[Elecraft] odds and ends...

[Matt Maguire]

On 20/08/2012, at 11:54 AM, Don Wilhelm <w3fpr at embarqmail.com> wrote:

> 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.

The reason is simple -- they are either misquoted, misunderstood, or mistaken. A sound card with a sample rate of 48kHz will allow cover the spectrum up to LO+/-24kHz, or 48kHz of spectrum centred around the LO. If the sound card has a sample rate of 96kHz, the panadaptor will display up to LO+/-48kHz, or 96kHz of spectrum.

If the sound card has a low pass filter in the audio chain, then this limits the width further (eg. a 20kHz LPF is common in quality soundcards, so the spectrum available is limited to LO+/-20kHz, or 40kHz of spectrum, even if the sample rate would be 192kHz).

73, Matt VK2ACL