[hpsdr] Cyclops project review

[Phil Harman]

Hi Doug,

Thanks for the suggestion and we will consider that for sure.

I remember the first tube spectrum analyser I used was a plug-in for a
Tektronix 'scope.  This had a push button on it that shifted the LO and
you could then watch the display to see which direction the traces moved.

You were left to interpret the resulting display which, without any
processing to remove the image signals, was demanding at times to say the
least!

73 Phil...VK6APH


> ***** High Performance Software Defined Radio Discussion List *****
>
> Hi Phil,
>
> I like the new concept for Cyclops.  As far as image detection is
> concerned, if the center frequency  (L.O.) is increased, shouldn't the
> real signals move left in the display and the images move right?  You
> could implement a image detect/reject mode that saves the FFT and then
> increments the L.O. slightly and then compares the new FFT to the old one,
> to determine the what direction the signals in the band scope moved.  Then
> use the information to either tag (color?) or eliminate the images in the
> display.  I am probably missing something but this is how I determine if
> images are present.
>
> 73,
> Doug - W8NFT
>
>
>
> On 1/7/2012 5:06 PM, hpsdr-request at lists.openhpsdr.org wrote:
>> Date: Sat, 7 Jan 2012 19:21:35 +0800
>> From: "Phil Harman"<phil at pharman.org>
>> To:<hpsdr at lists.openhpsdr.org>
>> Subject: [hpsdr] Cyclops project  review
>> Message-ID:<222745C761574EFF9A79DC08181F7C87 at phil>
>> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
>> 	reply-type=response
>>
>> Whilst the prototype Cyclops 1GHz spectrum analyser boards are working
>> quite
>> well, over the Christmas break I undertook a review of the project to
>> see if
>> there were any new, or alternative, approaches we could take before
>> committing to further development.
>>
>> I did some experiments that are documented on the Wiki and it would
>> appear
>> that there may be an alternative, simpler, architecture that has a
>> number of
>> advantages over the current design but also some potential
>> dissadvantages.
>>
>> The write-up on the Wiki explains in some detail what is proposed. It's
>> possible that others have already tried this approach and perhaps come
>> across issues that I've not thought of so I'd appreciate comments from
>> the
>> membership.
>>
>> The Wiki write up is athttp://openhpsdr.org/wiki/index.php?title=CYCLOPS
>>
>> Comments, feedback, suggestions etc. are most welcome.
>>
>> Thanks
>>
>> 73 Phil...VK6APH
>>
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