Digital Makes a Difference

 

This short article is about digital two way radios. There is so much information out there and most of it is rather confusing as it favours specific manufacturers only. We at Wall to Wall Communications hope you will find it helpful if you are on a crossroad and still not sure whether to migrate from analogue to digital radio systems.


According to Ofcom (Office of Communications, the UK regulator), the supply of available Private Mobile Radio (PMR) channels is almost exhausted in some areas. Undoubtedly, the radio comms industry needs more capacity for its current and future requirements and the way forward is adopting the spectrum-efficient digital modes. Digital standard is here to stay.
Digital two way radios are available in both licenced and licence-free forms. They digitise speech like mobile phones and transmit it over radio waves, whereas analogue equipment uses audible speech. Being capable of voice, data and a range of other features and applications in conventional and trunking mode, digital radios have received global recognitions.

The current protocols used to send digital signal are two – Time-Division Multiple-Access (TDMA) and Frequency-Division Multiple-Access (FDMA).

 

digital chart

 

Main benefits of digital radios over analogue ones:
 
  • better clarity of voice – through the use of coders and other techniques, digital processing is more consistent screening out noise and re-constructing signals from degraded transmissions
  • doubled capacity in existing licenced channels

TDMA retains the 12.5kHz channel width and divides it into two alternating 30msec timeslots where each timeslot acts as a separate communication path or channel
FDMA narrowband technology slices the signal in length and uses 2 x 6.25kHz channels which allows twice the amount of users on the radio spectrum as well (e.g. two simultaneous independent calls on one channel.
Both standards can be also used for reverse-channel signalling for improved control of the system operator.

  • reduced equipment and licencing cost – doubled capacity also means that less system equipment is needed in order to gain the same coverage for the same number of radio users
  • wider coverage and better performance at the edge of coverage area – no scratchy noises until the signal is completely gone beyond the communication footprint
  • longer battery life and greater power efficiency – this is achieved as the radio transmits only half of the time every other 30 msec (TDMA) and for FDMA the reduced noise components (with the narrower channel bandwidth) improve receiver sensitivity, which makes the radio transmit at a reduced power as well
  • backwards spectrum compatibility with legacy analogue systems – all digital equipment works in mixed mode (analogue and digital), therefore old analogue radios can still be used
  • easier integration with IP-based data applications, text messaging, telemetry or external tools like GPS and telephone interconnect – it is possible to separate voice and data streams into different communication paths in order to improve quality of service and utilize a computer to control the whole system via sophisticated software
  • (last but not least) secure connection – digital signal encryption is much easier to implement and more secure (as opposed to “scrambling” with analogue)

For further advice and consultation, do not hesitate to give us a call on 0208 770 1007 or 0500 016 500 (free phone) or send us an e-mail




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Recent News

  • How to reduce the interference to your radio system ?

     

     

    There are several changes you could make to your radio system that may reduce the signal interference it receives. Reasons for interference are various but the following tips usually solve the most common ones:

     

    •  Change the frequency(ies) of operation:


    >>
    probably the most simple but may not be practicable in dense urban areas where there may be a severe shortage of spare channels  
    >> changing from a Shared to an Exclusive Use channel should help significantly  

     

     

    • Enable channel access selection:


    >> this may be as simple as activating the CTCSS or changing the current CTCSS code. This will result in your only hearing the stations using the same code  

     

     

    • Reduce the gain of your base station antenna:


    >> this will reduce the interference from distant stations. NB: check that the revised gain will be sufficiently high to ensure sufficient reception from your mobile / handheld radios  

     

     

    • Change to a down-fire base station antenna:


    >> this will dramatically reduce the interference from distant stations, e.g. to 100th. NB: check that the revised coverage pattern will remain sufficiently wide to ensure adequate reception from your mobile / handheld radios  
    >> this method can also be used to increase weak radio coverage directly below an antenna, e.g. within tall office blocks. It may also result in a significant reduction in your licence fee  

     

     

    • Change to a base station antenna with electrical / mechanical down-tilt:


