Re: [time-nuts] Time Code generator
When audio/video time code is specified if its on a audio track its called LTC or Longitudinal Time Code and is generally IRIG-B, This is very uncommon these days as it went out of common use about the time 1 reel to reel was discontinued. Most common today on NTSC is VITC or vertical interval time code. Its encoded as a series of pulses in the vertical blanking interval. The display is generally called a 'Screen Burner' Sent from my Verizon Wireless BlackBerry -Original Message- From: Collins, Graham coll...@navcanada.ca Sender: time-nuts-boun...@febo.com Date: Fri, 3 Dec 2010 07:28:13 To: Discussion of precise time and frequency measurementtime-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: [time-nuts] Time Code generator On another list to which I subscribe, the question was asked about the suitability of recording WWV 2.5mhz audio as one track when recording off the air signals of interest as a time reference. The person who asked the question didn't really state his intentions but they seem very similar to my immediate needs. That is, simply a time reference - that is the time, the start of the minute, and periodic references (i.e. seconds) between the announcements. It seems that recording the audio of something like WWV or CHU is ideal. However, another approach would be recording a more proper time code signal as you might have available from a precision clock. Of course, a decoder would also be required. A quick Google search turned up lots of leads which I have yet to sort through. In the interim I thought I would pose the question to the learned members of this group for their suggestions. Keep in mind KISS and that a very high degree of accuracy is not required. Is there an opensource/freeware PC app that will generate an appropriate time code signal that can be recorded on one track of an audio recorder (either PC based i.e. Audacity or standalone) that will also decode via soundcard or other input? Cheers, Graham ve3gtc ___ 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] Time Code generator
scmcgr...@gmail.com wrote: When audio/video time code is specified if its on a audio track its called LTC or Longitudinal Time Code and is generally IRIG-B, This is very uncommon these days as it went out of common use about the time 1 reel to reel was discontinued. IRIG is uncommon in the audio/video industry, but still used in the telemetry and lab environment (IRIG is the Inter-Range Instrumentation Group, at White Sands Missile Range, after all). I confess I doubt anyone is still using magnetic tape with FM subcarriers on the range these days, but you never know.. government facilities tend to use really old equipment for a long, long time since the accounting rules don't use depreciation (you buy it once, and it's free after that), there's limited capital budgets for replacement, but often labor is available to repair/limp along. At JPL, we use IRIG to transfer time around between racks, particularly for things like MIL-STD-1553B monitors, which timestamp the bus traffic to the nearest microsecond or fraction, sync'd by the IRIG input. There's something really convenient about needing just one cable/fiber to perform the function. Audio LTC is encoded differently than IRIG.. Biphase manchester, different bit stream, different time encoding, etc. Conceptually similar though. Any programmable hardware that can generate IRIG can probably generate LTC as well. OTOH, if you built your IRIG generator out of discrete 7400 series TTL, you've got a lot of white wires to convert to LTC. Most common today on NTSC is VITC or vertical interval time code. Its encoded as a series of pulses in the vertical blanking interval. The display is generally called a 'Screen Burner' Sent from my Verizon Wireless BlackBerry -Original Message- From: Collins, Graham coll...@navcanada.ca Sender: time-nuts-boun...@febo.com Date: Fri, 3 Dec 2010 07:28:13 To: Discussion of precise time and frequency measurementtime-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: [time-nuts] Time Code generator ___ 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] reference oscillator input circuit
I'm looking for suggestions on a general circuit that can be used to receive an external frequency reference (nominally a real clean sine wave at, say, 10 MHz, although up to 100 MHz is possible) and turn it into a real clean square wave. Galvanic isolation is a plus (a transformer or capacitor would probably do that). I was thinking about rummaging through the schematics for test equipment reference inputs (since they've already solved the problem, eh?), but any other ideas would be welcome. I've scanned the archives of time-nuts, and while we have a fair amount of discussion on how to square up the 1Hz (or 100Hz) in a phase noise/ADEV setup, not so much on what to do with the 10 MHz. Rick has commented that you don't want to use a comparator. I have the papers by Dick, et al, and Collins, as well as all the others.. they tend to be looking at the low frequency problem, although the analysis is certainly applicable. I don't know that I'm looking for the whole multiple limiting stages scheme in any case. Oh, as far as performance.. Say the need is to not horribly degrade a good quality crystal oscillator... here's a typical set of specs: 76 MHz 1Hz -90dBc 10Hz -110dBc 100Hz -120dBc 1k-100k -125dBc Adevs of the oscillator run from 5E-12 at 0.1 sec, down to 1E-12 at 10 sec, and back up to 2 E-12 at 1000sec. ___ 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] reference oscillator input circuit
