Re: [time-nuts] Precisione GPS based led clock
A straightforward solution would be to use a string of divide-by-ten and divide-by-six BCD counters (HC390). First divide the 10 MHz output from a GPS receiver down to 100 Hz and feed that to the input of a divide-by-100 counter for the 1/100 seconds display, then to a divide-by-60 for the seconds and so on. The BCD counters would feed a series of eight CD4511 or equivalent decoders as previously suggested. The 1 PPS output from the GPS, properly stretched, could be used to reset the 1/100 s counters and to clock the seconds counter. Pretty straightforward and no display multiplexing, but a lot of wiring. Getting the time from the GPS to the clock circuit would be a little more complicated, and would almost certainly require some kind of microprocessor or PIC. One solution is to synchronize the clock to the GPS once a day at local midnight using the reset inputs to the counters. This would be relatively simple to do with a PIC, I would think, and would still leave the clock section alone, without the need for complicated wiring or deciphering of the display. I designed a similar clock, although without the 1/100 s digits display and using an OCXO rather than a GPS receiver. In the end I used an MK50250N clock chip I purchased on eBay, same chip I used back in 1974 to build a small alarm clock. This clock chip uses a multiplexed display, which might not work with a video recorder or camera. -- Flemming Larsen Fra: paolo.mart...@alice.it paolo.mart...@alice.it yes, I am working with for a timestamp on a FireWire Camera (MARLIN CAMERA) Unfortunately no free software can timestamp frame withouth data loss. My camera is unable to carry out an atuomatic timestamp (it is and old version). Thank you for info Paolo Martini ___ 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.
Re: [time-nuts] Precisione GPS based led clock
t...@leapsecond.com said: If you use 16- or 24-bit serial-parallel-latches or port expanders then you only need 2 or 3 pins of the microcontroller. Use one or more '595 or look at the wonderful chips by Unitrode/Allegro. There is still the problem of updating all of the expander chips at the same time. Here is a possibly crazy idea: use the decimal point. I think this recipe works: 1: figure out which digits you want to change 2: starting from the right, turn on the decimal points of those digits 3: again, starting from the right, update the digits and turn off the decimal points The clock ticks when you turn off the bottom decimal point. When reading: If the bottom decimal point is on, ignore the decimal points. You are in step 2. If the bottom decimal point is off but others are on, you are in step 3. The digits with the decimal points on need to be bumped by one. -- These are my opinions, not necessarily my employer's. I hate spam. ___ 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.
Re: [time-nuts] Precisione GPS based led clock
t...@leapsecond.com said: If you use 16- or 24-bit serial-parallel-latches or port expanders then you only need 2 or 3 pins of the microcontroller. Use one or more '595 or look at the wonderful chips by Unitrode/Allegro. There is still the problem of updating all of the expander chips at the same time. Hal, The expanders I've seen have serial-in and serial-out. So the trick is you daisy chain the serial lines of the chips but drive the latches in parallel. That way you can quietly shift in all N bits and then latch one and all. /tvb ___ 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.
[time-nuts] Precisione GPS based led clock
Dear all I am an amateur astronomer working in the field of minor planet occultation. To arrange a precise reference time I am looking for a 1/100 sec LED dispaly clock GPS based. (LED is usefull for night vision) My idea is to use a ebay used master clock such as ThunderBolt GPS disciplined clock to drive a timecode display. Particulary I wish to realize a PIC based LED clock to display hour min sec and use the 10 MHz reference to arrange an 1/10 and 1/100 sec disaply. Can anyone help me in finding schemes or any more flexible idea? thanks ___ 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.
Re: [time-nuts] Precisione GPS based led clock
Dear all I am an amateur astronomer working in the field of minor planet occultation. To arrange a precise reference time I am looking for a 1/100 sec LED dispaly clock GPS based. (LED is usefull for night vision) My idea is to use a ebay used master clock such as ThunderBolt GPS disciplined clock to drive a timecode display. Particulary I wish to realize a PIC based LED clock to display hour min sec and use the 10 MHz reference to arrange an 1/10 and 1/100 sec disaply. Can anyone help me in finding schemes or any more flexible idea? thanks A small Netbook PC locked to a good local NTP server should be able to achieve that. Your local NTP server can be locked to GPS (ideally) or to the Internet. GPS devices: http://www.satsignal.eu/ntp/FreeBSD-GPS-PPS.htm http://www.satsignal.eu/ntp/Sure-GPS.htm The PC's screen refresh rate would be marginal for 1/00s, though. Perhaps 1/20s is more realistic. If 1/10s is good enough, there are applications like Emerald Time for your iPad/iPhone: http://emeraldsequoia.com/et/index.html Are you actually trying to timestamp a video recording or light-level reading? Or time pressing a button? Cheers, David -- SatSignal software - quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ 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.
