Re: [time-nuts] GPS-audio interface
I'm not sure if any of you would be interested in this modified tg. Let me know if you do. I had submitted it to the NTP gurus some time ago, and they didn't seem too terribly interested. If anybody has bug fixes or enhancements to the ntp code base, I'll be glad to help get them merged into the official distribution package. Contact me off list. -- 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] GPS-audio interface
I'm looking for a way to take GPS time and generate a signal that can be recorded on the audio track of a video recording to time stamp it. This is so it can be aligned with other data that's collected with GPS based time. It needs to be portable/small (i.e. Something you could attach to a small camcorder, or such). Seems that a GPS-IRIG B interface would work, but I was wondering if someone has done this already (e.g. Someone must have made a IRIG encoder in a PIC or similar).. Another alternate is if something like a iPhone records accurate time with the video stream. (another of the data sources is an iPhone recording something else) I think the basic requirement is accuracy to some few milliseconds (e.g. Frame rate of the video).. (It's for a high school science project, where they want to record various things, and line them up.. I think they could deal with looking at the timestamps over many frames to do interpolation) Anyway, cheap and cheerful consumer gear is what is sought. (so no suggestions of synthesizing SMPTE from the output of my Z3801 and feeding it to a RED camera.. We're talking AIPtek and iPhone here..) Jim Lux Maybe this is what you're looking for: http://www.redhensystems.com/ ___ 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] GPS-audio interface
Lux, James P skrev: I'm looking for a way to take GPS time and generate a signal that can be recorded on the audio track of a video recording to time stamp it. This is so it can be aligned with other data that's collected with GPS based time. It needs to be portable/small (i.e. Something you could attach to a small camcorder, or such). Traditionally SMPTE 12M LTC is being used for this purpose. For most cases it is only known as LTC but SMPTE/EBU time code is among other names fairly common name. Seems that a GPS-IRIG B interface would work, but I was wondering if someone has done this already (e.g. Someone must have made a IRIG encoder in a PIC or similar).. I actually have a GPS with IRIG-B output in about the same size of a Thunderbolt. If you have your own encoder in the form of a PIC/AVR then maybe producing SMPTE LTC should be better or at least considered as an alternative output. Another alternate is if something like a iPhone records accurate time with the video stream. (another of the data sources is an iPhone recording something else) I think the basic requirement is accuracy to some few milliseconds (e.g. Frame rate of the video).. SMPTE LTC encodes the frame numbers. (It's for a high school science project, where they want to record various things, and line them up.. I think they could deal with looking at the timestamps over many frames to do interpolation) SMPTE LTC should be preferred in that case, as it is something that editing equipment understands. Anyway, cheap and cheerful consumer gear is what is sought. (so no suggestions of synthesizing SMPTE from the output of my Z3801 and feeding it to a RED camera.. We're talking AIPtek and iPhone here..) Locking the camera with a black burst GENLOCK signal with VITC does need to be done, but the LTC may very well be practical for the purpose. BTW. Cameras lacking GENLOCK is highly annoying, especially when they have el cheapo crystals... el cheapo crystals is fine, as long as they lock up to a GENLOCK when needed. Cheers, Magnus ___ 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] GPS-audio interface
On 5/10/09 11:21 AM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Lux, James P skrev: I'm looking for a way to take GPS time and generate a signal that can be recorded on the audio track of a video recording to time stamp it. This is so it can be aligned with other data that's collected with GPS based time. It needs to be portable/small (i.e. Something you could attach to a small camcorder, or such). Traditionally SMPTE 12M LTC is being used for this purpose. For most cases it is only known as LTC but SMPTE/EBU time code is among other names fairly common name. Yes.. But most consumer recorders (e.g. The cheap AIPtek) don't do timecode (or genlock, or other useful stuff).. So what they're really looking for is someway to time align after the fact. I actually have a GPS with IRIG-B output in about the same size