    >> adding a down-tilt of, say, 10 degrees may reduce the interference from distant stations whilst perhaps increasing the signals from your handhelds and mobiles. NB: more interference may occur if the antenna is mounted on a high mast and the amended tilt angle is then directed towards the horizon  

     

     

    • Reduce the height of the base station antenna:

     

    >> this will reduce the interference from distant stations. NB: check that the revised height will be sufficiently high to ensure sufficient coverage of your radio system  

     

     

    • Remove inter-modulation product (IMP) problems:


    >> inter-modulation products within a receiver can result in the reception of stations that aren’t transmitting on the selected frequency. This can be caused by the transmissions of two strong nearby radio systems mixing in the receiver and causing ghost stations. Changing to an alternative channel is probably the easiest solution, assuming that one is available in your area.  


    If the above tips do not make a significant difference or you encounter difficulties trying them out yourself, our Two Way Radio Systems Team will be happy to discuss your interference problems, identify the issues and recommend suitable solutions.

     

     
  • Create Your Two Way Radio System Planning Wish List

     

     

    Wall to Wall Radio Communications' system engineers have created a questionnaire to help you decide the basic requirements of your new / upgraded radio system. The answers and subsequent discussions will help us to design and supply the best radio system to meet your needs.

    If you do not understand any of the questions or would like to discuss your requirements further, feel free to give us a call on 0208 770 1007 or e-mail us.





    • What is the postcode, or National Grid Reference (NGR), for the radio system?

       

    • Do you have, or previously had, a radio system at this location and, if so, have there been any problems with it?

       

    • What is the required coverage area radius of the radio system?

       

    • How many radios will be used?

       

    • Will any radios be used at a fixed location, e.g. in a central control room?

       

    • Will all users be outdoors?

       

    • Will some / all users be within a tall building or in a basement?

       

    • Do you wish all users to hear each other, or only communicate within their working group(s) (e.g. managers, staff, and security), or only hear the controller / base station?

       

    • Do you wish some / all users the ability to occasionally send and receive calls to and / or from all users?

       

    • Do you wish some users to occasionally send and receive private calls between each other?

       

    • Do you wish to reduce the risk of casual eavesdropping?

       

    • Do you wish some / all users to send and receive pre-defined and / or free text messages between other users?

       

    • Do you wish some / all users the ability to send and / or receive an emergency call / alarm?

       

    • Do you require some / all radio users to be able to make telephone calls, e.g. to the emergency services?

       

    • Do you wish some / all users to automatically check-in regularly e.g. lone workers?

       

    • Do you wish to remotely monitor some / all radios, e.g. after an emergency alarm activation and / or after no reply from a lone worker?

       

    • Do you wish to remotely check the status of some / all radios, e.g. to ensure they are switched on and working?

       

    • Do you wish the ability to remotely disable and enable radios, e.g. if lost or stolen?


    DOWNLOAD QUESTIONNAIRE

    You can also print this list, answer the questions and send it back to us via fax.

     

     
  • How to reduce your two-way radio licence fee ?

     

     

    In the following article we provide a list of things that you could consider and take the opportunity to change in your existing two way radio licence in order to save on unnecessary high OFCOM business radio licencing fees. Every piece of advice given below is legal and with this educational material we try to demonstrate our commitment to your business needs and sensibility to your budgets.

    Wall to Wall Radio Communications' team wishes you a wonderful Christmas. We hope to stay your partner of choice through the whole 2012 and beyond.

