[hpsdr] PowerSDR Request

[Phil Harman]

Hi Mark,

I'm sure Bill, KD5TFD, will reply to your request regarding frequency 
adjustment.  You are correct that the version of Mercury in \trunk\Mercury 
V2 has some new test code for use with an external 10MHz reference input. 
There are a few folks working on this at the moment and I am sure they will 
let us know the results in due course.

The clocks on HPSDR  have the feature of being  phase locked to a 10MHz 
reference on either Penny, Mercury or via an external signal on Atlas bus 
C16.

Feeding an external GPS locked 10MHz clock into Atlas C16 is what is being 
worked on at the moment.  A 3.3v square wave with low Z drive and a 2/3nS 
rise time looks to be needed. This works OK when Penny or Mercury drives C16 
but is proving a little more difficult from an external source.

The latest test code samples the 10MHz source at 122.88MHz, a technique used 
successfully by Greg ZL3IX, and we are waiting to see the results.

Michael, N3UC, has found that replacing the 122.88MHz to 80kHz divider with 
a PLL increases the performance significantly.

There is also a facility to connect an external clock to Mercury at J8 - 
this has also been tested with very good results.

Good to see so much experimentation going on with  Mercury hardware and 
software.

73's Phil....VK6APH

----- Original Message ----- 
From: "Mark Amos" <mark at amos-family.com>
To: <hpsdr at lists.hpsdr.org>
Sent: Saturday, January 17, 2009 4:10 AM
Subject: [hpsdr] PowerSDR Request


> ***** High Performance Software Defined Radio Discussion List *****
>
> Thanks for adding the frequency calibration facility.  I'd like to be able
> to adjust out that last couple of Hz...  If the correction factor could be
> manually adjusted, I'm sure I'd be able to set it spot on.
>
> Speaking of spot on, I saw that there was an update to the Mercury code 
> that
> looks like it had something to do with an external clock on C16... I'd 
> like
> to be able to feed this clock pin from a GPSDO.  I had some notes on this,
> but can't seem to lay my hands on them.  What level should the clock be to
> fed to C16 and does it need to be square or will a nice sin shaped 
> frequency
> standard do the trick?
>
> I just replaced a horribly noisy ATX power supply with an Astek 16130 that
> seems to be much quieter (I used a little loop pickup and the SDR1000 to
> compare the two - the improvements were obvious.)  Also, a 12 V PC power
> supply fan blowing across the board stack seems to keep the Mercury ADC
> plenty cool.
>
> What a fun radio.  Thanks!
>
> Looking forward to Alex!
>
> Mark
>
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