[hpsdr] HPSDR Update

[Phil Harman]

All.

Just arrived home after a wonderful holiday on the  east coast of the USA.
It was great to meet old friends and make some new ones. I throughly enjoyed
the TAPR/ARRL DDC and the AMSAT Conference and many thanks to both
organisations for giving me the opportunity to present the progress we have
been making on HPSDR.

Whilst at DCC I had the opportuity to test a pre-producition Mercury board
with a PicoPSU.  Unfortunatly this does not look like a good combination
since, on the low bands a least,  the PSU generates a significant number of
spurs. That is not to say that all SMPSUs will cause problems, but at least
this particular model is not recomended.

It was also great to see the interest level in relation to Mercury moving up
as I toured the East Coast.  Just a couple of reasons why you may want to
think about increasing the number of boards you intend to order.

1. I have a prototype of Cyclops working and the performance looks very
good. I'm using Mercury at 96MHz as the second IF. To do so I bypass the
55MHz LPF on the front end, this is a permanent by-pass and not somthing
that is switchable - believe me we tried hard to make it switchable but this
introduced a number of issues that we wern't willing to compromise on.  If
you are interested in possibly adding Cyclops to your HPSDR boards in the
future then a dedicated Mercury board could be a wise investment.

2.  We intend that Mercury will support multiple receivers, and I'll have
some very exciting news on that subject shortly. Each receiver will share
the LTC2208 ADC and hence whatever antenna is connected to it. If you have a
multiband antenna - say a trapped vertical - this will allow you to listen
(and see) multiple bands at once. On the other hand if you have say a beam
on 6m and a wire antenna on 160m then some form of diplexer/combiner will be
required in order to receiver both bands at once.  An alternative, which we
propose to support in the future,  is to fit multiple Mercury boards on the
Atlas bus.  Each could be connected to a different antenna and overcome the
need for broadband antennas  or combining.

We will also start the Alpha build of Phoenix shortly as well as the design
and development of  Gibralter - more on that project shortly.

Still plenty of excitement in store for the HPSDR projects!

73's Phil...VK6APH


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