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Section 1

Packet Radio “The Basics

”         

A Packet Primer for the new Packeteer 

__  Page 2

About The Author

(Semper Fidelis)

Proud to claim the title of former United States Marine, the Corps’ own motto,

Semper Fidelis

, serves as a good description of G. E. “Buck” Rogers’ own attitude

toward family, work, and humanitarian service… ”always faithful.”  Married to Jean
Ann (Dyson) Rogers for over 41 years, Buck  and Jean Ann (WB4EDZ) have two children,
Glynn E. Jr.(WB4RHO), and Janice Evelyn (Rogers) Mata, and six grandchildren.

In addition to spending time with his family Buck provides technical support and
inspiration for the Southeastern Emergency Digital Association Networks (

SEDAN

), a

humanitarian organization comprised of licensed radio amateurs dedicated to helping
others in times of disaster.  In fact, it was Buck’s youthful interest in Ham radio
that eventually led to his present career position as Senior Systems Engineer for
Ericsson Communications.

 Buck is a recognized world-class expert in the field of RF communications,

having been instrumental in the design and implementation of the U.S. Air Force

Local Area Network, Wide Area Network, and Global Information Networks

 (LAN, WAN &

GIN).  His credentials in other fields of RF communications also include terrestrial
microwave systems design, television and radio broadcast station design, and Public
Service Specialized Communications systems design.  His communications consulting
travels have taken him throughout the United States, Europe, Asia and other

countries around the world.

Buck, K4ABT, is highly respected in the Amateur Radio community both as a

pioneer of Packet Radio and noted author, having published twelve books and written
many feature articles for the leading Amateur radio, commercial and trade
publications.  He is Packet Radio Editor of CQ MAGAZINE

CQ MAGAZINE and every month authors the

“PACKET USERS NOTEBOOK

PACKET USERS NOTEBOOK,” a popular column in CQ MAGAZINE

CQ MAGAZINE distributed world-wide

and translated into several languages.

Buck is a licensed radio Amateur for over 50 years and holds the “lifetime”

Commercial FCC First Class license, now called the General Class Commercial license.
He conducts forums and seminars on packet radio and digital communications, and is
the author of twelve books, some of which include:

 

Packet Radio Basics: The Beginners Guidebook

 

Packet Radio X1J4 System Node Operator’s Handbook

 

Packet Radio Operator’s Handbook (The PRO )

 

Packet Radio Operators Manual (PROM, from CQ Publications)

 

Packet Radio: General Information Handbook

 

The Advanced Packet Radio Handbook

Buck also grows the world’s best backyard tomatoes.

Richard Card, KD4JKX
President, Southeastern Emergency Digital Association Networks

Southeastern Emergency Digital Association Networks  (

SEDAN

SEDAN

)

July 1999

Reproduction or use, without express permission, of editorial or pictorial content, in any manner, is prohibited.
While every precaution has been taken in the preparation of this handbook, the author and publisher assume no
responsibility for errors or omissions. Neither is any liability assumed for damages resulting from the use of the
information contained herein.

           Copyright(c) 1992, 1995, 1996, 1997, 1998-99

Summary of Contents for K4ABT

Page 1: ...The Basics A Packet Primer for the new Packeteer __ Page 0 Two Packet Radio Books In One Cover Section I A Primerfor the Packet Radio BEGINNER Section II Section II A HANDBOOK for the ADVANCED Packet Radio System Node Operator by Buck Rogers Buck Rogers K4ABT E Mail k4abt packetradio com PacketRadio Editor CQ Magazine PacketRadio Networking http www packetradio com ...

Page 2: ...ther countries around the world Buck K4ABT is highly respected in the Amateur Radio community both as a pioneer of Packet Radio and noted author having published twelve books and written many feature articles for the leading Amateur radio commercial and trade publications He is Packet Radio Editor of CQ MAGAZINE CQ MAGAZINE and every month authors the PACKET USERS NOTEBOOK PACKET USERS NOTEBOOK a ...

