The new DMR System...
The Radioddity GD-77 Dual Band Handheld The Hytera MD785 Mobile The Retevis RT3/TYT MD380
DMR (Digital mobile Radio) is actually nothing new and has been around for some time. It is however new to the amateur radio world. Originally sold as a commercial system by Motorola under the brand MotoTRBO it is a highly effective system with a long pedigree and good track record not just for voice but also data.
Interest in all things digital in the radio world has been spurred on by the interest and growth of Icom's D-Star and Yaesu's C4FM Fusion systems. However for many the extremely high cost, (£400+ for a handheld, £500+ for a mobile) even when imported direct, cannot be justified. This is where the DMR sets come into their own for around 1/3 of the price.
However they do work in rather different ways to the other main amateur radio systems, and this is where some confusion can set in... like anything new it can be a steep learning curve until you get the hang of it. Icom & Yaesu's systems are mainly a case of programming in your amateur callsign and the mode FM or a digital one (Auto C4FM, Narrow Digital [for voice and data], Wide digital [for voice only], D-Star etc. You also have the ability to input a frequency either in memory or to use a direct entry VFO. DMR is different - it has no VFO, all information for each frequency/mode must be entered into a channel memory - then cross-linked with a common setup Zone. Each callsign must have a Radio ID which must be obtained from a central international registry. Like D-Star & Fusion, you can direct your call through a repeater network that is linked around the world to a specific location, or call set to set. The way this is done however is different with DMR in that it must be contained within the memory for each frequency, repeater or link. Again like other digital systems, voice transmissions are broken up into data packets of a fixed time duration and interleaved with header information to route the call to the appropriate destination. With DMR however, this is done by using TDMA.
Time-division multiple access (TDMA) is a channel access method for shared-medium networks. It allows several users to share the same frequency channel by dividing the signal into different time slots.[DMR uses 2 slots] The users transmit in rapid succession, one after the other, each using its own time slot. This allows multiple stations to share the same frequency channel while using only a part of the channel capacity. C4FM uses FDMA [Frequency-Division Multiple access]. see below. Each have their own advantages and drawbacks.
So which is best?
Thats a bit like asking which is better red wine or white wine. The answer is simply, its up to you.
Some people prefer red wine, some prefer white, some don't like either. In the case of Digital Radio a lot will depend on the depth of your pocket, the tolerance of your other half, your personal preference or what others are doing in your area. But for many it may well come down to cost. Can you justify spending ~£1000 for a mobile and handheld from the big 3 manufacturers (I, K & Y) or £300 - £400 for a DMR setup? (remember the days of VHS vs Betamax? Betamax was probably the better system but could not compete with the lower prices of VHS)
Do you get plagued by annoying cold calls for PPI, Accidents you may or may not have had in the past, double glazing & solar panel sales?
All telecoms providers will allow you to block several types of nuisance callers, withheld numbers, overseas numbers or specific numbers ... however they charge a hefty monthly fee for this privaledge of stopping this harrasment which they allow to happen....and in many cases there are limits to the number of callers that can be blocked. (BT has a maximum of just 10 UK numbers *), plus a seperate charge for blocking overseas, premium rate numbers etc. [* note BT has now introduced a new free blocking service for their customers. please see their website www.BT.com - (WD Raynet does not endorse any particular ISP/telecoms provider)]
So why/how do we get these calls? Why are they not outlawed by now?
Unfortunately it is not in the interest of the telecoms providers to stop them ... they make lots of money from them. The regulators (OfCom) have little time, staff or resources to deal with them and there is little political will to design enforcement. It is left with the industry to deal with the problem under a series of "Gentlemans Agreements" - run and funded by the industry itself, none of which have any weight in law and can and are widely ignored. ( mainly under TPS = the Telephone Preference Service.
Most cold calls are robot dialers who will call numbers at random by the thousand until some poor unsuspecting soul answers - now they have a live one and will circulate the number to all the call centres - and off the operator goes with the pre-scripted message. If they call, don't get angry with them - it does no good - just get their number and report it to the sites below to be circulated to blocking systems. (A useful trick however is to pick a single word in french/spanish/greek/russian and answer every question with it.) ... drives them nuts and more importantly is more likely to get your number removed from the lists.
