DP Tool Club 24/CD_ASCQ_24_0995.iso/vrac/aprs72a.zip/README/HF.TXT

Text File | 1995-07-14 | 9KB | 149 lines

HF.txt 7.1b              HF APRS BOAT AND RV TRACKING NET

New in 6.8c:
    * Now HF/VHF switches the PK-232 also
    * Added 2port command so that KAM will transmit on VHF & HF at same time
    * See DUAL PORT sections below

HF FREQS:  MFJ/KAMS  AEA'S    Mode  NORMAL USAGE
            10.151   10.1515  LSB   National HF tracking freq
             7.085    7.0855  LSB   Regional HF tracking nets
            14.100   14.1005  LSB   Recommended DX tracking freq
            14.105   14.1055  LSB   Packet Keyboarding freq

The 7 MHz frequency has a lot of QRM, but is good for shorter range APRS
mobile during the day.  Both the 10 and 14 MHz frequencies were very
carefully chosen to minimize interference to all present users of the band
and to provide some measure of QRM reduction to ourselves.  Please note
the SIDEBANDS used.  These are important and here's why:

30 METERS:  By using 10.151 LSB, the packet signal RF energy is 1.7 Khz
lower and is inside the band edge by 700 Hz.  The sideband energy is down
by 40 dB which meets the FCC requirements for band edge operation.  We
use the LSB convention in specifying the freq to be compatible with other
packet channels on the band.  Of course, the actual FSK frequency is
10.149.3 USB which is exactly the same frequency!  If your TNC (PK232)
uses tones centered at 2210 Hz or 2125 Hz, then you will need to tune
510 or 425 Hz higher using LSB.

20 METERS:  We have suggested 14.100 LSB since it is the International CW
beacon freq.  This means that if you dial in 14.100 and operate AFSK in
LSB, then your RF is actually transmitted at 14.098.3 which is 1700 HZ
away from the CW freq and well outside of a 500 HZ CW filter.  Hopefully,
most people might not understand this, so it is relatively quiet and QRM
free.  The real PACKET LSB freq to AVOID for the sake of the CW ops, is
14.102 +/- 500 HZ!

Recently we are seeing some APRS activity on the 14.105 LSB keyboarding
frequency.  Although APRS is not quite as effecient as a standard KEYBOARD
CONNECTION, it is a GREAT monitoring tool, to see who is on freq and who
wants to chat...  This frequency would be good for casual APRS DXing and
new user familiarization.  This will remove some of the QRM from the
10.151 LSB and 14.100 LSB tracking frequencies.  In the future, we should
also find a single APRS frequency on 18 and maybe 24 MHz.  Any pioneers?


TUNING:  To aid in tuning into an APRS HF net, I am suggesting that ONE
station on each frequency be designated as the TUNE station.  That station
should set his HF alias to TUNE.  Any newcommer on frequency that desires to
lock onto that station, simply sets his UNPROTO path to go via TUNE
temporarily.  Then he hits several PINGS.  As each Ping is digipeated bcak,
he can tune his receiver right on frequency.  This is the normal netting
procedure, but by using the generic alias of TUNE, a newcommer does NOT have
to know who the TUNE station is in order to find the exact frequency.
To avoid excess digipeating, the station must remove TUNE as soon as he
is finished.  Others should keep an eye on the DIGI page and remind anyone
that forgets and leaves TUNE in his path.  It may be possible to have
additional slave TUNE's on frequency (TUNE1,TUNE2), as long as they make
a DILLIGENT effort to zero to each other.  A new user getting no response
from TUNE can then try TUNE1 and TUNE2 in turn.  Obviously these other
slaves should be very widely separated.  On 10.151, the Naval Academy Club
station has the alias of TUNE, N2CZF is operating as TUNE1 and KN4IM is
TUNE2.


HF OPERATIONS:  The HF/VHF modes in APRS only change the packet timing to
account for the slower channel.  They also will shift the TRANSMIT port on
the KAM and shift the PK-232 between VHF and HF operation.  For other dual
band TNC's, you must do this manually using the OPS-COMM dumb terminal mode
to change bands according to your TNC instructions.  When you configure APRS
for HF instead of VHF, it simply multiplies all timing routines by 2 to make
up in the difference between 1200 with digipeaters and 300 baud without.  One other
thing it does is to change your default ALIAS from the generic callsign of
RELAY to the generic callsign of ECHO.  Read the info on the UNPROTO command
and in the DIGIs.txt to fully understand the implications of the generic
alias of RELAY used by all VHF APRS stations.  Obviously, for a nationwide HF
net, we do NOT want anyone digipeating everyone else's packets!  So the change
to the alias of ECHO is important in that it REMOVES the generic ALIAS of
RELAY!  For special operations only, of course, you can still digipeat your
HF packets off of another station under critical or emergency situations,
but you should specify exactly who, by callsign, NOT by the generic call of
ECHO.  (Only digipeat via ECHO if you are in extremis!)