Page 3: ... Systems EDACS is trademark of ERICSSON Inc IBM and IBM PC are trademarks of International Business Machines MFJ is a trademark of MFJ ENTERPRISES INC ENTERPRISES INC MULTICOM and MultiCom for Windows is of MFJ ENTERPRISES INC ENTERPRISES INC NETROM is of Software 2000 TheNET is Nord Link Packet Group of Germany TAPR Tucson Amateur Packet Radio is a non profit research group dedicated to amateur d...

Page 4: ...OST FREQUENTLY USED SysOp User COMMANDS Page 30 Chapter 12 Section II SYSOP VALIDATION HANDLING THE PASSWORD Page 31 CORRECTING MISTAKES IN TEXT ENTRIES to X 1J4 Page 31 Chapter 13 Section II HOST MODE Page 32 Chapter 14 Section II ROUTE QUALITY ANALYSIS Page 34 Chapter 15 Section II DIGIPEATING AND HOST INTERFACE Page 35 Chapter 16 Section II GATEWAY INTERFACING SETUP Page 36 Chapter 17 Section I...

Page 5: ...n length In our Packet TNC we have the option to increase this packet length up to 255 characters in length The TNC command that allows us to make this change is called PacLen Once the TNC has received the data from your computer it then breaks it into packets about 100 characters long and combines additional bytes information to the outgoing data The added bytes include the destination addressing...

Page 6: ...l be used with the TNC Determine the kind of microphone speaker jack and computer serial comport connectors that you re going to use In some cases the TNC manufacturer furnishes only the connector for the TNC This means that you must also furnish the cable that connects the TNC to your computer or terminal In most cases a 25 pin RS 232 serial cable is used between the TNC and computer The later mo...

Page 7: ...wonderful world of operating Packet Verify that all control signal and ground wires PTT RECEIVE AFSK and SIGNAL GROUND are connected to the correct connector pins TURN ON THE TNC When you first turn on the TNC you may see garbled text on the screen This is usually because the terminal to TNC baudrate is not set to the same parameters Some TNCs will do a search mode to find the setting that you hav...

Page 8: ...are several simplex 64 kB 100 kHz backbone frequencies within the 219 220 Mhz UHF band FCC approved 16 March 1995 with restrictions see CQ Magazine PUN June 1995 Below are a few frequencies that are set aside for Packet Radio use in the 420 450 Mhz band 430 050 430 150 430 250 430 350 430 450 430 550 430 650 430 850 430 950 440 975 441 000 441 025 441 050 441 075 446 500 As I mentioned earlier mak...

Page 9: ...IO OPERATOR S HANDBOOK MFJ Publications 2 PACKET RADIO OPERATOR S MANUAL CQ Publications Be sure to visit the PacketRadio Networks Home page s at http www packetradio com and at http www packetradio org Advanced levels of Packet include transmitting and receiving high resolution color pictures error free transmission of large ASCII and binary files and how to build and use nodes with Packet Radio ...

Page 10: ...acket 28 150 28 190 1200 baud Packet 6 Meters 50 60 51 78 Packet 50 62 Packet calling freq 51 12 9600 baud backbone only 2 Meters 144 910 145 090 Packet every 20 kHz 145 510 145 790 Packet every 20 kHz 144 910 through 144 950 Mhz used for DX Spotting and NOS operations 144 970 144 990 145 030 145 070 145 530 145 550 145 570 145 590 145 610 145 630 145 650 145 670 145 690 145 730 and 145 750 Mhz ar...

Page 11: ...for VHF and HF operations The MFJ 1278B is one such multimode controller that fits into this category The features may differ from one all mode controller to the next so it would be in your best interest to investigate the options which best suit your needs THE PACKET CONTROLLERS If you plan to operate packet only but you wish to use both HF and VHF packet you may want to look for a controller whi...

Page 12: ... together over the Packet network to allow messages to reach a broader user base than your local BBS users Private messages may also be sent to other Packet operators either locally or who use other BBSs Most BBS s have the latest Amateur radio news bulletins and propagation bulletins posted Many BBS s have a file section containing various text files full of information on amateur radio in genera...

Page 13: ...oncerned When I go to buy cable and connectors I purchase the best available coax and connectors When I go to buy cable or connectors I specify silver flashed connectors and cable of the best quality Over the years that is the part of my station that will get the least attention after it is installed so I want it to withstand the elements and provide dependable communications for a long time I am ...

