In-Band Vehicle Rebroadcast the simple way.
Posted: Fri Nov 21, 2008 3:08 pm
In reponse to a number of requests for sections of the LDSAMRA rebroadcast manual to be explained simply, here is the first attempt, a vehicle-based rebroadcast system using the simplest form of radio configuration and without the need for you to necessarily change the radio you currently have in your vehicles for normal voice comms.
There are programming points that will come up if you use the described method but these are simple to address. The primary one to remember is that the volume in the two radios forming the rebroadcast system, cannot now be set using a control head as one isn't needed in this application. As such it must be hard-programmed into the radios themselves and both should be set with a maximum and minimum volume setting of 15. Setting or leaving the minimum volume at the default zero will result in a carrier signal but no transmitted audio from the device.
The described solution falls into the "Slightly more expensive but easier to set up" catagory however it has been extensively tried by teams in the Lakes and other regions and has caused little or no problem in use. There are a number of variations on this theme that are not described here but if you have any special requirements of such a system then please get in touch and give me the excuse to play with the radios for a little longer.
The primary control of the two vehicle communications systems, main voice comms and rebroadcast, is left to a simple change-over switch that merely supplies 12 volts to either of the two setups. Although this function can easily be achieved by suitable programming of an SRM9030 main vehicle radio, here I've assumed that other regions already have different makes of radio in their vehicles. As such I've gone for the big switch approach. Some enhancement is still possible if a change-over switch can be found that has a different colour light for whichever side of the switch is activated, that sort of thing. In it's simplest form, the switch would be labled "Rebroadcast - On Off". It does need to be cabable of handling currents in the order of 10 amps or so however as power of this order may well be drawn when any of the radios transmit. They also tend to be a bit more robust when handling currents of this order. Direct connection of the switch to the vehicle battery or secondary battery is also needed or the rebroadcast will switch off when the keys are removed. This means that the on/off switch on the primary vehicle radio is the means by which that radio is turned on and off although this could be organised differently by an auto electrician if you have any special requirements along those lines.
The described approach really is the simplest method of achieving rebroadcast I believe but there are almost endless variations and enhancements that can be added if needed. Anyone wanting further information just needs to get in touch with what you want the system to do and we'll be happy to try and sort it for you.
There is always the danger that over-complication of what can easily be a very simple system occurs just because it sounds like a good idea to do something clever with the technology. Unfortunately that approach can lead to problems when it falls over or when someone does something they shouldn't and the local expert isn't on hand to sort things out. My own view is that if a simple solution does what you want then don't make it any more complicated just because you can. However, if you feel your team can handle a little complexity where it actually does improve the way the system works and not just makes it more complicated, then, yes, we can add that too. Again, drop us a line and we'll complicate it all you like!
If there's sufficient interest in this suggested method of achieving rebroadcast from a team vehicle then I'll post generic config files that will get it up and running in the shortest time. If any team wants config files specifically for them then just send me your team working channel number and I'll email the configs back to you.
There are programming points that will come up if you use the described method but these are simple to address. The primary one to remember is that the volume in the two radios forming the rebroadcast system, cannot now be set using a control head as one isn't needed in this application. As such it must be hard-programmed into the radios themselves and both should be set with a maximum and minimum volume setting of 15. Setting or leaving the minimum volume at the default zero will result in a carrier signal but no transmitted audio from the device.
The described solution falls into the "Slightly more expensive but easier to set up" catagory however it has been extensively tried by teams in the Lakes and other regions and has caused little or no problem in use. There are a number of variations on this theme that are not described here but if you have any special requirements of such a system then please get in touch and give me the excuse to play with the radios for a little longer.
The primary control of the two vehicle communications systems, main voice comms and rebroadcast, is left to a simple change-over switch that merely supplies 12 volts to either of the two setups. Although this function can easily be achieved by suitable programming of an SRM9030 main vehicle radio, here I've assumed that other regions already have different makes of radio in their vehicles. As such I've gone for the big switch approach. Some enhancement is still possible if a change-over switch can be found that has a different colour light for whichever side of the switch is activated, that sort of thing. In it's simplest form, the switch would be labled "Rebroadcast - On Off". It does need to be cabable of handling currents in the order of 10 amps or so however as power of this order may well be drawn when any of the radios transmit. They also tend to be a bit more robust when handling currents of this order. Direct connection of the switch to the vehicle battery or secondary battery is also needed or the rebroadcast will switch off when the keys are removed. This means that the on/off switch on the primary vehicle radio is the means by which that radio is turned on and off although this could be organised differently by an auto electrician if you have any special requirements along those lines.
The described approach really is the simplest method of achieving rebroadcast I believe but there are almost endless variations and enhancements that can be added if needed. Anyone wanting further information just needs to get in touch with what you want the system to do and we'll be happy to try and sort it for you.
There is always the danger that over-complication of what can easily be a very simple system occurs just because it sounds like a good idea to do something clever with the technology. Unfortunately that approach can lead to problems when it falls over or when someone does something they shouldn't and the local expert isn't on hand to sort things out. My own view is that if a simple solution does what you want then don't make it any more complicated just because you can. However, if you feel your team can handle a little complexity where it actually does improve the way the system works and not just makes it more complicated, then, yes, we can add that too. Again, drop us a line and we'll complicate it all you like!
If there's sufficient interest in this suggested method of achieving rebroadcast from a team vehicle then I'll post generic config files that will get it up and running in the shortest time. If any team wants config files specifically for them then just send me your team working channel number and I'll email the configs back to you.