Wenzel has some discussion and circuits at: http://www.wenzel.com/documents/waveform.html. The Shera GPSDO made clever use of the input circuit of a 74HCT4046 PLL chip for squaring. John On 12/8/2010 10:31 AM, jimlux wrote: I'm looking for suggestions on a general circuit that can be used to receive an external frequency reference (nominally a real clean sine wave at, say, 10 MHz, although up to 100 MHz is possible) and turn it into a real clean square wave. Galvanic isolation is a plus (a transformer or capacitor would probably do that). I was thinking about rummaging through the schematics for test equipment reference inputs (since they've already solved the problem, eh?), but any other ideas would be welcome. I've scanned the archives of time-nuts, and while we have a fair amount of discussion on how to square up the 1Hz (or 100Hz) in a phase noise/ADEV setup, not so much on what to do with the 10 MHz. Rick has commented that you don't want to use a comparator. I have the papers by Dick, et al, and Collins, as well as all the others.. they tend to be looking at the low frequency problem, although the analysis is certainly applicable. I don't know that I'm looking for the whole multiple limiting stages scheme in any case. Oh, as far as performance.. Say the need is to not horribly degrade a good quality crystal oscillator... here's a typical set of specs: 76 MHz 1Hz -90dBc 10Hz -110dBc 100Hz -120dBc 1k-100k -125dBc Adevs of the oscillator run from 5E-12 at 0.1 sec, down to 1E-12 at 10 sec, and back up to 2 E-12 at 1000sec. ___ 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] reference oscillator input circuit
John Ackermann N8UR wrote: Wenzel has some discussion and circuits at: http://www.wenzel.com/documents/waveform.html. The Shera GPSDO made clever use of the input circuit of a 74HCT4046 PLL chip for squaring. John Doh... I was thinking that there was some vendor with ap notes on stuff like this, and I couldn't recall who it was, and I'm actually looking at a Wenzel OCXO sitting here on the desk. ___ 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] Another GPS .. this is a true boatanchor
Hi Pete, I have that Raytheon QFHA Quadrofiliar Helix-Antenna, bought as used part. This antenna is really good and does an excellent job directly connected to Trimble Thunderbolt (5V alim.)! The cable can be fed Inside via the mounting thread part, enjoy it, Arnold Am 03.12.2010 23:31, schrieb Pete Lancashire: If too far off topic let me know, or is there a GPS-nuts list ? Raystar 920. I think i have 2 two, did find two antennas one new. http://petelancashire.com/gallery/main.php?g2_itemId=21152 This one may be fun to see if can make it run .. anyone with a manual ? -pete ___ 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] Time Code generator
Thanks for update on current LTC usage!. In the studios I worked in in college with the old type-c decks we did use IRIG-B but even then everyone was moving to VITC. As editing was moving away from the razor blade and tape era to deck to deck on U-Matic decks! Scott Sent from my Verizon Wireless BlackBerry -Original Message- From: jimlux jim...@earthlink.net Date: Wed, 08 Dec 2010 07:20:14 To: scmcgr...@gmail.com; Discussion of precise time and frequency measurementtime-nuts@febo.com Subject: Re: [time-nuts] Time Code generator scmcgr...@gmail.com wrote: When audio/video time code is specified if its on a audio track its called LTC or Longitudinal Time Code and is generally IRIG-B, This is very uncommon these days as it went out of common use about the time 1 reel to reel was discontinued. IRIG is uncommon in the audio/video industry, but still used in the telemetry and lab environment (IRIG is the Inter-Range Instrumentation Group, at White Sands Missile Range, after all). I confess I doubt anyone is still using magnetic tape with FM subcarriers on the range these days, but you never know.. government facilities tend to use really old equipment for a long, long time since the accounting rules don't use depreciation (you buy it once, and it's free after that), there's limited capital budgets for replacement, but often labor is available to repair/limp along. At JPL, we use IRIG to transfer time around between racks, particularly for