     


    OFCOM uses three basic licence fee structures for private mobile radio (PMR) equipment operation in the UK:

    ________________________________________________


    TECHNICALLY ASSIGNED LICENCES

     

    Ofcom licence fees for these systems include a combination of the following:

    • antenna location (outdoor / indoor / underground);
    • antenna height;
    • antenna type (omni-directional / directional / down-fire / radiating cable);
    • radiated power from the antenna;
    • frequency band of operation;
    • number of channels licensed;
    • exclusive or shared channel use;
    • channel bandwidth (12.5 / 6.25kHz);

     

    The following changes may therefore have a significant effect on your licence fee either now or as part of a system upgrade:

     

    • reducing the antenna height;
    • changing from an omni-directional to a directional or down-fire antenna;
    • reducing the radiated power from the antenna;
    • change the frequency band of operation;
    • reduce the number of radio channels used;
    • change from exclusive to shared channel use;
    • change from a 12.5kHz channel system to a 6.25kHz channel system;


    ________________________________________________


    AREA DEFINED LICENCES

     

    Ofcom licence fees for these systems include a combination of the following:

     

    • number of countries covered within the UK;
    • number of 50km x 50km NGR squares covered;
    • frequency band of operation;
    • reduce the number of radio channels used;
    • change from exclusive to shared channel use;
    • channel bandwidth (12.5 / 6.25kHz);

     

    The following changes may therefore have a significant effect on your licence fee either now or as part of a system upgrade: 

     

    • amend an All-UK licence to include only the countries covered by the radio system;
    • amend a country licence, e.g. England, licence to include only the 50km x 50km NGR squares covered by the radio system;
    • amend the system coverage so as to only cover the NGR squares covered by the system;  
    • change the frequency band of operation;
    • number of radio channels used;
    • exclusive to shared channel use;
    • change from a 12.5kHz channel system to a 6.25kHz channel system;

       

    • ________________________________________________ 

       

      SIMPLE / LIGHT LICENCES

       

      Simple UK (NB: mobiles only for use anywhere within the UK):

    • these licenses have a fixed fee of £75 for 5 years. No licence fee reduction is therefore possible;

     

    Simple Site (NB: may include a low-power base station at a site):

    • these licenses have a fixed fee per site of £75 for 5 years. No fee reduction is therefore possible;

     

    ________________________________________________


    LICENCE EXEMPT EQUIPMENT

     

    Those would be radios that conform to the relevant requirements, (e.g. Ofcom’s IR2009 for PMR446 walkie-talkies), which may operate on a licence free basis. No licence fee is charged so no fee reduction is possible here.  

    Wall to Wall Radio Communications will be pleased to discuss your current radio system arrangements with you and suggest ways, including those shown above, in which you may be able to reduce your licence fee.

     

    the number of radio channels used;
     
  • Wall to Wall, Liz Hurley, James Corden and Louie Spence all at one place – Selfridges London



    We are announcing that over the next few days starting from 5.30pm today (28th September), everybody in town will get the chance to enjoy themselves in the company of Elizabeth Hurley, James Corden and Louie Spence who will be celebrity gueasts at different events taking place in Selfridges London.

    The first event for today (in less than an hour): Come and experience a spectacular dance performance by Louie Spence.
    "Still Got It, Never Lost It" is the much-anticipated autobiography from the star of Pineapple Dance Studios and Louie Spence’s Showbusiness. It is the story of a real-life Billy Elliot, beginning with a little boy with high ambitions who loved to dance.
    The location is confirmed to be in WHSmith Shop at Selfridges, where the dance expert and his dancers from Pineapple Dance Studio will entertain you before the booksigning at 6:00pm.

    Tomorrow (29th September) Liz Hurley will be supporting a Breast Cancer campaign along with beauty company Estée Lauder. You will have the opportunity to make a contribution and get products signed by the famous British model and actress. Selfridges will join the prestigious list of iconic global locations to be lit pink by Estée Lauder as a part of their Breast Cancer Awareness initiative, which currently includes the Sydney Opera House, The Empire State Building and Niagra Falls.

    On the next day (30th September) everyone can meet Britain’s much loved actor, television writer, producer and presenter and all round comedian – James Corden and buy his autobiography book, in which he reveals his disruptive teen years, his trials to make it in a boy band and the journey he went through to co-write Gavin and Stacey.

    As always our team at Wall to Wall Communications will be taking care of the two way radio communications equipment on site adding another 10 radios (Opus and Motorola) to Selfridges’ existing and growing multi channel security system. We will make sure that every management and security staff member will recieve a seamless communication expereince.

     

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