[aprssig] A Closer Look at the WA8LMF TNC Test CD

Rob Riggs mobilinkd at gmail.com
Sat Jan 2 01:04:44 CST 2016


Hi John,

Some of the distortion you show, especially the ones Dire Wolf shows the
volume level over 100, look a lot like what one sees when overdriving the
inputs on an audio capture device.

How much of the distortion you are seeing is caused by the capture and
recording process?  How much is due to the radio used to capture the
signal?  Those seem to be unknowns and ought to be accounted for.


Kind Regards,

Rob Riggs WX9O
Mobilinkd LLC

On Fri, Jan 1, 2016 at 8:07 PM, John Langner WB2OSZ via aprssig <
aprssig at tapr.org> wrote:

> How can we compare how well different TNCs decode less-than-ideal APRS
> signals?  The de facto standard of measurement is the number of real-world
> frames decoded from WA8LMF's TNC Test CD.
>
> Let's take a closer look at some of the frames on the TNC Test CD in hopes
> of gaining some insights into why some are easily decoded and others are
> more difficult.
>
> WARNING!
>
> This document contains images of really ugly APRS radio signals that some
> will find disturbing.  Viewer discretion is advised.
>
>
> https://github.com/wb2osz/direwolf/blob/dev/doc/A-Closer-Look-at-the-WA8LMF-
> TNC-Test-CD.pdf
>
> There are a lot of ugly signals out there.   Many can be improved by
> decreasing the transmit volume.   Others are just plain weird and you have
> to wonder how they are being generated.
>
>
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