Hi Bill,
That's not as straight forward of a question as one might think.
D-STAR really isn't about linking, in the same way that analog systems
are "linked" -- which has its pluses and minuses.
The D-STAR "common air protocol" has an addressing scheme that has a
notion of a source (MYCALL) station, a destination (URCALL, specific
or general such as CQCQCQ), repeater 1 (RPT1), and repeater 2
(RPT2). The idea is that the source or originating station declares
to whom s/he wants their transmission to be sent by setting a
destination and optionally can include information about a first
repeater and second repeater. For example, I could set my D-STAR
address information to:
UR: CQCQCQ
MY: K7VE
RPT1: WD7STR B
RPT2: NR7SS B
And if the ATM bridge (Icom's $10K 10 gHz. backbone system) was set up
between the two site's controllers, my signal would be relayed via
repeater WD7STR B to NR7SS B and would be a general call to anyone
listening to either repeater, but they would not be linked, it would
simply be signal switching. For someone to reach back to me from the
NR7SS B side of things they would have to set their radio to:
UR: K7VE (or CQCQCQ)
MY: N7XXX
RPT1: NR7SS B
RPT2: WD7STR B
And their signal would traverse the switching back the other
direction. This also work for two repeaters on the same same
controller, e.g.:
UR: CQCQCQ
MY: K7VE
RPT1: K7LWH C [2 meters]
RPT2: K7LWH B [70 cm]
In all of these scenarios, signals traversed two repeaters but there
was no linking.
The next approach is using the gateway, again there is no linking
involved.
UR: N7XXX
MY: K7VE
RPT1: VE7VIC C [2 Meters]
RPT2: VE7VIC G [A "virtual" repeater called a gateway]
On the gateway, it looks up N7XXX and determines if any of the 400 or
so other gateways on the Internet have seen N7XXX and switches my
signal to that gateway, which in turn send my signal out the
appropriate attached repeater. Again no linking, just signal
switching. If someone made a "local" call through VE7VIC C, it would
not be relayed beyond the repeater, even while I was calling the
remote station. Lets suppose N7XXX was in Logan, UT, the signal
would routed to the NU7TS G gateway, which in turn would send it out
the NU7TS B [70 cm] repeater. I don't know that N7XXX is in Logan
or what repeater he is on, it just doesn't matter, I just want to talk
to him.
He would have to set up the return as:
UR: K7VE
MY: N7XXX
RPT1: NU7TS B
RPT2: NU7TS G
Note, N7XXX doesn't know what repeater I am on, just my callsign.
A variation of this is equivalent to CQCQCQ on a known remote repeater:
UR: /NU7TS B
But again this doesn't create a "link", it just tells the gateway
where to switch the signals with this information in their headers.
The gateway software also has a notion of Multi-cast groups, where you
can transmit on up to 10 repeaters simultaneously by using a
designator setup up by the gateway administrator. Let's say the
gateway admin creates a multicast group similar to this WWARPT
(Western Washington Repeaters] and in that group he puts [WD7STR B,
K7TUL B, NR7SS B, WA7FW B, K7LWH B]
Now if I setup:
UR:/WWARPT
MY:K7VE
RPT1:K7LWH B
RPT2:K7LWH G
My signal will show up on the 6 repeaters in the multicast group. (See
Example at: http://www.ladstar.org/mc.htm)
This still uses native D-STAR routing, no "links" are created, the
signals are just switched to these repeaters (up to 10) simultaneously
and other stations wish to participate must program their radios
similarly, such as:
UR:/WWARPT
MY:WA7DAD
RPT1:WA7FW B
RPT2:WA7FW G
Moving on from native D-STAR, there is the DPLUS "linking". DPLUS is
an add-on written AA4RC and found on a majority of gateways.
Under DPLUS linking a few new scenarios arise, for brevity I'll just
show the UR information, but you use RPT1 and RPT2 with the "G"
repeater in RPT2.
UR:WA7FW BL -- Link the local repeater to WA7FW B
Every transmission on either repeater (local or remote) will be
relayed to the other as long as the "G" (gateway) is in RPT2
There are also reflectors, you can hook as many repeaters to a
reflector as the administrator of the reflector allows (usually based
on available bandwidth) so:
UR:REF001CL -- Link the local repeater to reflector REF001C
When linked to a reflector, signals on the local repeater will be
repeated via the reflector to every other repeater that is also linked
to that reflector, for stations that have the "G" gateway in the RPT2
field.
So the net of all of this is, on native D-STAR there is no linking.
Using D-PLUS its how many repeaters do you want to link (using a
reflector)?
On Sep 4, 2009, at 12:02 PM, Bill Cherepy wrote:
How many repeaters can Link to a single D-Star repeater at any one
time?
Thanks,
Bill WB4WTN
John D. Hays
Amateur Radio Station K7VE
PO Box 1223
Edmonds, WA 98020-1223 VOIP/SIP: [email protected]
Email: [email protected]
