> -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Neville Michie > Sent: Sunday, October 05, 2008 5:20 PM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] TBolt Monitor > > The clock displays are of two types. The analogue dials use > alternate negative and positive pulses and are easily > generated with a 0.5 Hz square wave signal. These dials are > either slaves from master clock systems or a cheap quartz > clock dial with leads to the driver coil. A totem pole driver > drives a capacitor that delivers the appropriate impulse to > the dial motor. This can be conveniently generated by a PPS > signal straight from the TBolt. > The other display is a series of decimal counters decoded to > produce a 60 X 60 X 24 display. This also can be driven from > the PPS from the TBolt. > The problem is setting either clock to UTC (or local time). A > pulse counting system can always either miss a pulse or > respond to a glitch to get the count out of sequence. A two > phase clocking system can reduce this problem but there still > remains the problem of start up and confidence checking. > The TBolt could just drive the displays directly, but loss of > signal or power drop-out requires a procedure to > resynchronise the indicators and it would be better to have > the displays autonomous in the absence of the GPS timing. I > am thinking of a TCXO to carry over the timing for long power > failures, that can be done with a milliwatt. > Leap seconds are another consideration, so what I think might > be most useful is a BCD seconds output from the monitor. > This could be jammed into the pulse counter to correct it and > could be decoded to give one minute pips like WWV to set an > analogue dial. > Just having a low power monitor indicating UTC is 99% of the > required solution. > All of this is the alternative to running a PC to support the > TBolt and so avoid the power demand and inconvenient size of the PC. > So what I want is a tiny black box to connect to the TBolt > that would indicate UTC. Constructing a micro project is no > problem, but the program development and installation is a > sticking point. > cheers, Neville Michie >
Neville, All this is quite feasible, but would require more time and motivation than I have for this at the moment. However, the Tbolt Monitor outputs GPS time on its display, and it would be easy to output the time and/or date in BCD in sync with the GPS packets on the serial port, or in an serial SPI format. I anticipate having a real PWB for the Tbolt Monitor in a month or two, if you can wait, that will be an easy fix. Didier KO4BB _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