of a Thunderbolt. Is that an off the shelf, not hideously expensive, widget? (There are other applications...) Another alternate is if something like a iPhone records accurate time with the video stream. (another of the data sources is an iPhone recording something else) I think the basic requirement is accuracy to some few milliseconds (e.g. Frame rate of the video).. SMPTE LTC encodes the frame numbers. (It's for a high school science project, where they want to record various things, and line them up.. I think they could deal with looking at the timestamps over many frames to do interpolation) SMPTE LTC should be preferred in that case, as it is something that editing equipment understands. I don't think real editing gear is in the cards. Probably more like iMovie or something on a PC. As a model for what they're trying to do, say you were going to measure the acceleration due to gravity by videotaping a falling object against a scale in the background. Except that the motion is more complex.. Maybe imagine putting an accelerometer in the payload of a trebuchet... And you want to time align the position of the trebuchet components (from the video) with the forces on the payload. That's not what they're doing, but now that I describe it, that WOULD be a cool science project. And get away from the here, I built a trebuchet and launched a projectile X meters which is kind of tired. (get one of those analog devices 3 axis accelerometers, hook it to a suitable datalogger..) Anyway, cheap and cheerful consumer gear is what is sought. (so no suggestions of synthesizing SMPTE from the output of my Z3801 and feeding it to a RED camera.. We're talking AIPtek and iPhone here..) Locking the camera with a black burst GENLOCK signal with VITC does need to be done, but the LTC may very well be practical for the purpose. BTW. Cameras lacking GENLOCK is highly annoying, especially when they have el cheapo crystals... el cheapo crystals is fine, as long as they lock up to a GENLOCK when needed. That pretty well describes just about everything they'll have available. Cheers, Magnus ___ 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] GPS-audio interface
As a model for what they're trying to do, say you were going to measure the acceleration due to gravity by videotaping a falling object against a scale in the background. Except that the motion is more complex.. Maybe imagine putting an accelerometer in the payload of a trebuchet... And you want to time align the position of the trebuchet components (from the video) with the forces on the payload. That's not what they're doing, but now that I describe it, that WOULD be a cool science project. And get away from the here, I built a trebuchet and launched a projectile X meters which is kind of tired. (get one of those analog devices 3 axis accelerometers, hook it to a suitable datalogger..) For something like that, you could: start the camera start the recorder in the payload whack the payload with a stick to inject a calibration marker (the stick has to be visible in the camera) maybe re-aim the camera launch the payload... -- 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] GPS-audio interface
Hi James: You might want to get a KIWI-OSD, Video overlay of GPS precision time stamp. It adds HH:MM:SS FF at the bottom of the image and so can be seen in every field. They have also developed a way to calibrate the camera shutter in relation to the frame time by using a number of LEDs. The main use if for star occulation timing. http://www.geocities.com/kiwi_36_nz/kiwi_osd/kiwi_osd.htm Have Fun, Brooke Clarke http://www.prc68.com Lux, James P wrote: I'm looking for a way to take GPS time and generate a signal that can be recorded on the audio track of a video recording to time stamp it. This is so it can be aligned with other data that's collected with GPS based time. It needs to be portable/small (i.e. Something you could attach to a small camcorder, or such). Seems that a GPS-IRIG B interface would work, but I was wondering if someone has done this already (e.g. Someone must have made a IRIG encoder in a PIC or similar).. Another alternate is if something like a iPhone records accurate time with the video stream. (another of the data sources is an iPhone recording something else) I think the basic requirement is accuracy to some few milliseconds (e.g. Frame rate of the video).. (It's for a high school science project, where they want to record various things, and line them up.. I think they could deal with looking at the timestamps over many frames to do interpolation) Anyway, cheap and cheerful consumer gear is what is sought. (so no suggestions of synthesizing SMPTE from the output of my Z3801 and feeding it to a RED camera.. We're talking AIPtek and iPhone here..) Jim Lux ___ 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] GPS-audio interface
