[hpsdr] Hermes

Robert Meuser w2xj at nyc.rr.com
Wed Aug 11 09:11:15 PDT 2010 


Subject: Re: [hpsdr] Hermes

I think at this point USB is just an unnecessary bottleneck to
experimentation with Hermes. Beyond the complexity of supporting two
hardware interfaces, the ongoing issue of supporting two sets of drivers for
software could be a problem. There is not much difference between a limited
length USB cable between the radio and the computer and an Ethernet
crossover cable of the same length. On the other hand, Ethernet permits
wireless connections, fiber optic and wide area connection which will permit
things previously extremely difficult for the experimenter.


On 8/10/10 10:25 PM, "Rob Frohne" <rob.frohne at wallawalla.edu> wrote:

> ***** High Performance Software Defined Radio Discussion List *****
> 
> Hi Phil,
> 
> That is more pins than I thought (without looking).  I'm still in favor
> of the Ethernet, but I was trying to make sure that there wasn't an easy
> solution that would make everyone happy.
> 
> 73,
> 
> Rob
> 
> On 08/10/2010 06:57 PM, Phil Harman wrote:
>> Hi Rob,
>> 
>> I will look at that since it would solve the problem of FPGA pins. One
>> other advantage of the Ethernet solution is that a 125MHz clock is all we
>> need for the entire board.  We would need an additional 24MHz clock for
>> the USB.
>> 
>> Jumper selecting some 20+ pins could also be a problem particularly since
>> the PHY data is at 250MHz.
>> 
>> I've also had a chance to use the Ethernet connection to HPSDR for a few
>> days.  It is so much nicer than USB. No driver issues, at Gig-E I can
>> unplug all the cables (with the PC and OyzII still connected) and plug
>> then back in and it all starts automatically.
>> 
>> 73's Phil...
>> 
>> 
>> 
>>    
>>> Hi Phil,
>>> 
>>> Have you considered possibly having both circuits on the board, so that
>>> one or the other could be selected with a set of physical jumpers to
>>> connect the pins to the USB part or the ethernet part of the circuit?
>>> 
>>> 73,
>>> 
>>> Rob
>>> 
>>> On 08/05/2010 08:20 PM, Phil Harman wrote:
>>>      
>>>> Hi Rob,
>>>> 
>>>> I don't think we will have enough FPGA pins to have both options.
>>>> 
>>>> 73's Phil...
>>>> 
>>>> 
>>>> 
>>>>        
>>>>> ***** High Performance Software Defined Radio Discussion List *****
>>>>> 
>>>>> Hi Phil,
>>>>> 
>>>>> I vote for ethernet as well, but I'm wondering how much it would add to
>>>>> the complexity and cost to leave the USB interface on there as well.
>>>>> 
>>>>> 73,
>>>>> 
>>>>> Rob, KL7NA
>>>>> 
>>>>> On 08/04/2010 07:18 PM, David McQuate wrote:
>>>>> 
>>>>>          
>>>>>> ***** High Performance Software Defined Radio Discussion List *****
>>>>>> 
>>>>>> I vote for Ethernet.  (I believe I heard you had a way of loading the
>>>>>> FPGA over Ethernet. True?)
>>>>>> 73,
>>>>>> Dave
>>>>>> 
>>>>>> Phil Harman wrote:
>>>>>> 
>>>>>>            
>>>>>>> ***** High Performance Software Defined Radio Discussion List *****
>>>>>>> 
>>>>>>> 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
>>>>>>> 
>>>>>>> 
>>>>>>> 
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>>>>>>> 
>>>>>>> 
>>>>>>>            
>>>>>> _______________________________________________
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>>>>>>            
>>>>> --
>>>>> Rob Frohne, Ph.D., P.E.
>>>>> E.F. Cross School of Engineering
>>>>> Walla Walla University
>>>>> 100 SW 4th Street
>>>>> College Place, WA 99324
>>>>> (509) 527-2075    http://people.wallawalla.edu/~rob.frohne
>>>>> 
>>>>> _______________________________________________
>>>>> HPSDR Discussion List
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>>>>> 
>>>>>          
>>>> 
>>>>        
>>> --
>>> Rob Frohne, Ph.D., P.E.
>>> E.F. Cross School of Engineering
>>> Walla Walla University
>>> 100 SW 4th Street
>>> College Place, WA 99324
>>> (509) 527-2075    http://people.wallawalla.edu/~rob.frohne
>>> 
>>> 
>>>      
>> 
>>    

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