Hello esteemed time nuts, I'm looking for device with an external clock input as well as inputs for multiple PPS signals that outputs timestamped messages for each input pulse via RS232. The initial need will be for two PPS inputs. I've considered a number of options, but I wonder if there a more prepackaged solution available since the device will for someone less technical than myself.
A bit more about the device. It needs to be clocked with an external reference. Ideally, taking 10 Mhz sine from the PRS-10, but I can easily enough convert the sine wave that to a square wave. Also, I can use a TAPR ClockBox to convert to other reference frequencies. The purpose of the device will be to measure PPS periods for at least two oscillators over a course of a few months, sending the data via RS-232 to a logging computer for each input PPS input. The minimum the serial record will need to have is a time stamp of seconds.nanosecons and a label of which PPS signal triggered. About options I've considered, 1) A Soekris 4501 clocked by the PRS-10 to a ClockBox, and then using the TMR1IN and a GPIO input to time stamp the PPS signal. However, that'll require one 4501 for each PPS signal, so scaling effort is moderate. 2) Writing a firmware for an AVR XMEGA that is clocked from the PRS-10 and uses external interrupts and timers to output RS-232 messages. Certainly less expensive than #1 option, but takes more time programming. 3) Using some other micro-controller with external clock and times, perhaps an ARM. 4) Using a dedicated time counter for each PPS. However, reading the manual for my PM6680/B as well as a Agilent 53230A, that won't work because in standard gating mode, some time would be missed between PPS signals. While the 53230A has a continuous mode, that would require the polling computer to accurately keep time of the requests unless the 53230A is collecting data under its 1,000,000 sample limit (only ~11 days at a PPS). Also, at $3500 per PPS input, a 53230A is the most expensive to scale.. 5) Using a FreeBSD or Linux box with multiple RS-232 inputs and using their PPS API. However, outside of some ARM boards, I haven't found any boxes that can be clocked by a external reference. And, I haven't enough experience running FreeBSD or Linux on ARM to know how well this will work for me. 6) I'm quite familar with using something like a Thunderbolt and its PPS to make a stable clock with NTP which could be used with an Intel FreeBSD or Linux box in #5. However, rather than NTP, the device should be clocked only by the external reference clock. The goal is to see how the input PPS signals deviate from the reference clock. 7) Use a box like in #5, and capture the PPS from the PRS-10 as well and using that to scale the other PPS inputs that arrive around the same time. I've done web searches, found some data loggers, but I haven't found something that can run continuously for months collecting data and meet the other needs. I'd really like to find a more prepacked solution for the user of this device. I'm surprised by my inability find such a device for this seemingly straightforward task. Thanks for considering the issues. I feel I'm overlooking some perfect device that exists outside of just my imagination. Kevin _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.