Page 14: ...ave moved in this direction If it is distance you want then the class of beam antenna that we use for voice will be sufficient If it is coverage you prefer again I prefer the beam type antenna as a power booster I tend to try for a happy medium with respect to the digital and or packet modes The yagi type antenna in a horizontal configuration is one way to go if you want coverage and reduced wind ...

Page 15: ...e the better value The coaxial coax cable or the transmission line plays a major role in the antenna performance The coax is a very vital part of the overall antenna system but the coax has a personality of its own and can reek havoc if it is not cut to or tuned for optimum performance along with the antenna It is even more important to say that antenna performance will depend on the behavior of t...

Page 16: ... later time Some BBSes allow multiple connects to them When this is the case BBS activity may slow down while multiple users are downloading files from the BBS A connect to your local area network LAN BBS is made in the same manner as a connect to another Packet station If this is your first connect to the BBS you will need to provide some information about yourself There are four questions and th...

Page 17: ...mand is used to read a file stored on the system The format of the command is D filename where filename is the name of the file to down load To see what files are available for downloading use the W command To download a file in a subdirectory use D FILENAME I by itself gives hardware configuration of the system ID gives a list of the ports and digipeaters gateways available The J command lists st...

Page 18: ...ut a particular command type x where x is the letter of the command Putting at the beginning of a line makes it a comment It also suppresses the next command prompt but the system will be waiting for another command is useful to answer the SYSOP if you get a MESSAGE FROM SYSOP ONE FINAL NOTE After you read any messages directed to you please kill that message using the KM command ...

Page 19: ... latest EPROMS for user friendly program for EPROM maintenance As I described in the August 1993 issue of CQ magazine PACKET USERS NOTEBOOK the EPROM for the X1 node is burned into a 27C512 EPROM in two parts The Needham Electronics EPROM burner makes the process easy because we can set the first address to blow the EPROM from 0000 to 7FFF then the second half of the EPROM is burned from address H...

Page 20: ... message 32 The ability to enable or disable any command 33 Improved command prompting with only valid commands shown 34 Routes show optionally as alias callsign or callsign alone 35 Additional control over system reset 36 KISS as an alternative to the crosslink protocol 37 Hardware handshake controlled host mode operation 38 MODE command for configuring additional parameters 39 BBS command to aut...

Page 21: ...vel tweaked until it appears to work reasonably error free The idea of this add on is that having done that you then connect to the node and display the heard list to see an indication of your actual deviation It may then be fine tuned to set it correctly Local advice must be taken over the correct setting as it depends on the channel spacing being used e g 12 5 25 or other KHz The METER command i...

Page 22: ...e all of those left in the conference get a message from the node telling them of the station who has left the conference If you force a disconnect the other stations are not told of your departure A string of text may be entered on the same line as the talk command when the command is given If this is done before the user is connected to the conference that string of text is sent to all the other...

Page 23: ... disrupting user connections in progress TheNET X1 supports three methods of updating its routing information local remote and automatic Initial routing information may be entered manually by an on site operator using a local terminal Routing changes may be made remotely by a SYSOP or network manager over an ordinary packet radio connection randomized verification algorithm effectively prevents ch...

Page 24: ...ou cannot load too many packets one after the other into the node SYSTEM NODE OPERATOR OR SNO The System Node Operator SNO can use Manager or SYsop command to validate the SysOp MAnager privilege in the node This enable the SNO to make manual changes to the routing table IDENT to establish a mnemonic node identifier PARMS to set or display various node parameters The RESET command can allow the SN...

Page 25: ... together by means of an RS232 cable MULTI FREQUENCY Node Three or more TheNET X1 nodes operating on different frequencies and interconnected via their RS232 ports using a diode matrix coupler LINK An AX 25 connection involving a node at one or both ends Node to node links always use AX 25v2 protocol User to node links use AX 25v2 protocol if the user s TNC supports it otherwise AX 25v1 UPLINK An ...

