Firstly for our American friends, we also have chocolate fire guards in the UK, but as no one can afford fuel anymore they are soon to be relegated to the bin. Perhaps in 39 years someone will start
www.chocoloatefireguardchocolate.com !
Also assuming 1 gallon = 4.55 litres, we pay rought £1.10 per litre so thats about £5 per gallon or roughy $10 - how much does anyone else pay around the world ????
but to be serious....
i'd be interested to see an alternative to doing 90degree shift in software other than a hilbert transform, if someone could post I'd be gratefull.
The willcox patrent
http://www.freepatentsonline.com/3944735.pdf has a host of goodies in it.
I've read it about 50 times and each time I get a bit more into, the maths are way beyond me. What I get from it is essentuialy each channel is made up of its original content + other channel information at various phase shifts and applitude that cause crosstalk.
What you have to do for each channel is see what shouldn't be there and remove it and at the same time make sure that the total power output from all 4 channels remains the same as the original level (I suspect if this doesn't happen correctly you get the classic "pumping" of logic decoders)
To implement in software would be possible as it's all basic maths on a sample at the end of the day, it would take time to execute as you have to apply some quite involved maths to each sample . This is the what the detector does in the original patent.
If someone could explain how to do the identification I can probabbly provide the coding skills.
Interesting the patent talks about a different set of values fo SQ and QS so it would be possible to set up a common "logic" module to handle any basic decodes from both systems.
I've previously written about the developent of a basic SQ decoder (with some blends from the mc1312 data sheet) which I can resurect if any one is interested.