things like MIL-STD-1553B monitors, which timestamp the bus traffic to the nearest microsecond or fraction, sync'd by the IRIG input. There's something really convenient about needing just one cable/fiber to perform the function. Audio LTC is encoded differently than IRIG.. Biphase manchester, different bit stream, different time encoding, etc. Conceptually similar though. Any programmable hardware that can generate IRIG can probably generate LTC as well. OTOH, if you built your IRIG generator out of discrete 7400 series TTL, you've got a lot of white wires to convert to LTC. Most common today on NTSC is VITC or vertical interval time code. Its encoded as a series of pulses in the vertical blanking interval. The display is generally called a 'Screen Burner' Sent from my Verizon Wireless BlackBerry -Original Message- From: Collins, Graham coll...@navcanada.ca Sender: time-nuts-boun...@febo.com Date: Fri, 3 Dec 2010 07:28:13 To: Discussion of precise time and frequency measurementtime-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: [time-nuts] Time Code generator ___ 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] Time Code generator
Adding time code to video would be redundant. All video is already time coded. It turns out the time code is required to support editing. Editors don't actually move bits of video data around. What they do is create and modify an EDL which is a text file with a list of all the cuts and effects to be applied. The cuts are defined by the time. For example a close up of an actor's face might be specified at camera roll XX from time T1 to time T2. Later during final rendering the software will search the video data for frames with the required time codes But many consumer level cameras fake it by defining time = zero at the start of a tape or the first frame in memory. If absolute time needs to be record on a consumer level camera then I'd shoot a few frames of a digital clock and then later in a video editor adjust the time code OK, all that said there is a group of people who routinely record WWV audio on their video. Amateur occultation timers do this. These people use video cameras through telescopes to record when a asteroid passes in front of a star and blocks its light. This can produce very acuate orbital data for the asteroid and if enough people all over the world record it you can even deduce the shape of the asteroid. On Wed, Dec 8, 2010 at 5:27 AM, scmcgr...@gmail.com wrote: When audio/video time code is specified if its on a audio track its called LTC or Longitudinal Time Code and is generally IRIG-B, This is very uncommon these days as it went out of common use about the time 1 reel to reel was discontinued. Most common today on NTSC is VITC or vertical interval time code. Its encoded as a series of pulses in the vertical blanking interval. The display is generally called a 'Screen Burner' Sent from my Verizon Wireless BlackBerry -Original Message- From: Collins, Graham coll...@navcanada.ca Sender: time-nuts-boun...@febo.com Date: Fri, 3 Dec 2010 07:28:13 To: Discussion of precise time and frequency measurementtime-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: [time-nuts] Time Code generator On another list to which I subscribe, the question was asked about the suitability of recording WWV 2.5mhz audio as one track when recording off the air signals of interest as a time reference. The person who asked the question didn't really state his intentions but they seem very similar to my immediate needs. That is, simply a time reference - that is the time, the start of the minute, and periodic references (i.e. seconds) between the announcements. It seems that recording the audio of something like WWV or CHU is ideal. However, another approach would be recording a more proper time code signal as you might have available from a precision clock. Of course, a decoder would also be required. A quick Google search turned up lots of leads which I have yet to sort through. In the interim I thought I would pose the question to the learned members of this group for their suggestions. Keep in mind KISS and that a very high degree of accuracy is not required. Is there an opensource/freeware PC app that will generate an appropriate time code signal that can be recorded on one track of an audio recorder (either PC based i.e. Audacity or standalone) that will also decode via soundcard or other input? Cheers, Graham ve3gtc ___ 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. -- = 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] reference oscillator input circuit
jimlux wrote: I'm looking for suggestions on a general circuit that can be used to receive an external frequency reference (nominally a real clean sine wave at, say, 10 MHz, although up to 100 MHz is possible) and turn it into a real clean square wave. Galvanic isolation is a plus (a transformer or capacitor would probably do that). In the 5071A at 80 MHz, we capacitively coupled a sine wave into a 74AC series logic gate, that had DC bias resistors to hold it at half the supply voltage. Rick Karlquist ___ 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] reference oscillator input circuit
