// UIDIGI.TXT FAQ
//
// Faq Version History
//
// Version 220600 - First version started by Joao Lopes, CT2HME
//
// Version 270600 - Included your changes to version 2206.
//                  Polished the English here and there (check again item 1.2 please)
//                  Good work on items 3.1 and 3.2. Small English polish here.
//                  Added items 2.3 to 2.6 (please pay special attention to this new items)
//                  Moving slowly but surely... :-)
//
// Version 050800 - Added item to section 3
//
// Version 241100 - Added item to section 3
//
// Version 081200 - Added item to section 2 / 3
//
//
// If you have some comment, Q/A o other to be included to this file please send it 
// at: iw3fqg@amsat.org
//
// Thanks
//
// Marco IW3FQG
//

-----------------------------------------------------------------------------------------------
1. Introduction
1.1 What is this FAQ file for?
1.2 What is UIDIGI.TXT?
1.3 Who wrote this file?
1.4 Where can I get more info?

2. UIDIGI.TXT Configuration Parameters
2.1 DigipeaterCallsign
2.1.1 What is SSID?
2.2 DigipeaterAlias
2.3 BeaconDestination
2.4 Beacon1Path
2.5 Beacon2Path
2.6 Beacon3Path
2.7 NorthPath
2.8 SouthPath
2.9 EastPath
2.10 WestPath
2.11 BudList
2.12 UIDigiCall
2.13 UIFloodCall
2.15 UITraceCall
2.16 Txdelay
2.17 Fullduplex
2.18 PPErsistence
2.19 Slottime
2.20 Frack
2.21 Maxframe
2.22 Retry
2.23 RespTime
2.24 LinkCheck
2.25 Beacon1Interval
2.26 Beacon2Interval
2.27 Beacon3Interval
2.28 Beacon1Offset
2.29 Beacon2Offset
2.30 Beacon3Offset          
2.31 DuplicateSuppression
2.32 LoopSuppression
2.33 HandleUISSID
2.34 Reply to Query
2.35 UIFLOODOptions
2.36 UITRACEOptions
2.37 UIDIGICallSubstitution
2.38 SysopPassword
2.39 InfoText
2.40 Beacon1Text
2.41 Beacon2Text
2.42 Beacon3Text

3. Other Questions
3.1 What TNCs have been tested with UIDIGI?
3.2 What EPROM should I use on my TNC?
3.3 How callsign duplication checking is implemented?
3.4 How does UIDIGI implementation of WIDEn-N Flooding compare ...
3.5 Why when somebody try to send the SYS command, the DIGI seems to be locked ...?
3.6 Why I can't connect via serial port with a terminal program?
3.7 How can I connect to the digipeater via serial port?
3.8 Why UIDIGI use APZxxx as beacon destination instead of APRS?
3.9 Is possible to connect a WX station to the serial port of the TNC that run UIDIGI?
3.10 How to connect to a distant digi via a local UIDGI 1.7 ?
3.11 How to enter in local sysop mode in UIDIGI?
3.12 How to logon remotely the netrom algorithm?
3.13 Why the connect and status led of TNC2 does nothing when connected?
3.14 How can I disconnect the digipeater by sysop command?
3.15 Why with UIDIGI 1.8 BETA 3 with default parameter the digipeater repeat nothing?
3.16 What shall I do if I want to stop *only my digipeater beacon* from being digipeated 
3.17 Is 31 a valid number for UILOOP?
3.18 Why 3 beacon?
3.19 How can I set the beacon timers?


-----------------------------------------------------------------------------------------------
1.Introduction
1.1 What is this FAQ file for?

This file explains all the parameters on the setup file UIDIGI.TXT.


1.2 What is UIDIGI.TXT?

UIDIGI.TXT is a text file that contains all the parameters that configure the UIDIGI software.
You should edit this file and change it to suit your digipeater configuration.
UIDIGI.TXT will be processed by UIDGCFG.EXE and written (in binary form) in the eprom image
file that will be recorded latter (with a EPROM recorder) into the TNC eprom.
If by any means you wish to leave the default value allready defined in the suplied UIDIGI.TXT
you can do the follwing:

- leave the default value has it is.

- leave a blank space (UIDGCGC.EXE will assume you wish to use the default value).


1.3 Who wrote this file?

This FAQ was written by Marco Savegnago, IW3FQG and Joao Lopes, CT2HME.

