Re: [DSTAR_DIGITAL] Re: Coordinating DD mode repeaters
Nice answer John! On our very first 23cm DD mode deployment in 2007 one of our users did not turn off updates. Killed the network until one of the K5TIT guys walked over and pulled the plug on that guys laptop. I like the D-RATS program. We have used it here in Northern VA for testing. Not yet in a activation but that will come. As an aside, for the Inauguration 2008 we used an unequipped port on a local D-STAR gateway/repeater to serve as a chat server. We had DVDongle users that met on that port for coordination. For the lack of a local reflector worked pretty nicely. I would like to see a slower speed DD mode we could use on lower bands. Might be an improvement on 9600 bps packet on a band with better propagation than 23cm. 73, Tom Azlin n4zpt John Hays wrote: Hi Ron, There are two data type services on D-STAR. The first is part of the DV (Digital Voice) mode. The DV data stream
Re: [DSTAR_DIGITAL] Re: Coordinating DD mode repeaters
Thanks Bob. And very nice to see new D-STAR repeaters going in to the NCR area! As we push coverage East and North we open up new opportunities. 73, Tom n4zpt Robert Spindle wrote: Tom, Well thought out! I agree. Bob Spindle W3AGB Trustee D-Star Washington, DC --- In dstar_digital@yahoogroups.com, Tom Azlin, N4ZPT n4...@... wrote: Hi Scott. Yes, it is nice to be coordinated on our DD mode access point. I manage
Re: [DSTAR_DIGITAL] Re: Coordinating DD mode repeaters
Hi Ron, I have been setting up D-STAR 23cm DD access points for the Marine Corps Marathon for three years now with other hams using their ID-1s at a dozen or so aid station and command locations. Works great to distribute tcp/ip access to the sports database via the ID-1s to remote computers using chat, browsers, and email. Crashes when some forgets to turn off automatic updates for their computer. Latency also tends to crash chat more than we are used to seeing. You should not operate two access points on the same frequency if they can see each other. D-STAR Digital Data (Icom calls it DD) is not like AX.25 packet. It is not packet radio in the sense that we use AX.25 packet radios and nodes. It is a mode for transporting tcp/ip using ethernet over radio in a 128kbps raw channel between a user and an access point or other user. The DD Repeater is actually a one to many access point so that many ID-1s can connect to network services via one access point. It is not a packet node. Multiple ID-1 pairs can work as Ethernet bridges on the same frequency sharing the single 128kbps channel but effective bandwidth goes down. You are better off putting different pairs on different frequencies. Since there is no collision detection like on a wired Ethernet you just start getting bit errors, retransmissions, and delays when you have too much traffic. But works great as a long range bridge. The DD mode as well as the DV mode are described in the protocol definition that Icom, the ARRL and others have on their web sites. I do not think that packet type operations is a good match for D-STAR. But there are several nifty data applications (D*Chat and D-RATS). If you are using the slow speed data/voice mode called DV then you are chewing up a 4800 bps channel to try to get about 900 bps data across. Better to just set up a 1200 bps AX.25 packet channel. Or a 9600 bps AX.25 packet channel. In fact for the Marine Corps Marathon we set up a 9600bps access point and run packet in parallel. Depending on how well you type versus how well you mouse one or the other works better. In addition we run our 9600 bps packet on 2m so with the D-STAR DD up on 23cm there is considerable propagation difference as well. We are required to provide redundant data paths so this is our solution. Works great. I would say pick you solution based on what you are trying to accomplish. If you are just loading messages into a BBS use packet. If you have users trying to use WebEOC then use the 23cm D-STAR DD mode (but make sure they do not try to pull up the page with the huge map with all the nice detail.). And so on. There has been some reports of being able mesh network a set of ID-1s but have not tested it myself. Also, D-STAR is an acronym (silly one but means Digital Smart Technology for Amateur Radio) so I do not shorten it as DS but say D-STAR or D*. Sorry for being picky. 73, Tom Azlin n4zpt Ron Wright wrote: Tom Scott, I am still learning about DS and wanting to take advantage of the digital modes. I know my question will show I know little, hi. I am interested in the Packet type operation of DS. That is a system that uses a simplex one freq mode for passing info as the old analog Packet system. Mostly used here for APRS and wx stns, but still some comm. Is DD mode this, but using DStar? If so are packet modems used or is another true non-tone digital like DS digital used? 73, ron, n9ee/r --- In dstar_digital@yahoogroups.com, Tom Azlin, N4ZPT n4...@... wrote: Hi Scott. Please TRIM your replies or set your email program not to include the original message in reply unless needed for clarity. ThanksYahoo! Groups Links
Re: [DSTAR_DIGITAL] Re: Coordinating DD mode repeaters
