From: DL4YHF@aol.com
Message-ID: <19d.5b8364f.2a6efc2c@aol.com>
Date: Tue, 23 Jul 2002 14:36:28 EDT
Subject: Re: LF: Sound Cards
To: rsgb_lf_group@blacksheep.org
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<HTML><FONT FACE=arial,helvetica><FONT  SIZE=2>Hi Sandy,
<BR>
<BR>from own experiments with several soundcards I found only marginal differences as long as simple waterfall display is concerned - so I confirm Alberto's comments.
<BR> &nbsp;&nbsp;&nbsp;(Instead of a bit more dynamic range, I would love to have 
<BR> &nbsp;&nbsp;&nbsp;&nbsp;a soundcard with two DC-coupled inputs, 
<BR> &nbsp;&nbsp;&nbsp;&nbsp;for I/Q processing as last stage of a digital receiver 
<BR> &nbsp;&nbsp;&nbsp;&nbsp;with simple but good analog frontend).
<BR>
<BR>A problem with audio cards on the mainboard is that they often catch noise from the digital components on the board. This can be very annoying, because sometimes the noise appears like "interesting looking" noise on the waterfall (water on the mills of the anti-soundcard fraction again ;-). 
<BR>On the other hand, if the soundcard "noise" is mostly random type, it is effectively reduced by the narrow-band gain of the FFT. So, for high frequency resolution, the usable dynamic range for a waterfall display often exceeds 120 dB (more than the dynamic range of a 16 bit ADC !).
<BR>
<BR>----
<BR>Related topic: I bought some a low-cost PIC with 10-bit ADC (PIC16F870) recently, planning to connect it to the serial interface as replacement for my laptop's audio device (which only has a lousy *mono* MIC input). Has anyone on the group ever tried to use this PIC for weak-signal work and check the ADC's performance, compared to a soundcard ?
<BR>
<BR>
<BR>
<BR>Regards,
<BR> Wolf &nbsp;DL4YHF
<BR>
<BR></FONT></HTML>