1.4 Where can I get more info?

Read ALL the UIDIGI documentation!
Or subscribe to uidigi mailing list at http://www.egroups.com/subscribe/uidigi

Contact Marco Savegnago. He is the author of the UIDGI software.
Or subscribe to uidigi mailing list at http://www.egroups.com/subscribe/uidigi
Try also the following sources of information:

- Go to www.packetradio.com to get a lot of info about packet radio.

- Another source of information about APRS is www.tapr.org where you can find
the APRS specification written by the APRS Working Group.

- www.aprs.net is a source of information about APRS.

First, to start the experiment, I think you need to understand how the AX.25
and APRS perform reading the information that you may find in the APRS for
dos documentation and the manual of your TNC.

Contact Marco Savegnago using:
e-mail: iw3fqg@amsat.org
packet radio: iw3fqg@i3kuh.iven.ita.eu

-----------------------------------------------------------------------------------------------

2. UIDIGI.TXT Configuration Parameters
2.1 DigipeaterCallsign

This will set the digipeater ax.25 address callsign (with SSID if necessary).
For example, a local digipeater in Lisbon, Portugal is using the following callsign:

DigipeaterCallsign     =       CT2HME-8

2.1.1 What is SSID
In AX.25 every station callsign can have up to 15 SSID (Secondary Station Identifier),
so the callsign IW3FQG (-0 default SSID) may be addressed differently from IW3FQG-1,
-2, -3 etc.


2.2 DigipeaterAlias

Any station in packet radio may have an alias that can be up to 6 characters
long (without SSID). Use this option if you want your digipeater to have an alias
(an acronim of the city or the mountain is a good choice).
For example, a local digipeater in Lisbon, Portugal is using the following alias:

DigipeaterCallsign     =       SINTRA

SINTRA is the name of a local mountain where the digipeater is located.


2.3 BeaconDestination

This is the destination where UIDIGI addresses its beacon frame.
The APRS protocol allows that any APRS software may choose its own destination when
sending its own frame (for example the Kenwood TH-D7A/E and WinAPRS are capable of this).
Since UIDIGI doesn't have it's own beacon destination code I've used the experimental code
(APZnnn) as stated in the APRS Protocol specifications.
Other sysops have changed this code to APRS.
This parameter does not affect how the digipeater performs so

BeaconDestination      =       APZ17

is a good choice.


2.4 Beacon1Path

UIDIGI supports 3 beacons and 3 beacons paths.
You can choose the path for the first beacon by altering this option.
If you leave

Beacon1Path            =       WIDE, WIDE

then this beacon will be repeated by a maximum of 2 digipeaters that can
repeat the WIDE frame.
Try to make sure that your digipeater reaches at least a WIDE digipeater.


2.5 Beacon2Path

You can choose the path for the second beacon by altering this option.
If you leave

Beacon2Path            =       WIDE3-3

then this beacon will be propagated over your local area using the special
flooding algorithm introduced in APRS to avoid a long path in propagation.
This frame will be repeated by another UIDIGI (or by other APRS digipeater 
that support flooding algorithm) as follow:

UIDIGI>APZ17,WIDE3-3:...
UIDIGI>APZ17,WIDE3-2:...
UIDIGI>APZ17,WIDE3-2:...
UIDIGI>APZ17,WIDE3-1:...
UIDIGI>APZ17,WIDE3*:...

This allow multiple hop without long path.

UIDIGI has a feature (UIFLDFL bit 1) that enable the digipeater to insert 
its callsign on every  hop (the same as ID function of KPC3).


2.6 Beacon3Path

You can choose the path for the second beacon by altering this option.
If you leave

Beacon3Path            =       TRACE7-7

This frame will be repeated by another UIDIGI (or by other APRS digipeater
that support Tracing and flooding algorithm) as follow:

UIDIGI>APZ17,TRACE3-3:...
UIDIGI>APZ17,DIGI1*,TRACE3-2:...
UIDIGI>APZ17,DIGI1,DIGI2*,TRACE3-2:...
UIDIGI>APZ17,DIGI1,DIGI2,DIGI3*,TRACE3-1:...
UIDIGI>APZ17,DIGI1,DIGI2,DIGI3,DIGI4*,TRACE3:...

then this beacon will be propagated over your local area using the special
trace and flooding algorithm introduced in APRS to enable reverse path.