The document cited is full of plausible sounding but misleading information, if you want really low jitter. This type of oversimplification of the problem was present when the HP53131 series counters were designed, with the result that the Allan deviation of an external 10 MHz reference is degraded to only a part in 10^11 at 1 second. Rick Karlquist jimlux wrote: John Ackermann N8UR wrote: Wenzel has some discussion and circuits at: http://www.wenzel.com/documents/waveform.html. The Shera GPSDO made clever use of the input circuit of a 74HCT4046 PLL chip for squaring. John Doh... I was thinking that there was some vendor with ap notes on stuff like this, and I couldn't recall who it was, and I'm actually looking at a Wenzel OCXO sitting here on the desk. ___ 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] reference oscillator input circuit
Just an FYI guys, I'm pretty sure the 3rd circuit down on the Wenzel page is identical to the input circuit for the TAPR TADD-2 frequency divider. The TADD-2 adds a transformer and load resistor. Schematic is in the manual here: http://www.tapr.org/~n8ur/TADD-2_Manual.pdf -Bob On Wed, Dec 8, 2010 at 8:46 AM, John Ackermann N8UR j...@febo.com wrote: Wenzel has some discussion and circuits at: http://www.wenzel.com/documents/waveform.html. The Shera GPSDO made clever use of the input circuit of a 74HCT4046 PLL chip for squaring. John On 12/8/2010 10:31 AM, jimlux wrote: I'm looking for suggestions on a general circuit that can be used to receive an external frequency reference (nominally a real clean sine wave at, say, 10 MHz, although up to 100 MHz is possible) and turn it into a real clean square wave. Galvanic isolation is a plus (a transformer or capacitor would probably do that). I was thinking about rummaging through the schematics for test equipment reference inputs (since they've already solved the problem, eh?), but any other ideas would be welcome. I've scanned the archives of time-nuts, and while we have a fair amount of discussion on how to square up the 1Hz (or 100Hz) in a phase noise/ADEV setup, not so much on what to do with the 10 MHz. Rick has commented that you don't want to use a comparator. I have the papers by Dick, et al, and Collins, as well as all the others.. they tend to be looking at the low frequency problem, although the analysis is certainly applicable. I don't know that I'm looking for the whole multiple limiting stages scheme in any case. Oh, as far as performance.. Say the need is to not horribly degrade a good quality crystal oscillator... here's a typical set of specs: 76 MHz 1Hz -90dBc 10Hz -110dBc 100Hz -120dBc 1k-100k -125dBc Adevs of the oscillator run from 5E-12 at 0.1 sec, down to 1E-12 at 10 sec, and back up to 2 E-12 at 1000sec. ___ 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] Time Code generator
Professional cameras have a integrated VITC generator which in addition to the time add the frame index to the time code which allows for creation of frame level Edit Decision Lists. Consumer cameras cheat and synthesize time. If you run a consumer tape through a professional system you will not have a time index. And one will need to be added Scott Sent from my Verizon Wireless BlackBerry -Original Message- From: Chris Albertson albertson.ch...@gmail.com Date: Wed, 8 Dec 2010 08:54:15 To: scmcgr...@gmail.com; Discussion of precise time and frequency measurementtime-nuts@febo.com Subject: Re: [time-nuts] Time Code generator Adding time code to video would be redundant. All video is already time coded. It turns out the time code is required to support editing. Editors don't actually move bits of video data around. What they do is create and modify an EDL which is a text file with a list of all the cuts and effects to be applied. The cuts are defined by the time. For example a close up of an actor's face might be specified at camera roll XX from time T1 to time T2. Later during final rendering the software will search the video data for frames with the required time codes But many consumer level cameras fake it by defining time = zero at the start of a tape or the first frame in memory. If absolute time needs to be record on a consumer level camera then I'd shoot a few frames of a digital clock and then later in a video editor adjust the time code OK, all that said there is a group of people who routinely record WWV audio on their video. Amateur occultation timers do this. These people use video cameras through telescopes to record when a asteroid passes in front of a star and blocks its light. This can produce very acuate orbital data for the asteroid and if enough people all over the world record it you can even deduce the shape of the asteroid. On Wed, Dec 8, 2010 at 5:27 AM, scmcgr...