[hpsdr] Hermes

[Dan Habecker]

I was wondering would there be any issues with latency with Ethernet?  I've
seen some pro audio gear that uses special MACs to minimize this.  Or of
this would be no worse than USB?

Also if you do have to do a board spin, I was wondering if it would worth
having a exposed ground track around the 'front end' so one would have the
option of putting a shield over it.

Looking forward to playing with Hermes soon.

73,
Dan W9EQ


On Wed, Aug 4, 2010 at 10:06 PM, Phil Harman <phil at pharman.org> wrote:

> ***** High Performance Software Defined Radio Discussion List *****
>
> All,
>
> Having completed the Beta testing of Hermes we are now preparing to make
> the necessary changes to bring the board into a production ready state.
>
> There are quite a few changes which are mainly due to the fact we want to
> ensure the product lives up to the 'High Performance' name tag.
>
> One of the changes is to replace one of the high current linear regulators
> with a SMPSU. We are fortunate to have Kjell, LA2NI,  on our design team.
> Kjell has designed a high frequency SMPSU that works well when
> incorporated on the Hermes PCB and does not introduce significant spurs.
> This substantially reduces the current drain and also the heat
> dissipation.
>
> The other potential change is this.  I have this week build a prototype
> OzyII Gigabit Ethernet board. It works very well and I'm impressed with
> how rugged Ethernet appears to be in comparison to USB and Firewire.
>
> We therefore have the opportunity to replace the USB interface on Hermes
> with Ethernet.  There are a number of advantages in doing this:
>
> - we overcome the USB driver issues when using different operating systems
> - we can 'network attach' Hermes
> - we will have a very high speed interface to the board for future features
> - we can use a much longer Ethernet cable than USB allows
>
> the disadvantages
>
> - it may need more that one spin of the PCB which will delay the delivery
> - we will use approximately 10% of the FPGA to implement the Ethernet
> interface.
>
> I'm not too concerned about using more of the FPGA since the device we are
> using is 70% larger than that used on Mercury.
>
> So "to USB or not to USB - that is the question"?
>
> 73's Phil...VK6APH
>
>
>
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