Decode TETRA as easy as FM on SDR Sharp

No, really.. It’s simpler now to listen to unencrypted (clear) Tetra on SDR Sharp than it is to listen to FM

DSD isn’t needed, because it doesn’t support Tetra, and i thought one of the unpleasant bits of getting SDR Sharp set up – was having to ‘send’ the audio output from SDR Sharp – with a ‘virtual cable’ over into DSD or DSD PLus, both of which work well, but The UI of the DMR decoders is pretty messy and unintuitive, with several separate windows springing open it’s and a mess of separate windows opening up.
You don’t need anything except the file I’ve zipped up for you here, an aerial and an RTL-SDR Dongle – and of course, a Tetra signal.
I have zipped up a working SD Sharp folder ready with the Tetra Decoder already built in. Here is the link below.
it will ask you for a password, type in   MBARS


To use, just unzip it to anywhere on your C: drive.  It contains all you need. You may need to run Zadig if you do not have SDRsharp another SDR installed already. instructions below.

Running ZADIG (if you need to)

select Options – then List All devices and then from the drop-down, select “Bulk In Interface 0” In the drop down box, choose Bulk-In, Interface (Interface 0) though it might also show up as something like  ‘RTL 28320’ or something similar, and that’s ok.
Just make sure that ‘WinUSB’ is selected as the target driver, and then click on ‘Replace Driver’.. you may have to reboot, but next time you start SDRsharp, your RTL SDR should now be in the list of available devices, select it.

Preparing SDR sharp for Tetra decoding.

Once you have selected the correct USB device and have SDR sharp running, you can test it out on normal analogue transmissions and, once you are happy, It’s time to go and search out some unencrypted Tetra.

Firstly, set SDR Sharp up, you can either be in Wide FM or Normal Narrow mode – all you need to know is that whatever FM mode you choose, set the filter width to 25khz. i use NFM and zoom in, and drag the passband out wider that way, but you can use the Wide FM or the option in the Radio menu, it’s more precise, but it’s not too critical, unless you go too narrow.

Now in the Audio tab, make sure that the’ filter audio ‘ button is NOT checked. then go to the Tetra Demodulator panel and select the first option, Demodulator and if you are looking for `DMO Tetra, you must tick the DMO checkbox to it’s right also.
Also, underneath the config button.. click & select the Voice tickbox and click AUTO.
These are your 4 Tetra timeslots, so they need to be set at AUTO unless you are interested in monitoring just one particular slot. If you are listening to a Tetra base station, or DMO just leave it to AUTO

When you have found a valid Tetra frequency, the red text “Received’  will appear  – along with any errors, like in weak signal areas or mistuning.

DMO tickbix

In the UK, there is clear Tetra above 420mhz, some pirate activity around 420.125 mhz where non techs and non Hams set up, as many codeplugs on the UK secondhand market come with some DMO frequencies here. This is illegal but is often referred to as DMO 1 and so on for other channels. Up to and above 460mhz too you may find Tetra, and often hiding in between the usual DMR, FM and carriers – tune carefully,, if you find a valid Tetra signal – a TMO one, get to recognise the harsh high pitched nasty sound of a TMO transmission the Tetra panel will display ‘”Received’ in red font and for more info you can click the Net Info button and serch through there and see the cell info and all kinds of lovely tech info, and whether there is encryption.
You want to see ‘Air Encryption = 0’  towards the bottom of the info cell panel, though there are other Group call panes too, once you do hear things.

What You want to see – .

You will see what talkgroups are being used also in the Groups and more detailed info in the Calls tab too.
Of course current cell  refers to the Tetra base station that you are currently tuned to, and as Tetra is Trunked, Neighbour cell is, as the name suggests, the next cell on the Trunking system. With another USB SDR receiver, and a little plugin called Tetra Trunk Tracker will enable you to follow calls from site to site. I didn’t include Tetra Trunk Tracker because it’s at an early stage of development sill, and not simple to set up and get working.

There is no DMR or other digital voice decoding in this build of SDR sharp. just the Tetra plugin. When youclick the Tetra decode button ON the volume slider on SDR Sharp should have a cross through as Tetra mutes it, to use FM again, uncheck the Tetra demodulator tick box, and you can then slide the SDR Sharp volume slider back up.

We use Tetra around Morecambe, on 430.3125   GSSI 10 (talkgroup)  we think the 430.000 Tetra frequency is a bit of a poor choice as you will still be radiating outside of the Amateur band. That’s why we use 430.3125 locally and It’s only a 5 minute job getting most commonly available Motorola Tetra gear on to 70cms anyway, and most Tetra sets are the 380mhz to 430mhz band only, not the preferred 410-470 mhz but the 380-430mhz band sets are perfectly fine a few mhz up from 430.000 anyway.

This is just a basic How To on how to hear non encrypted Terra. It’s up to you to get scanning the airwaves and discover things in places you wouldn’t normally expect.

it’s Tetra time .. so DMO yourself a favour and try it out ..

Time marches on, and it’s hardly news that our MotoTrbo DMR repeaters GB7MB and GB7UZ and the short lived TAC-9 have both passed into memory, but it’s okay, P25 continues in the Morecambe bay area, and although P25 is approaching what must be it’s seventh year or so of usage around Morecambe Bay, it was recently given an additional boost last year too with Dave G6CRV’s construction of the P25 – DMR repeater, GB7MP. Nice one Dave.

For several years I’ve been reading about Tetra, Many years back i purchased an old Dolphin Tetra HT just out of curiosity, but at that time P25 and even DMR overtook my Tetra interests back then, and the crappy old Dolphin HT stayed in the junk drawer, and i think i even threw it in the bin eventually.

Until a few months ago I’d been playing with SDR Tetra receivers, and had been doing so for a few years, Telive and Gnu Radio weren’t easily accessible for most, as for years it was the preserve of Linux users who love compiling stuff from source, not exactly a turn-on for most SDR users, but as i am pretty comfortable with Linux, starting as i did, messing with RedHat Linux and Solaris back around 1997/1998 after i upgraded from NT4, so it was easy, 
It has been interesting to see Tetra SDR decoding move over to windows and become somewhat mainstream, now, where it’s pretty much as easy as installing any Windows SDR program. and the looming ‘lockdown’ seemed like a good time to pick up a couple of bits of Tetra stuff to play with, so a couple of MTM800s were bought, an MTM800e and a MTP850S and a whole pack of paracetamols – for the inevitable headaches coming my way.