@gmail.com wrote: When audio/video time code is specified if its on a audio track its called LTC or Longitudinal Time Code and is generally IRIG-B, This is very uncommon these days as it went out of common use about the time 1 reel to reel was discontinued. Most common today on NTSC is VITC or vertical interval time code. Its encoded as a series of pulses in the vertical blanking interval. The display is generally called a 'Screen Burner' Sent from my Verizon Wireless BlackBerry -Original Message- From: Collins, Graham coll...@navcanada.ca Sender: time-nuts-boun...@febo.com Date: Fri, 3 Dec 2010 07:28:13 To: Discussion of precise time and frequency measurementtime-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: [time-nuts] Time Code generator On another list to which I subscribe, the question was asked about the suitability of recording WWV 2.5mhz audio as one track when recording off the air signals of interest as a time reference. The person who asked the question didn't really state his intentions but they seem very similar to my immediate needs. That is, simply a time reference - that is the time, the start of the minute, and periodic references (i.e. seconds) between the announcements. It seems that recording the audio of something like WWV or CHU is ideal. However, another approach would be recording a more proper time code signal as you might have available from a precision clock. Of course, a decoder would also be required. A quick Google search turned up lots of leads which I have yet to sort through. In the interim I thought I would pose the question to the learned members of this group for their suggestions. Keep in mind KISS and that a very high degree of accuracy is not required. Is there an opensource/freeware PC app that will generate an appropriate time code signal that can be recorded on one track of an audio recorder (either PC based i.e. Audacity or standalone) that will also decode via soundcard or other input? Cheers, Graham ve3gtc ___ 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. -- = 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] reference oscillator input circuit
I can confirm that -- that's where I found it (and my schematic in the TADD-2 manual gives credit to Wenzel)! I chose that design mainly because it worked over a wide range of input levels. John On 12/8/2010 12:48 PM, Robert Darlington wrote: Just an FYI guys, I'm pretty sure the 3rd circuit down on the Wenzel page is identical to the input circuit for the TAPR TADD-2 frequency divider. The TADD-2 adds a transformer and load resistor. Schematic is in the manual here: http://www.tapr.org/~n8ur/TADD-2_Manual.pdf -Bob On Wed, Dec 8, 2010 at 8:46 AM, John Ackermann N8URj...@febo.com wrote: Wenzel has some discussion and circuits at: http://www.wenzel.com/documents/waveform.html. The Shera GPSDO made clever use of the input circuit of a 74HCT4046 PLL chip for squaring. John On 12/8/2010 10:31 AM, jimlux wrote: I'm looking for suggestions on a general circuit that can be used to receive an external frequency reference (nominally a real clean sine wave at, say, 10 MHz, although up to 100 MHz is possible) and turn it into a real clean square wave. Galvanic isolation is a plus (a transformer or capacitor would probably do that). I was thinking about rummaging through the schematics for test equipment reference inputs (since they've already solved the problem, eh?), but any other ideas would be welcome. I've scanned the archives of time-nuts, and while we have a fair amount of discussion on how to square up the 1Hz (or 100Hz) in a phase noise/ADEV setup, not so much on what to do with the 10 MHz. Rick has commented that you don't want to use a comparator. I have the papers by Dick, et al, and Collins, as well as all the others.. they tend to be looking at the low frequency problem, although the analysis is certainly applicable. I don't know that I'm looking for the whole multiple limiting stages scheme in any case. Oh, as far as performance.. Say the need is to not horribly degrade a good quality crystal oscillator... here's a typical set of specs: 76 MHz 1Hz-90dBc 10Hz-110dBc 100Hz-120dBc 1k-100k-125dBc Adevs of the oscillator run from 5E-12 at 0.1 sec, down to 1E-12 at 10 sec, and back up to 2 E-12 at 1000sec. ___ 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. ___ 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] reference oscillator input circuit
Rick Karlquist wrote: jimlux wrote: I'm looking for suggestions on a general circuit that can be used to receive an external frequency reference (nominally a real clean sine wave at, say, 10 MHz, although up to 100 MHz is possible) and turn it into a real clean square wave. Galvanic isolation is a plus (a transformer or capacitor would probably do that). In the 5071A at 80 MHz, we capacitively coupled a sine wave into a 74AC series logic gate, that had DC bias resistors to hold it at half the supply voltage. that's similar to what Said recommended last year.. he uses a big resistor from output to input to set the bias, rather than a divider. ___ 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] Time Code generator
