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Date Posted: 07:25:42 09/11/02 Wed
Author: Potter
Subject: Re: new 50mhz sx-18 codes? tips?
In reply to: majikthise 's message, "new 50mhz sx-18 codes? tips?" on 12:03:11 09/10/02 Tue

Hi
Back from the dark side?
It will get a bit darker as IRD2 gets phased in at least.
I'm in a PAL area but my technique for real time fine tuning the code should work for you also. I found the 50MHz code is a bitch to set up just right and the resonators do vary quite a bit but it can be done with perseverance. I found the 20MHz SX18 version is not much worse off in terms of quality and a lot easier to get results. Simply, I used a single pushbutton to increment a counter in the code which adds 1 cycle per click to the final delay in MAKEHLINE. When the result is satisfactory I just hard code the count and burn the code into the chip and that's it.
One other tip: set the oscillator mode to HS3 and try enabling synchronous inputs.
If you've got an email address I could send an example of the 50Mz code (50Hz PAL but you'll get the idea).

>Hi,
>
>I'm back to this 3chip stuff after 2 years of living
>in digital satellite world. Amazingly, my area still
>has standard supressed sync analog cable.
>
>I built Dan's experimental board thats based on Piu's
>1.0 layout with a sx-18 and 50mhz resonator. The
>programming stuff seems to be all fine now and its up
>and running. The timing, I guess, is whats still out
>of whack here. Lock LED is blinking pretty wildly and
>is out for a good amount of time. Has anyone done any
>work on code that adjusts the timing on the fly? Or
>other new developments here? Should I scrap the 50mhz
>stuff and install a VCXO and run the 20mhz turbo code?
> I seem to remember that it may be the resonator's
>somewhat inexact frequency that may be a problem.
>Maybe I'll try a 50mhz oscillator can.
>
>anyone on ntsc still doing this stuff?

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