This is a Motorola MTM800E

Tetra sets are often a little low powered in comparison to other PMR sets, MTM800s are all around 3 or 4 watts RF out which is a little disappointing, but as radio amateurs we are quite capable of pushing a low power signal over a reasonable distance, negating losses, and tweaking aerials etc, so not a huge hurdle, but one to bear in mind.

Typical Motorola build quality,  Physically it’s a standard DM4600 type body and uses the same mounting brackets and screws, power lead and fist mic. There’s no infernal speaker, so you will need a suitable connector, The DM4600 type connector do look similar on a computer screen, but thy are not,  they are different dimensions, so i picked a small box of used 16 pin connectors over on Epay, the rear connector is 20 pin and you do need the full 20 pin connector for the programming lead, (buy one instead) but a 16 pin connector will be just fine for speaker output. They have a nice chunky underside heatsink, a very familiar casing, and DM4600 mics will fit.  From all i gather though, most MotoTrbo IMPRES mics will work okay, but the navigation keys aren’t supported, sadly. Some Epay sellers sell an MTM800E version with the Amateur 70cms band codeplug programmed in already too, but to me, i see no point buying the more expensive one, because you will still need to edit the codeplug for UK Ham usage anyway.  We use our CCS7 ID, but there is no reason to yet. Most Tetra sets you will see are 380mhz to 430mhz, but with a simple codeplug hack, you can allow frequencies up to 440mhz to be programmed in to the CPS without it complaining then refusing, but the seller told me much above 435mhz and it’s going to be noticably less sensitive anyway, but it’s great at 430mhz and 431 mhz, which is where most Tetra users are anyway.

Most sets are 380mhz to 430mhz, but there are the rarer, (and pehaps slightly more useful) 410mhz to 470mhz versions, there are 800mhz variants too, but they are no use to us in Europe. Many sets will come with encryption in – so you may see ‘TEA’ mentioned. UK Airwave (emergency services) use TEA2, but that is of little or no interest to Amateurs as well as it being TEA2 being illegal to own, or have in your set, or something like that.

And this (below) is a MTP850S

Actually, it’s a MTP850s fug (German emergency service special) the ‘proper’ MTP850S just has a little speaker grill on the top front corner, but anyway, the MTP850S is a very popular Tetra HT, i prefer these as the MotoTrbo DP3600 / DP4600 speaker mics fit and they’re a nice size and form factor too, they have plenty of cheap accessories and some have a high-power option too, which this set has, nearly a full watt of RF output extra, and is, of course, switchable like on any other Moto HT.  The FuG version which you see here is a slightly different version to the standard MTP850S, and it has an interesting feature which enables it to be used as a DMO repeater, Note: There is a plain vanilla MTP850 also (no S or other suffix) which does NOT have the big chunky milti-way MotoTrbo DP3600/4600 external mic connector, instead, it has a more conventional 2.5mm and 3.5mm jacks instead. Perhaps DMO repeater function is of limited use on a HT, but very interesting nonetheless a bit of fun to play with all the same, and it does work too. The usual (hidden) extended MS147 Hirose external antenna socket is still there, in the back of the HT under a rubber flap, and is a little more accessible (but not much) than the (Motorola-special) MS147 in the DP4800 / DP4801 DMR HTs, but i have yet to try connecting it to an external aerial, Of course Motorola sell a special, elongated MS147 adaptor for testing purposes which needs to be as long as the MS156, but the Motorola specific version you need is, er,  as expensive as the HT itself (cheers Moto)
Standard MS147s just about reach the MTP850’s ext aerial socket, and could, with a little bit of non-invasive and careful work, allow connection to outside aerials to the MTP850S when sat in the shack.

It goes without saying that you can’t hear the emergency services on these,  that’s not something we’re interested in here anyway, we’re interested in the tech, as radio Amateurs.  Of course TETRA is first and foremost a trunked system,  with little (or no) accessible Amateur Tetra TMO repeaters in the UK – that we’re aware of, there are several TMO ones on the continent, but as we’re up in Lancashire – we use DMO mode – (rig-to-rig or simplex)

(below) the older version of the popular MTM800 (not ‘e’ suffix)

Much the same as the MTM800E but an arguably less attractive control head and a few other refinements, It’s a GM380 styled Tetra mobile, and some older GM series RJ45 mics and bits fit. The rear programming cable is exactly the same on both MTM800 and MTM800e versions.

DMO repeaters are easily available, but there seems to be a lack of interest in Tetra in the UK Amateur radio scene, although pleasingly there seems to be many little pockets of Tetra users all across the UK however, but it’s a great pity that there is no MMDVM or PI-star type device for Tetra, which would really create a boom in UK Amateur Tetra use.

I notice there is some illegal use around 421mhz, but low powered sets and inefficient aerials on HTs mean they will go mostly undetected. Some UK sourced sets come with something called ‘National 430’  already programmed in, in addition to often the unofficial 421mhz pirate channels, but with a centre frequency of 430.000 mhz, this means that half of your TX signal falls outside of the Amateur band anyway, so that is not a wise choice.

Many LPD devices use 430.000 as a spot frequency too, and a depressingly large amount of other ‘license free’ plastic Epay crap pollutes these frequencies on 70cms too, so we decided to use a carefully chosen frequency that’s largely out of the way of most things, and seems pretty clear, for the most part, so 430.3125  is where we live on Tetra. We chose TG 10 (in Tetraspeak that’s GSSI 10) although perhaps ‘1’ would be more logical.

Local usage around Morecambe Bay is of course, low, only three of us are using it for occasional local chats, but hopefully a few more Amateurs will take the plunge, and as our antennas improve, maybe with some Tropo in the summer months too, it will provide a little more chance of some activity, and if in the coming months we are all allowed out of the house on non-essential trips to go up the hills and go out mobile, perhaps the reasonably cheap MTM800Es on Epay will all get bought by UK Amateurs.

