[Lowfer] Billboard display - LEK

[Lyle Koehler]

>No way to slow down the modulation so that you would have something closer
to 30 sec dot times?

Slowing down the modulation is easy. The timing factor is expressed as a
4-digit hexadecimal number in the device EEPROM, and my present setting is
00 A0. Lots of room for expansion there!! The frequency resolution of the
exciter is the limiting factor. With a 12.8 MHz clock, the smallest
frequency steps are about 0.085 Hz, and I am presently using a frequency
shift of 4 steps between rows in the display. Reducing this to the minimum
of 1 step, and increasing the timing factor by a factor of 4, the result
would be approximately 30-second dots and a total bandwidth of about 0.34
Hz. I think that's about as slow as it makes sense to go, anyway, because of
the QSB cycle time. The Argo settings would probably have to be something
like QRRS60, slow mode. I'll run it that way for a while this afternoon and
see what the characters look like on the screen.

Lyle