Another good way to stop them is to get a call ansaphone/blocking machine... they are fairly cheap and a fraction of the cost of your telecoms providers "filtering services" a reasonably good one will cost ~ £50'ish although online versions can cost hundreds of pound annually (OK if you run a big business but not really for home use.) A big advantage is that they will all screen your calls and can let you know who is calling - they can also surpress the first few rings so that you are not disturbed unnescessarily. Each can log who calls and allow you to block numbers by type, location or specific numbers. Unfortunately the less than scrupulous callers will insist on hiding or disguising their number. OK no problem they dont get through. Overseas call centres - killed in one go. If a company is genuine and needs to speak to you why hide their number? Add a message to your answering machine to say unknown numbers are not accepted.
Allways report nuisance callers!
Another way you will get plagued by cold calls is when you fill in "registration cards", "sales cards", "repairs slips" or you register "on-line" One of the few laws governing cold calling is that companies may call you when there is an "existing relationship" i.e. you have done business with them in the past. NEVER, EVER give your telephone number UNLESS IT IS ABSOLUTELY VITAL! i.e. certain government bodies or your doctor/hospital etc.
Always make sure you make sure that they endorse any sales document that you will not accept any sales or maketing calls and you do not give permission for them to "share" your details with ANY 3' party - whether connected with the company or not.
Unfortunately some websites are getting crafty and will not let you register unless you give them a valid telephone number - ask yourself -> do I really want to deal with a company that treats me like this? if NO vote with your feet/pen/mouse and take your business to a company that respects you as a person and not a revenue source. If YES or you do not have an alternative and the website absolutely insists on a number, enter the following...
0 333 8888 8888
(0 then 3 three's and 8 eight's) if the website will not let you enter more than 11 digits you can drop off the last 8 (0 333 8888 888)
this is a free service offered and run by trueCall38 - please note we do not have any connection with this company.
Now when call centres try to call they get a polite message saying that this person does not accept uninvited sales and marketing calls and they should write or email as directed.
Again, always make sure you make sure that you endorse any sales document that you will not accept any sales or maketing calls and you do not give permission for them to "share" your details with ANY 3' party - whether connected with the company or not.
So who do I report them to?
The first stop should be a complaint to TPS (The Telephone Preference Service) - Yes I know what I said above about their lack of any real powers, however most reputable business will and do abide by a "do not call" request.
The second line should be to make a complaint to the Information Commissioners Office (ICO)
If there is any suggestion of criminal activity please contact Action Fraud the national police cyber crime unit.
A lot more information may be found through Which? at
and a more pro-active approach can be found at http://www.saynotocoldcalls.com/ which involves billing them for your time. It's true you can make them pay you - but it does take a bit of persistence.
You could get yourself an 08 or even an 09 number. You telecoms provider will try and dissuade you as they are not designed for 'home' use, but they are not limited to business use by legislation... But, you will always have to announce or that this is a premium rate call line and offer the option of hanging up. (08 series number charges are ~ 45 - 80p/min, but especially important for 09 series numbers where the cost is normally £2 - £10/min and can run into hundreds of pounds very quickly. - these numbers are normally used for gaming and competition lines as well as adult content.) You may also be charged a one-off call connection charge cost of up to £6. You can find out the access charge for these numbers – which is the rest of the call cost – from your phone company.
The good news though is that you get paid evey time someone calls you. The actual charge will vary from provider to provider and is made up of an access charge (paid to the telecoms company) and a service charge (paid to the 'number holder'). This will also vary according to whether a calls is made from a landline or mobile. However, please remember that any-one who calls you will have to pay this ... family, friends, doctor, hospital, school government departments (Job Centre, DWP, HMRC etc.) and so should not be used lightly and only as a last result.
|Switch & Circuit||Function||Circuit||Wire Colors||Use|
|Connector Block 1 – (new block)|
|Switch cct 1||Locking||1||Light Green||Amber Strobes|
|Switch cct 1||Locking||1||White||Amber Strobes|
|Switch cct 2||Locking||2||Blue||Amber & Red Strobes|
|Switch cct 2||Locking||2||Green/Yellow||Amber & Red Strobes|
|Switch cct 3||Momentary||3||Green||Not used|
|Switch cct 3||Momentary||3||Orange/Black||Not used|
|Rocker switch 4||Locking||4||Orange||Locking PTT|
|Rocker switch 4||Locking||4||Black/Blue||Locking PTT|
|Push Switch 5||Locking||5||Pink/Black||Radio Power on/off via relay|
|Push Switch 5||Locking||5||Red/Yellow||Radio Power on/off via relay|
|Connector Block 2 - (same as original)|
|Engine Stop cct 6||Variable||6||Sep. Plug|
|Headlight Hi/lo 7 & 8||Adjustable||
|Engine Start||Push||9||Separate plug|
Fitting the new switch pod on the ST1100 is straightforward.
