I decided to make it a separate post.
Some updates, I still have not been able to get my unit to output 1 pps, I ended using a picdiv to do this for sync from GPS pps then driven from the 10MHz from the SA.22C.
Second I've gotten the unit partially tuned to the GPS. it's an involved process but will outline for anyone interested, I now have 3 unit totally in-sync with a small deviation but drift between them at about 7ns per 18 hours based on my scope (1 unit tuned below to the GPS and the other tuned to the pps of the first unit using picdiv).
Steps used:
1) Get LH 6.14, a GPS that outputs a PPS, a terminal software (putty?) for com access and of course a ttl - serial and interface working for the unit.
2) Use a very stable GPS module (I've used the "Huawei" GPS modules both the ublox LEA-8T and the trimble -- the trimble one is far superior as it actually does it's survey automatically and synthesizes the pps! while you need to manually tune the ublox and it's PPS will vary to the GPS signal quality)
3) start up your terminal software, set the control register to 0 (it enables everything) and exit
4) Make sure the SA.22C has been running for at least 6 hours
5) Start lady heather, set the com port and issue /rxsa (/rxsb if confirm a non 60Mhz crystal??).
6) issue "&" then "a" in lady heather, and give it a period of 12 hours (43200)
7) let it run and complete note what it's set the DDS to, if you have any value at e-13 leave it there's no point it's already as good as it gets based on it's spec sheet..
![Cool 8)](https://www.eevblog.com/forum/Smileys/default/xcool.gif.pagespeed.ic.cOxV6sPNRd.png)
if you have e-12 or worst (ie anything at e-11, e-10, or e-9), take the first set of numbers so let's say -5.1234e-10. take that and do -5.1234 x 10^(11-##) so in this example -51.234
9) start up the terminal software
10) set the dds to 0 (f then 0)
11) set the dds to the value from 7 (from example f then -51.234)
12) save (t and 5987717)
13) exit terminal software, repeat 5 to 12, until your last two reading are e-12 or you get an e-13, and if you never get to two e-12 values in a row then your GPS pps has way too much variability.
Notes:
-- if you have a scope you can check it or if you have a GPSDO, you can also compare it to that to verify you've moved to the right direction and stability before doing step 12.
-- from what I can tell the t does save the f value on save, once saved the f value seems to be reset to 0 again, or I lucked out in my limited testing between 3 units split in the method above.
-- j command in the terminal software clearly shows it is tracking the pps (you can remove the source and see the value change).
Update 2: Sorry I had the wrong base unit it should be e-11, I've updated this in the write up to also cleaned up the language a bit.