The Best Name for Signal Recovery Matched Filtering

On 4/19/2012 2:43 PM, Bret Cahill wrote:
> I just assumed "matched filtering" included the deconvolution and
> other steps to recover the original signal's shape.
>
> In this case it was actually easier to invent a new filter -- I
> assumed it already existed --  than to be scholarly and do some
> research.
>
> To avoid confusion with the terminology from now on the filter that
> takes the convolution of a noisy signal like a conventional matched
> filter and then takes the deconvolution to recover the original wave
> form should be called "signal recovery matched filtering."
>
> This will distinguish it from the signal detection matched filter
> _even if the new filter is used for signal detection_.
>
> I've updated http://www.bretcahill.com to reflect the new terminology.
>
> If anyone can think of a better name, i.e., the "Cahill Filter" please
> post.
>

Filtering (convolution) in the time domain is multiplication in the 
frequency domain, and is therefore associative.  If you apply a filter F 
and its inverse F^-1 to a signal G,


F^-1 (F G) = (F^-1 F) G = G.

No free lunch, I'm afraid.

(I once tried something reminiscent of that to improve loop stability of 
a PLL.  It turned out that I'd made an algebra error, and was in fact 
trying to make a time machine.  It didn't work.) ;)

Cheers

Phil Hobbs




-- 
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

Phil Hobbs wrote:
<snip>
>
> (I once tried something reminiscent of that to improve loop stability of
> a PLL.  It turned out that I'd made an algebra error, and was in fact
> trying to make a time machine.  It didn't work.) ;)
>

I've been trying to make a time machine* all week. It's damned 
difficult, I must say!

*In this case, a filter with alpha of 0.001 with no delay. Er
rather, a filter plus some other furniture. Or, as
it turns out, not. Stupid Second Law!

> Cheers
>
> Phil Hobbs
>
>
>
>

-- 
Les Cargill

On 06/26/2015 11:08 PM, Les Cargill wrote:
> Phil Hobbs wrote:
> <snip>
>>
>> (I once tried something reminiscent of that to improve loop stability of
>> a PLL.  It turned out that I'd made an algebra error, and was in fact
>> trying to make a time machine.  It didn't work.) ;)
>>
>
> I've been trying to make a time machine* all week. It's damned
> difficult, I must say!
>
> *In this case, a filter with alpha of 0.001 with no delay. Er
> rather, a filter plus some other furniture. Or, as
> it turns out, not. Stupid Second Law!

Gummint has time machines. But they don't much understand how they work. 
They ship things off into time but they don't come back until much 
later. They have no idea where they went.



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