[Elecraft] odds and ends...

[N8LP]

Hi Don. I posted a response to your post yesterday, but apparently it didn't
get posted to the list. Here is another attempt using Nabble. Copy of
message follows...

Hi Don. I just received the digest version of your post. I don't recall ever
having said that a 48kHz sampling rate will produce a 96kHz display span.
All my postings and web site info states that the span will be roughly equal
to the sampling rate (minus a tiny amount due to the rolloff of the
anti-aliasing filter in the sound card). I saw Joe's comment copied in the
same digest message, and it is not correct. I'm sure it was just a slip of
the fingers. The confusion comes in that the displayed span is roughly equal
to twice the sound card bandwidth... not twice the sound card sampling rate.
The bandwidth of the card, of course, is roughly half the sampling rate if
it is properly implemented.

73,
Larry N8LP



On 8/19/2012 11:51 PM, elecraft-request at mailman.qth.net wrote:
> From:elecraft-bounces at mailman.qth.net
> [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Don Wilhelm
> Sent: Sunday, August 19, 2012 9:54 PM
> To: WB4JFI
> Cc:elecraft at mailman.qth.net
> Subject: Re: [Elecraft] odds and ends...
>
> I don't know the advertized numbers, but Mr. Nyquist aside, there is a
> reason that two independent experts with panadapter displays (Joe Subich
> W4TV and Larry Phipps K8LP of LP-Pan fame) state that a soundcard with a
> 48 kHz rate will produce a 96 kHz span on the pan display.
>
> I do not doubt Nyquist, but I think the treatment of the numbers are a bit
> different (factor of 2)  Could it be due to the two channels? I really
> don't
> know the answers and do not have the energy to investigate such things
> anymore, I just choose to trust the experts who deal with this I/Q stuff
> on
> a daily basis.  I guess my scientific curiosity has declined with
> advancing
> years - it is no longer enjoyable to argue on the basis of observations
> vs.
> theory to sort out the differences - that was "fun mind games" many years
> ago. but today it is no longer a challenge.
>
> 73,
> Don W3FPR 




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