Page 26: ...fix from N to 15 N For example if your callsign is NT4XXX the downlink uses NT4XXX 15 if your callsign is W4KGS 2 the downlink uses W4KGS 13 and so forth To utilize the full store and forward capability of the nodes you would use a three step procedure 1 Connect to your local node then 2 Issue a CONNECT command with the callsign or node identifier of the distant node 3 Issue a CONNECT command with...

Page 27: ...N node at Macon Georgia can determine if there are any other stations awaiting a reply to a CQ by issuing the USERS command If there is an armed CQ at MCN node the station who issues the USERS command will see Circuit WA4GSO 7 Uplink CQ WA4GSO The station may reply to such a pending CQ by issuing a CONNECT to the user callsign In our example C WA4GSO 15 the callsign and SSID specified in the CQ po...

Page 28: ...to reserve one radio frequency exclusively for inter node traffic to provide end user access to the nodes on one or more separate frequencies and to discourage ideally to prevent ACL end users from using the inter node backbone frequency This approach requires network nodes that can access two or more frequencies A REAL SIX PACKet NODE STACKS PERFORM CROSSLINKING BETWEEN TWO OR MORE FREQUENCIES OR...

Page 29: ...ffic is passed over the cable between TNCs at relatively high speed See installation instructions for wiring of the interface cable below This gateway interface cable enables node communications between two X 1J4 nodes port to port This configuration allows the SNO to bridge from one frequency to another or from one baud rate to another OR BOTH Set the DIP switches to the same RS 232 port baud rat...

Page 30: ...aters do not fully provide error control For an AX 25 packet to traverse a multi hop path it must not fall victim to a collision or other error during any of the hops otherwise it must be retransmitted by the originating station and start its journey all over again The probability that a data packet can complete its journey through several digipeaters deteriorates rapidly as the number of hops inc...

Page 31: ...ion remotely To delete current INFO from the node the sysop while in the sysop command mode may enter an I followed by an asterisk i e I A space is placed between the I and the asterisk The MHeard command enables the user to see a list of stations recently HEARD by the node In addition it the X1 node is equipped with the Suffolk Data Group MFJ model MFJ 52 DEV add on PC board the MHeard list will ...

Page 32: ...no spaces when I send the corresponding five characters to the node THERE WILL NOT BE A REPLY FROM THE NODE You may also enter letters or numbers before or after the five letters of the password as long as you make sure the five characters are in the order called for by the numbering sequence of the password In addition they must be all together there are no spaces and they are in the correct case...

Page 33: ... or identifier of the destination node but the routing is handled automatically by TheNET X1 Automatic routing is handled by the Routing Manager and is controlled by its routing table The routing table within a node contains a list of all other nodes known to the node together with their mnemonic identifiers You can ask to see this list by using a parameter NODES command The routing table can keep...

Page 34: ...rk manager you may observe a more complete routing list with in the X1 node by entering the sysop command level and sending an N to the node The node will return a complete list of all the nodes contained in the NODES LIST This list will be displayed in ascending order with up to three nodes to the right of each node showing the routes and routing order to the neighbor nodes and their neighbor nod...

Page 35: ... point we suggest the following values to be used as baud quality parameters Baudrate Description Quality Perfect 9600 baud RS232 wire interconnect 2 port 255 99 9600 baud RS232 satellite interconnect 2 port 252 98 9600 baud RS232 wire interconnect 3 port 248 97 9600 baud HDLC isolated inter node backbone 240 94 1200 baud HDLC isolated inter node backbone 224 88 1200 baud HDLC user accessed freque...

Page 36: ... the 1 SSID The chances are great that a connect to the mailbox of the known station will be made INITIAL CONNECTIONS TO THE NODE IN HOST MODE PARAMETER SETUP After setting up the TNC2 hardware connect a terminal to the RS232 port Power up the TNC2 and make sure you see the TheNET X1 sign on message Then perform the following steps VERIFY THE NODE S CALLSIGN The callsign of the node as burned into...

Page 37: ...together in the TNC to TNC cable SET BAUD RATE SWITCHES Follow the switch setting instructions in the TNC2 manual I have performed extensive reliability testing of TheNET X1 at HDLC and RS232 baud rates up to 9600 it runs reliably at these high baud rates even at slow CPU clock speed For dual or multi frequency operation I suggest setting the RS232 speed at 9600 baud or the highest RS 232 port bau...

