From: Jim Lux <[EMAIL PROTECTED]>
Date: Fri, 25 Aug 2006 Time: 07:10:29
>At 07:03 AM 8/25/2006, Jim Lux wrote:
>
>>Then, the I/Q audio signals run through separate channels, so there's a
>>"audio frequency" dependent variation between I and Q. This is fairly
>>fixed, independent of
>
>DDS frequency (not audio frequency.. it varies a lot with audio frequency)
>
>>, but is also not particularly well
>>represented by a single phase/amplitude calibration value (as currently
>>used in PowerSDR), especially when used with wideband audio interfaces
>>(e.g. 96 kHz sampling, etc.). The audio interface manufacturers do a
>>fairly good job keeping phase and amplitude matched beween channels in the
>>middle ranges (say, 100 to 10 kHz), but not so wonderful farther out: their
>>primary criteria is making sure it "sounds right" and phase/amplitude
>>problems in the lower end of the range would result in "stereo imaging"
>>artifacts {Phase difference between L and R being one of the big cues for
>>how you tell what direction a sound is coming from}.
>
>
Jim,
Many thanks for all your comments. I found them most helpful and
encouraging.
73
Ian, G3NRW
--
Ian Wade
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