On 4/7/2010 4:40 PM, Nicholas wrote:
I may be asking a question that has already been answered. What is the
difference between Linking (UR: KJ4MMCCL) and Source Routing (UR:
/KJ4OXTC)? This is something I have yet to figure out.
Thank you and 73s,
Nick KF4SEK
Cocoa, FL
Quite a bit.
Source routing is a one-shot route... you key up and the system routes
that single transmission to the person's last known location. You get
confirmation that it routed all the way to the far end gateway server,
back in your radio. "UR" vs. "RPT" displayed after each transmission.
It's the "original" Icom design. It's also the only way to talk across
Trust Server networks to the Japanese system. They do not have... (see
below...)...
Linking is provided to D-STAR on the U.S. Trust Server network by the
D-PLUS add-on software, and isn't built-in by default to Icom's Gateway
software. Once you issue the command, you and everyone else (you switch
back to "CQCQCQ" for your UR field after this type of "hard" link is
established between two repeater modules, or a repeater module and a
reflector channel) who talks on the local frequency is heard at the far
end until the link is terminated. You get no confirmation that your
transmission was transmitted end to end, but it's the only GOOD way to
do point to multipoint linking.
Icom DID provide a system that allows for Source Routing point to
multipoint, called "Multicast" (not to be confused with IP network
Multicast, which is a different thing altogether). It requires that all
of the participating Gateway operators set up a specific fake "callsign"
that all users "route" to, and every Gateway must be both programmed to
send that callsign's traffic to all other repeaters in the group, and
also must have enough bandwidth at the repeater site to send that many
streams... each repeater in the multicast list gets its own stream.
Haven't really played with this one, but in practice, the bandwidth and
other limitations make it pretty "wimpy" compared to nice high-bandwidth
Reflector server and D-PLUS.
In practice, both work pretty well, but for calling CQ and general
rag-chews, D-PLUS linked to a Reflector is probably the easiest way to
do that. Direct Source Routing works best for finding an individual...
or perhaps routing to your own radio at home when doing something mobile
with low-speed data (as long as you have two Terminals registered, and
the rig's "Your Call:" is programmed appropriately so the system sees
them as two completely different end-points... especially if you don't
know where they are, and they don't bounce around repeaters too much.
(Source Routes are only updated slowly in the national database, so
"chasing" someone from repeater to repeater using only their callsign,
usually doesn't work too well. They're based on the last repeater
module the person keyed up on... Example... if I fly from Denver to
Hawaii, and key up there... you source routing to me would still work if
I made sure to key up 5-10 minutes before your call in Hawaii...)
Hope that helps...
Nate WY0X
