[MLB-WIRELESS] 1200 MHz data. If your a ham!

[Mark Aitken]

Hi Ppl,

There is an interesting development in Amateur radio circles of late.  
Although the protocol has been available for a number of years, it has 
just started to take off in Australia, thanks to the donation of 
equipment by ICOM.

Basically it is Digital voice over a RF carrier.  No big deal to those 
that use VoIP all the time.  But to amateur radio operators it is.  The 
system used a 4800 GMSK carrier comprising of 2400bps encoded audio with 
1200bps FEC and a 1200bps data subcarrier used to transmit Callsign 
identification, test and GPS data.  Allowing realtime tracking of a 
mobile system. The carrier contains routing information that allows the 
user to set up the radio to access a repeater station to tunnel through 
the internet to another suitable repeater anywhere in the world and 
conduct a conversation with other amateur radio operators.

The system is known as Dstar standing for  Digital Smart Technologies 
for Amateur Radio.  The system is available for use on teh 2m (144 - 148 
MHz). 70cm (430 - 450 MHz) and 23cm (1240 - 1300 MHz) bands allocated to 
Amateur Radio operators worldwide.

The ability for the system to recover audio from a weak signal situation 
is very good.

The story doesn't end there.

On the radio for use on the 23cm band, the Dstar protocol allows for 
128Kbps Data, known as Dstar Dats or DD for short.  Maybe not the Mpbs 
you are used to on the Wifi bands but none the less a decent speed to 
allow a internet style use for data transfers.  The protocol has a 
bandwidth of 140Khz and power levels of the Icom ID1 is up to 10 watts 
allowing many many Km coverage with rock solid throughput and of course 
an amplifier may be used to give much more power output.

The data can also be routed via the internet.  Current regulations only 
allow for a VPN style tunnel so as non Amateur Radio Operators can not 
access the HAMNET side of things and visa versa.

Anyway,   Just an interesting tid-bit on RF data technology.


Regards

Mark