Fellow time nutters: Any input or advice on the following project would be appreciated.
I want to make a small, portable, batter-operated clock that will spend most of its time docked into a charging bay with access to a signal from a GPS receiver -- either 1 PPs or 10.00000000 MHz. The device will have a voltage-controlled TXCO that will be disciplined by the GPS input unless the unit is traveling. I have seen several designs for disciplined oscillators using a uP, such as an Arduino or a PIC. The main decision seems to be between 1 PPs or 10 MHz as the input. 1 PPs might be preferable because not all cheap GPS receivers seem to provide 10.000000 MHz out. Mostly, I want accurate time but a frequency reference with decent phase noise would be useful. 1. I am tending towards a published design from Lars Walenius, in part because it uses a familiar uP (an Arduino) but am open to other designs. 2. What advice to people have on glitch-free switching when docking/undocking the unit from the GPS??? This seems to be something like the de-bouncing problem for a push-button. 3. Has anyone used the Arduino time library withOUT the Dallas RTC chip -- i.e., some other source of time such as the from the locked oscillator? 4. Can anyone share experience with conditioning the power going into the TXCO -- to what extent can digital noise from the uP or counters contaminate the phase noise of the TCXO? Does a separate isolating buffer help for the "osc out" port? I have had good success in the past with so-called "active bypassing" to deliver very clean power to an oscillator. Thanks to all for your attention to this message -- I am glad to look at any and all possible designs. Happy time-keeping! _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