Lux, James P skrev: On 5/10/09 11:21 AM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Lux, James P skrev: I'm looking for a way to take GPS time and generate a signal that can be recorded on the audio track of a video recording to time stamp it. This is so it can be aligned with other data that's collected with GPS based time. It needs to be portable/small (i.e. Something you could attach to a small camcorder, or such). Traditionally SMPTE 12M LTC is being used for this purpose. For most cases it is only known as LTC but SMPTE/EBU time code is among other names fairly common name. Yes.. But most consumer recorders (e.g. The cheap AIPtek) don't do timecode (or genlock, or other useful stuff).. They should be hackable thought. So what they're really looking for is someway to time align after the fact. This does not prohibit you from just recording the LTC onto the soundtrack anyway. I actually have a GPS with IRIG-B output in about the same size of a Thunderbolt. Is that an off the shelf, not hideously expensive, widget? (There are other applications...) I bought one of those Brandywine GPS4 devices as announced available on the list not too long ago. Not hideously expensive IMHO. Another alternate is if something like a iPhone records accurate time with the video stream. (another of the data sources is an iPhone recording something else) I think the basic requirement is accuracy to some few milliseconds (e.g. Frame rate of the video).. SMPTE LTC encodes the frame numbers. (It's for a high school science project, where they want to record various things, and line them up.. I think they could deal with looking at the timestamps over many frames to do interpolation) SMPTE LTC should be preferred in that case, as it is something that editing equipment understands. I don't think real editing gear is in the cards. Probably more like iMovie or something on a PC. There should be editing gear that chews LTC over audio-interface. We did frame-grabbing tricks with a cheap video-recorder, LTC on audio track and an SGI Indy back in the days... and a remote hacked with CMOS switches steered by a DTMF decoder so the Indy played DTMF tone-pairs on the port, real-time decoded LTC and frame-grabbed 10 frames at the time, rewinded, played again etc. Some of the cheap/free programmes would be able to decode LTC and tag the pictures accordingly. As a model for what they're trying to do, say you were going to measure the acceleration due to gravity by videotaping a falling object against a scale in the background. Except that the motion is more complex.. Maybe imagine putting an accelerometer in the payload of a trebuchet... And you want to time align the position of the trebuchet components (from the video) with the forces on the payload. That's not what they're doing, but now that I describe it, that WOULD be a cool science project. And get away from the here, I built a trebuchet and launched a projectile X meters which is kind of tired. (get one of those analog devices 3 axis accelerometers, hook it to a suitable datalogger..) In that case you want the line-frequency locked or traceable by other means. You have more use for the frequency aspect than time-notation actually, which is more handy for a matter logging which event. Still, LTC should be easier to get locked to the phase attached to the frames, as the infrastructure is expected to be there for some apps, but the IRIG-B support is not expected to be there. If you do not hack the camera to accept a reference signal (hacking the crystal oscillator may be all you need to do), after the fact frequency calibration can be done with either IRIG-B, LTC or just a 1 kHz sine. Anyway, cheap and cheerful consumer gear is what is sought. (so no suggestions of synthesizing SMPTE from the output of my Z3801 and feeding it to a RED camera.. We're talking AIPtek and iPhone here..) Locking the camera with a black burst GENLOCK signal with VITC does need to be done, but the LTC may very well be practical for the purpose. BTW. Cameras lacking GENLOCK is highly annoying, especially when they have el cheapo crystals... el cheapo crystals is fine, as long as they lock up to a GENLOCK when needed. That pretty well describes just about everything they'll have available. Well, the two initial strategies is to either hack the cameras and replace the XO with a VCXO which locks to a 10 Mhz. Usually it is 27 MHz and relationship to 10 MHz is fairly trivial. After the fact synchronisation using a 1 kHz signal (such as given by TADD-2, tvb PIC-div or something) into the audio signal would also do, if only the audio sample rate and the video rate is locked in the el cheapo camera, which one can hope for at least. Cheers, Magnus ___ 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
