[hpsdr] New Hermes board

Fri Jun 2 09:20:01 PDT 2017

Mine isn't working yet - it's still in a box. So I can't answer that. (I know only that pihpsdr can "see" it, so it is executing code)

I have seen youtube videos of where people have been able to improve the dynamic range of the Red pitaya by the odd 20+ dB by removing the input buffer amplifier and replacing it with a 9:1 unun transformer (essentially this gives the voltage gain at the same power by transforming to a higher impedance). That could be a part of the issue - the input circuit isn't ideal "as shipped". 

And if that technique does work, it could be something a revised Hermes might consider to replace its preamp. It hinges on the input impedance to the ADC itself. If that's a few kohms and resistive, then the transformer would work.

Laurence Barker G8NJJ

laurence at nicklebyhouse.co.uk

-----Original Message-----
From: K4KV [mailto:k4kv at k4kv.com] 
Sent: 02 June 2017 16:47
To: laurence at cmlelectronics.co.uk; hpsdr <hpsdr at lists.openhpsdr.org>
Subject: Re: [hpsdr] New Hermes board

Laurence,

I have heard reports of quite a few spurs with Red Pitaya on rx.

Can you confirm or deny this?

73

Glen K4KV

Moultrie, GA

On 6/2/2017 11:43, Laurence Barker wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
> Helmut
>
> I agree with you, but I think it would be a different project. Kjell seems not to be starting from scratch - it sounds like a lot of the thinking is already done. And it sounds like it fills a need right now. I also think Kjell's project needs some space without competition.
>
> You don't need to design & make the FPGA part; there are commercial products that do that. The bit you can't get anywhere else is the combination of ADC/DAC/clocks. Look at the "zedboard" family http://zedboard.com/ based on Xilinx Zynq; those boards could be the basis for a radio. The "Microzed" or "Picozed" board seem suitable. A possible problem is: the interface between those boards and the ADC/DAC /Clock board keeps changing. But done this way the protocol executes in C code, and the complete processing side works on day 1. For a simple radio all of the code could execute in the ARM cores. That gives a radio architecture with options for no extra processor, raspberry PI, or PC. My personal view is that's the future - but I'm not ready to start today.
>
> My plans are:
> 1. Get Red Pitaya based radio (with own design RF front end) working - 
> I'm part of the way along with that 2. Use the Red Pitaya as a testbed 
> to get hands-on FPGA design experience 3. Make an ADC/DAC front end board that attached to a "Microzed" or "Picozed" board. That way the Microzed/Picozed gives you working Zynq FPGA, running linux, working Ethernet etc; you "just" need to add the RF front end and SDR code.
> 4. I'll also look at open source software frameworks for the Linux/C/VHDL code: for example openCPI that could be relevant.
>
> Something that would help all of the projects is a modular RF front end. Alex has obsolescence issues, and is single receiver. I'd be very interested in working right now on a more modular filter/interface architecture that all similar projects could work with. I'm working on mine, but I'd abandon or adapt it quickly if something else was better.
>
> I won't be starting on the Micro/Picozed project for at least a year - partly to get the other bits ticked off, and partly because I've already spent too much money on RF bits this year. My reason for wanting to do this is simple - to be able say that I've done it. I'm quite happy to chip away for as long as it takes. I don't **need** a radio - I just want to make one, eventually!
>
>
>
> Laurence Barker G8NJJ
>
> laurence at nicklebyhouse.co.uk
>
> -----Original Message-----
> From: Hpsdr [mailto:hpsdr-bounces at lists.openhpsdr.org] On Behalf Of 
> Helmut Oeller
> Sent: 02 June 2017 08:25
> To: 'Dick Faust' <k9ivb at cox.net>; 'Kjell Karlsen' <la2ni at online.no>; 
> hpsdr at lists.openhpsdr.org
> Subject: Re: [hpsdr] New Hermes board
>
> ***** High Performance Software Defined Radio Discussion List *****
>
>
> All proposals, wishes and requirements give a clear profile. We need an advanced Red Pitaya with two 16 Bit ADC/DAC and the approved Zilinx programmable SoC, extended by an audio-codec and eventually a  2/5 W amp. The board would be diversity, undersampling and adaptive pre-distortion capable.  Flexible Nyquist filtering, RX-preamps and other RF stuff can be placed on a little separate board. Estimated cost of components can be below USD 300.- I m not kidding. Perhaps this is better approach than a face-lifting of HERMES.
>
> 73, Helmut, DC6NY
>
> -----Urspr ngliche Nachricht-----
> Von: Hpsdr [mailto:hpsdr-bounces at lists.openhpsdr.org] Im Auftrag von 
> Dick Faust
> Gesendet: Donnerstag, 1. Juni 2017 21:41
> An: Kjell Karlsen; hpsdr at lists.openhpsdr.org
> Betreff: Re: [hpsdr] New Hermes board
>
> ***** High Performance Software Defined Radio Discussion List *****
>
> Hi Kjell
>
> I have a small request in the redesign.  It would be nice if you could incorporate an output of the the 122.88MHz clock similar to the Mercury EXT CLK [J1] and a 3 pin header.  A SN65LVDS1DBVR in a SOT-23-5 is a nice small part to do the job.
>
> Thanks for your efforts, 73
>
> Dick K9IVB
>
>
> On 5/31/2017 12:42 AM, Kjell Karlsen wrote:
>> ***** High Performance Software Defined Radio Discussion List *****
>>
>> Hi All.
>>
>> Thank you all for the interest and comments about the new Hermes board.
>>
>> As I informed in my first mail, describing what the plans are, this 
>> is not a new project. The plan is to improve Hermes in many ways, not 
>> making a new Angelia or Orion board. We are going to keep all the 
>> good performance that Hermes already has and add some new features 
>> such as
>> 2 meter coverage, less power consumption, new 5W PA, new FPGA and 
>> some more I/O s.
>>
>> And we want that Hermes 2M should be possible to build by a Ham with 
>> some experience and normal tools and equipment for soldering and 
>> re-soldering. That means that there will not be any ball grid components.
>>
>> We are still open for new improvements.
>>
>> I see that many of you are going to be disappointed but if somebody 
>> wants to start a new OpenHPSDR project, that is fine!
>>
>> 73, Kjell.
>>
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