[aprssig] Multiple TNC's connected to one radio

[vk2tv]

That would invalidate the results through different rx performance if 
the objective is to compare two TNCs.

Ray vk2tv


On 27/10/17 13:11, Michael Barnes wrote:
> For a receive only situation, I think I would scrounge up an old 
> scanner and have a completely separate receive setup. You can find 
> cheap programmable scanners for just a few dollars. I keep several 
> around for just such purposes.
>
> Michael WA7SKG
>
> On Thu, Oct 26, 2017 at 12:41 PM, spam8mybrain <spam8mybrain at yahoo.com 
> <mailto:spam8mybrain at yahoo.com>> wrote:
>
>     Ah, but what if DireWolf is one of the TNC's he wants to test? :-)
>     It sounds like he wants to compare different TNC's audio processing.
>
>     Probably a larger issue here is if the TNC's being compared demand
>     different audio levels. Adjusting the shared audio signal
>     amplitude for best performance on one TNC might ruin the
>     performance of the other TNC (signal lost in the noise or
>     overloading and clipping/distorting in the TNC's analog input). If
>     you really want to do this right, you might want to use an audio
>     distribution amplifier with independently adjustable levels for
>     each output feeding a TNC; incidentally, this would also eliminate
>     all issues of loading down the input source.
>
>     Just my $.02.
>
>     Andrew, KA2DDO
>
>
>     -------- Original message --------
>     From: "John D. Hays" <john at hays.org <mailto:john at hays.org>>
>     Date: 10/26/17 14:43 (GMT-05:00)
>     To: Max Harper <kg4pid at yahoo.com <mailto:kg4pid at yahoo.com>>
>     Cc: aprssig <aprssig at tapr.org <mailto:aprssig at tapr.org>>
>     Subject: Re: [aprssig] Multiple TNC's connected to one radio
>
>     It should work, but I can't vouch for specific TNCs.
>
>     Another approach would be to use Direwolf
>     (https://github.com/wb2osz/direwolf
>     <https://github.com/wb2osz/direwolf>) which would give you more
>     sampling opportunites.
>
>     On Thu, Oct 26, 2017 at 9:21 AM, Max Harper <kg4pid at yahoo.com
>     <mailto:kg4pid at yahoo.com>> wrote:
>
>         I would like to connect 2 tnc's to one radio. One would be
>         transmitt/recieve and the other recieve only. This would be to
>         test the decoding of a couple different tnc's. Am I likely to
>         run into any problems connecting the speaker jack audio into 2
>         tnc's? Would the additional load cause me to have to readjust
>         the audio level when I connect/disconnect the second tnc? My
>         thoughts are since the speaker jack audio is low impedance (8
>         ohm) and the tnc input is much higher (hopefully) is that it
>         will have little to no effect.
>
>         Just thought I'd ask before wasting my time making a cable.
>
>         Max KG4PID
>
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>
>
>
>     -- 
>
>     ------------------------------------------------------------------------
>     John D. Hays
>     Edmonds, WA
>     K7VE
>
>     <http://k7ve.org/blog> <http://twitter.com/#%21/john_hays>
>
>
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