Re: [time-nuts] GPS-audio interface
Brooke The KIWI-OSD is no longer available. However some circuit detail is available at: http://spiff.rit.edu/richmond/ritobs/kiwi/kiwi.html It really should be reworked to use a more reliable time source such as a GPS timing receiver. Bruce Brooke Clarke wrote: Hi James: You might want to get a KIWI-OSD, Video overlay of GPS precision time stamp. It adds HH:MM:SS FF at the bottom of the image and so can be seen in every field. They have also developed a way to calibrate the camera shutter in relation to the frame time by using a number of LEDs. The main use if for star occulation timing. http://www.geocities.com/kiwi_36_nz/kiwi_osd/kiwi_osd.htm Have Fun, Brooke Clarke http://www.prc68.com Lux, James P wrote: I'm looking for a way to take GPS time and generate a signal that can be recorded on the audio track of a video recording to time stamp it. This is so it can be aligned with other data that's collected with GPS based time. It needs to be portable/small (i.e. Something you could attach to a small camcorder, or such). Seems that a GPS-IRIG B interface would work, but I was wondering if someone has done this already (e.g. Someone must have made a IRIG encoder in a PIC or similar).. Another alternate is if something like a iPhone records accurate time with the video stream. (another of the data sources is an iPhone recording something else) I think the basic requirement is accuracy to some few milliseconds (e.g. Frame rate of the video).. (It's for a high school science project, where they want to record various things, and line them up.. I think they could deal with looking at the timestamps over many frames to do interpolation) Anyway, cheap and cheerful consumer gear is what is sought. (so no suggestions of synthesizing SMPTE from the output of my Z3801 and feeding it to a RED camera.. We're talking AIPtek and iPhone here..) Jim Lux ___ 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] GPS-audio interface
On 5/10/09 12:10 PM, Hal Murray hmur...@megapathdsl.net wrote: As a model for what they're trying to do, say you were going to measure the acceleration due to gravity by videotaping a falling object against a scale in the background. Except that the motion is more complex.. Maybe imagine putting an accelerometer in the payload of a trebuchet... And you want to time align the position of the trebuchet components (from the video) with the forces on the payload. That's not what they're doing, but now that I describe it, that WOULD be a cool science project. And get away from the here, I built a trebuchet and launched a projectile X meters which is kind of tired. (get one of those analog devices 3 axis accelerometers, hook it to a suitable datalogger..) For something like that, you could: start the camera start the recorder in the payload whack the payload with a stick to inject a calibration marker (the stick has to be visible in the camera) maybe re-aim the camera launch the payload... Yes.. This is called a slate or clapper board in the movie trade. ___ 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] GPS-audio interface
On 5/10/09 12:15 PM, Brooke Clarke bro...@pacific.net wrote: Hi James: You might want to get a KIWI-OSD, Video overlay of GPS precision time stamp. It adds HH:MM:SS FF at the bottom of the image and so can be seen in every field. They have also developed a way to calibrate the camera shutter in relation to the frame time by using a number of LEDs. The main use if for star occulation timing. http://www.geocities.com/kiwi_36_nz/kiwi_osd/kiwi_osd.htm Have Fun, Brooke Clarke Yes, but that requires getting access to the video stream, which isn't easy in a camcorder environment. Separate video recorders actually cost more than camcorders. ___ 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] GPS-audio interface
Lux, James P skrev: On 5/10/09 12:15 PM, Brooke Clarke bro...@pacific.net wrote: Hi James: You might want to get a KIWI-OSD, Video overlay of GPS precision time stamp. It adds HH:MM:SS FF at the bottom of the image and so can be seen in every field. They have also developed a way to calibrate the camera shutter in relation to the frame time by using a number of LEDs. The main use if for star occulation timing. http://www.geocities.com/kiwi_36_nz/kiwi_osd/kiwi_osd.htm Have Fun, Brooke Clarke Yes, but that requires getting access to the video stream, which isn't easy in a camcorder environment. Separate video recorders actually cost more than camcorders. What precision of anything do you need? Expect 50-100 ppm oscillators in there. Recorded material is compressed. Consider how that affects your readout. Recorded material is said progressive/interlaced. This may not reflect how the CCD is snapshot and readout. You may not have the expected 1125 or 750 lines per frame, and exactly what frame rate do you have? Cheers, Magnus ___ 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] GPS-audio interface