Re: [time-nuts] Precisione GPS based led clock
Hi Paolo! On 03/11/2011, at 10:44, paolo.mart...@alice.it paolo.mart...@alice.it wrote: Dear all I am an amateur astronomer working in the field of minor planet occultation. To arrange a precise reference time I am looking for a 1/100 sec LED dispaly clock GPS based. (LED is usefull for night vision) My idea is to use a ebay used master clock such as ThunderBolt GPS disciplined clock to drive a timecode display. Particulary I wish to realize a PIC based LED clock to display hour min sec and use the 10 MHz reference to arrange an 1/10 and 1/100 sec disaply. Can anyone help me in finding schemes or any more flexible idea? thanks I am, at the moment, developing a led clock with an Arduino board that synchronizes its clock with the use of a NTP GPS server in my LAN. The clock can be configured through telnet and it syncs with the NTP server every 8 seconds. I expect to have it ready next week. I can send you the schematic if you so desire. Cheers, Miguel ___ 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.
Re: [time-nuts] Precisione GPS based led clock
Hi, Obviously you cannot read a 100Hz display. I assume you have some kind of signal that you want to use to generate a timestamp, like a stopwatch but for absolute time rather than relative. Some timing GPS receivers have a trigger (event capture) input that generates a time stamp. Trimble's Acutime and earlier Palisade units have this feature. The acutime has an event resoultion of about 0.5uS, 20,000 times better than your 1/100 of a second requirement. I have a used Palisade that I could sell you. The manual is here http://www.dc2light.pwp.blueyonder.co.uk/Webpage/PALISADE-Manual.zip I'm in the UK. Regards, Robert G8RPI From: paolo.mart...@alice.it paolo.mart...@alice.it To: time-nuts@febo.com Sent: Thursday, 3 November 2011, 10:44 Subject: [time-nuts] Precisione GPS based led clock Dear all I am an amateur astronomer working in the field of minor planet occultation. To arrange a precise reference time I am looking for a 1/100 sec LED dispaly clock GPS based. (LED is usefull for night vision) My idea is to use a ebay used master clock such as ThunderBolt GPS disciplined clock to drive a timecode display. Particulary I wish to realize a PIC based LED clock to display hour min sec and use the 10 MHz reference to arrange an 1/10 and 1/100 sec disaply. Can anyone help me in finding schemes or any more flexible idea? thanks ___ 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. ___ 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.
Re: [time-nuts] Precisione GPS based led clock
Hi Paolo: Is there some reason for not using the Kiwi Video Time Inserter, it was made for occultation timing.? http://www.pfdsystems.com/kiwiosd.html Have Fun, Brooke Clarke http://www.PRC68.com http://www.End2PartyGovernment.com/ paolo.mart...@alice.it wrote: Dear all I am an amateur astronomer working in the field of minor planet occultation. To arrange a precise reference time I am looking for a 1/100 sec LED dispaly clock GPS based. (LED is usefull for night vision) My idea is to use a ebay used master clock such as ThunderBolt GPS disciplined clock to drive a timecode display. Particulary I wish to realize a PIC based LED clock to display hour min sec and use the 10 MHz reference to arrange an 1/10 and 1/100 sec disaply. Can anyone help me in finding schemes or any more flexible idea? thanks ___ 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. ___ 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.
Re: [time-nuts] Precisione GPS based led clock
I also have had need of a high resolution display clock for photographic time stamping. For those of you working on this make sure not to use a LCD or VFD display. The response time is too slow. Also you can rule out any sort of TV display. If using LED make sure not to multiplex the digits. This is a common trick, especially when using microprocessors, and works well for human eyes, but fails completely with high resolution photos. So having ruled out everything but direct drive LED the only other concern is to make sure the decade counters which drive the display are synchronous or at least that all the digits are latched at the same time. Otherwise you get false readouts due to ripple carry or sequential scan. Be careful using a microprocessor for this. For millisecond displays you need a total of 21 pins; for microseconds you need 42 pins. An external serial-parallel (e.g., shift register with latch) chip might be safer since neither a PIC nor an Arduino can update that many pins in one instruction. /tvb ___ 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.
