Eric Lemmon wrote: > Don, > > The "on-the-hour" tone is an 800 ms burst of 1500 Hz. I have built a PLL > 1500 Hz tone detector into a Hamtronics WWV receiver, and it works fine- > giving me a relay contact closure exactly on the hour. Unfortunately, that > would only allow me to jam-set the minutes and seconds to zero, and would > not correct an hour error- such as when DST starts and stops.
Eric, There are a number of "easy" WWV and GPS projects to drive things like Nixie clocks, etc... from simple microcontrollers like the Microchip PIC and Atmel AVR. Those are a good starting point for a project to set a controller's time remotely. Adding code to the microcontroller to then drive a DTMF encoder (or even an R2R ladder for sine-wave output from multiple digital outputs if your micro is fast enough) to set a controller's time, is fairly simple. One of the local clubs here in town has had such a system for a long time, but hasn't published anything about it. From talking with their techs, they receive WWV at a ham's house, set the clock in the Atmel, and then it has a transmitter on a common control receiver frequency for all of their machines. They had DST hard-coded to specific weeks of the year in their microcontroller code, and had to modify their code during the great DST mess that Congress created (with little to zero impact on energy use, which was supposedly their goal) the last couple of years. My club never built such a gadget, we just go in and bump the time around as necessary and don't get too wigged out if it's off by a minute or two. Everyone has network-synced cell phones in their pockets these days, and worrying about the repeater time just doesn't seem "worth it" at this point. We get it close and then have to deal with DST. We also got rid of the hourly chimes/announcements/etc. The only time you hear the time announced is after an autopatch, and that's really just in case we had a need to record the autopatch calls for abuse, etc. Building an auto-time set device and having another transmitter just seems like it breaks the KISS principle. As someone else mentioned, an IRLP node that is properly NTP synchronized can also handle sending DTMF time-set commands easily. Nate WY0X
