[hpsdr] Mercury V2.9 Question

[Graham / KE9H]

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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