Tetra gear seems a little less easy to find for sale, but do keep looking. There are a couple of good sites on Facebook where there’s no clique, and all information is shared in good humour, the Facebook grup below is only for licensed Amateurs interested in learning about the mode, and not for those strange blue-light fantasists and plastic paramedics who like to dress up in high viz gear and try to look a bit official. You know the type 🙂

I monitor 430.3125 Tetra TG 10 most of the time on a HB9CV up 4 storeys pointing South from Morecambe and it looks like there’s going to be plenty of time for us all to play radio whilst sat at home, where we can even wait for a Tetra rig arriving in the post !


After GB7MB

Although we have seen the demise of the GB7MB DMR repeater, the site itself is not going anywhere. I am hopeful that Hax will continue to add the odd posts as he as always done so. I personally feel he has a excellent way of passing his knowledge on. Locally we are still served by GB7MP thanks to Dave, which caters for both DMR and P25 digital modes. I shall however be diversifying the site to cover more of my other hobbies as well. The only reason for this is to justify my continuing funding of the site. If you are a member and wish to be removed from the site due to these changes just drop me a quick note to admin(at) and i will remove you.

Regards to all



GB7MB closes down

Unfortunately, between 27th December 2019 and 28th December 2019 GB7MB will be going off-air and closing down because of site loss.

If anyone is able to offer a practical working site to relicense and host GB7MB – a UHF MotoTRBO 25w repeater, please get in touch with anyone here at

Many Thanks to everyone who supported GB7MB and kept it in operation.
This Mbars website should continue however.


GB7MP Morecambe Bay P25 repeater comes on-air

A new UHF repeater has come on-air this week,  It is a P25 / DMR digital repeater.
It’s transmitter output is on : 439.750 and it’s RX: 430.750.

The P25 repeater uses the default NAC of 293 and Talkgroup 2 and, and if you are out of the area or are unable to get in via normal RF means, It is also linked to the ‘Morecambe Bay Talkgroup 2 reflector’ which also allows P25 users to access the repeater via the internet.
The DMR side of GB7MP is colour code 3, and is connected to Brandmeister, and here’s the thing, there are no Brandmeister talkgroups assigned, so you will need to check the standard Brandmeister Talkgroups that you intend to use before you program.

The reason GB7MP does not carry Brandmeister talkgroups by default is that the repeater is primarily a P25 repeater and lots of busy DMR traffic would render the P25 part of the system unavailable to the primary P25 users, but you have the option on using GB7MP or GB7MB, remember GB7MB is DMR only and thus 100% availabile for DMR use anytime, and MB is on the Phoenix network, not Brandmeister. MP and MB are *not* directly TG9 linked like UZ was before UZ went off-air.
Just a note about the echoserver, program it as a private call, not a group call, like it is on Phoenix.

I quote Dave, G6CRV the Repeater keeper of GB7MP
“All the reflectors have an associated Talk Group, if you don’t want to enter all the talk groups into your radio, then you can connect to the associated Reflector by using a private call. IE private call to 4412 connects you to TG23520 (North West) and connections to reflectors time out after 5 minutes if not being used ”

Thanks Dave, If you need more information on the operation of GB7MP, please check out the Facebook group at:

GB7MP Facebook group 

Here are some links to check on the system status of GB7MP:

GB7MP P25 Last heard 

GB7MP Brandmeister (DMR) Last heard

MW0MWZ’s list of Brandmeister talkgroups 

Armchair stormchasing & webcam links

I think most people are interested in thunderstorms and weather, so here are a few links here if you’re interested.

Here is a link to a newly created UK Thunderstorm and severe weather Facebook page,
it was created as most UK storm sites on Facebook seem to be full of non UK storm info.
on this, Only UK content allowed.   Link HERE

As this is Morecambe Bay, here is the obligatory live streaming webcams..

Met Office Observations
  Might as well start with the UK Met Office.  This link is centred on GB7MB and ‘LIGHTNING’ – but of course you can drag or search any part of the UK and set it for rain or whatever by clicking on the ‘cog wheel’ and selecting the weather type you are interested in. The lightning is live and is triangulated via a very well established network of sensors, apparently.

Worldwide Youtube webcams
– (a list of about 180 on the right hand side) 

Lightning Maps
 A European wide real time lightning display.


Much the same as the European display above, You can’t drag the map like on LightningMaps, but the noise of the lightning as it strikes is remeniscent of an old Geiger counter if there’s a storm on..


Webcam Taxi
Not a storm site, but a streaming video site, with some really great cameras from many parts of the world. There are full video, not flickery updating photographs. Some have sound.


Much the same cams as above.


Severe Studios USA
No, it’s not a dominatrix site, it’s a North American Storm chasing site.
Live maps from the storm chasers vehicles and full streaming video from inside the vehicles whilst hunting, travelling to and chasing severe weather in North America. 
Some are professionals working for News stations or weather centers, some are science estalishments or groups or individuals.
Be aware that in some parts of the country these storm chasers get into, their 4G or mobile data signal can get broken and disappear for seconds, minutes or completely !


Live Storm Chasing
Similar idea to the above website, seems less busy at times, but it’s a different group and different organization, well worth keeping an eye on too.


UK full video webcams

There are more, but UK webcams seem to come and go regularly, some don’t re-appear,
these are working as on Mid June 2019    Expect interruptions or outages, as most folks don’t take webcams oo seriously any more.


Arnside Pier  Live Webcam 


Bracklesham Bay   (West Sussex)


Brighton Runway webcam 


Bristol Surfcam


Dawlish (Devon)


Derbyshire (Nr Buxton)


Great Yarmouth


Hastings Pier


Haverford West


Hoylake (Wirral)


Bognor Regis Pier


Langland Bay (S. Wales)


Blackpool Promenade


Dover Beach (Kent)


Camsecure UK    a clickable map with a few streaming video cams in different areas of the UK


Oxford School 


Pembroke sea front


Polzeath beach (Cornwall)


Port Isaac Harbour (Cornwall)


Portpatrick (Dumfries & Galloway)


Various Shetland Isles cameras

Shropshire sailing club

Streamdays UK

Surfcheck UK beaches

Anglesey beach

Southampton – New Holmwood Hotel on the Solent

Some Golf Course in Scotland

Berwickshire, Scotland

Banbury Cross

Weymouth B&B Dorset coast

Whitstable Yacht Club


Block it !

Most places you go to on the web now, will almost certainly be serving you adverts, or tracking you, or worse, and this is only an basic article about adblocking, Ublock origin in particular, as it’s the one that gets recommended by security analysts and researchers, and i install it in every browser first thing, i watch a fair bit of Youtube like most of us, and i still see many people complaining about adverts, so let’s go.

