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<a class="moz-txt-link-abbreviated" href="mailto:Sct599@aol.com">Sct599@aol.com</a> wrote:
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<div>In a message dated 12/23/2005 9:06:32 P.M. Mountain Standard
Time, <a class="moz-txt-link-abbreviated" href="mailto:wa7ixk@earthlink.net">wa7ixk@earthlink.net</a> writes:</div>
<blockquote style="padding-left: 0px; margin-left: 0px;"><font style="background-color: transparent;" color="#000000" face="Arial" size="2"><a class="moz-txt-link-abbreviated" href="mailto:Sct599@aol.com">Sct599@aol.com</a> wrote:<br>
> You could try using HF. There is an APRS network on 10.151mhz,
LSB, 300 <br>
> baud. There are HF to VHF gates and I-gates too.<br>
> <br>
> Scott<br>
____________________________<br>
I have never heard anything on that freq.<br>
I do not try very often.<br>
Have you tried it or just repeating hearsay?<br>
I wanted to used it in the wilds of Idaho for my annual trip.<br>
I wanted to add a TXO-9 and ping every hour with 5 watts with a 9 ft
whip.<br>
Don.t think it will work.<br>
I only want one or two internet connections per day.<br>
I am conened about frequency tolerance from 40 degrees F to 110 degrees
<br>
F. in the boonies.<br>
i<br>
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<br>
"The wilds of Idaho" is exactly the kind of place that 30M HF APRS is
ideally suited for. The band is open to SOMEWHERE almost 24 hours a
day. It's not uncommon to get into an HF igate 500-1000 miles away
depending on time of day. <br>
<br>
What is a "TXO-9"? <br>
<br>
HF APRS is conducted with standard 300 baud 200-hertz FSK normally
generated by feeding shifting AUDIO tones, into the mic jack of an SSB
transceiver. The object of this is ultimately to produce an FSK
signal that shifts back and forth between 10.149.2 and 10.149.4 MHz
. You MUST be within 10-20 Hz of these two freqs to be received by
most fixed stations. <br>
<br>
o 5 watts is very unlikely to work well in the noise and qrm on 10
MHz. You really need a flull-powered 100W HF rig to be heard
consistently. <br>
<br>
o A solid 9' whip will feed directly on 10 or 11 meters where it is
a natural quarter-wave long. It will require some sort of matching
system or tuner at the base on 10MHz (30 meters) where it will be far
shorter than a quarter wave (or a loading coil inserted somewhere in
the whip). <br>
<br>
=== Background on HF/SSB FSK (A post I have made many times on various
lists) follows ==<br>
<br>
Packet data transmission is done by rapidly shifting an audio tone
between two frequencies traditionally referred to as the "MARK" and
"SPACE" frequencies. On 1200baud VHF-FM packet, these two tones are
1000 Hz apart and standardized on 1200 and 2200 Hz. On 300 baud HF,
the two tones are 200 Hz apart and ARE NOT STANDARDIZED. <br>
<br>
Simply quoting the RF "dial frequency" for HF data modes is ABSOLUTELY
MEANINGLESS unless you qualify it with the AUDIO tone freqs being used
by the TNC or other device. <br>
<br>
o The indicated "dial frequency" on SSB is the suppressed carrier
frequency. <br>
o The supressed carrier frequency is NOT transmitted. <br>
o What IS transmitted are sidebands that are offset below the
carrier freq on LSB (or above the carrier on USB) by the exact value of
the AUDIO tones fed into the radio mic jack from the TNC, soundcard,
modem, etc. <br>
<br>
Since the actual transmitted RF frequencies (on lower side band) are
the indicated suppressed carrier frequency (i.e. "dial frequency")
minus the audio tone frequencies, the actual dial frequency you want
WILL DEPEND ON THE PARTICULAR AUDIO TONE FREQS your TNC or other device
produces. <br>
<br>
<br>
-----> NOTE THIS ESSENTIAL FACT!!! <-----<br>
-----> Unlike 1200 baud VHF packet, there is no standard for the
audio tone frequencies used by various devices on 300 baud/200-Hz shift
HF packet! <-----<br>
<br>
Frequencies Devices using them<br>
<br>
1600/1800 Hz Kantronics KAM, TAPR TNC2 (MFJ 127x. etc), TinyTrak<br>
2130/2230 Hz AEA/Timewave PK-232<br>
1100/1300 Hz TigerTronics TigerTrak (300 baud HF mode)<br>
2100/2300 Hz AGW Packet Engine softmodem (300 baud mode)<br>
<br>
<br>
This is really not a problem on SSB since (unlike FM) you can always
change the audio frequencies at the receiving end by tuning the
receiver a little higher or lower. <br>
<br>
[ This cuts both ways. If the transmitter is off frequency, the tones
recovered at the receiving end will be correspondingly off-frequency.
