[hpsdr] Mercury Receiver Board

[Dave Larsen]

Joe --
  
  Very nice reply!  I have wanted to do the same thing as well, as I
suspect many others.  I would, with your permission, like to capture
this information on the Wiki.  

Thanks for the information.  

  Dave KV0S

On Tue, 2010-07-27 at 13:51 -0600, Joe Martin K5SO wrote:
> ***** High Performance Software Defined Radio Discussion List *****
> 
> As Phil is in bed right now I'll take a stab at this:
> 
> The short answer to your question is, yes, there are things that need  
> to be done in hardware to implement two Mercury boards.
> 
> 1) A jumper on GPIO pair 3,2 (Channels_8_1) on J5 needs to be placed  
> on both Mercury boards to specify that the board will use only one  
> Atlas bus line for communication with Ozy (not eight bus lines).
> 
> 2) No additional jumpers on J5 makes the board logically Mercury_ID =  
> 0, one of the Mercury boards needs this configuration to specify which  
> Atlas bus line the communication will occur.
> 
> 3) An additional jumper on GPIO pair 5,4 makes the board Mercury_ID =  
> 1, the second Mercury board needs this configuration to specify that  
> it will use a different Atlas bus line from the first board for its  
> communication with Ozy.
> 
> 4) Both boards should use the same 122.88 MHz clock.  There are  
> several options to do this.  For example, you can use the LVDS  
> functions and header J1 on Mercury (using a twisted wire pair) for  
> this between the Mercury boards and place the CLKSEL jumper in the  
> "I" (internal) or "E" (external) position as appropriate for the board  
> (master or slave relative to the 122.88 MHz Mercury oscillator) or,  
> alternatively, simply remove the CLKSEL jumper entirely and run a  
> twisted wire pair (one of the wires is ground) between the middle pin  
> of CLKSEL on the slave Merc board and the middle pin of CLKSEL on the  
> master Mercury board (CLKSEL jumper installed, in "I" position).   
> Also, I remove the jumper on JP9 on the slave Mercury board, removing  
> power to its 122.88 MHz osc.  This is probably not necessary but it  
> will be a quieter system overall with this unused oscillator turned  
> off so I did it.
> 
> 5) In my view, although I haven't tried otherwise, both Mercury boards  
> should be using the same 10 MHz clock too.  Atlas bus line C16 from  
> Excalibur works well for this.
> 
> 6) You need Mercury v3.0 or later FPGA code loaded in both Mercury  
> boards.  The local parameter NR in the Mercury Verilog code should be  
> set to 2 (or greater is okay, but not 1!) for dual Mercury board  
> operations; v3.0 has NR=8, that's okay but not necessary...it takes  
> much longer to compile if NR=8 (~1hr) than if NR=2 (~3minutes)!
> 
> 7)  Command and control byte C4 to Ozy from the PC needs to be 0x08  
> (when C0 = 0x00, assuming no DUPLEX mode or ALEX relay info is  
> selected), specifying 2 receivers so that Ozy knows to insert  
> additional IQ data bytes, from the second Mercury board,into the USB  
> data stream to the PC.
> 
> HOWEVER, I have recently discovered that the current FPGA code does  
> not implement any kind of synchronization of the serial data stream  
> from the second Mercury board, at the present time at least, so the  
> insertion point is currently random (with respect to power up and data  
> rate selection changes) for the data stream from the second Mercury.   
> This causes havoc on the PC side, of course.  That's a problem that  
> has been brought to Kirk's attention and is currently being reviewed  
> by Kirk (as the heavyweight Verilog coder, and me as a lightweight  
> helper, hihi) for a solution.
> 
> Fear not, this is simply a temporary glitch that won't last long.   
> It'll get fixed shortly.  Or, of course, if you want to do some  
> Verilog coding you're more than welcome to join in to help resolve  
> this little issue!!
> 
> Hope this info helps!
> 
> 73,  Joe K5SO
> 
> 
> On Jul 27, 2010, at 12:47 PM, David McQuate wrote:
> 
> > ***** High Performance Software Defined Radio Discussion List *****
> >
> > Hi Phil,
> >  I'm curious as to where are there differences between multiple  
> > receivers on one Mercury board,
> > and two, or more, Mercury boards ?  As I see nothing in the USB  
> > protocol V1.27 that
> > would distinguish between the two, I wonder if something needs to be  
> > done in hardware...
> >
> > Thanks! & 73,
> > Dave
> >
> 
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