[GreenKeys] Range and Bias

[COURYHOUSE at aol.com]

Great explanation Jeff  Thanks!
 
Ed#
 
 
In a message dated 7/21/2013 8:43:39 A.M. Mountain Standard Time,  
jdangus at att.net writes:

All in  all the operation of the selector magnet and the range finder is  an
absolute marvel when you come to think about what it really  does.

It begins with the start pulse. The selector lets go and trips  the clutch
to start the "lets go and see what happens during one  revolution."

The combined mechanical levers, clutch and rotating shaft  are in effect,
just a 5 bit serial in parallel out shift  register.

As the shaft rotates, it takes a sample of what condition the  selector
magnet is in. This "look" is only about 1-2 mS long. The  equivalent
electronic analogy would be "sample and hold" or in the case of  a
digital shift register, the clock signal that loads each sequential  bit.

Normally, the "look" is down at 33 mS after the the start pulse  leading
edge. That would put it right in the middle of the first data bit.  Then the
next 4 "looks" are done every 22 mS.

Depending on the  amount of distortion, meaning the mark to space or
space to mark  transitions not being where they should be, the range
finder will allow you  to move the "look" slightly before or after the
middle of the data bit to  correct for the transitional errors.

As the shaft continues to rotate,  after the 5th data bit is "stored" the
machine "strobes" the register and  outputs the data. By printing or
doing one of the other  functions.

The reason for the extra 1/2 width stop pulse it to give the  machine
time to settle in case it's not quite running at the correct  speed.

Then it waits for the next start pulse to go through the entire  sequence
again.

The ranger finder does not change the sampling  interval. That is fixed
by the machine speed. But it does skew it one way  or the other time
wise to help deal with transitional  errors.

Jeff-1.0
wa6fwi

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