Hi Ron, There are two data type services on D-STAR. The first is part of the DV (Digital Voice) mode. The DV data stream is 4800 bps, of which 2400 bps are used for the digitally encoded voice and 1200 bps are used for FEC (Forward Error Correction) of the digitally encoded voice, this leaves about 1200 bps for other data to travel with the signal. They are not separate, if you are sending voice, you are sending the 1200 bps data, if you are using the 1200 bps data, you are also sending the 2400+1200 bps voice. The 1200 bps data section has no handshake, no error detection, no error correction (unlike AX.25 packet), think of it as a very long serial cable, but software has been developed to overcome this. One of the most actively developed pieces of software is D-RATS (http://www.d-rats.com/wiki/ ) which has an extensive feature set including many of the applications you see on packet radio. Current Features * Instant-messaging style chat * Multiple automatic QSTs at varying schedules, containing: o Simple messages o Command output o File contents o Weather Underground reports o GPS position reports o RSS/CAP feed items * FileTransfers using DDT with adjustable-sized packets o Transparent block compression o Highly efficient binary encoding for fast file transfers, despite the limitations of D-STAR radios o Unattended operation with automatic negotiation * Online/offline status notifications * Callsign highlighting and tracking (currently supporting US and Australian calls) * Ignore capability to dim messages that match a search string * Notice capability to highlight messages that match a search string * Multi-platform: runs on Linux/UNIX, Windows, and MacOSX * Canned messages * Chat logging * Tabbed interface to filter traffic based on a search string * Structured data (i.e. Forms) transmission with multiple form templates, graphical editor, and HTML exporting * Form-to-Email gateway support for providing email access to distant stations * Arbitrary TCP forwarding over the RF channel * GPS position tracking, distance/direction calculation, static beacon support, and integrated map viewer with offline caching * Network-linkable repeater/proxy co-application - From the Wiki page The second is the DD (Digital Data) mode, only available on the 23cm band using the ID-1 radio from Icom. Basically, it provides an Ethernet bridge encapsulated within D-STAR. The D-STAR gateways, provide a TCP/IP service for DD that allows you to exchange data with any other ID-1 equipped station that is associated with the gateway network. Anything that fits into the TCP/IP family of protocols and applications can be run here (within the bandwidth and amateur radio rules limitations); webservers, full email, file transfer, etc. On simplex, you can run any Ethernet protocol, such as TCP/IP, Apple talk, etc., in fact, one of the challenges is making sure your computer is not chatty - sending unnecessary traffic on the Ethernet as the radios will try to relay everything. DD is the network builder's swiss army knife if you have RF connectivity (due to the wider bandwidth, you need about 12db more path gain over a DV signal). I hope this gives you a peek as to what is possible. On Mar 26, 2009, at 8:11 AM, Ron Wright wrote: Tom Scott, I am still learning about DS and wanting to take advantage of the digital modes. I know my question will show I know little, hi. I am interested in the Packet type operation of DS. That is a system that uses a simplex one freq mode for passing info as the old analog Packet system. Mostly used here for APRS and wx stns, but still some comm. Is DD mode this, but using DStar? If so are packet modems used or is another true non-tone digital like DS digital used? 73, ron, n9ee/r --- In dstar_digital@yahoogroups.com, Tom Azlin, N4ZPT n4...@... wrote: Hi Scott. John Hays Amateur Radio: K7VE j...@hays.org [Non-text portions of this message have been removed]
RE: [DSTAR_DIGITAL] Re: Coordinating DD mode repeaters
Ron, the ID-1 uses the GMSK modem and is not like that of AX25. plus the Ethernet side is half duplex. Yes, the id 1 will do LOW SPEED Data as well so you KEYBOARD if you will with other D-Star radio's using any of the various Low Speed Data programs out there... Evans
RE: [DSTAR_DIGITAL] Re: Coordinating DD mode repeaters
Answers below. From: dstar_digital@yahoogroups.com [mailto:dstar_digi...@yahoogroups.com] On Behalf Of Bill Powell Sent: Wednesday, March 25, 2009 12:11 AM To: dstar_digital@yahoogroups.com Subject: [DSTAR_DIGITAL] Re: Coordinating DD mode repeaters Scott and Group, As VP Coordination for the ARCC I have been asked by a number of our users to consider establishing a STRICTLY VOLUNTARY coordination program for DD and other digital non-repeater modes. All coordination is voluntary, Bill. :-) - Can a DD channel be shared in the same manner as an AX.25 system? Likely to degrade rapidly. Proper use of callsigns by users would make it technically POSSIBLE, but problematic. Until 1.2 GHz is full it's probably better to spread them out. - Does DD perform CMSA or is it a blind system? If it's like other D-STAR implementations by Icom, it can only hear D-STAR. So it would probably not transmit if other D-STAR signals are present, but would jump right on top of an analog or other signal sharing the frequency. Ultimately someone would have to go test this, or get an answer from Icom on it. - Does DD operate on a single channel or can it be operated on a split (pair) of channels? How is it normally used? Single channel. Very wide. - What is the definition of interference in a DD system? The same as any system, something that keeps communications from occurring! (GRIN) - What is the result of interference? Packet loss. The system behaves like a wireless access point, if that helps. - What level of interference is tolerable Personally I find the whole system would be mathematically too slow to use beyond 5 local users anyway at 128 Kb/s -- so my personal opinion would be any interference would render the system even slower, and unusable in most cases. - What is the true (measured) receiver sensitivity for a DD central station and at what BER? Good luck getting this from the manufacturer, let alone the Amateurs that own the systems. Nate WY0X [Non-text portions of this message have been removed]
RE: [DSTAR_DIGITAL] Re: Coordinating DD mode repeaters
Yes, Utah is way ahead of the curve in the technical analysis of D-STAR signals from Icom rigs, and the rig's behavior. I agree! :-) Nate WY0X From: dstar_digital@yahoogroups.com [mailto:dstar_digi...@yahoogroups.com] On Behalf Of John Hays Sent: Wednesday, March 25, 2009 3:09 PM To: dstar_digital@yahoogroups.com Subject: Re: [DSTAR_DIGITAL] Re: Coordinating DD mode repeaters Some work has been done in Utah: http://utahvhfs.org/dstar_channel_spacing.html#dd_128k John Hays Amateur Radio: K7VE j...@hays.org mailto:john%40hays.org [Non-text portions of this message have been removed]
