----- Original Message ----- From: "Peter" To: "Microcontroller discussion list - Public." Sent: Thursday, January 12, 2006 1:18 AM Subject: Re: [PIC] Fine-tuning oscillator > Similarly, one could tune to 15625 Hz horizontal line freq. anywhere > near a TV (certainly in a house and withing at least 10 meters of any > working normal size crt TV), using a ferrite antenna not unlike tuning > into a LW atomic clock frequency. In fact I have built such receivers > before (receiving TV line freq. radiated as H field by the deflection > coil assembly), but for a different purpose. A clock referenced to this > frequency should be as good as the (digital) clock of the transmitter > chain, and better than the color subcarrier probably. Of course the TV > will have to be on air (cable box or sattelite). Watching DVDs or > Nintendo won't work. I don't think that any digital sattelite or cable > box can get away with an unsynched data stream. It would frame drop like > crazy (this is very annoying to spectators). Due to the synchronizing technology of a TV the V + H rates are not exact what you can name a "standard". A much easier way is to use an ISDN telefon line or if a SDH/SONET transmission line with operators tact is in use to apply the tact frequency to a quartz oscillator for synchronizing . The ISDN line tact or the transmission line tact is in minimum bound to a time signal broadcaster (better than 1 ^-12), mostly to a caesium or rubidium atomic clock (better than 1 ^-16). Regards Enrico -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist