[hpsdr] libusb, Vista/Win 7 and Kiss now working

[Al]

A close varient of this speech processor technique was implemented in 
the hardware speech option for the Collins KWM-380 in 1980...  This form 
of instantaneous envelope limiting seems to be very effective and has 
near absolute control of the speech envelope peak with minimal 
distortion products.

AL, K0VM

> Date: Sun, 17 Jan 2010 11:37:15 +0800
> From: "Phil Harman" <phil at pharman.org>
> To: "Alberto I2PHD" <i2phd at weaksignals.com>
> Cc: HPSDR <hpsdr at openhpsdr.org>
> Subject: Re: [hpsdr] libusb, Vista/Win 7  and Kiss now working
> Message-ID:
> 	<89c23ecd861a8373542ae325d3101b55.squirrel at webmail.eftel.com>
> Content-Type: text/plain;charset=iso-8859-1
>
>
>> > Phil,<br>
>> > <br>
>> >   do you have any documentation on this ? Also the source code of the
>> > routine could be of help, without having to dig it out from the SVN. Or
>> > at least a pointer to the<br>
>> > specific file in the SVN where it can be found. And, better yet, a few
>> > lines maybe from Peter describing the algorithm behind.<br>
>> > <br>
> Hi Alberto,
>
> I'll do a block diagram of this shortly but my drawing tools are on my
> shack PC and it 42C today so sending this from the comfort of the A/C
> study.
>
> Lyle's link is correct but Peter shared this with me some time ago in
> relation to his 3rd method SSB generation technique.
>
> Assuming your mic signal is a float, ± 1.0 max.
>
> - Create a complex signal from the mic signal
> - Multiply I and Q by the required compression gain
> - Calculate the envelope for each I&Q pair i.e. E = SQRT(I2 + Q2)
> - if E > 1 then divide I by E.
> - This divided signal becomes your new mic signal.
>
> Really simple but really effective, and impossible to do using analog
> techniques.
>
> KISS Konsole uses mic AGC and an optional 6dB per octave bass cut before
> the clipper.
>
> 73's Phil...VK6APH
>

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