8
Digital Modes
The DV4home can handle five digital modes:
D-Star
D-Star was developed in Japan 1999/2000 especially for ham radio and it became the
leading system worldwide due to its clear and relative simple user interface. Voice is
being transformed by the AMBE Vocoder into a compressed digital data stream of
3600 bits/s.
In addition, there is a data channel with 1200 bits/s for a total data rate of 4800
bits/s. This data signal modulates a carrier, so that a logical 0 is one frequency and a
logical 1 a second frequency. This is called 2FSK (two frequency shift keying) or GMSK
(which are the same, however the signal is modulated using a bell curve). This signal
can be used to modulate most FM transceivers (via the packet radio socket).
This is the reason why there are many homemade D-Star solutions.
Three reflector systems are used for communication. DCS (most common), D-Plus,
REF reflectors (mostly in English speaking countries), and the x-Reflector system
which plays a minor role. The DV4home enables communication on all these systems.
DMR
DMR was originally designed by ETSI for commercial applications. This is evident in
the user interface where numbers are used in lieu of call signs. DMR modulates with
4FSK, indicating that it uses 4 frequencies (compared to D-Star with 2 frequencies).
This allows doubling the data rate to 9600 bit/s. The higher rate allows the
transmission of 2 channels at the same time (2 time slots). The DV4mini always works
in simplex mode in DMR.
If you use time slot one (TS1) you have to set your radio to color code 1 (CC1) and the
talkgroup you want to use, i.e TG311 or TG262 etc.
Be aware that you have to enter
the talkgroup number into the receive group list of your radio
too, or your squelch
will not open. This is a common error made by first time users and it is very
frustrating.
When you use TS2, you always transmit and receive on TG9 (local) Then this routed
by the DV4mini and the DMR Plus system into the selected rooms.