Youtube pre-rolls and ads have been around for years, but people really like money by doing nothing, and so adverts have bled their way into Youtube, one of the most high profile sites on the web. 
If You’re ready to watch a video, it’s incredibly annoying to have to sit through some unwanted crappy advert about something you hate, using your bandwidth, electricity, hardware and most insidious, your time.

Adblockers are plugins or extensions for your web browser which aim to stop this, they’ve also been around donkeys ages too, but, like every other bit of software, it doesn’t always do what it ‘says on the tin’ and, sometimes it does rather more… some Adblockers actually bring in adverts to your browser (mentioning no names) as they feed you tailored ads, different to what you may otherwise get fed, and for this, the adblock company gets a pay-off. Ad blockers, not blocking ads for money, sweet, no ?

This last year or two, the one everyone has been raving about is Ublock Origin  by Gorhill.
Actually, it’s not just an adblocker, as Gorhill himself says, it’s a wide spectrum blocker. so It’s a little like a java script blocker and firewall too, and a bit more too. but DO NOT confuse “Ublock Origin” with the similar sounding “UBLOCK” use Ublock Origin(al)

Default settings are, of course, pretty conservative, and try not to break anything too much, there’s always a trade-off between security and convenience, and you’re the only one who knows where the balance is for the way you use the web. The ‘tyranny of the default’ is a problem, and most bits of software – of any description, often benefit from a check through the preferences, in some cases, doing so can often turn a pain in the arse program into a pleasant to use and safer thing.

For me, i put all settings pretty much up to maximum, and if a website breaks, then so-be it, it can be whitelisted, turned off or adjusted until the site functions as expected if really needed.
Ublock Origin is available for every browser, FirefoxChrome, Chromium, Brave, Iriduim, Safari and even Edge although You really should try NOT to use Microsoft Edge Browser even if Microsoft have started building it underneath the bonnet from the Google Chromium browser, but if you must, enable WDAG at very least  before you start fixing it..
If You really want to tighten up privacy with Ublock Origin, go into the settings and enable the extra lists and Prevent WebRTC and for extra privacy i  block CSP reports too, although some people criticized Ublock Origin for being over zealous.

Above: i add extra privacy by clicking the “WebRTC” and “Block CSP”

One of the least discussed, but wonderfully useful things i like about some advert, or content blockers, is ‘element hiding’
where you can either temporarily or forever hide unwanted parts of a web page, sometimes it it *extremely* handy and can get you past some casual pay walls or some only-logged-in parts of some sites or remove bulky or screen wasting photos or guff.

 Here is a rather extreme example of element hiding on the same MSN homepage, these 2 pictures are before and after, i spent a couple of minutes hiding bits of the website – by using the mouse and highlighting it, and  i got rather carried away and deleted pretty much everything !

Properly set up, Ublock origin should stop almost all adverts, even Youtube pre-rolls and in video pop ups whilst enhancing your privacy a little bit more, and it might speed up your browsing too and keep websites leaner and faster, but if you get into element hiding, you can extremely easily break a website (for you and that browser only) in a big way, or you might just hide the video, or login button, so you’d have to go into the ptions in ‘my filters’ and delete the filter lines the program has added.


TDMA – what’s that all about then ?

It’s not always obvious when you get into DMR exactly what makes DMR so ‘special’ and why everyone is jumping on the bandwagon, compared to most other types of digital voice modes, one of the coolest things about DMR over most other forms of digital voice modes is TDMA. that’s the secret sauce.

Conventional FM repeaters, along with older FDMA types work very well indeed, but more can be done, especially nowadays. On an FM transmitter, as soon as you transmit, your transmitters PA (RF power Amp) shoots right over to solidly pumping out 100% constant carrier, this is simple to understand, as indeed is a FM repeater’s basic operation, and we’re all used to and happy with that.
However, one conversation on a FM (or FDMA) repeater generally means that you have to wait until the repeater is free before you can use it of course, so if your message is important, you’re stuffed, unless you have another repeater to make the call on.
Imagine though, a repeater which can carry 2 separate conversations at the same time using the same two frequencies an FM repeater would use ? How ?

The answer, is TDMA, Time Division Multiple Access, it has been around years, longer than you might think, but it’s basically a channel access method – a way of data streams sharing the same channel, (because *everything* is data nowadays) and there are different types of channel access too, but as we are discussing DMR really, we’ll stick to that for now. Most of us, back in the 1990s will likely be familiar of the annoying and somewhat unpleasant ‘buzz’ or interference when your old cell phone was near an amplifier or stereo (remember those?) and the rat-a-tat buzz from the 2G Nokia cell phone you had.. that was a TDMA transmission.

Very basically, and because it’s a little abstract, i’ll attempt to give a ‘duffers’ way of imagining it. I know very little, but there seems to be very few write-ups anywhere on the web about it, particularly for hobbyists or folks who aren’t computer whizz kids, there are many DMR websites and discussions on forums and Facebook, but many others, though thorough and correct, require the imagination the size of a planet and a leap of faith to match.

Here goes, if you were to chop your FM transmitter on and off very quickly indeed, you could also imagine that in between your brief TX bursts, and the snapping of your PTT, that someone else, if just as quick, could send their quick TX bursts out too, on the same frequency in-between yours, no-one would be harmed, but you couldn’t speak fast enough to get your voice over could you ? and neither could the station that you’re trying to talk to.
Now, digital radio takes all your TX audio, throws away what it thinks is unneeded, and compresses the rest.
Now your voice is digital and in squeezed into a tiny IC in your radio, we can do fancy things with it, we can, for instance, break it up into blocks and transmit these blocks in, er, blocks, or packets, –  the quick pulses we mentioned earlier, but faster and electronicaly timed and controlled.
The receiver collects these ‘blocks’ and re-constitutes them, back into a whole lump, like adding water to a 1970s Vesta Chow Mein and you’ve got your audio back at the receiver, albeit after a lot of processing, and of course, you can do this through a repeater or simplex. You can even have two concurrent QSOs on simplex, on the same frequency!

A basic one way QSO through a DMR repeater is pretty simple to envisage,
here’s the first of my (sad and tragic) attempts at basic animation in The Gimp, a open source, free software graphics program, (For Windows, Mac & Linux) which i only found out did animation a couple of hours ago, so be kind to my first attempts !

