi1utr.ampr.org:8901/.

What the AT also noted was that the 70 cm band was quite underused and that there were many requests for digital voice repeaters. The frequency allocation for digital repeaters was expanded and that resulted in a wave of new repeaters, mostly DMR. If you look at the current repeater coverage map it is clear that there are only few places in Holland without DMR coverage. Coverage_DMR_NL-2015-081Unfortunately for System Fusion users this means that their repeaters aren’t getting permits to go on air. Part of the problem is that areas are already covered by DMR and D-Star repeaters and part is that System Fusion repeaters run in dual mode: analog FM and digital C4FM. Running an analog repeater in the digital segment of the band or vice versa doesn’t make sense, of course, hence the rejections.

Curious about the fast rise of DMR I decided to check it out a couple of weeks ago while I was in Holland on a family visit. I pre-ordered a Tytera MD-390 which was waiting for me the day I arrived. Unfortunately, without programming (installing a codeplug) the thing won’t work. Being a DMR newbie I decided to call in the help of the local chapter of the VERON, who meet every Friday night in their own club shack in Arnhem.dmr-veron1I wasn’t the only one who brought a DMR rig, which confirmed again that DMR is quite popular in Holland. The local DMR repeater owner Cor (PD0GHF) knew immediately what I wanted and called Dave (PD5DOF) in to help me out. Here he is working hard to get the codeplug in order.dmr-veron2After a while he got it right and my rig sprang to life. The MD-390 came with two antennas and the longer one was necessary to be able to hit the repeaters when we were indoors.dmr-veron3Cor then explained the use of Talk Groups and reflectors and although I understood most, DMR is still rather complex if you come from the analog world. But back home on the camping where we stayed I tried it out and it worked. My first DMR QSO was with Cor (PD0GHF), so that was fun.

After two weeks of using the MD-390 I was totally hooked. The rig can do both DMR and analog NFM and I did make a few QSOs via PI2NOS in good old NFM mode. But NFM pales in comparison with DMR. I have never been able to stand the white noise that is so typical in FM mode; it tires my ears too much. When there is a signal I really have to strain my ears to follow the conversation, especially with weaker signals that have a lot of artifacts. Because of this I have never liked having an FM rig in my car, either.

DMR, on the other hand, is crystal clear. The signal is either there or not there, but when it is there it seems the person is standing right next to you. There is a little “robotic” sound effect, often associated with digital voice, but overall I didn’t find it disturbing. There were no problems hitting local and more distant repeaters and quality was very constant. Amazing that they can put all this in 6.25 kHz of bandwidth. It makes good old NFM look “old” to me.

And then there is the linking of repeaters. Via my local DRM repeater I could talk to any one in the Netherlands on the repeater in their neighbourhood, not just the hams within reach of my repeater. The internet helps out here and linking is global. Saturday at 16 UTC the DMR-MARC World Wide Net is held and you can hear hams from all over the world checking in on Talk Group 2. Amazing!

Now I know many of you old timers will object to digital and the use of the internet in ham radio: “First it was Echolink, now it’s all this digital voice stuff hooked into the net. If it’s not radio, it’s got nothing to do with us hams. And digital signals don’t make for good DXing anyway. FM, AM and SSB degrade more gracefully and provide better signals under challenging conditions.

I understand the objections. Even I rather listen to good old AM radio on shortwave and SSB on the ham bands. Unfortunately, these modes are fading out and are being replaced by others, if you like it or not. I still don’t understand the attraction of using any of the JT-modes, but they are more popular than ever. To me they are not what ham radio is about, but I accept that many others don’t agree with me. Luckily ham radio is such a diverse a hobby that everyone can find his or her “thing” and be happy with it.

And besides, we hams are quite innovative and always keep radio in the back of our head. We want to be independent, after all. Up and coming in the Netherlands is Hamnet. In short: HAMNET is a high speed amateur radio multimedia network based on commercial wireless devices using mainly the 6 cm band. An internet for hams via radio waves. Guess what you can use to connect all those DMR repeaters with each other instead of the internet? Analog is dead. Long live digital!

Hans "Fong" van den Boogert, BX2ABT, is a regular contributor to AmateurRadio.com and writes from Taiwan. Contact him at [email protected].

8 Responses to “Goodbye FM, welcome DMR”

  • Ben Walters PA2OLD:

    Very nice article about DMR in the Netherlands and the Veron department Arnhem.

  • Mike KG9DW:

    Hans, I’ve been bit by the DMR bug as well. I’m still a huge D-STAR fan, and I have a lot invested in this technology. I do enjoy DMR having two timeslots on the same frequency pair allowing more than one qso on the repeater at the same time. There is still a lot that is hard to grasp…the fact that there are a lot of configuration settings, getting everything in place when you travel…but so many benefits as well. For instance, incredible battery life since the transmitter isn’t on the entire time when you’re pushing the PTT, and the two-way communication between the repeater and HT while you’re talking means you don’t double with someone else nor do you fall off the digital cliff without knowing! Add to that the new Brandmeister network…lots to be excited about and a lot to experiment with. Have fun! 73, Mike

  • PA1FJ:

    Please do not DMR or D-Star in the Netherlands, 95% of the Ham’s in the Netherlands do not have DDMR or D-star. No mode for a select few!

    73 Fred PA1FJ

  • @KG9DW: glad you enjoy DMR too, Mike and indeed, there is a lot to grasp.

    @PA2OLD: a pity that I didn’t meet you at the club meetings, Ben. Maybe next time.

  • Jason KC5HWB:

    DMR is getting more and more popular here in the USA. Great article.

  • VA3AGV:

    DMR is viral, it’s like crack or bath salts, DMR is exploding in CANADA and as it gets more popular the radios are becoming cheaper. Great article. VA3AGV.com

  • G7BHH:

    Hi Hans,

    Thanks for a very interesting and informative article. I’m just returning to the hobby after being QRT for quite a few years. I’ve just ordered a DMR portable and I’m very much looking forward to trying out DMR. I think that it’s a very exciting and interesting new technology. I was reading around getting a feel for how it works and stumbled across your article.

    Thanks and 73’s

    Leigh

  • Hans (BX2ABT):

    Welcome back Leigh. Glad you liked what I wrote.

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