2.7 NorthPath
Set the destination path for frame addressed to North (SSID 8 or 12)
This is an experimental routing algorithm that allow to set the preferred frame
routing direction.
To be completed, for more info about it read the UIDIGIE.TXT

2.8 SouthPath
Set the destination path for frame addressed to South (SSID 9 or 13)
This is an experimental routing algorithm that allow to set the preferred frame
routing direction.
For more info about it read the UIDIGIE.TXT

2.9 EastPath
Set the destination path for frame addressed to East (SSID 10 or 14)
This is an experimental routing algorithm that allow to set the preferred frame
routing direction.
For more info about it read the UIDIGIE.TXT

2.10 WestPath
Set the destination path for frame addressed to West (SSID 11 or 15)
This is an experimental routing algorithm that allow to set the preferred frame
routing direction.
For more info about it read the UIDIGIE.TXT

2.11 BudList
Set a list of callsign that the digipeater do not repeat.

2.12 UIDigiCall
Set the list of generic callsign that digipeater repeat (eg RELAY, WIDE ..)

2.13 UIFloodCall
Set the callsign to be used in the flooding algorithm (default WIDE)

2.15 UITraceCall
Set the callsign to be used in the flooding/trace algorithm (default TRACE)

2.16 Txdelay
Set the TXDELAY the time after PTT on and the start of valid data. Or the
length of sync signal from the PTT on and start of HDLC data.

2.17 Fullduplex
Enable/Disable the digipeater to operate in fullduplex mode (ignore or not DCD).

2.18 PPErsistence
Probably to transmit seed number. This nomber is used to generate a random value
to be used to access to the radio channel.

2.19 Slottime
Probably to transmit delay. This value is used to delay the transmitter after
the radio channel become free.

2.20 Frack
This parameter is only for L2 link (eg remote sysop). Frame acknowledgment timer

2.21 Maxframe
This parameter is only for L2 link (eg remote sysop). Maximum number of frames
sent in a packet.

2.22 Retry
This parameter is only for L2 link (eg remote sysop). Maximum number of retry
during frame sending.

2.23 RespTime
This parameter is only for L2 link (eg remote sysop).

2.24 LinkCheck
This parameter is only for L2 link (eg remote sysop). Inactive link timer

2.25 Beacon1Interval
See section 3.19 

2.26 Beacon2Interval
See section 3.19

2.27 Beacon3Interval
See section 3.19

2.28 Beacon1Offset
See section 3.19

2.29 Beacon2Offset
See section 3.19

2.30 Beacon3Offset
See section 3.19

2.31 DuplicateSuppression
Set the time in between a frame if heard is not repeated.

2.32 LoopSuppression
Se discussion 3.17

2.33 HandleUISSID
Enable the digipeater to treat SSID differently and use geographic routing

2.34 Reply to Query
Enable digipeater to reply to an ?APRS? query

2.35 UIFLOODOptions
To be completed, for more info about it read the UIDIGIE.TXT

2.36 UITRACEOptions
To be completed, for more info about it read the UIDIGIE.TXT

2.37 UIDIGICallSubstitution
Enable the digipeater to make call substitution for generic address.
This feature is useful to understand which digipeater repeat a frame and
to avoid duplication

2.38 SysopPassword
See section 3.10

2.39 InfoText
Set the info text for the digipeater

2.40 Beacon1Text
Set the text of beacon 1

2.41 Beacon2Text
Set the text of beacon 1

2.42 Beacon3Text
Set the text of beacon 1

-----------------------------------------------------------------------------------------------

3.1 What TNCs have been tested with UIDIGI?

The following TNCs have been tested with UIDIGI:

 - TAPR TNC2 (used by Marco, IW3FQG)
 - 100% compatible TAPR TNC2 clone (used by Marco, IW3FQG)
 - Symek TNC2H (used by Marco, IW3FQG)

Other people have reported the follwing hardware:

 - MFJ 1270B
 - MFF 1270C (must be modified)
 - PACCOM Tiny II

Mark Cheavens KC5EVE report:
I have two Pac-Comm Micropower 2's. One will work with this firmware and the other will NOT. 
The later one  is very picky as to what I load in it. ( Early: S/N 229 Board Rev is TMR rem 1.2)
(Later: s/n M0865 TMR rev 1.5)
 
If you have information on this subject please e-mail Marco (iw3fqg@amsat.org)
so we can add the hardware to the list.