TDMA – the Secret sauce

As you can see above, transmitting one DMR transmission over a DMR repeater all seems to make some kind of sense, you can see the packets arriving at the repeater, and the repeater transmitting them on.

The interesting bit about DMR is whilst they’re nattering on there, we can start up another QSO on the same repeater and the other QSO will be totally unaware, so, if there’s just one QSO on the DMR repeater, it will be sat idle a good proportion of the time, yet still continue to relay a full QSO on one of the slots, but there’s another slot we can play with, lets look at that.

Slots o’ fun

Above, on grubby animation number two, is what the repeater is seeing when someone else calls through the repeater, hugely slowed down, as for a short time it listens in the (lets call it a ‘gap’) and if it hears any valid DMR on the input at that time, it calls that slot 1, then automatically and without waiting, listens again on the same frequency in the other ‘gap’ or slot, and if a valid chunk of tasty DMR comes in at the expected slot 2 time, well, we will call that slot 2 then, and so it goes, back and forth, many times a second, constantly, until both transmissions stop and it can rest. 

So, to recap, there are now two simultaneous QSOs going on in the repeater, and as we can see, as the repeater is easily hearing both transmissions, the DMR repeater is also sending back control information to your radio, stuff like telling both transmitters when to TX their blocks of data back, all DMR receivers expect to hear packets or these blocks of data, so everybody is happy. Win, Win.

It’s a busy, busy busy job …

Above, in crap animation number three, (I’ll stop soon, i promise) – is a very poor attempt to envisage a DMR repeater in the midst of, er, repeating. Two QSOs are taking place on the one repeater at the same time, neither QSO knows or needs to know about the other QSO,

QSO one (slot 1)  is blue, and QSO two (slot 2) is green, neither know or can hear, (or join in with) the other QSO, they’re both completely independent, try doing that without TDMA.

In the crude graphic, massivley slowed down, the repeater is flashing the colour of the QSO it is currently TXing, it really onl haas one transmitter and one receiver really, but as you can see, it switches between both ‘slots’ automatically and very fast indeed, with the effect that the end user can’t tell. congratulations, because instead of having to buy another repeater, you’ve just got a free one by using DMR.

There are more DMR benefits too, stuff that the FM and FDMA stuff can only dream about,Myself, i like the old P25 phase 1 digital, a mostly American emergency service digital system, but it’s old and FDMA, not TDMA and and has only half the capacity of a these two slot TDMA system, bit TDMA is so important in comms, that P25 ‘phase 2’ is now TDMA, because it makes NO SENSE to invest in a poor propriety digital amateur only mode, or really any FDMA nowadays, unless it’s foe low end or retro fun, it’s a technological dead end street now, technology has moved on, some companies thought they’d lock users into substandard and propriety modes and dropped the ball completely or refused to update, as their cash cow was still bringing in the $$$ whilst other, superior standard, industry wide modes, well supported and still in active development continue to offer future development, rather than just at the whim of some proprietary bean counting exec.. but i digress..

One feature we enjoyed when we started playing with DMR, was to de-key each other .. the locals here are an often cruel and cheeky bunch who used to delight in, lets say, if someone was transmitting for a really long time, and listeners were starting to doze off or get bored, we send a DMR command from our rigs to the Guy who is still in waffle mode – still in TX -and  instantly setting the (surprised) waffling station’s rig back into receive mode – whilst they still had their finger on their PTT !   for a while it was a challenge to not be boring or waffle too much, lest you would be remotely de-keyed in mid sentance !

Such is the fun we had, but alas the tumbleweeds have taken over the hobby and i have to get my kicks by writing articles on MBARS 🙂

Next Article:
“Talkgroups what the bloody hell are they then”

Changes are a comin’

We’re trying to diversify a little bit on MBARS here, Digital radio is just one tiny part of the whole electronics and hobby radio thing we’re all addicted to here, so we’re just mixing it up a little bit, as there’s not really enough happening in the DMR or digital voice part of the hobby to inspire me to pen many articles, the hobby is far bigger than just digital, We’re interested in a wider array of hobby radio and electronics.

I have added more areas, with more specific titles to reflect our other interests, and hopefully you’ll not be not forced to scroll and click around endlessly just to browse this (little) site of ours, with all the areas up the top instead, MBARS is only a 2 man effort, and i do most of the waffling and Quack does all of the Admin. If there are any menus or areas you think we should have, tell us !

So much content is on Facebook nowadays, so it’s a little hard not to be drawn into the Quagmire that is Zuckerberg-world (Giggidy) so please don’t expect a huge quantity of material on here, but we do like the idea of quality, and that is instead, what we will strive for, and that is also why joining is pretty much a slightly more tedious ‘send us an email’ type instead of the more usual email-loop – like you get on most other sites, though that may very well change, but it does keep out most of the spam, so there is method in our madness.

I’m no writer, or journalist, but when i have time (or the inclination) i do enjoy writing, especially on MBARS, but I found the digital radio bias rather restrictive, as i’m mostly a HF SSB Guy really, so I have added up some more categories up on the menu where hopefully you can jump to a particulat type of thing, instead of scrolling around, i found navigating the site a chore myself, so i need to make navigation easier and more straightforward.

Stick with us, and i hope we all can develop MBARS a little more, and take away some of the focus from DMR and cater to the far wider interests that we have, yet we still will stay mostly in the Hobby radio domain…


GB7MB is still on-air, but we use P25 & HF SSB 28.495

The demise of DMR in the area has seen a resurgence of a few of the locals go back to 10m SSB instead.  We have been using 28.495 USB (on and off) for over 10 years now, with a brief flirt with DMR in between when we put GB7MB on air.  Activity is low of course, but is monitored most of the time, so fire your HF rig up and shout up. We are vey relaxed on there and fun, please don’t get offended by the goings-on on 28.495 – instead, just join in,

The photo above is a MMDVM – a little radio board that sits on top of a Raspberry Pi – those tiny twenty quid computers – and it’s a hotspot for your P25 rig.
You can buy them ready built too,  they work fine. here’s an example.

After a bit of a config you need a P25 set, they pop up on Ebay and other places occasionally.
you shouldn’t need to pay much above £100 for one, the chinese haven’t yet made a cheap P25 set yet, and likely never will, have a google for P25 digital if you don’t know what it is.

