[OZAPRS] We need a standard HF APRS Audio frequency pair

[Richter, Mike W]

Now that the RF frequencies for each band have been standardised, as well
the baud rate (300BPS) and the Frequency Shift (200Hz), it is still hard
to work out what frequency you need to set your Transceiver to. That is
only because there is no standard as yet for what Audio Tones will go into
and out of an SSB Transceiver - just have a look at the list below.

WHY DO WE NEED TO STANDARDISE AUDIO TONES
 - It makes it hard to successfully decode signals if HF transmissions
occur rarely and you are not sure what frequency to tune to.
 - If changing Terminals (e.g. Tiny Trak to TM-1) you would need to change
RF Frequency.
 - Different OnAir frequencies through operator confusion makes it hard to
operate in a Net.
 - As people use more basic crystal-controlled transceivers, it will be
hard to change the RF frequency for different Terminals.
 - As new equipment is developed, (e.g. TinyTrak for HF) there is
uncertainty about which frequencies to select.

DECIDING ON STANDARD AUDIO FREQUENCIES
 - There is a big range of Frequency-Pairs to choose from at the moment -
there is no obvious, predominant standard.
 - The frequencies should be away from the edges of Transceiver audio
passband to minimise distortion
 - The frequencies should be compatible with Narrowband IF Filters used
for CW.
 - The frequencies should be compatible with the Narrowband modes in DSP
units

The table below shows the RF frequency you will need to dial up for LSB
and for USB for the different Audio Tones in use. By Virtual Carrier
Frequency, I mean the average of the two frequencies sent - the only value
independent of Audio frequency and Sideband used - perhaps we should
specify APRS RF frequencies this way !!!

Mike VK2BMM

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  Virtual Carrier  7083.30, 10149.30, 14098.30, 14103.30,     Mark, Space

Bell 103 Orig LSB, 7084.47, 10150.47, 14099.47, 14104.47,     1070, 1270
Bell 103 Orig USB, 7082.13, 10148.13, 14097.13, 14102.13,     1070, 1270

Tig TM1 LSB,       7084.50, 10150.50, 14099.50, 14104.50,     1100, 1300
Tig TM1 USB,       7082.10, 10148.10, 14097.10, 14102.10,     1100, 1300

MFJ1270 LSB,       7085.00, 10151.00, 14100.00, 14105.00,     1600, 1800
MFJ1270 USB,       7081.60, 10147.60, 14096.60, 14101.60,     1600, 1800

KamPlus LSB,       7085.00, 10151.00, 14100.00, 14105.00,     1600, 1800
KamPlus USB,       7081.60, 10147.60, 14096.60, 14101.60,     1600, 1800

Bell 103 Answ LSB, 7085.43, 10151.43, 14100.43, 14105.43,     2025, 2225
Bell 103 Answ USB, 7081.18, 10147.18, 14096.18, 14101.18,     2025, 2225

MFJ1278 LSB,       7085.50, 10151.50, 14100.50, 14105.50,     2100, 2300
MFJ1278 USB,       7081.10, 10147.10, 14096.10, 14101.10,     2100, 2300

PK232 LSB,         7085.51, 10151.51, 14100.51, 14105.51,     2110, 2310
PK232 USB,         7081.09, 10147.09, 14096.09, 14101.09,     2110, 2310

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