Hi Didier, a time (GPS) and date display would be excellent, the only really useful enhancement might be a 60th second output, one pulse per minute. That would enable quite a few useful timing functions in conjunction with the PPS signal. Outputting the formatted time data may start to get very specific to a project, but the pulse per minute overcomes a major part of the problem of identifying which pulse is which with the PPS at little cost to the project. Neville Michie
On 06/10/2008, at 12:13 PM, Didier Juges wrote: > > >> -----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. _______________________________________________ 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.
