[hpsdr] Using External 10 Mhz on Hermes Board

[Larry Dodd]

Bruce:
Thanks. That is a good reason to disable the on board clock.
I do see spurious traces in the waterfall even with no antenna connected and
suspect it is coming from internal Hermes noise/signals.
Thanks.
Larry K4LED

Message: 6
Date: Sat, 1 Dec 2012 21:07:14 -0500
From: "Bruce Beford" <bruce.beford at myfairpoint.net>
To: <hpsdr at lists.openhpsdr.org>
Subject: Re: [hpsdr] Using External 10 Mhz on Hermes Board
Message-ID: <8FB18CD694AC4541A3BC772B1D7AED27 at HPE250f>
Content-Type: text/plain; charset="US-ASCII"

It -can- be left on. However, in my experiments with Mercury, Penelope and
Excalibur (upon which the Hermes design was based) I noted that the 10 MHz
clock from Penny, the one from Excalibur and mixing products could be seen
in received traces. I modified my Penelope to allow disabling of it's
onboard 10 MHz osc when using Excalibur.

For most uses, it probably wouldn't matter. For some critical apps, it may
not be desirable to have an unused oscillator contributing to the received
signal spectrum. This is one of the reasons disabling the onboard clock was
made possible in the Hermes design.

73,
Bruce, N1RX
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