Since the typical TNC or soundcard softmodem (i.e. AGW Packet Engine or
MixW in packet mode) will ignore any audio tones that are more than
about 20-30 Hz off, frequency setting is --VERY-- critical and high
frequency stability is essential. You MUST be able to set the
frequency to within 10 Hz and KEEP IT THERE indefinitely. This is
especially critical if you are going to transmit in the blind without a
signal to tune in on receive first! Ideally you want a modern
synthesized rig with a TCXO high-stabilty master oscillator. ]<br>
<br>
<br>
<br>
The ==ONLY== constants are the ACTUAL RF freqs of the 200 Hz shift mark
and space tones on 30M APRS. They are:<br>
10.149.200<br>
10.149.400<br>
NOTE: The traditional ham convention is to specifiy the actual RF
frequencies of the tones. The commercial/military/regulatory convention
is to specify the single frequency midway between the two tones, along
with the shift. In this format, the 30M APRS channel would be quoted as:<br>
"10.149.300 with +/- 100 Hz shift" or "200 Hz Shift Centered on
10.149.300" .<br>
<br>
<br>
To produce the correct RF frequencies with a KAM, TNC2 or TinyTrak III
(300 Baud HF mode) whose default audio tones are 1600/1800 Hz, you must
set your radio to <br>
<br>
10.151.00 LSB: <br>
10.151.000 - 1.800 = 10.149.200<br>
10.151.000 - 1.600 = 10.149.400 <br>
<br>
Or set the radio to 10.147.60 USB:<br>
10.147.600 + 1.600 = 10.149.200<br>
10.147.600 + 1.800 = 10.149.400<br>
<br>
<br>
<br>
To produce the correct RF frequencies with a PK232 whose default audio
tones are 2110/2310 you must set your radio to <br>
<br>
10.151.51 LSB:<br>
10.151.510 - 2.310 = 10.149.200<br>
10.151.510 - 2.110 = 10.149.400 <br>
<br>
Or set the radio to 10.147.09 USB:<br>
10.147.090 + 2.110 = 10.149.200<br>
10.147.090 + 2.310 = 10.149.400<br>
<br>
<br>
<br>
To produce the correct RF frequencies with a TigerTrak whose 300
Baud/narrow shift audio tones are 1100/1300 (weird pairing centered
around the 1200 Hz low tone for 1200 baud packet -- but actually very
nice because the tone pairs are in the dead center of the typical SSB
filter bandpass and suffer the absolutely least amount of phase and
group delay distortion) you must set your radio to <br>
<br>
10.150.50 LSB:<br>
10.150.500 - 1.300 = 10.149.200<br>
10.150.500 - 1.100 = 10.149.400<br>
<br>
Or set the radio to 10.148.10 USB:<br>
10.148.100 + 1.100 = 10.149.200<br>
10.148.100 + 1.300 = 10.149.400<br>
<br>
<br>
<br>
To produce the correct RF frequencies with the AGW Packet Engine
softmodem, whose default audio tones on 300 baud HF are 2100/2300 you
must set your radio to <br>
<br>
10.151.50 LSB:<br>
10.151.500 - 2.300 = 10.149.200<br>
10.151.500 - 2.100 = 10.149.400 <br>
<br>
Or set the radio to 10.147.00 USB:<br>
10.147.100 + 2.100 = 10.149.200<br>
10.147.100 + 2.300 = 10.149.400<br>
<br>
<br>
Note that some HF radios with "DATA" or "FSK" modes offset the
indicated dial frequency to correct for the difference between the
suppressed carrier freq and the actual mark frequency, typically
assuming the lower tone is 2125 Hz (or sometimes 1800 Hz). This will
force you to compute offsets different from what I have listed for
LSB/USB.<br>
<br>
AGAIN: Quoting "dial frequency" alone is ABSOLUTELY MEANINGLESS unless
you qualify it with mode (USB/LSB/DATA, etc) and the AUDIO tone freqs
in question. <br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
Stephen H. Smith wa8lmf (at) aol.com <br>
EchoLink Node: 14400 [Think bottom of the 2M band]<br>
Home Page: <a class="moz-txt-link-freetext" href="http://wa8lmf.com">http://wa8lmf.com</a><br>
<br>
"APRS 101" Explanation of APRS Path Selection & Digipeating <br>
<a class="moz-txt-link-freetext" href="http://webs.lanset.com/wa8lmf/DigiPaths">http://webs.lanset.com/wa8lmf/DigiPaths</a> <br>
<br>
Updated APRS Symbol Chart <br>
<a class="moz-txt-link-freetext" href="http://webs.lanset.com/wa8lmf/miscinfo/APRS_Symbol_Chart.pdf">http://webs.lanset.com/wa8lmf/miscinfo/APRS_Symbol_Chart.pdf</a> <br>
<br>
<br>
New/Updated "Rev G" APRS <a class="moz-txt-link-freetext" href="http://webs.lanset.com/wa8lmf/aprs">http://webs.lanset.com/wa8lmf/aprs</a><br>
Symbols Set for UI-View, <br>
UIpoint and APRSplus:<br>
<br>
<br>
<br>
<br>
<br>
<br>
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