3.2 What EPROM should I use on my TNC?

A TNC2 can address up to 32KB of ROM. That is the capacity of a 27x256 EPROM.
Is possible to use a 27x512 (64KB) that is pin to pin compatible with a 27x256
and programming the upper 32KB bank (8000h to ffffh).
You can also use 2 different firmware by alternatively switching the state (GND or +5V)
of A15 EPROM pin.


3.3 How callsign duplication checking is implemented?

The digipeater on every digipeated frame store the hash value for that frame
in a circular buffer.
It never repeat an equal frame within the period defined in the parameter.
This is how 1.6 perform the duplication check.

In version 1.7 (thank to the suggestion received from the sysop) I've
introduced also the Loop Suppression feature that is user definable (via bit
field param) and act as follow:

Since the digipeater perform call substitution on generic call (RELAY, WIDE,
TRACE ... up to 8 and sysop definable in 1.7) the digipeater do not repeat
frame with source address equal to digipeater call or alias (its beacon) and
also do not repeat frame with the digipeater call in the already digipeated
via list.

The duplication check algorithm when check for an already digipeated frame
with a WIDEn-n or TRACEn-n callsign in the vialist do not use the SSID byte
to calculate the hash value.
This avoid ping-pong or loop between two or more digipeater with WIDEn-n or
TRACEn-n addressed frame.

3.4  How does UIDIGI implementation of WIDEn-N Flooding compare to Kantronics
with regard to the ID setting (in Kantronics have the choice for UIFLOOD
or WIDE,28,ID or WIDE,28,NOID)?  
I see no setting for this in your software.  How do you handle this?

Following the indication of Bob Bruninga WB4APR in his manuals of APRSDOS my
code is equivalent to WIDE,[UICHECK],NOID.
If you want to turn on the ID function set to 1 the bit 1 of UIFLDFL.


3.5 Why when somebody try to send the SYS command, the DIGI seems to be locked
and nobody can acces the DIGI anymore. The TNC2 send ***BUSY ! So, it is
necessary to reboot the node.

Check your TNC2 schematics and see if pin 22 of the SIO is connected to GND or +5V?
With UIDIGI this pin must be set to GND.


3.6 Why I can't connect via serial port with a terminal program?

Check your TNC2 schematics and see if pin 22 of the SIO is connected to GND or +5V?
With UIDIGI this pin must be set to GND.

Gene W4IMT send to me how to modify the PacCOMM Micropower 2:

TNC is PacCOMM Micropower 2.  I believe similar to Tiny -2.  Micropower 2 
is low current version.
SIO pin 22 voltage is determined by an inverter output connected to pin 22 
through modem disconnect header.
Input to inverter is connected to pin 9 of the serial port.
When serial port is not plugged in, pin 22 is at ground.  When serial port 
is plugged in, pin 22 goes to 5 volts!
(This is true of my setup.  May not be of all.  I use HyperTerminal with 
desk top PC.)
Solution:  Scrape off circuit trace from modem disconnect header and ground 
pin 22.



3.7 How can I connect to the digipeater via serial port?

First, you must be sure that PIN 22 of SIO is connected to GND (not +5V).
In this manner you may be able to connect the digipeater also via serial port
using a simple terminal program as Hyperterminal (in Win95) or an old dos terminal 
program (Procomm, Q-Modem, Telix etc).
To connect to the digipeater console via serial port once you have connected it, 
you must issue the command <ESC> C <ENTER> and then you are connected to the sysop 
console where you may send any command to the digipeater.
To enter in the sysop console from the radio port, you need first to connect to
the digipeater, then send the S command reply with the right sysop letter then you
can access to any digipeater command.


3.8 Why UIDIGI use APZxxx as beacon destination instead of APRS?

I use APZxxx becouse in the APRS Spec is indicated for experimental
software, I've already asked to Bob Bruninga how to obtain an unique
destination address for my firmware, but I never received answer...

3.9 Is possible to connect a WX station to the serial port of the TNC that run UIDIGI?
No, actually there is no support and plan for WX station connected to TNC the serial port.

