R PR.SEMINARS.BAY.AREA COMPLETE *** PR.SEMINARS.BAY.AREA 1-AUG-81 PARENT=*ASCII USAGE= 97 A seminar series on Packet Radio, as it now exists (and where it will probably go), will be held by Hank Magnuski, KA6M, who operates the Menlo Park packet repeater. He says: "The high level of interest in packet radio concepts and technology, plus the need to get some design groups going to work on establishing new networking protocols and hardware has prompted me to arrange a series of meetings. Anybody interested in helping...or giving a presentation please contact me (Hank, 415-854-1927 home)." Times & Place Tymnet Training Room, Tymnet, 20665 Valley Green Dr., Cupertino. I-280 to DeAnza...go South...Right at Valley Green to 1st 2-story bldg...Enter at East end.....All meetings at 8:p0 PM. 7 July --- VADCG protocol discussion 4 August --- problems and issues 1 September --- interfacing to packet radio 6 October --- AMICON/AMINET 3 November --- Gateway/Repeater design 1 December --- Advanced hardware Call Hank 415-854-1927 for more info; Wm. Putney 408-446-7190 for better di- rections to meeting if needed. +++ SUBMESSAGES +++ *** PROBLEMS&ISSUES 5-AUG-81 PARENT=PR.SEMINARS.BAY.AREA USAGE= 90 Last night your fairwitness went to the second, of a series of seminars that are being held by Hank Magnuski, KA6M, on Packet Radio. (see parent msg) My first (this way). So if you are coming from the north the turnoff is AFTER hwy85, but BEFORE the Lawrence Exp. If you are coming from the SOUTH the directions work fine. I was about an hour late for the meeting, so I can't give you a complete report, but I met a few users of the Conference Tree there, who might want to elaborate a bit more. (Please feel free to addto these branches) Upon arriving, the topic of discussion was on how various stations would communicate to one another through various methods, including, satellites and repeaters, and the various protocols that would allow this communication. The basic flow was drawn out as follows::: Terminal Node --- Single User Station Host Node --- Multi-user Station Repeater --- Reproduces Packets Station Node --- Global Ctrl. PR/net Gateway --- Protocol/Media A discussion then followed on into what I would call the "stacking" order of the data and the problems and solutions of addressing data to other stations. All in all, it was a pleasure attending this seminar, listening to the info that Hank and the other participants exchanged, and highly recommend the sem- minars to follow. (see parent msg) PACKET RADIO HDLC PROTOCOL NOTES The protocol used by the Vancouver Digital Communications Group controller board, and also used by the packet radio repeater is based on a subset of HDLC standard protocol. In this protocol the standard unit of information is the frame: ------------------------------------------------------------------------------ | SYNC | SYNC | FLAG | ADDR | CNTL | TEXT | ... | TEXT | FCS1 | FCS2 | FLAG | ------------------------------------------------------------------------------ where SYNC - preframe synchronization, idle flags or zeroes FLAG - start of frame, bit pattern 01111110 ADDR - address byte, hex 00 to FF CNTL - control byte, indicates type of frame, other info TEXT - optional information field FCS1 - first byte of frame check sequence (CRC) FCS2 - second byte of frame check sequence FLAG - closing flag other features used bit stuffing - provides fully transparent transmission of data NRZI encode - Zeroes cause transition which allows clock recovery multiframe - Up to (7) frames permitted in a single transmission types of frames Non-sequenced-information - Used for Connect/Disconnect Supervisory - Used for window & flow control Information - Used for transmission of text *** P&I2 5-AUG-81 PARENT=PROBLEMS&ISSUES USAGE= 88 NSI Frames: FLAG ADDR CNTL FMCALL TOCALL FCS1 FCS2 FLAG ADDR - Address of calling station (assigned to each station) CNTL - 17H = Connect request 07H = Connect acknowledge 53H = Disconnect request 43H = Disconnect acknowledge The Poll/Final (P/F) bit, 10H, is used to force a response from the receiving station. Used here and in other frame types for this function. FMCALL - Call of station originating the frame (6 characters) TOCALL - Call of station receiving the frame (6 characters) The callsign is left-justified in the field and pad- ded with trailing blanks if the call is shorter than 6 characters. Supervisory Frames: FLAG ADDR CNTL FSC1 FCS2 FLAG ADDR - Address of sender CNTL - 7 6 5 4 3 2 1 0 ----------------------------------------- | Nr |P/F| 0 0 0 1 | Receive Ready ----------------------------------------- ----------------------------------------- | Nr |P/F| 0 1 0 1 | Zcv Not Ready ----------------------------------------- Nr = Sequence count of next expected I-frame P/F = Poll/Final bit Information Frames: FLAG ADDR CNTL TEXT ... TEXT FCS1 FCS2 FLAG ADDR - Address of sender CNTL - 7 6 5 4 3 2 1 0 ----------------------------------------- | Nr |P/F| Ns | 0 | I-frame ----------------------------------------- Nr = Sequence count of next expected I-frame P/F = Poll/Final bit Ns = Sequence count of this I-frame TEXT - Text field, 128 bytes maximum, ASCII code Timeouts: T1 - Receive timeout, 2-3 seconds T1S - Frame timeout, time for frame of maximum length Tr 0 - Delay time (random) prior to