Hi-resolution Crank angle sensor

[Peter Wales]

>
>
>> >Not necessary. Add one sensor instead.
>> >
>> >
>> >  *     x
>> >  _   _   _   _   _   _
>> >_/ \_/ \_/ \_/ \_/ \_/ \_
>
>Peter Wales wrote:
>
>> This doesn't make sense. For every peak there will be a trough and each
>> sensor will detect the same thing.
>
>Ah, but the key is in the phase difference between the two sensors.  This 
>will only work if the tooth is asymmetrical, ie the peak is much narrower 
>than the trough.  Assuming that this is the case, sensor waveforms will 
>appear like this:
>                 _       _       _       _
>Sensor A   _____| |_____| |_____| |_____| |_____
>             _       _       _       _       _
>Sensor B   _| |_____| |_____| |_____| |_____| |__
>             _   _   _   _   _   _   _   _   _
> A + B     _| |_| |_| |_| |_| |_| |_| |_| |_| |__   (logical OR of the two)
>
>Voila, double the output frequency.  

Ah ha, now I see it. However, getting an asymettrically toothed flywheel
won't be easy. Would this still work if the pickup was moved away from the
tooth to make only the peak of the tooth effective, thus changing the m/s
ratio artificially.

As a matter of interest the Nissan 300 ZX Twin Turbo distributor has 2
sensors in it. One reads crank angle from the 360 lines on the disc and the
other reads an encoded cylinder number from the 3 digit code. Japanese
engineering!
Peter Wales
President Superchips Inc
Chairman Superchips Ltd        "Timing is everything"
Superchips home page with all the answers http://www.superchips.com