[aprssig] KISS TNC - Calibration function to set deviation correctly

[KF4LVZ]

Off the top of my head I don't know of a way to trigger the individual
tones directly but I do think there's a way to partially cheat.  You
would basically have to construct a packet that could defeat at minimum
the NRZI encoding and possibly the bit stuffing mechanism.

You can get a short burst of a single tone by sending a constant stream
of ones (data packet with a string of 0xFF) but this will be broken up
by the bit stuffer.  You could potentially prolong it by setting a very
low on-air symbol rate.

Getting the opposite tone is harder because the NRZI is using the other
tone only when sending zeros so a string of zeros is going to flip flop
between the tones.

If you construct a bit sequence of something like:

0x7B 0xDE 0xF7 0xBD 0xEF

you will get a zero followed by four ones in a repeating pattern.  The
zero would trigger a tone change and the four ones would hold the tone
until the next zero.  With a slow symbol rate you could potentially get
both tones for a short amount of time.

On 2015-08-19 22:12, Mark Cheavens via aprssig wrote:
> You are assuming the other stations are set correctly!
> - I have a service monitor and KNOW how to set the levels (Using
> Calibrate) on a TNC with a non-KISS rom.
> - I know how to do it by swapping roms (on TNC's with replaceable roms)
> - I know how to do it on Argent Data TNC's with a calibrate function.
> 
> - Let's go back to the original question:
> Is there a way to SEND the 2200 and 1200 hz tones individually on a KISS
> TNC?
> 
> Mark
> KC5EVE
> On 8/19/2015 9:51 PM, John Langner WB2OSZ via aprssig wrote:
>>> I am looking for a way ... to set the deviation correctly.
>>
>> Consider the following approach.
>>
>> (1) Put your TNC into normal operation so that it will transmit
>> occasionally.
>>
>> (2) Set up a receive-only instance of direwolf using a different receiver
>> and a good antenna.
>>
>> (3) Observe the audio level lines for stations heard directly.
>>
>>
>> Example:
>>
>>
>> $ direwolf -t 0 | grep -v "^Digipeater" | grep -A 2 "audio level ="
>>
>>
>> W1MHL audio level = 96(53/33)   [NONE]   _||||||||
>> [0.4] W1MHL>APN382:!4223.32N/07115.23W#PHG3640/Waltham Amateur Radio
>> Association - N1OMJ Digipeater NoW1<0x0d>
>> Position, DIGI (white center), Kantronics KPC-3 rom versions, 9 W
>> height=640
>> 4dBi omni
>>
>> ...
>>
>> W1CCE-1 audio level = 82(40/22)   [SINGLE]   ____:____
>> [0.4] W1CCE-1>TR2S0S,WIDE,WIDE2-2:'c4cl#H>/]"4p}<0x0d>
>> MIC-E, normal car (side view), Kenwood TM-D700, En Route
>>
>> ...
>>
>> KB1JKJ-8 audio level = 32(13/7)   [NONE]   __|||||||
>> [0.5] KB1JKJ-8>T2SS5R,WIDE1-1,WIDE2-1:`c+ll \(/"5'}
>> MIC-E, Mobile Satellite Station, Unknown manufacturer, In Service
>>
>> ...
>>
>> W1WCI-11 audio level = 99(58/34)   [NONE]   ___|||||:
>> [0.5] W1WCI-11>APX200,WIDE2-2:=4243.14N/07106.12W-XASTIR-TNC-PI<0x0d>
>> Position, House, Xastir
>>
>> ...
>>
>> KB1QV-10 audio level = 34(11/13)   [NONE]   ||||||___
>> [0.2] KB1QV-10>APTT4,WIDE2-1:!4305.18N/07131.34W#<0x16>PHG34803/Bow,NH
>> Position, DIGI (white center), Tiny Track
>>
>> ...
>>
>> KB1ZSE-8 audio level = 79(39/28)   [NONE]   ___:::|:_
>> [0.6] KB1ZSE-8>TRTU7P,WIDE1-1:`cPso|m>0]"8,}MOBILE=<0x0d>
>> MIC-E, OVERLAYED CAR w/overlay 0, Kenwood TM-D710, Off Duty
>>
>> ...
>>
>> K1ABC-9 audio level = 75(41/26)   [NONE]   __:::|||_
>> [0.5] K1ABC-9>T2SX6X,WIDE1-1:`c4~r-8>/`"4G}146.520MHz de Paul from
>> Nashua,
>> NH_%<0x0d>
>> MIC-E, normal car (side view), Yaesu FTM-400DR, In Service
>>
>> ...
>>
>>
>> (4) Notice how the audio levels vary all over the place.  32 to 99 and
>> everywhere in between.
>>
>> Kenwood and Yaesu fall near the middle, 75 to 82.  Assuming these have
>> the
>> factory settings, that level should be close to ideal.  If you don't
>> see any
>> of them, just take the average of the crowd.
>>
>> (5) Adjust your transmitter to have a similar level.
>>
>>
>>
>>
>>
>> Exercise for the reader:
>>
>> (a) What is the impact of setting the transmit volume level too high?
>>
>> (b) What are the other two numbers and the vertical bars after the audio
>> level?
>>
>> Hint:  See http://www.tapr.org/psr/psr128.pdf page 13
>>
>>
>>
>>
>>
>>
>>
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> 
> 
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