[time-nuts] Simulating LORAN-A GRI Timing Generator

Magnus Danielson magnus at rubidium.dyndns.org
Sat Jan 8 03:54:18 UTC 2011

On 08/01/11 03:28, J. Forster wrote:
> I'm looking at building a LORAN-A simulator to run a vintage display.

Hmm. Generating blips programmed in repetition rate and delay as steps 
of a 10 MHz clock should be sufficient and fairly straight forward. A 
lower clock such as 1 MHz would probably work well (and simplify the 
design). A programmable delay (needs to be 19 bit for 10 MHz and 15 bit 
for 1 MHz) using standard synchronous counters should not be too hard. 
Once designed it's a matter of deciding how many slaves shall be 
supported. A PIC or AVR could do the NMEA position to delay conversions 
needed, and I mostly worry about the math-support on them, which only 
shows that I haven't done any real project on any of them.

> I used to design stuff with gates and counters by hand, and can still do
> so, but it's tedious.
> Does anyboby know of any freeware that can be used to draw up logic and
> simulate its operation, including propagation delays? I don't need exotic
> chips or any analog functions. A library of common 74...  and 40.. would
> be nice.
> Freeware strongly preferred.

Eagle, GEDA/GNUCAP, Electric and KICAD would be my main suspects.


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