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)mbars.co.uk and i will remove you.
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:
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
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.
Blitzortung 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.
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.
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, Firefox, Chrome, 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.
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”
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…
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, DONT BE a LISTENER !
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.
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…