3.10 How to connect to a distant digi via a local UIDGI 1.7 ?

Actually the UIDIGI implementation don't allow the digipeating of AX.25 frames that are 
not of UI type.
So you can't use an UIDIGI to make L2 connection (using via syntax) using UIDIGI as 
digipeater. This is due to avoid the use of APRS digipeater for normal packet traffic.
If you are the sysop of each digipeater that you use to make the connection with distant 
digipeater you could make the connection using the CONNECT command (available at uidigi 
command prompt only to authenticated sysop (using S command)) on each digipeater.

For example:

from you command prompt connect the first digi:

>C DIGI1
<***connected to digi1
>S
<UIDIGI:DIGI1> 1 2 3 4 5
>abcde
>C DIGI2
<***connected to digi2
>S
<UIDIGI:DIGI2> 1 2 3 4 5
>abcde

and so on...


3.11 How to enter in local sysop mode in UIDIGI?

In order to enter local sysop mode you will need the following:
comm program set at 8n1 set to the baud rate (jumper) on the tnc. Echo OFF
If you can power the tnc on and get the Call of the digi and the version/copyright info you are close!
        - then press [esc] c [enter]    (this will log you on locally)
from there you should be able to Connect to another tnc
NOTE: the remote tnc will show you connected as (digicall-ssid) less 15 (max number of ssid)
Example:
If your UIDIGI call is mycall-5 then you will show as being connected as mycall-10.
If you UIDIGI call is mycall-10 then you will show as being connected as mycall-5
In other words the INVERSE of what your ssid is.
This has something to do with the netrom algorithym

3.12 How to logon remotely the netrom algorithm?

In order to logon remotely the netrom algorithm is as follows:
If you have your password set to: "MYPASSWORDISSHORT"
         Netrom:        "12345678901234567"
when prompted for password (example) 3625
you would respond with: PSSO

3.13 Why the connect and status led of TNC2 does nothing when connected?

Both LED do not follow the normal function (as in standard firmware). Both LED is remotely set
and reset by sysop commands.

3.14 How can I disconnect the digipeater by sysop command?

There is not diconnect command in UIDIGI remote command. Use local command of your packet program
or TNC.

3.15 Why with UIDIGI 1.8 BETA 3 with default parameter the digipeater repeat nothing?

UIDIGI1.8B3 has a bug so that you MUST set UIPID to 0 recompile the image file and reprogram
the EPROM.

3.16 What shall I do if I want to stop *only my digipeater beacon* from being digipeated
by other digis on the area?

Put your digi call in budlist of the other digipeater.

3.17 Is 31 a valid number for UILOOP?

The UILOOP value is the result of the binary OR (or more simply the SUM) of the follow values:

Please check the version of UIDIGI you are using because the value meaning was
changhed between the releases of software (sorry)!

0x01 hex = 1 decimal = The digipeater DO NOT repeat incoming frames with ax.25 source address equal to digipeater call or alias

      Eg: with this flag ON a frame like:
      IR3FAL>APRS v RELAY, WIDE, WIDE
      IS NOT digipeater by a digipeater with DIGICALL equal to from IR3FAL to IR3FAL-15 or DIGIALIAS equal to IR3FAL

      (This is valid in UIDIGI 1.7 and 1.8)

0x02 hex = 2 decimal = The digipeater DO NOT repeat incoming frames with the digipeater call in the already digipeated via list

      Eg: with this flag ON a frame like:
      IW3FQG>APRS v IR3FAL, IR3VIF*, WIDE
      IS NOT digipeater by a digipeater with DIGICALL equal to from IR3FAL to IR3FAL-15 or DIGIALIAS equal to IR3FAL

      (This is valid in UIDIGI 1.7 and 1.8)

0x04 hex = 4 decimal = Ignore SSID in UIFLOODCALL and UITRACECALL callsign to verify if a frame was already been digipeated

      Each time a frame addressed to WIDEN-n or TRACEN-n (normaly the values of UIFLOODCALL and UITRACECALL parameters) is repeated
      an hash value is calculated  and stored in a circular buffer to check duplication. Since for WIDEN-n and TRACEN-n frames there is no
      call substitution (until WIDEN-0 and TRACEN-0) and decrementation of SSID on each repetition change the hash value of the packet, setting this
      flag to ON the functions that to avoid repetition and duplication ignore the SSID of the frames and avoid that digipeated repeat the same packet more
      than one time.