We have a Morecambe bay reflector for P25 and several users, though again, activity is low 🙁

So, that’s an overdue update, just so you know what’s happening (not too much) but feel free to use GB7MB and have fun.

GB7UZ off-air

As most DMR locals may have noticed, GB7UZ is off-air and there is no way of knowing if it will ever return.
So It isn’t your radio – the repeater is gone.

turn your smartphone into a P25 or DMR HT ?

Well, You can certainly do some neat tricks with SDR’s nowadays, clever things like making your Raspberry PI transmit AM/FM/SSB and the (slightly pricey) but very interesting HackRF board. I see Fenton Dynamics have been busy lately, they’ve rebranded now from BriCom, and i completely missed them first time around,   Anyway, this device, which is sort of a set of modular clip-on-goodies for your smartphone can magically turns it into a VHF / UHF P25 / DMR / FM / HT is available, and, not that you can tell, but the photo above is of the 2w VHF iPhone 6 version apparently, well so it says in the blurb, all wrapped up in a  Nextpaq case.

For more info check out their August 2015 Youtube posting HERE  and head over to Fenton Dynamics too, if you have a supported Android or IOS device it may appeal to you .. it does far more than what you’d think, with a dual band module, DMR, and P25 modes, analogue signalling like MDC1200 etc, trunking, GPS, ROIP, SOS, alarms etc, and there’s an SDK kit available for third party developers too, and hopefully the apps that will appear as well. It all seems very modular and well thought out, the clipon goodies even has their own mic and speaker and battery, and it’s all neatly wrapped up in a $99 Nextpaq case – with the actual Dxbm modules beginning at $65 it’s beginning to look mildly Interesting. Watch this video or this earlier video which hopefully gives a better idea of it…

All work, text and images ©GB7MB and

Sommerkamp FT 277 ZD sale ((now sold ))

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Sommerkamp FT 277 ZD MK III  – From a warm, dry, pet free and smoke free home.
It’s got all the WARC bands, and will never ever have been CB’d as far as i’m aware, as i bought it directly off Harry G3LLL, the famous Yaesu 101 Guy who lives locally to us here at MBARS HQ – all that’s changed is that i fitted a FM board, which works, but there is an earth loop buzz on TX (but on FM tx only) i never got ’round to to fixing it as we used SSB !

The mic is a standard taxi type mic and the power lead comes with the set of course. The set has been looked after, RX’s well and TX’s well, the tubes seem good too, i never bothered checking them as the set just kept running fine and never let me down. It’s been kept switched on for long periods sometimes, weeks at a time, (heaters off) and is quite a nice example of the Sommerkamp badged FT 101 ZD mkIII

I will be sad to see it go, it’s like an old friend, but it’s time for me to move on, so here you are.
It’s in used, but working condition, don’t expect showroom condition, and know these sets are about 40 years old.

Best thing is to come and collect it, it’s too damn heavy to post, but if you really can’t get here to pick it up, maybe we can arrange a courier or something, but it’ll likely be pricey, and i’m not even sure i can package it in any meaningful way that would protect it during transport.

Really really, do come and pick it up.

Nice set .. and it will help keep you warm in the winter too.
Come and collect it from Morecambe promenade,

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All work, text and images ©

Never mind the fugly, feel the er, quality..


Yes, that’s a real photo of a real chinese electrolytic someone found during a repair.

I’ve not been doing much radio lately, as life kind of got in the way and my interest in amateur radio is somewhat on the wane, but every now and again it’s good to raise your head from out of the trough long enough to taste the cool summer breeze, as i do, i notice a new email from China in my inbox, i wonder if the air is as fresh over in Quanzhou, Yes, it’s another Chinese radio for me to purchase, or not, this time it’s DMR (TDMA) and it’s a Wouxun, it’s the first DMR Wouxun i’ve seen, and the previous FM set whatever it was was, probably wa the best selling (useable) dual band HT after the ‘christmas cracker quality’ Baofengs which hit the streets, so it slightly caught my attention. It kind of goes without saying that the Wouxun i foolishly bought, shuffled off it’s mortal coil after a only couple of years, after randomly crashing, rebooting, reverting to the default mandarin and forgetting everything. dreadful. At least it was a one minute job to re-upload the frequencies back in the set via the USB lead, Worse still was the Yupiteru 7100 scanner which lasted about the same span, then randomly crashed and burned at random moments too, and occasionally forgot it’s nearly 1000 memories. No USB programming there, that got old really quickly, so sold it as scrap, which reminded me of several Yaesu’s having done the same to me since i was a kid SWL, leaving me fed up and with a broke radio, not good enough.

I moved over to Motorola hardware several years ago and have never been let down with their solid hardware (just their occasional crappy DMR firmware) Yaesu have let me down hundreds of pounds for years, and forced me away with bad gear and worse after sales support, so obviously won’t be buying Yaesu or any of the other Ham names anymore, besides which, i think It all looks like it comes from the same Baofeng factory anyway. I love my FT 101 ZD, probably the best HF rig Yaesu Musen ever made, i love the build quality, but i will get rid soon, as i don’t use HF anymore.

Bad experiences aside, i must say I’m quite pleased that the Chinese manufacturers are now making DMR, obviously the quality is not the main priority when they’re knocking these things out en masse, and predictably the programming software is crap too, thank goodness then for Chirp the open source CPS that does a few other (not just Chinese branded radios) and hooray, i don’t have to even use Windows. Thank goodness for that. 2016 huh.

The firmware in the Chinese sets is often poor, but somewhat shockingly, even Motorola screws up firmware releases, the affected Gen2 MotoTRBO Motorola sets crashed and rebooted if you set the DSP and scanlist in certain combinations, and as if Moto didn’t learn by that mistake, the code monkeys at Motorola recently released a firmware which stopped the sets going into transmit mode. Nice job Moto,  but hey, why bother actually testing this stuff ?   I am available as a beta tester, email me for my details Moto.

If you’ve got a Chinese radio you may have the added bonus of fixed, naff, and quiet TX audio too, which seems to be getting solved nowadays, and with some recent Chinese DMR sets, there is talk of slot timing issues which slightly worries some DMR repeater keepers (but which Amateurs measure the slot timing accuracy and rise / fall on TDMA sets anyway ?) – these sort of things should be sorted out, if only they spent as much refining these things as they do with bloody cell phones.. but i digress, there seems to be little evidence slot-timing issues are much of a real world problem at present for Amateurs, my guess is the MotoTRBO repeaters are perhaps adjusting their tolerance ‘on the fly’ in these circumstances, but i’ve no proof..