KAM DUAL PORT OPERATIONS:  When APRS is configured for HF using the KAM,
AND the CONTROLS-2PORT command is given, the KAM will not
only send out packets on the selected port, but APRS will also send out
duplicate packets on the other port by using the stream switch character.
These characters are ~ for HF and | for VHF.  Only the following packets
are duplicated:  BEACON, POSIT, OBJECTS, MESSAGES, and ACKS.  All other
packets are only sent on the selected port.  Now in vesion 7.a, APRS also
properly initializes the KAM MYalias command to ECHO/RELAY.
Please do not use 2PORT while chatting on VHF!  You will kill the HF band.

GATEWAYS:  By assigning the generic callsign of GATE to the gateway function
in the dual port Kantronics or AEA TNC's, any HF station can gate-way into
the local VHF net.  HF stations can probably use the VIA path of GATE
most of the time, because the slow HF operation could hardly clutter up any
local VHF APRS networks.  But users on VHF APRS networks should NEVER use
GATE on the VHF side of their gateways except under extreme circumstances.
This is because there are hundreds of times more VHF users than there are HF
users and the 1200 baud users would totally saturate the HF net!

     To repeat:  The purpose of HF/VHF gateways is to permit VHF local area
APRS nets to see the movements of nationwide RV and BOATER mobiles.  For
example, when I go GPS mobile, I do not want to leave my HF station running
at home so my wife can follow my status.  But If I send my HF mobile APRS
reports via the local HF GATEway, then my wife can see me on our computer
which only needs to have a VHF TNC.  Please DO NOT GATEWAY from VHF through
a gateway ONTO HF except under very unusual circumstances!  Similarly, if
you are on HF, only use ONE WIDE after the GATE so as not to clutter up
everyone's VHF nets.


KAM GATEWAY SET UP:  You may connect two or more KAMS, each with an HF radio
on different HF frequencies.  The audio of their VHF sides are tied together
into a low power VHF radio on 145.79.  Both KAMS run with the GATEWAY callsign
of GATE so that any HF APRS packets using the VIA path of GATE will be seen
on our local 145.79 APRS net.  This is for bringing both HF bands onto VHF,
NOT for QRMing 2 HF bands by VHFers NOR for ANY back-to-HF gating!

    The HF and VHF parameters for the KAM Unproto command are separated by a
slash character as follows:

UNPROTO APRS VIA HFDIGI1,HFDIGI2/APRS VIA VHFDIGI1,VHFDIGI2 etc

To set up your KAM using the APRS UNPROTO-VIA command, you need to
remember to include the second half of the command as noted above.  If you
omit the second half of the command, then the KAM applies the Unproto
command identically to both ports.  Since I want my KAM to go out on VHF
via the local WIDE area digipeaters (WIDE,WIDE) but I want the HF packets
to go via any HF GATEway node (GATE), I can do that via the APRS UNPROTO
command with the following:
    ... Enter new VIA path:  GATE/APRS VIA WIDE,WIDE
Notice that APRS automatically inserts the UNPROTO APRS VIA ... for the first
part of the UNPROTO command and all I have to do is type the DIGI address
(GATE here), but for the dual port KAM, that I must type "APRS VIA" again
myself after the slash for the second half of the command (for the VHF port).


HF TRACKING DEMONSTRATIONS:  To see the results of some actual APRS HF
tracking events, use the FILES-REPLAY command to replay the ACADEMY.HST file.
The boats were transmitting once every 10 minutes or so.  My first HF mobile
excursion was over Xmas 93 holidays.  When I returned 2 weeks later the file
XMAS93.hst showed me all that was received in Annapolis of my journey (before
the computer crashed).  It shows good tracking from Knoxville TN to Florence
Alabama.   In fact, N2CZF (then in NJ) was able to track me all day, just
about everyday, for the two week period, during daylight hours!