Page 38: ...nications between two X 1J4 nodes port to port This configuration allows the SNO to bridge from one frequency to another or from one baud rate to another OR BOTH Set the DIP switches to the same RS 232 port baud rate The DIP switches are located at the rear of the MFJ 1270B and MFJ 1270C TNC s Most applications at VHF have the 1200 baud node DIP switches 5 7 ON and all others OFF On the 9600 baud ...

Page 39: ... a diode matrix coupler A schematic for a four frequency coupler is shown below It uses 24 diodes 1N4148 1N914 or equivalent Configuring a multi frequency TheNET X1 node for three or more frequencies is almost as easy as dual frequency operation A TNC2 with TheNET X1J4 EPROM installed is used for each frequency Once again the TNCs are interconnected via their RS232 ports Interconnecting three or m...

Page 40: ...8 Network time to live initializer 32 32 0 255 9 Transport timeout seconds 180 180 5 600 10 Transport level 4 maximum tries 3 3 2 127 11 Transport level 4 ack delay seconds 2 2 1 60 12 Transport level 4 busy delay seconds 60 60 1 1000 13 Transport level 4 requested window size 4 4 1 127 14 Level 4 Congestion control threshold 4 4 1 127 15 No activity timeout Level 7 seconds 1800 1800 0 65535 16 Pe...

Page 41: ...route that has been newly added or updated by the node s automatic routing table update mechanism The obsolescence count of a route is also reinitialized to this value whenever the route is actually used successfully The obsolescence count of a route is decremented once each auto update broadcast interval see parameter 7 below However such periodic decrementing of route obsolescence counts can be ...

Page 42: ... corresponds to a slot time of 100 milliseconds Parameter 18 Link T1 timeout FRACK seconds minimum 1 maximum 15 Defines the number of seconds between link layer retries When digipeating is used this value is multiplied by 2D 1 where D is the number of digipeaters Parameter 19 Link transmit window size MAXFRAME frames minimum 1 max 7 Defines the maximum number of outgoing information frames that th...

Page 43: ...cket so no legal requirement to have ID s turned on As an example In the MODES PARAMS setting BEACON time to 600 will cause an ID by the X IJ node every 10 minutes or set it to 3600 and it will ID once each hour Parameter 26 CQ Broadcasts 1 0n 0 off minimum 0 maximum 1 Defines whether or not the node will broadcast AX 25 UI frames in response to the CQ command Even if such broadcasts are disabled ...

Page 44: ...ansceivers add 5 mSec for radios with relays nodes using external power amplifier 0 0 1 Full Duplex enable 0 if node is operated in simplex normal operation 500 0 65535 RS 232 PORT 1 node broadcast period in seconds 600 Updates nodes every 10 minutes 0 0 3 Node broadcast algorithm flag 0 off 2 RS 232 port 1 or 3 not used 600 600 3600 Beacon interval in seconds 600 Although beacons are enabled in P...

Page 45: ... 9600 baud modem and this is where I have some beef with the supplier CAVEATE In some recent mail and truck deliveries to my QTH I have seen HEARD rattling inside the TNC s prior to opening them Seems the carriers uses them for base ball practice and toss them hard enough to make the EPROM pop out of socket U 23 This same scenario may be occurring with other deliveries of TNC and nodes to you If y...

Page 46: ...sted several ways to make the decision as to which nodes are neighbor nodes and which nodes we should lock in This kind of node housekeeping is called locked routing and thus removes the guess work that occurs when the routing is left to the so called automatic routing that is built into the node firmware When you first set up your LAN node on the network not the backbone or just after performing ...

Page 47: ...when propagation is low I find this time to be between the hours of 2 30 PM and 5 00 PM eastern time 1 Pick your real neighbor nodes from the routes table and lock them in at the recommended default quality 192 for 2m 224 for backbones 2 Where there is a gateway 2 nodes via RS 232 neighbor node lock these routes at 255 If you are locking 3 nodes in a node stack via RS 232 using a diode matrix set ...

