[hpsdr] Comparison of Hermes to Atlas HPSDR Hardware

[Phil Harman]

Hi Rick,

Thanks for your question, I'm sure that others will be having the same
thoughts.

Hermes is basically Metis + PennyLane + Mercury + Excalibur(less TCX0) on
one board.

There are a few minor changes based on "things we would do differently if
we did these boards again" but its basically these boards plus a nice low
noise SMPSU.

So the advantages of Hermes are all the hardware has been thoroughly
tested in previous designs and everything is on one board.

Since we don't have any Atlas bus then adding additional receivers (7
currently) is simpler as will be increasing the sampling rate.

The disadvantage is that the hardware is fixed - any new features will
come via FPGA code updates.

The reason we are able to offer Hermes is because it builds on the HPSDR
boards on the Atlas bus.  Whilst others are now starting to sing the
virtues of DDC/DUC we have been using this technology for years!

Building Hermes years ago would have been a much more risky project
without the heritage of the previous HPSDR boards.

The advantage of the HPSDR boards is it provides a platform for testing
new techniques/ideas/devices as they become available without having to
design a completely new radio.

For example, the move to Ethernet from USB was relatively painless and
inexpensive and your investment in the other boards was retained. I think
that the current Alex board set will see us through many future
generations of PAs and Receivers.

Current work on a GPS locked TCXO will employ an Atlas size board. The new
high speed ADC chips will allow a Mercury II board to be built that has
multiple independent receivers and extend into the VHF region.

Cyclops will also initially be Atlas based but I am aware of the interest
in using this with Hermes so will try and incorporate a way of doing this
interface.

There is potential to replace PennyLane with a board that will generate RF
directly on 2m and 70cm.

Adding an Atlas board that has a processor running Linux is also possible
(although my personal preference is to connect the ADC directly to the PC
and do all the processing there!).

The limitation of the Atlas based designs is the speed limitation of the
bus.  However, we are currently investigation using parallel data
transmission to increase the number of receivers and sampling rates. Also,
we can, with future boards, remove the high speed data from the bus and
use say LVDS to interconnect boards.

I would expect that when some of these techniques have been proven and
tested then they will be incorporated in a HermesII.

The other thing to bear in mind is that a DDC/DUC radio will soon become a
'black box' and the users impression of the device will be via the
'window' that the associated software provides. That is one reason I'm
very excited about the work Hermann, DL3HVH,is doing with his cuSDR code
since doing as much of the signal process as possible on the PC, and
keeping it open, is the key to future innovations.

HPSDR is about being at the bleeding edge of SDR technology - others are
catching up but we are still maintaining our lead.

Hope that helps with your decision making.

73 Phil...VK6APH


>> On 7/8/2012 3:00 PM, Richard Stasiak wrote:
>> ***** High Performance Software Defined Radio Discussion List *****
>>
>> I presently have almost two Atlas HPSDR Sets. They have provided a lot
>> of fun for me over the past few years.  I am grateful to all of the
>> Amateurs that made the system a reality.
>>
>> Now that Hermes is about to be released and it has been announced that
>> there will be a two week purchase window, I am sitting on the fence
>> trying to decide whether to take the plunge and invest in the latest
>> hardware without having a lot of information to make the decision.
>>
>> One of my concerns is being left behind if all further software
>> development concentrates on the Hermes hardware and is not applicable to
>> the Atlas HPSDR set.
>>
>> Is it possible to have a comparison of the advantages and dis-advantages
>> of Hermes vs the original Atlas based board set?
>>
>> 73
>>
>> Rick ve3mm
>>
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