Re: [time-nuts] Precisione GPS based led clock
Hi Paolo: Is there some reason for not using the Kiwi Video Time Inserter, it was made for occultation timing.? http://www.pfdsystems.com/kiwiosd.html Have Fun, Brooke Clarke Production of the KIWI-OSD has ended - perhaps? Cheers, David -- SatSignal software - quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ 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.
Re: [time-nuts] Precisione GPS based led clock
Hi Tom, How about using Binary for the last couple of digits? 4 LEDs for a digit in BCD. Saves on pins and wiring. Robert G8RPI. From: Tom Van Baak t...@leapsecond.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Thursday, 3 November 2011, 16:29 Subject: Re: [time-nuts] Precisione GPS based led clock I also have had need of a high resolution display clock for photographic time stamping. For those of you working on this make sure not to use a LCD or VFD display. The response time is too slow. Also you can rule out any sort of TV display. If using LED make sure not to multiplex the digits. This is a common trick, especially when using microprocessors, and works well for human eyes, but fails completely with high resolution photos. So having ruled out everything but direct drive LED the only other concern is to make sure the decade counters which drive the display are synchronous or at least that all the digits are latched at the same time. Otherwise you get false readouts due to ripple carry or sequential scan. Be careful using a microprocessor for this. For millisecond displays you need a total of 21 pins; for microseconds you need 42 pins. An external serial-parallel (e.g., shift register with latch) chip might be safer since neither a PIC nor an Arduino can update that many pins in one instruction. /tvb ___ 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. ___ 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.
Re: [time-nuts] Precisione GPS based led clock
Hi, Hi Tom, How about using Binary for the last couple of digits? 4 LEDs for a digit in BCD. Saves on pins and wiring. I had the same idea, although my idea was to just make it completely binary and use OCR on the photograph to find the time. Maybe adding 2 surrounding always-on other colored LEDs to frame the sequence would be nice? Greetings, Pieter. Robert G8RPI. From: Tom Van Baak t...@leapsecond.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Thursday, 3 November 2011, 16:29 Subject: Re: [time-nuts] Precisione GPS based led clock I also have had need of a high resolution display clock for photographic time stamping. For those of you working on this make sure not to use a LCD or VFD display. The response time is too slow. Also you can rule out any sort of TV display. If using LED make sure not to multiplex the digits. This is a common trick, especially when using microprocessors, and works well for human eyes, but fails completely with high resolution photos. So having ruled out everything but direct drive LED the only other concern is to make sure the decade counters which drive the display are synchronous or at least that all the digits are latched at the same time. Otherwise you get false readouts due to ripple carry or sequential scan. Be careful using a microprocessor for this. For millisecond displays you need a total of 21 pins; for microseconds you need 42 pins. An external serial-parallel (e.g., shift register with latch) chip might be safer since neither a PIC nor an Arduino can update that many pins in one instruction. /tvb ___ 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. ___ 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. ___ 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.
Re: [time-nuts] Precisione GPS based led clock
It would be easy to serial shift through an SPI interface. At 1MHz, which is conservative for SPI, you would be done in a few uS, which would be more than adequate even for a mS clock. Since my Thunderbolt Monitor already decodes the Trimble TSIP protocol, it would be easy to modify the software to drive an array of 7 segment LED displays through SPI instead of the LCD. A divider running from the 10MHz would generate a mS interrupt which would update the display. The offset caused by the slow serial data would have to be compensated, or maybe the 1PPS can be fed to the processor as well for synchronization. It seems quite feasible within the constraints of the small processor used by the TBolt Monitor. Now that I think of it, the VFD display I have been using with my TBolt Monitor is considerably faster than the LCD display and might be fast enough, at least for 100th of a second. Didier KO4BB Sent from my BlackBerry Wireless thingy while I do other things... -Original Message- From: Tom Van Baak t...@leapsecond.com Sender: time-nuts-boun...@febo.com Date: Thu, 3 Nov 2011 09:29:42 To: Discussion of precise time and frequency measurementtime-nuts@febo.com Reply-To: Tom Van Baak t...@leapsecond.com, Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Precisione GPS based led clock I also have had need of a high resolution display clock for photographic time stamping. For those of you working on this make sure not to use a LCD or VFD display. The response time is too slow. Also you can rule out any sort of TV display. If using LED make sure not to multiplex the digits. This is a common trick, especially when using microprocessors, and works well for human eyes, but fails completely with high resolution photos. So having ruled out everything but direct drive LED the only other concern is to make sure the decade counters which drive the display are synchronous or at least that all the digits are latched at the same time. Otherwise you get false readouts due to ripple carry or sequential scan. Be careful using a microprocessor for this. For millisecond displays you need a total of 21 pins; for microseconds you need 42 pins. An external serial-parallel (e.g., shift register with latch) chip might be safer since neither a PIC nor an Arduino can update that many pins in one instruction. /tvb ___ 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. ___ 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.