      Eg: with this flag OFF a frame like:
      IW3FQG>APRS v WIDE3-3

      Repeated (1st time)
      IW3FQG>APRS v WIDE3-2

      Repeated (2nd time)
      IW3FQG>APRS v WIDE3-1

      Repeated (3rd time)
      IW3FQG>APRS v WIDE3-0

      Repeated (4th time)
      IW3FQG>APRS v DIGICALL*

      May be repeated more than one time by the same digipeater, with this flag OFF no.

      (This is valid in UIDIGI 1.7)

0x08 hex = 8 decimal = Ignore via path in the frames comparation

      With this flag ON, the functions that to avoid repetition and duplication compare the frames do not consider the VIA path fields of the frames.
      Only the destionation and source field of the ax.25 frame is checked. (*)

      (This is valid in UIDIGI 1.8 BETA 3 and was dropped in 1.8 B4)

0x10 hex = 16 decimal = Check the duplication frame list with every incoming packets

      With this flag ON, each incoming frame is compared with the buffer that contain the already sent frame.

      (This is valid in UIDIGI 1.8 BETA 3 and was dropped in 1.8 B4)

(*) This flag bias all the comparation functions

I`m now considering to implement all this functions in another way ...

If you want to enable all these flags 31 (decimal) is (in theory) a valid
value only in UIDIGI BETA 3.

3.18 Why 3 beacon?

UIDIGI provide 3 different beacon to support several destination, rate etc.
All 3 beacon may be configured to run indipendently.
This was due to a user request not from me!

3.19 How can I set the beacon timers?

    With:

    Beacon1Interval=300, Beacon2Interval=600, Beacon3Interval=900
    Beacon1Offset=0, Beacon2Offset=0, Beacon3Offset=0

    At  00:05:00  (Beacon1Interval+Beacon1Offset expire) Beacon 1 will be sent
    At  00:10:00  (Beacon1Interval+Beacon1Offset expire and
                  Beacon2Interval+Beacon2Offset expire and )
                  Beacon 1 and Beacon 2 will be sent
    At  00:15:00  (Beacon1Interval+Beacon1Offset expire and
                  Beacon3Interval+Beacon3Offset expire and )
                  Beacon 1 and Beacon 3 will be sent
    At  00:20:00  (Beacon1Interval+Beacon1Offset expire and
                  Beacon2Interval+Beacon2Offset expire and )
                  Beacon 1 and Beacon 2 will be sent
    At  00:25:00  (Beacon1Interval+Beacon1Offset expire) Beacon 1 will be sent
    At  00:30:00  (Beacon1Interval+Beacon1Offset expire and
                  Beacon3Interval+Beacon3Offset expire and )
                  Beacon 1 and Beacon 3 will be sent

    With:

    Beacon1Interval=1200, Beacon2Interval=1200, Beacon3Interval=1200
    Beacon1Offset=0, Beacon2Offset=300, Beacon3Offset=600

    At  00:20:00 (Beacon1Interval+Beacon1Offset expire) Beacon 1 will be sent
    At  00:25:00 (Beacon2Interval+Beacon2Offset expire) Beacon 2 will be sent
    At  00:30:00 (Beacon3Interval+Beacon3Offset expire) Beacon 3 will be sent

    At  00:40:00 (Beacon1Interval+Beacon1Offset expire) Beacon 1 will be sent
    At  00:45:00 (Beacon2Interval+Beacon2Offset expire) Beacon 2 will be sent
    At  00:50:00 (Beacon3Interval+Beacon3Offset expire) Beacon 3 will be sent

3.20 Where SSID routing may be used?

This was suggested by Dario IV3HLG

Consider this scenario:

In a rally race we want to use APRS to monitor the some of the cars (or
ambulance etc). All the traffic is generated by cars that is moving in a
circuit near and around mountains, inside valley...
We have 4 mounatin (A B C D) that is sufficent to cover all the circuit
where we put one APRS digipeater, and the race direction (G) where all the
packet must be sent.


      (North)

       B   C
(West)       (East)
       A   D

      (South)
  G

We want that all the frame generated by the cars go to race direction (point G)
with minumum duplicationsm and frame lenght. The cars operator cannot change
the route of the frame during the race.


I have proposed to mount 4 UIDIGI in the top of the mountain (A B C D) and set
on each digipeater the right south path to reach G. The tracker mounted on
each car need only to address its frames to -13 SSID to go directly at race
direction.