You do get what you pay for of course, and the Chinese sets and Motorola are of course aimed at 2 different markets, and i hope the Chinese manufacturers one day could open-source their software and get the community to do some of the bug testing and development for them, but maybe the Chinese manufacturers are protecting their own IP (insert: irony) or maybe they’re reluctant to anger DVSI and Motorola’s legal department.  Only joking 🙂 – well,  it’s not stopped them making clones has it, and if it’s not all fake cell phones, and dodgy copies of Windows98 in China, let it be known there were or maybe still are some fake Apple “STOERS” (sic) over there, apparently even some of the employees thought they were actually working for Apple… You can’t make this stuff up can you..  Hopefully the chinese manufacturers will use their famous ingenuity to embrace a emerging market (us lot) my guess is that maybe there aren’t the numbers in the hobby to justify them spending on such R & D..

do know however, that exactly what the hacking / Ham community needs are people like Travis Goodspeed there in this Youtube presentation over at ShmooCon giving a presentation of his now famous firmware hack of the Chinese TYT MD380 handheld.. and there needs to be more of this. This retro looking website might be interesting if you’re interested. Travis’s blog is interesting too, even if it seems he’s not updated it for a few years.

After seeing this brand new shiny Wouxun KG D901  i was reminded of something else the Chinese HT designers should fix, less important perhaps, it’s the look of some of the sets, this bugs me way more than it should, appearances are of course subjective, but to me, the vast majority of chinese radios seem plain Fugly  indeed, some look like they’ve gone out of their way to make them as ugly or as infantile as possible, and some look like they’ve just dropped out of a clown’s arse, stop making them look crapkeep it understated and tasteful, I’m not asking for Johnny Ive  to design the bloody things (i mean, it wouldn’t have any buttons would it ?) but make them look like a proper radio, not something that is so ugly you’re likely to get beaten up for just having one at the next radio rally.

Amazingly this DMR Wouxun has a variable mic gain (must have given the designers sleepless nights) but still, they have 16 channel max scan lists ? – not all DMR sets are so limited, so any arguments about scan speed and missing calls ‘because of large scanlists’ is based on an incorrect premise, that such large lists increase likelihood of missing calls, well possibly, do dealers programme huge scanlists into commercial users systems, instead of only just what they need ?  

Somewhat refreshingly, there are occasional breaks from this ‘tradition’,  as an example, I do like the huge number of contacts you can add to the Connect Systems HT (a few thousand i think it is) – they’ve gone that extra step, which makes it better for masochists who like keeping full contact lists, it seems like Jerry as Connect Systems checked his email, and took notice, and i do understand that there are limitations on what can be done with the hardware and firmware, but it looked interesting and it peaked my interest originally, but i thought the CS700 seemed quite overpriced when compared to what North American buyers were paying, as it’s still a chinese HT, and i refused on principle, I’m an Amateur and i’m tired of pointless restrictions, life’s too short, and if you’re charging Amateur prices, give Amateur facilities.

Some advertising burb even suggest the TYTERA / TYT MD 380 are a copy of the Motorola DP4800, er, no.
I know the TYTs are popular sets, i might even try one, but damn, they need a bit of a makeover, they’re not like a DP4800 other than the keyboard is under the display, the proper place for it. I only just forgave Motorola for making the nice but FUGLY DP3600 and then replacing it with a model that *is* pretty, and screwing the pooch by neglecting to fit an SMA on it – (unless you pay another couple hunded pounds for the blue ATEX model) Yes, Motorola, you suck too, Hams buy your gear too, Moto, and some are about to stop, but to be practical, I require a VFO and other amateur features on my sets now,

know Moto are not consumer Ham type sets, but i’m already tired of the DP4801’s lack of SMA and lack of real FPP ond no VFO’s and real FPP, it’s not even a real option for us in the west, and vendor lock-in is bad for buyers, if only they recognised it, and If i find a DMR HT with the features below, my DP4801 will be on Ebay and i’d likely buying a HT with hackable firmware. for me a useful DMR HT needs:

  • SMA aerial
  • standard 2 pin TRS (jack) or something stronger / more pins features, non proprietry but Moto style.
  • scanlist not limited to 16ch
  • open source firmware / programming software for general hackability, so we can avoid the hateful chinese CPS
  • obvious mic gain & other standard features in radio menu you’d expect to find in any other radio
  • RSSI
  • Full FPP including up/down VFOs and full TG creation without PC. ALL TG rx like the hack for the TYT / Tytera / Retevis MD380 sets
  • doesn’t look like crap, good font and display on set too.
  • rugged

There may be more, like not being overpriced, but that’s obvious, and i don’t mention roaming, though i use roaming on our TAC-9 repeaters, and so think it’s very useful, MotoTrbo compatible roaming would be a sure winner in non-Moto sets, but i can live without it. I do wish the HTs were as pretty as the Moto’s however, below are some of the ugliest HTs i’ve ever seen, apologies if you own one, actually no, but why can’t they make them look less crap ?

wouxunDMRAbove: Wouxun DMR
Below: three Hytera’s. Hytera, you should be ashamed.

Below: no idea about any of them, just FM sets, but they are excruciatingly ugly.

There are no more words  🙂
All work, text and images © GB7MB


Heads-up: beware cloning codeplugs, & why you should really write your own ..

oldie pc
It’s time to give a heads up to people and to try and encourage more amateurs to write their own codeplugs.
Our hobby is primarily a technical hobby, and as such we’re all interested in tech and playing with this kind of stuff, and so perhaps this is a good time to maybe sit down and write your very own codeplug, as a recent post on a {professional radio site} warns that there can be problems sometimes, when cloning someone else’s codeplug into your set – if they’re differing codeplug versions that is, it seems you could end up with bad audio settings, or worse still, missing features, so really do check before you commit the changes to your radio. Codeplugs contain much more data than just the channel information and rig settings you get to see and change in the CPS.

