[hpsdr] Introducing the Hermes-Lite

Sun Apr 13 21:55:00 PDT 2014

I definitely think there needs to be some thought on what, if any 
changes should be made. Obviously, in order to get the price in the 
range where it is, this is a very minimalist design. There's no I/O on 
the board other than the antenna connectors. The I/O is either on the 
FPGA board (LAN connector to talk HPSDR protocol) or non-existant, i.e. 
you have to use your PC I/O.

I'm thinking about the various differences in terms of where this fits 
in compared to the SDR stick boards, etc. The main thing this brings to 
the table is transmit capability at low cost. If you just want receive 
you'd be better off with a SDR stick HF1 board. However if you want 
transmit capability you need to buy the HF2 and the TX2 which gives you 
Hermes equivalent performance at a price that is a significant part (but 
still cheaper) of the cost of a full Hermes board.

If I am reading the specs correctly, the output is 10 mW. I'm wondering 
what functionality could be added to the board without significantly 
raising the price. In my opinion, some sort of gain stage that could get 
the output up into the range of 100-500 mW would make sense if it could 
be done relatively cheaply.

I think there definitely needs to be some further development on this 
idea before a significant number of people jump in. Also, I think we 
need a more complete enumeration of what you get and what you don't get 
in terms of performance and features, in order to properly set 
expectations. This is a Hermes "Lite", so there are significant 
tradeoffs, but that shouldn't surprise anyone given the price.

What do others think?

John
AC0ZG

On 4/13/2014 5:01 PM, John Marvin wrote:
> Steve,
>
> This is really cool! I suspect this is going to take off, especially 
> if TAPR is willing to produce finished boards (after a little more 
> shakedown and polishing by early adopters). Even if not, I've been 
> wanting to take my surface mount skills to the next level, but wasn't 
> willing to try something as expensive and as complicated as a Hermes 
> board from scratch.
>
> So, who wants to be in the first wave of early adopters? Can we get 
> together a group purchase of PCB's and components? Perhaps there 
> should only be a small number of people in the first wave, who are 
> willing to build immediately and help refine things for the next 
> group. I'm willing to help or coordinate things, but I would need help 
> with understanding and completing the process of preparing the gerber 
> files for submitting to a PCB vendor. I would also need someone else 
> to do any modifications that might be required (since I am not 
> familiar with the tools involved), based on Steve's replies to the 
> questions below?
>
> Some quick questions and a request:
>
> 1) The picture you provided showed some small jumper wires, one on the 
> FPGA board and one on the Hermes Lite board.  What were these required 
> for? If required, I'm assuming the Hermes Lite board can be modified 
> to remove the need for the jumper wire, correct? Are there any more 
> jumpers that are not visible?
> Any other changes you would suggest for a version 2 board?
>
> 2) Any chance you could provide higher resolution photos of both the 
> front and back of the Hermes Lite board without the FPGA board attached?
>
> Thanks!
>
> John
> AC0ZG
>
> On 4/13/2014 4:05 PM, Steve Haynal wrote:
>> ***** High Performance Software Defined Radio Discussion List *****
>>
>>
>>
>> Hello List,
>>
>> I have been working on a lower cost variant of the Hermes which I am 
>> calling Hermes-Lite. All the details are at
>>
>> https://github.com/softerhardware/Hermes-Lite
>>
>> The design is entirely open source and open hardware. The cost of all 
>> materials (including the BeMicro SDK board) is around $150. The FPGA 
>> firmware is a port of the Hermes RTL and is compatible enough to work 
>> with existing Hermes software. The ADC/DAC is the AD9866 12-bit 
>> integrated device intended for cable modems which I have repurposed 
>> as a 0-36 MHz transceiver. RX/TX tests of my prototype show good 
>> performance. The github site has instructions for listening to the 
>> receiver online.
>>
>> I had hoped to have a more polished project before releasing, but I 
>> am starting a new job tomorrow and will have limited time for this 
>> project. Any help on this project or derivatives is welcome.
>>
>> Thank you to all the people at openhpsdr who developed the Hermes and 
>> provided valuable IP to reuse in this project.
>>
>> 73,
>>
>> Steve
>> KF7O
>>
>>
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