It's most likely a binary signal (BCD - binary coded decimal) that is
lighting the segments of the LCD. You may have a voltage to freq.
converter running to a counter then to your BCD decoder or the voltage
amplitude is being sampled and running to the BCD decoder. Also
probably using grey scale coding to prevent the read out from jumping
all over the place....

"AHS3903" wrote in message
s.com...
I have a Brantz International 2 Pro rally trip meter which can, when
seleced
by a toggle switch, give a display of your average speed on an LED digital
display.
This trip meter is positioned in fron to the navigator in Targa Rallying
and
I want to duplicate the average speed readout on a panel in front of me,
the
driver.
What is likely to be the signal that creates this digital display, would
it
be a voltage that is interpreted by the LED readout or some thing else
entirely?
Any help or guidence on how to do this would be very much appreciated.

Mike S