Re: [time-nuts] Precisione GPS based led clock
How about using Binary for the last couple of digits? 4 LEDs for a digit in BCD. Saves on pins and wiring. The pin savings is minor (10 bits of binary is 12 bits of BCD) and the inconvenience to the user viewing the photograph is great. So I rejected binary. Remember even 1950's frequency counters were nice enough to display in decimal (1-of-10 neon lamps or dekatron or nixie tubes). If you're comparing LED segments vs. binary then, yes, it's a 7:4 advantage to do binary. But again, unless you are trying to create a novelty or museum piece it's worth avoiding binary displays. If you drive 7-segment LEDs with 4511 chips you get the latch, a 7-segment decoder, and the LED driver for free. If you use 16- or 24-bit serial-parallel-latches or port expanders then you only need 2 or 3 pins of the microcontroller. Use one or more '595 or look at the wonderful chips by Unitrode/Allegro. BTW, if 1/100th second is all that is needed for the photograph, don't discount analog dials; that is, a synchronous clock with hour, minute, second, and [60 Hz] cycle hands. /tvb ___ 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.
Re: [time-nuts] Precisione GPS based led clock
I assume you are taking video of the occultation and want to time tag each frame? If so then there is a better way. All current video standard allow a place in the video stream for time tags. This works much the same way as with still cameras that recordthe date in the image files. You would need a camera that was an input from the time code data. The other way it is done some times is to put something like IRIG on the audio track. This can be microsecond level accuracy. One more idea... If all you need is 1/100th second accuracy and you have a computer near by then let that computer run and NTP server using a GPS is the reference clock. Even an un-sophisticated NTP setup can run at the millisecond level, ten times better than your requirement. Now that the computer's clock is good any kind of time code canbe generated in software I am an amateur astronomer working in the field of minor planet occultation. To arrange a precise reference time I am looking for a 1/100 sec LED dispaly clock GPS based. Chris Albertson Redondo Beach, California ___ 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.
Re: [time-nuts] Precisione GPS based led clock
Tom, I checked the spec for the VFD display I am using with my GPS Monitor, but there is no spec for how fast the segments are updated. I know that the external interface is much faster than that of the LCD, even though the commands are the same and the two are generally compatible. Visually, the VFD display is much faster, but without a high speed camera, I am not sure how to check if it would be fast enough. Looking at the number of pins on the display itself, it must be multiplexed, so that may not be fast enough for your application. Didier KO4BB Sent from my BlackBerry Wireless thingy while I do other things... -Original Message- From: Tom Van Baak t...@leapsecond.com Sender: time-nuts-boun...@febo.com Date: Thu, 3 Nov 2011 09:29:42 To: Discussion of precise time and frequency measurementtime-nuts@febo.com Reply-To: Tom Van Baak t...@leapsecond.com, Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Precisione GPS based led clock I also have had need of a high resolution display clock for photographic time stamping. For those of you working on this make sure not to use a LCD or VFD display. The response time is too slow. Also you can rule out any sort of TV display. If using LED make sure not to multiplex the digits. This is a common trick, especially when using microprocessors, and works well for human eyes, but fails completely with high resolution photos. So having ruled out everything but direct drive LED the only other concern is to make sure the decade counters which drive the display are synchronous or at least that all the digits are latched at the same time. Otherwise you get false readouts due to ripple carry or sequential scan. Be careful using a microprocessor for this. For millisecond displays you need a total of 21 pins; for microseconds you need 42 pins. An external serial-parallel (e.g., shift register with latch) chip might be safer since neither a PIC nor an Arduino can update that many pins in one instruction. /tvb ___ 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. ___ 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.
