If in doubt, please contact secretary dpmr-mou. From maintaining the grounds to keeping staff secure dPMR can work to keep the site at its best. Radio systems can also be used for sports and field trips. Working from goods inwards, through refrigeration to front of house dPMR can keep service at its best for restaurants and smaller hotels.
From goods in to the warehouse, through process control and quality testing dPMR can let you drive productivity to the highest possible level. To connect teams deployed in shops, town centres and more dPMR can be the on the ground advantage that your business needs.
For everything from security through to sales, dPMR is how to bring it all together, especially in larger retail spaces e. For equipment to be legal it is required to adhere to strict specifications in order that it operates in the way it is intended to do for it's purpose and does not cause any undue interference to other services or users.
PMR equipment operates in short range peer-to-peer mode and shall be used neither as a part of infrastructure network nor as a repeater".
If modifications are made to the equipment, such as adding an antenna connector, the overall maximum ERP or other technical parameters must not exceed the permitted levels set out in the Interface Requirement".
So this is where the confusion arises. The second document appears to suggest that you may be able to use non-standard equipment or modify equipment as long as the operating characteristics of the radios remain within the relevant specifications, the most important being that the radio output power does not exceed mw ERP.
Of course you would need to be able to demonstrate that any modified equipment met these standards to ensure you remain legal, something which would likely require some rather expensive test equipment. It should be noted that the sub-title of this document says 'Business Radio' which further muddies the water as is it not clear as to whether the document only applies to business users or users in general! Because a close transmisson on a similar frequency causes radios to desensitise, the output and input frequencies will be sevearl hundred khz or even mhz away from one and other as well as emplying large cavity filters to prevent this effect.
If there were no filters or the input and output of the repeaters were too close, the second a transmission from the input is detected and rebroadcast, the signal from the repeaters own output would overcome the weaker input and stop the transmission entirely. Since PMR only spans a mere Khz of spectrum, a semi-duplex type system is unsuitable and unattaniable. Instead what is known as a parrot repeater system is employed. A parrot system, needs only one channel to operate on, and as the name suggests, the radio simply rebroadcasts any transmission heard on the frequency after said transmission is over Think of a parrot, repeating what the owner has said.
Apart from the obvious disadvantage of hearing your own transmission repeated back to you, it is effective on PMR and is the most common way of range-extending especially when the repeater is installed at high ground.
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