[hpsdr] Clock Jitter on C16

[Phil Harman]

Hi Gerd,

Thanks for doing these tests.  Kirk, KD7IRS, is working on a way to 
eliminate the need to send the 12.288MHz over the Atlas bus which will make 
things easier.

73's Phil...VK6APH

----- Original Message ----- 
From: "Gerd Loch" <g.loch at nt-electronics.de>
To: <hpsdr at lists.hpsdr.org>
Sent: Thursday, February 12, 2009 8:47 PM
Subject: [hpsdr] Clock Jitter on C16


> ***** High Performance Software Defined Radio Discussion List *****
>
> Hi,
>
> I have done some tests on the 10 MHz clock "jitter" which causes problems
> dependent on the placement on the Atlas bus.
>
> I have uploaded the pictures on hamsdr.
> http://www.hamsdr.com/personaldirectory.aspx?id=948
>
>
> 1) shows the clock on C16 when you have selected Penelope as 10MHz source.
> 2) shows the 12.288MHz signal on the panadapter when you have selected
> Penelope as 10MHz source.
> 3) shows the clock on C16 when you have selected Mercury as 10MHz source 
> and
> configured 3.0LVTTL for the clock output pin.
> 4) shows the 12.288MHz signal on the panadapter when you have selected
> Mercury as 10MHz source and configured 3.0LVTTL for the clock output pin.
> 5) shows the clock on C16 when you have selected Mercury as 10MHz source 
> and
> configured 3.0LVCMOS for the clock output pin.
> 6) shows the 12.288MHz signal on the panadapter when you have selected
> Mercury as 10MHz source and configured 3.0LVCMOS for the clock output pin.
>
> I do not really understand why a pin configuration LVTTL gives a very
> different signal shape compared to LVCMOS.
>
> However since the debounce is implemented in the Mercury code by Phil 
> there
> is no more difference on the 12.288 MHz clock whatever pin configuration 
> is
> used for the 10MHz output pin.
>
> 73, Gerd
> DJ8AY
>
>
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