[hpsdr] Mercury V2.9 Question

Sat Nov 21 21:25:08 PST 2009

Hi Dave,

Perhaps you could check if these parts are actually fitted to production 
boards since I remember there was concern regarding their effect of the rise 
time of the 10MHz clock from C16.

73's Phil.... VK6APH

----- Original Message ----- 
From: "David McQuate" <mcquate at sonic.net>
To: <hpsdr at openhpsdr.org>
Sent: Sunday, November 22, 2009 1:06 PM
Subject: Re: [hpsdr] Mercury V2.9 Question

> ***** High Performance Software Defined Radio Discussion List *****
>
> It looks like a better way to make the connection between Mercury's J8
> "Aux_Clk"
> and Atlas C16 would be to connect from J8 to the common terminal of D18,
> or the
> end of R37 connected to D18.  This way the FPGA input CLK15 is given the
> same
> protection as the input originally connected to Atlas C16.
>
> Dave / WA8YWQ
>
> Graham / KE9H wrote:
>> ***** High Performance Software Defined Radio Discussion List *****
>>
>> Phil:
>>
>> Rather than run a two wire jumper from the Mercury Aux Clock Connector,
>> to J2 on Excalibur, could we run a  "blue wire" (gasp!, choke!) from the
>> Mercury Aux Clock connector down to pin C16 on the Mercury connector
>> and eliminate the board-to-board cable?
>>
>> Reading your note, my understanding that if Mercury sees a 10 MHz clock
>> signal on both the normal C16 input and the Aux Clock Input, that it will
>> automatically use the Aux Clock Input as the preferred input source for
>> frequency reference and lock, so no issue in having the same signal
>> appear
>> at both.
>>
>> Thanks,
>> --- Graham
>>
>> ==
>>
>> Phil Harman wrote:
>>> ***** High Performance Software Defined Radio Discussion List *****
>>>
>>> Hi All,
>>>
>>> Mercury V2.9 is available for testing.  You will find it here;
>>>
>>> < svn://206.216.146.154/svn/repos_sdr_hpsdr/trunk/Mercury V2.9 >
>>>
>>> and you can use the usual update process from here;
>>>
>>> < svn://206.216.146.154/svn/repos_sdr_hpsdr/trunk/USBBlaster-Binaries >
>>>
>>> I recently moved to Quartus V9.1 so have added that programmer
>>> selection to the menu.
>>>
>>> Mercury V2.9 adds a new feature for those using Excalibur as their
>>> 10MHz reference clock.
>>>
>>> Mike, N3UC found that by using PLLs, rather than digital dividers, to
>>> divide the 122.88MHz  master clock  and 10MHz reference clock to
>>> 80kHz then the frequency accuracy of Mercury improved considerably.
>>> In fact Mike is acheiving an accuracy of 2mHz  (that's two milli Hz
>>> !) using an external GPS locked reference.  Using this technique he
>>> came third out of 97 participants in the recent ARRL Frequency
>>> Measurement Tests - congratulations Mike.
>>>
>>> V2.9 uses this PLL technique.  In order to use it you need to connect
>>> a short coax lead between  Excalibur J2 and Mercury AUX_CLK ( J8 -
>>> located directly below the FPGA). Unfortunatley we can't pick up the
>>> 10MHz signal from Atlas C16 since the PLLs will only work from a
>>> dedicated FPGA clock input - hence the need for a short coax lead.
>>>
>>> LEDs  3 and 4 respectivley on Mercury indicate that the 122.88MHz and
>>> 10MHz PLLs are locked.
>>>
>>> Be careful when connecting the coax lead to J8 on Mercury since this
>>> pin is connected directly to the FPGA - usual practice, make sure the
>>> power is off and follow anti-static precautions.
>>>
>>> If you would like to use this feature permantly then disable the
>>> 10MHz TCXO's on Mercury (and Penelope) by removing power to these
>>> devices using the links and jumpers provided.
>>>
>>> To use this new feature just select Excalibur as the 10MHz clock
>>> source in PowerSDR or KISS Konsole.  If the connection between J2 and
>>> J8 is made then Mercury will automatically select the PLL method - if
>>> not present it will use the 10MHz clock from Excalibur on Atlas C16.
>>>
>>> I also found that the wrong Cordic code had been used in V2.8.  The
>>> latest version rectifies that and will produce a few less spurs.
>>>
>>> As usual, please report your findings via the reflector.
>>>
>>> 73's Phil...VK6APH
>>>
>>>
>>>
>>>
>>>
>>>
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