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

J. Forster jfor at quik.com
Sat Jan 8 04:04:38 UTC 2011


See my post of a few minutes ago.

The GRI and Delay counters need to be 5 decimal digits. My current
thinking is manual entry of the numbers via BCD coded thumbwheel switches.

LORAN-A has 24 possible GRIs; in three blocks of 33 PPS; 25 PPS; and 20
PPS. It also has 4 RF frequencies.

Currently I plan only one Slave, but a second would be an easy addition.



> 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.
> Cheers,
> Magnus

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