Page 48: ...ies between nodes In many cases it prevents the familiar RETRIED OUT AT NODE SUMMARY SETTING NODE ROUTES The Node command may be used to make a manual entry in the node table When this is done it may also make an entry in the routes table if necessary The syntax of the command is NODE Callsign Ident Quality Count Port Neighbor callsign is the callsign of the destination node ident is the alias of ...

Page 49: ...e the first and only parameter was the deviation meter scaling factor 1 The meter mode flags 2 The deviation meter scaling factor 3 The signal strength meter noise floor value 4 The S meter display format multiplier 5 The dBm meter display format multiplier 6 The dBm noise floor value 7 The voltmeter channel 1 multiplier 8 The voltmeter channel 2 multiplier 9 The voltmeter channel 1 offset value 1...

Page 50: ...1 If the ADC reading is 254 or higher then in order to indicate an overrange the symbol will precede the corresponding deviation entry in the heard list The signal strength meter noise floor value This parameter sets the no signal offset applied to input readings from the signal strength meter It is subtracted from the count read from the ADC to give a reading based on a no signal value of zero If...

Page 51: ...view doc The voltmeter channel 2 multiplier This is the multiplier that controls voltmeter channel 2 ADC channel 4 It is set as described in section 3 34 of the X1J4 overview doc The voltmeter channel 1 offset value This is the value subtracted from the ADC reading before it is multiplied by the multiplier parameter It is described more fully in section 3 34 of the X1J4 overview doc The voltmeter ...

Page 52: ...ency and proceeded to use the system for DX spotting during an ongoing weather watch activity After all else had failed did we invoke the ACL feature and excluded his node callsigns and SSID s from the network This won t be the last time this problem surfaces in any network TACT DIPLOMACY If you find that you as a sysop are confronted with a similar situation try first to remedy the situation with...

Page 53: ...90 no suffix MJF 1270 Most MFJ 1270 B versions and all C versions are already configured with this feature To perform this modification connect one end of a wire to pin 23 of the RS232 connector Connect the other end of the wire to pins 1 2 3 of JMP9 these three pins are already connected together on the circuit board This modification allows the TheNET X1 firmware to be configured for multi frequ...

Page 54: ...stem Node Operators Handbook __ Page 54 This drawing illustrates how the X 1J4 EPROM is installed and connected in the MFJ 1270B TNC Note that PIN one of the EPROM is not inserted into the socket at U23 Pin one 1 also has a wire attached to it and is routed to pin 8 of the MoDem header This mod also illustrates how the MFJ 1270 B version is configured with the MFJ 52B DEViation meter installation ...

Page 55: ...ndbook ILLUSTRATION SECTION Charts Node Drawings TheNET X1J4 System Node Operators Handbook __ Page 55 Another overview of how the X 1J4 EPROM is installed and connected in the MFJ 1270B and earlier See following pages for the installation of the EPROM in MFJ 1270 C Rev 10 The MFJ 1270 C REV 11 and later follows the REV 10 illustration ...

Page 56: ...1J4 System Node Operator s SNO Handbook ILLUSTRATION SECTION Charts Node Drawings TheNET X1J4 System Node Operators Handbook __ Page 56 An overview of how the X 1J4 EPROM is installed and connected in the MFJ 1270 C Rev 10 See next drawing for the installation of the EPROM in MFJ 1270 C Rev 11 and later ...

Page 57: ... SNO Handbook ILLUSTRATION SECTION Charts Node Drawings TheNET X1J4 System Node Operators Handbook __ Page 57 In this drawing I have outlined how the X 1J4 EPROM is installed and connected in the MFJ 1270 C Rev 11 latest version A detailed list of procedures to transform the MFJ 1270C REV 11 into a node are on the following page ...

Page 58: ...UT any other trace Cut ONLY the trace between pads of JMP X Use extreme caution when cutting This step is optional and may not be necessary unless you are concerned with the node hearing itself in RF rich environments 5 If TNC is to be used as a GATEWAY between two frequencies or baud rates insure that R14 R15 are installed If they are not remove the PC board and add R14 and R15 R14 and R15 are 10...

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