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From: "James Moritz" <james.moritz@btopenworld.com>
To: <rsgb_lf_group@blacksheep.org>
References: <B4F25C37-5F28-48AD-AE84-1B9FD1F9A2D9@gmail.com> <4E5E9DE7.8050107@tee.gr>
In-Reply-To: <4E5E9DE7.8050107@tee.gr>
Date: Wed, 31 Aug 2011 22:52:54 +0100
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Subject: Re: LF: Netbooks for WSPR and Spectrum Lab?
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Dear Roger, Costas, LF Group,

I have recently had similar audio problems with a Compaq CQ10 netbook. This 
has a single 4-pole 3.5mm socket for audio in/out from the sound card, which 
is not actually compatible with any audio leads I have.... It seems to have 
some sort of sensing circuit which detects whether headphones or microphone 
are connected to a particular audio socket pin and route the signals 
accordingly - which doesn't seem to work most of the time, with the sound 
card reverting to the internal microphone. There also seems to be some sort 
of low-pass filter, which restricts the upper audio frequency irrespective 
of the sampling rate. Also, the audio socket appears to be "floating", with 
no direct ground continuity to the rest of the machine, causing noise 
problems with the high RF field strengths at this QTH. Quite what is wrong 
with just having one socket for audio in and another for audio out I don't 
know... The audio output seems to work OK.

Most of the time I use it with the SDR-IQ RX, or a USB sound card, for which 
it is fine. It may be possible to make the audio input work properly - I 
haven't really investigated. But I would definitely recommend looking for a 
netbook with seperate audio sockets, just so that you get the full soundcard 
stereo input/output functionality.

Cheers, Jim Moritz
73 de M0BMU