[aprssig] HF APRS Transceiver

Scott Miller scott at opentrac.org
Sat Mar 8 00:19:41 EST 2008

> made from color burst xtals.    [SIDE THOUGHT:   Are 3.579 color burst 
> xtals going to become rare hard-to-find commodities with the switch to 
> ATSC (digital) TV???]

I doubt it.  First, NTSC is still going to be around for a long time - 
how many millions of CCTV cameras are out there?

Second, how many TVs and other devices still use an actual color burst 
crystal?  I happen to have the data sheets for a couple of 
NTSC/PAL/SECAM decoder chips here and they operate on a 14.31818 MHz 
clock, and derive all timing from that reference.  I wouldn't be 
surprised if your average modern TV doesn't have a color burst crystal 
anywhere in it.

Lots of non-NTSC devices use color burst crystals (MX-614 modems, for 
one) because they're cheap and widely available.  The crystal 
manufacturers will keep producing them because the demand is there. 
There are a lot of common crystal frequencies out there that'll be 
around for a long time - multiples of common baud rates, for example.


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