Hi, low tech solution may be to produce second pips of audio with long one minute pips, a bit like WWV, and inject them into the mic plug (in parallel to the mic) or use a small speaker. That together with a clap-board start should enable any frame to be timed. cheers, Neville Michie On 11/05/2009, at 3:48 AM, Lux, James P wrote: I'm looking for a way to take GPS time and generate a signal that can be recorded on the audio track of a video recording to time stamp it. This is so it can be aligned with other data that's collected with GPS based time. It needs to be portable/small (i.e. Something you could attach to a small camcorder, or such). Seems that a GPS-IRIG B interface would work, but I was wondering if someone has done this already (e.g. Someone must have made a IRIG encoder in a PIC or similar).. Another alternate is if something like a iPhone records accurate time with the video stream. (another of the data sources is an iPhone recording something else) I think the basic requirement is accuracy to some few milliseconds (e.g. Frame rate of the video).. (It's for a high school science project, where they want to record various things, and line them up.. I think they could deal with looking at the timestamps over many frames to do interpolation) Anyway, cheap and cheerful consumer gear is what is sought. (so no suggestions of synthesizing SMPTE from the output of my Z3801 and feeding it to a RED camera.. We're talking AIPtek and iPhone here..) Jim Lux ___ 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] GPS-audio interface
On 5/10/09 4:26 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Lux, James P skrev: On 5/10/09 12:15 PM, Brooke Clarke bro...@pacific.net wrote: Hi James: You might want to get a KIWI-OSD, Video overlay of GPS precision time stamp. It adds HH:MM:SS FF at the bottom of the image and so can be seen in every field. They have also developed a way to calibrate the camera shutter in relation to the frame time by using a number of LEDs. The main use if for star occulation timing. http://www.geocities.com/kiwi_36_nz/kiwi_osd/kiwi_osd.htm Have Fun, Brooke Clarke Yes, but that requires getting access to the video stream, which isn't easy in a camcorder environment. Separate video recorders actually cost more than camcorders. What precision of anything do you need? Expect 50-100 ppm oscillators in there. Yes, but probably fairly good in the short run, and if you were recording almost any sync signal (e.g. The 1kHz sine) you could calibrate that out. Recorded material is compressed. Consider how that affects your readout. Recorded material is said progressive/interlaced. This may not reflect how the CCD is snapshot and readout. You may not have the expected 1125 or 750 lines per frame, and exactly what frame rate do you have? I think that's something they'll need to experiment with... Jim ___ 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] GPS-audio interface
Hi there, It turns out that the NTP package has a built-in utility called tg which can generate IRIG-B time code. I'm not familiar with what you are trying to do. If you have a computer that is keeping accurate time (through your GPS clock??), you can generate a nice audio IRIG-B. It was developed to allow testing of the NTP IRIG-B **input** function. NTP has a bunch of front ends for all kinds of code inputs. I played with tg from NTP 4.2.2p3 quite extensively some time ago, and created a version with a bunch more options, including IEEE 1344 extensions, and corrected a couple of bugs etc. Also, I play a bit with the timing to allow tg to omit or insert strategic single cycles to correct for the clock error on the audio card. Plus much more, mostly to help me test an IRIG-B decoder. Oh yes, I also did a bunch of adjustments to the WWV(H) output option from tg. Not many folks care about WWV(H) any more, though :-) I'm not sure if any of you would be interested in this modified tg. Let me know if you do. I had submitted it to the NTP gurus some time ago, and they didn't seem too terribly interested. Regards, Dean Weiten. ___ 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.