The Police Switch pod comes with 2 connector blocks (Red & Green). The smaller (Red) is the same as the original connector for the standard unit and plugs straight in. This is for the Engine start, kill switch and headlight hi/lo switch.
The extra block (green) is the connector for the P Spec ST1100, this needs to be adapted for a standard Pan.
The new pod has 10 wires (9 in a bundle into the new block, plus 1 free) and the colours are as shown. Unless you have the correct 10 way block already on your ST1100, it is easiest to cut the wires out of the block as close to the block as possible.
The maximum current rating for each of these cables is 5 amps. If you intend to connect anything which draws close to or more than 5 amps you will need to go via a standard relay.
I used a 7 core cable to run from the front to the rear pannier which housed all the extra battery and strobe gear, plus a 2 core PTT line to locking and momentary PTT switches in parallel. You could combine this and use a 9 core cable, but getting a cable rated at 5 amps is not easy and costs a small fortune. Also the cable diameter gets rather large.
To Fit the Pod:
Note you will need new fitting bolts to hold the unit as the old ones will be too short.
- Remove the brake lever to give easier access.
- Loosen the brake master cylinder/fluid reservoir and slide it as far inboard as possible. The new pod is ~ 5 – 8mm wider than the original.
- Remove the retaining bolts and remove the old switch unit. Careful to not dislodge the throttle cables.
- Remove the old engine/headlight connector (Red?) making sure not to damage the sockets.
- Plug in the new engine/headlight connector (Red?) making sure not to damage the sockets. Wrap in waterproof/self amalg tape.
- Loosely fit the new switch pod onto the handle bar taking care not to trap the throttle cables or engine control wires.
- Adjust the position to allow correct operation of the throttle. Bolt down unit, again making sure free movement of throttle.
- Slide the brake unit back against the new switch pod and tighten locking nuts.
- Refit brake lever.
- Check for full and free movement.
Wiring the new Switch Pod:
You will need a 12v auto relay for the radio plus further relays for any kit drawing more than 5 amps.
- Run the 7 core cable to the rear o/s pannier.
- Run PTT cable to Radio as normal
- Identify each of the 10 wires from the new switch pod and arrange them in pairs.
- Connect pair 1 (light green) to amber strobe controller + and (white) to battery +
- Connect pair 2 (blue) to red strobe controller + and (green/orange) to battery +
- Isolate pair 3 (dark green & orange/black)
- Connect pair 4 (orange & Blue/black) to PTT line in parallel to push PTT switch on left handle bar and to Radio.
- Connect pair 5 (red/yellow) to 12v relay coil input (pin 86), connect (pink/black) to battery +, connect relay output (pin 85) to earth.
- Connect relay power input (pin 30) to battery.
- Connect relay power output (pin 87) (n/o) to radio.
4 Pin 12v Relay Pin 30 is 12v live, 85 & 85 Relay coil, 87 ground.
5 Pin 12v Relay has an extra contact 87a. This pin is normally closed (& live) when the coil is un-powered.
North Devon Night Walk
How about this for a bit of fun....
Each year the hard working team at the North Devon Hospice, hold a charity night walk for ladies only, between Barnstaple and Bideford, Starting at either end. Each year thousands of determined and boisterous ladies gather to take part, oure role is to make sure the event goes off smoothly, keeping the organisers updated on locations and numbers, plus anything untoward.
This years Ladies only Nightwalk is overnight 20 - 21 May 2017. - good luck to all those involved.
At the annual Tavistock Goose Fair which is held on the second Wednesday in October each year, we act as the link for the Police, South West Ambulance, St John Ambulance, Tavistock Town Council, West Devon Borough Council, the Bus services and the Park & Ride Scheme.... as well as a general information and lost property, children and granny point!!!!
Here the "ISU", "battle-beast" or "Thunderbird 5" as it is variously known, is setup and running in the centre of Tavistock beside the Ambulance and First Aid points.
Each year, we run from around 05:00 to 01:00!!!
...quick more coffee!!!