[Wormnet] filter design

[mIB]

The thing is that I want to program the filter into a VHDL model -
the current vhdl technology allows to program hardware with its
own langauge. It has been a US military project, you define
ciruits by programming code and it nails as gates. Its popular
in Radio design what I have learned.
you can program multiple receivers. There is also something called 
Cellcomputing.
With other words - we have to go the long way understanding the current
technology some of it is located in the liberary - I found a nice DSP
book I read but need some help to find the answers that is behind / beneeth
the lines.


----- Original Message ----- 
From: "David R. Wilson" <david at wwns.com>
To: "mIB" <m8114 at ing-steen.se>
Sent: Sunday, December 04, 2005 6:33 PM
Subject: Re: [Wormnet] filter design


> Hello Marcel,
>
> The highest resolution with conventional hardware also means the slowest
> scan times.  The other problem you have is the wide bandwidth that your
> trying to cover.  That range of frequencies would give you problems on a
> number of levels.  A low IF frequency would give you the mix products
> inside the frequencies your looking to sample.  That would be a problem
> like the old HP 141 spectrum analyzer had with ghost images of the
> original scanned frequencies showing up on the opposite side of the IF
> frequency.
>
> You might be able to do what your looking for with DSP hardware, however
> you will be running into a sampling time problem with that due to the
> exceptionally high processing speed that would be needed to handle that
> bandwidth.  One way I could imagine making that work is multiple DSP
> filters with an IF mixing a portion of spectrum down to a base band for
> each sampling system.  That would make it possible to scan several
> sections of spectrum, however that would also get rather expensive
> quickly.  I am a bit out of date on what is available in DSP hardware,
> so there may be some hardware capable of handling more than 200 Mhz or
> so, however I have not looked for that hardware in a few years.
>
> Dave
>
>
> On Sun, 2005-12-04 at 14:54 +0100, mIB wrote:
>> Resolotion shall be highest possible.
>>
>>
>>
>> ----- Original Message ----- 
>> From: "David R. Wilson" <david at wwns.com>
>> To: "mIB" <m8114 at ing-steen.se>
>> Sent: Wednesday, November 30, 2005 7:50 PM
>> Subject: Re: [Wormnet] filter design
>>
>>
>> > Hello Marcel,
>> >
>> > Typically a spectrum analyzer sweeps through some fixed range of
>> > frequencies and records the strength of what it finds.  Since it is 
>> > only
>> > doing a sample on a very narrow spectrum at any particular time it may
>> > miss a lot of the data your looking for.  You might be able to adopt
>> > some of what the GNU Radio project is doing for your purposes.
>> > I still have not heard the frequency range you are looking to scan, or
>> > the resolution needed, or whether this would be something that would
>> > need to be used only as test equipment or possibly integrated into a
>> > tranceiver of some sort.
>> >
>> > Dave
>> >
>> >
>> > On Wed, 2005-11-30 at 12:28, mIB wrote:
>> >>
>> >> I am still figuring on this sweaping filter for the digital spectrum
>> >> analyser.  I have found by mind that the bandpasfilter must be exact
>> >> one wavelength of the given frequency one listens to so that the data
>> >> from this given frequency can be sampled and stored.
>> >>
>> >> Whats unclear is the bit deep for the A/D converter for the best
>> >> silent sampling enviroument..
>> >>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >> ______________________________________________________________________
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>> >
> -- 
> David R. Wilson <david at wwns.com>
>