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 </++_ deals with the directions.  If you are coming from the NORTH
there is no sign saying DeAnza or Cupertino ---->  (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