I find the mpeg3 16kbps/11khz 16bit mono encoder under WinXP provides
excellent playback with weak signals and very efficient file size
compression (~7MB/hr ?). I assume it was installed with the OS/Media Player
but I also installed CoolEditPro and that might have provided the codec.
IMHO, RS isolation xfmrs are fine. A while back I did frequency sweeps of a
few xfmrs, and unless you're doing hifi ssb and need the very lowest
frequencies, the RS xfmr does a good job. I notice no distortion products
with them. If you want to take a step up, I recommend the xfmrs that W2IHY
sells for $10.
73,
Barry N1EU
www.n1eu.com
>From: "Eric Scace K3NA" <eric@k3na.org>
>Reply-To: eric@k3na.org
>To: "'WriteLog Reflector'" <writelog@contesting.com>
>Subject: [WriteLog] codec performance, isolation transformers
To: <writelog@contesting.com>
>Date: Tue, 18 Feb 2003 07:36:39 -0500
>
>CODECS:
>
> There is a bewildering array of codec choices around. As a HF/MF
>contester and DXer (CW, SSB and RTTY), I would like to be able
>to listen to a contest or DXpedition recording and have a good chance of
>hearing that extremely weak station who was responding to
>me while other nearby enormous signals were still calling. This ability to
>handle a large dynamic range seems pretty demanding...
>
> Does anyone know of an authoritative site containing comparisons on the
>technical performance of various codecs?
>
>ISOLATION TRANSFORMERS:
>
> The WL help files suggest using the small Radio Shack isolation
>transformers. They work pretty well for RTTY signals at
>2125/2295, but others have pointed out that performance in the lower
>frequency range is less than good with lots of distortion
>products.
>
> A search of Mouser Electronic's catalog shows conventional audio
>isolation transformers are in the $50/each level. That adds up
>to serious money quickly.
>
> Confessing now to the fact that I am not an audio engineer, could
>someone more experienced in these matters suggest an approach
>to choosing audio isolation transformers that introduce a minimum of
>impairments to receiver and transmitter audio? My application
>is pretty typical for a WriteLog-equipped contest station:
> -- computer with 2 soundcards.
> -- W5XD Multi+ keyer for SO2R operation.
> -- two transceivers, with ~1mW line-level audio input to the
>transmitter... and separate line-level audio output, speaker, and
>headphone outputs. For my particular transceiver of the moment, the
>headphone and speaker audio are from the same source.
>
> Thanks.
>
>-- Eric K3NA
>
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