[hpsdr] Hermes

[Phil Harman]

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