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

John Wiseman john.wiseman at cantab.net
Thu Aug 20 02:55:26 CDT 2015


Mark,

The general answer is no - the KISS protocol doesn't define a calibrate
command. But some KISS TNC's have added a (non-standard) calibrate function.
The TNC-PI (a Raspberry PI version of the TNC-X) has a calibrate function
that sends 5 deconds of each tone. . I think John talked about adding it to
the standard TNC-X firmware, but I don't know if he has.

You could generate a few seconds of modulated signal be creating a file of
KISS format frames, and copying it to the TNC serial port. A full size frame
would be a little over 2 seconds, so a file of 5  frames would give you
around ten seconds.

73, John G8BPQ


-----Original Message-----
From: aprssig [mailto:aprssig-bounces at tapr.org] On Behalf Of Mark Cheavens
via aprssig
Sent: 20 August 2015 06:12
To: John Langner WB2OSZ; TAPR APRS Mailing List
Subject: Re: [aprssig] KISS TNC - Calibration function to set deviation
correctly

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
>
>
>
>
>
>
>
> _______________________________________________
> aprssig mailing list
> aprssig at tapr.org
> http://www.tapr.org/mailman/listinfo/aprssig


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