On the forums over at Communication SupportMars here, posted a heads-up about this issue to Amateurs, and when Mars says it, you’d be wise to listen. so might i suggest you read Mars’ Post here  The forum is for professionals, so don’t even think of posting on there without having done your homework first, or you may not get much help at all, but what you will get is a huge forum full of technical discussions and, more often than not, you will find out exactly what you want – by just reading the forums, you also may enjoy the dry humour that occasionally pervades the site too, and maybe you’ll get answers to questions you’ve never even thought of asking, and hopefully save yourself a little stress into the bargain…

Writing a MotoTRBO codeplug isn’t too bad once you have the basics, It may help your understanding of how DMR works too, if you’re not familiar with it, there are guides to using it and documentation on programming with Motorola CPS on this very site, but first option for help is the CPS’s built in documentation and the area specific help system, that’s a real great feature of the Mototrbo CPS, or, if you care to browse back through the archived posts, you can look there too for some Amateur specific bits of info, and then you can set your radio for how You use it, not how the original author of the codeplug you downloaded uses his, and also you’ll not fall foul of any of this cloning codeplug stuff Mars warns us about. You can drag ‘n’ drop channels from other Mototrbo codeplugs with ease, you can open other codeplugs in the CPS at the same time, FM channels are much easier, and dragging ‘n’ dropping can save you much time, but make sure to check the exact name of things like talkgroups before dragging digital channels between codeplugs, If you don’t, you’ll find out later why you *should*

Writing a codeplug is all part of the ‘learning about radio technology’ thing we all signed up for.. sure, it’s not waving a soldering iron inside a valve transmitter like the early days, not quite as dangerous either, but technology has allowed up to swap the soldering iron for the keyboard in some ways, and me, i’m not complaining, they are both skills the modern amateur radio hobbyist will benefit from, and it really does bring back a sense of DIY to the hobby, now that much of the premade gear is often too small and fiddly for most of us nowadays.

Don’t be afraid of the CPS, give it a go, it can be quite interesting trying out your ideas, and you’ll be putting something In to the hobby too, which leads to getting more out of the hobby too, & it kind of beats watching funny cat videos on youtube doesn’t it !

Happy programming !

All work, text and images © GB7MB

TAC-9 logos for Motorola DP4800 / DM4600


Just because i was a bit bored, i thought i’d trim our TAC-9 logo’s and see how they would look as a startup bmp for the MotoTrbo sets.
The portable ones are a bit stretched out to fill the (little) screen the HTs have. They’re quite fetching i think.
Download>>   Download

All work, text and images © GB7MB

A Thankyou ..

To everyone that came to visit us at Blackpool rally yesterday and very kindly surprised us with donations, we’d like to say a big Thankyou to You all, and also of course, to Everyone who has supported us this far, either with donations, equipment, time or other assistance along the way,. even just by joining in,  It shows the true Amateur spirit is still alive and kicking !

-Hax, Mot and Paul-
All work, text and images © GB7MB

MB and UZ last heard lists

We were asked by some folks at Blackpool rally to add a few links to the last heard pages, the web pages where you can see who’s been using the repeater and what their rough signal quality was like into them.
So here we are, First link is to the Phoenix last heard list for GB7MB:

GB7MB Last heard list   (these links open in a new browser tab)
and GB7UZ below,
GB7UZ Last heard list

So .. Hope that helps..

All work, text and images © GB7MB

some codeplugs retired, and and an updated CS700 codeplug for GB7UZ and GB7MB

We are in the process of moving some old codeplugs we had on the site into an ‘archive’ or ‘retired’ section, as since they were uploaded, the DMR landscape in the UK has changed. They may have incorrect or not used anymore talkgroups, i spotted one or two CS700 ones with errors, so i strongly advise you not to use these, unless you want to see how DMR has changed since they were uploaded, and we have a new, hopefully easier, download system on the site, so all the codeplugs will magically re-appear in there soon.

Some of the ‘retired’ codeplugs still contain huge amounts of valuable data, like FM repeaters, contact lists and many simplex frequencies that you can still drag over into your current MotoTRBO CPS, but the DMR repeater Talkgroups have changed massively, most, (but not all) Phoenix talkgroups on other Phoenix DMR repeaters generally follow the ones we carry on GB7MB and GB7UZ, talkgroups such as the old American slot1 and uk wide slot2 and other unused stuff should be removed.

Anyway, here is an updated CS 700 Codeplug for GB7MB and GB7UZ users.
There are no other DMR repeaters programmed in.
It is here mainly for testing purposes, and i request feedback of any errors you may notice.
Please bear in mind i do not own a CS 700 to test this codeplug on, so please do expect errors and differences, and bear this in mind whilst submitting errors for inclusion into the proper finished version, which i will re-check in a month or two.

It is up to you to fill in your DMR ID and assign buttons etc. to your liking.

Please (ALWAYS) back up your current codeplug and take a look at the MBARS test CS700 codeplug before you write it to your radio, and adjust it to your needs, like side buttons and your ID. You can then use it after that, but most users will want to customise it and add a few extra channels of their own. There are DMR simplex and FM simplex channels, local FM repeaters and, of course GB7UZ and GB7MB.  FM channels are all 12.5kc, and there are basic scanlists set up.

I cannot find any way to re-order the channels in their zones, as i am pretty unfamiliar with the (dreadful) CS700 programming software, I hope someone out there knows how to and, either tells me, or submits or uploads a re-ordered and tweaked codeplug. I’m pretty much a CS700 newb !

Notes to fellow codepluggers, on Phoenix DMR repeaters in the UK, there is NO UK wide on slot 2, the long time gone North America Talkgroup is no more, it was spotted in several codeplugs, but as that TG disappeared before GB7MB got on air, i thought it should be made clear. TG8 roaming is no more either. The more efficient User activated Talkgroups  made this moot. The full list of our Talkgroups are listed on this site, plainly and simply, and they are the same for GB7UZ nd GB7MB, there are no ‘secret’ or undocumented talkgroups. talkgroup9 slot 2 (local) is called TAC-9 now because it is linked between UZ and MB.

We hope this helps, as i say, i do not have a CS 700 to test this codeplug, so please do not complain of any errors or omissions, instead, just drop us a message on here, or better still, upload your fixed CS 700 codeplug, saying what you fixed, (but lets not have any non Amateur frequencies though), so let’s help each another in the true spirit of the hobby 🙂

All work, text and images © GB7MB