transmission of first frame of a sequence, 950 milliseconds to 1.25 seconds (cont.) *** P&I3 5-AUG-81 PARENT=P&I2 USAGE= 86 Addresses: 00 - No operation 01-7F - Station direct connect addresses 80 - Reserved 81-9F - Repeater input channel addresses A0 - Reserved A1-BF - Repeater output channel addresses C0-FE - Reserved FF - All parties addressed A great deal of information is to be gained from attending the seminars. If you cannot attend then write to: Hank Magnuski, KA6M 415-854-1927 311 Stanford Avenue Menlo Park, CA 94025 -cas- *** WHAT-IS-NRZI 6-AUG-81 PARENT=PROBLEMS&ISSUES USAGE= 86 What is the NRZI encoding that is mentioned everywhere in this packet radio conference? The only NRZI I know about is used in digital magnetic tape recording and is not self-clocking. I use a format called SDLC which is very similar to HDLC and I encode it with a scheme called Phase Modulation which works like this: Starting bit stream: 0 0 0 1 0 1 1 1 0 1 1 Encoded bit stream: 0 1 0 1 0 0 1 1 0 0 1 0 1 0 1 1 0 0 1 0 1 Is this what is called NRZI in packet radio? I think it is wonderful that people are working on packet radio and I would like to learn more about it, thanks for all the technical info in the preceding (I hope I put this message in the right place so they are preceding) messages. Peter Ryan *** ANSWER??? 15-AUG-81 PARENT=WHAT-IS-NRZI USAGE= 58 Peter, if you have access to 'Reference Data For Radio Engineers' (c Howard W. Sams Co.,Inc.) look on page 40-24. There, NRZ, NRZI and PM are discussed. From what info I have on P/R, the protocol is SDLC. NRZI is a transition whenever the data changes states, SDLC is a 0 (Zero) whenever 5 consecutive 1's (one's) are encountered. The receiver is tasked with the removal of the 0. I can understand why you don't see how to recover a clock from NRZI. Frankly, I don't either. Send a binary 63, and recover the clock from it (without the sync field, that is) My disk system, and I think a lot of others uses NRZI, with sync, so the clock is easily recovered. If you need more info, I'll type it in. (My kingdom for a flying spot scanner interfaced to this machine!) And Curtis, if you can get the March 1981 issue of 'the packet' it has what you just explained in your review of the seminar. Someone ought to get all of the newslettess, articles ect together, and print them up. Very interesting reading, for what I have. Enough computering for today, snooze time. Rick *** IF/NW 11-SEP-81 PARENT=PR.SEMINARS.BAY.AREA USAGE= 15 The third seminar in our series on packet radio was held last evening, and was attended by 25 people. The theme of the meeting was "Interfacing to the Network". Announcements - Howard Nurse, W6LLO, has his 20M packet station available for schedules. He would like to make some contacts to checkout the equipment, as no one else in this area is ready. The station will, in general, be connected to the mailbox system here, but it is currently not continously on. Please call me or Howard, or send us a message. Hank Magnuski distributed a 555 baseon his VADCG board to implement a downline loaded version of the protocol. pvolunteered to try mounting 3 MK4118N3 1kx8 RAMS on his VADCG board to implement a downline loaded version of the protocol. The VADCG 1200 baud modem schematics, recently received, were inspected byCqthe group. Brian Yee and Dave Altekruse described their recent meeting with Larry Kayser, VE3QB. There were several questions concerning the satellite channel, and more information is needed on the details of the Vancouver-Ottawa link. Speakers - The main topic of the meeting was a description of how some of our network users have connected their persnal computer systems to packet. Bob Rekkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk CNTL - 17H = Connect request 07H = Connect acknowledge 53H = Disconnect request 43H = Disconnect acknowledge The Poll/Final (P/F) bit, 10H, is used to force a response from the receiving station. Used here and in other frame types for this function. FMCALL - Call of station originating the frame (6 characters) TOCALL - Call of station receiving the frame (6 characters) The callsign is left-justified in the field and pad- ded with trailing blanks if the call is shorter than 6 characters. Supervisory Frames: FLAG ADDR CNTL FSC1 FCS2 FLAG ADDR - Address of sender CNTL - 7 6 5 4 3 2 1 0 ----------------------------------------- | Nr |P/F| 0 0 also pointed out the treme~dus diversity of systems in use, and yet there is little trouble in getting these systems to communicate with the current packet setup. Network Usage Survey - To wrap up the meeting and to get an answer to |he question of "What are we going to use it for?" a matrix of in|erests vs. potential users was contructed by the group: Topic Votes Experimentation/Design/Technical 9 Compof sender CNTL - 7 6 5 4 3 2 1 0 ----------------------------------------- | Nr |P/F| Ns | 0 | I-frame ----------------------------------------- Nr = Sequence count of next expected I-frame P/F = Poll/Final bit Ns = Sequence count of this I-frame TEXT - Text field, 128 bytes maximum, ASCII code Timeouts: T1 - Receive timeout, 2-3 seconds T1S - Frame timeout, time for frame of maximum length Tr 0 - Delay time (random) prior to transmission of first frame of a sequence, 950 milliseconds to 1.2