OK, as a geek that does not yet have his Tech license (probably testing in the next 15 days or so), I’ve read just about all I can find about D-STAR, including the various excellent presentations that have been given to local user groups and conventions. I have a few questions on the technology.
My background experiences are mostly telephony (I’m a VoIP engineer by day) as well as emergency communications, including P-25 (I’m a fire lieutenant by night). I know enough to make me dangerous most of the time.
Firstly, I think that the *system* that D-star presents in a package to be extremely umm, groovy, and I’d like to get a bit more in-depth to understand it better.
Question 1: Is the communications protocol between the Band Modules (i.e. A, B and C repeaters) and the controller proprietary? It appears to be an RJ-45 connection. What is the distance limitation for this connection? Maybe 100 Meters? Can it be networked to a WAN?
Question 2: Relative to Multicasting, I see on
www.LADSTAR.org/mc.htm (as an example) a list of Multicast sites in their group. In this example “/CA1200” performs a multicast on the A module across all pre-defined nodes. I’m assuming that a multicast URCALL address can be pre-built/pre-named for any circumstances so long as it’s not duplicated elsewhere in the network (where is this ‘domain naming’ managed?). Is there a limitation on a multicast group to the same Band Modules (i.e. all A or all B or all C) or can an ‘all call’ type multicast be defined? For example, a system named “ZA” that has 12 nodes (all A, B, C and G enabled) I could envision 4 multicast groups: /ZA1200 (all A), /ZA0440 (all B), /ZA0140 (all C) and /ZAALL (all A and B and C). I key up a URCALL of “/ZAALL” and I can CQ/QSO to all nodes and all channels. Correct?
Question 3: Regarding Gateway linking, what are the error mechanisms? For example, what happens if a user forgets to “unlink” after a conversation? Since this is typically an internet connection, what if a link is established and two users are talking and the internet is lost thereby disrupting the conversation? Does each user get a message or some type of failure tone when they try to key up? Can a node be defined to send a message out to the local users in a loss of Gateway/internet communications (i.e. “system in Local repeater mode only”)?
Question 4: Has anyone built (real or in their head) a fully-meshed system that has the gateways communicating on some other network other than the internet (maybe a microwave link system) and then have one or two exit points out of the system to the internet? The picture in my mind is a multi-node system (say 12 nodes or repeater sites) that are all interconnected via microwave with redundant paths and then only have 2 of these sites with internet access for inter-dstar communications. I have a problem with deploying internet at each node (I have a hard enough time with Comcast at my home, let alone at the top of a hill) and since the bandwidth is so minimal, this seems pretty easy. Obviously an IP Router running some routing protocol would have to be deployed at each gateway node but this seems like pretty standard IP Routing to me.
Question 5: What’s a site cost from the ICOM hardware perspective? I don’t need an exact price, just an intelligent SWAG.
Thanks in advance,
/Jeff
Edited to fix a URL error.