Chris Albertson wrote: Adding time code to video would be redundant. All video is already time coded. All *digital* video is timecoded.. Record that video on an analog 1/2 or 3/4 deck and you need the timecode on the longitudinal audio track. Yes, primarily as you say, to support editing. It's been 12 years since I sat in an edit bay, so I'll bet that analog gear is pretty much out of the picture by now, though. But many consumer level cameras fake it by defining time = zero at the start of a tape or the first frame in memory. If absolute time needs to be record on a consumer level camera then I'd shoot a few frames of a digital clock and then later in a video editor adjust the time code That would work..(e.g. it's just like slating at the beginning of a film take) Sometimes it would be more convenient to just record an audio timecode on the audio track. Where I could see timecode being handy is when you're trying to do automated processing. I worked on a system 15 years ago where we had 100 cameras, and we did the alignment by hand, and it was pretty painful. What's easy when syncing A and B roll gets tedious when there's 100 takes you're essentially cutting together. I think there's also a lot of utility in figuring a way to do it in the consumer electronics space. Say I was doing a radio interferometer kind of experiment and just wanted to do a poor man's VLBI, using a GPSDO at each station for time sync. OK, all that said there is a group of people who routinely record WWV audio on their video. Amateur occultation timers do this. These people use video cameras through telescopes to record when a asteroid passes in front of a star and blocks its light. This can produce very acuate orbital data for the asteroid and if enough people all over the world record it you can even deduce the shape of the asteroid. ___ 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] reference oscillator input circuit
One problem with this circuit is that tolerances in the resistors produce an offset between the 2 transistor bases in addition to any transistor mismatch, It's better to share a single divider and short (eg a transformer winding. Or at least connect them with a low impedance at low frequencies) the transistor bases together. Capacitively coupling the emitters can also be useful. Bruce Robert Darlington wrote: Just an FYI guys, I'm pretty sure the 3rd circuit down on the Wenzel page is identical to the input circuit for the TAPR TADD-2 frequency divider. The TADD-2 adds a transformer and load resistor. Schematic is in the manual here: http://www.tapr.org/~n8ur/TADD-2_Manual.pdf -Bob On Wed, Dec 8, 2010 at 8:46 AM, John Ackermann N8URj...@febo.com wrote: Wenzel has some discussion and circuits at: http://www.wenzel.com/documents/waveform.html. The Shera GPSDO made clever use of the input circuit of a 74HCT4046 PLL chip for squaring. John On 12/8/2010 10:31 AM, jimlux wrote: I'm looking for suggestions on a general circuit that can be used to receive an external frequency reference (nominally a real clean sine wave at, say, 10 MHz, although up to 100 MHz is possible) and turn it into a real clean square wave. Galvanic isolation is a plus (a transformer or capacitor would probably do that). I was thinking about rummaging through the schematics for test equipment reference inputs (since they've already solved the problem, eh?), but any other ideas would be welcome. I've scanned the archives of time-nuts, and while we have a fair amount of discussion on how to square up the 1Hz (or 100Hz) in a phase noise/ADEV setup, not so much on what to do with the 10 MHz. Rick has commented that you don't want to use a comparator. I have the papers by Dick, et al, and Collins, as well as all the others.. they tend to be looking at the low frequency problem, although the analysis is certainly applicable. I don't know that I'm looking for the whole multiple limiting stages scheme in any case. Oh, as far as performance.. Say the need is to not horribly degrade a good quality crystal oscillator... here's a typical set of specs: 76 MHz 1Hz-90dBc 10Hz-110dBc 100Hz-120dBc 1k-100k-125dBc Adevs of the oscillator run from 5E-12 at 0.1 sec, down to 1E-12 at 10 sec, and back up to 2 E-12 at 1000sec. ___ 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. ___ 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] reference oscillator input circuit
Assuming a transformer coupled input (with biasing via a secondary center tap) why not use a fast differential PECL to CMOS level translator? For example, the IDT ICS508 will take 0.3 to 1.0 V p-p input and give 2.5, 3.3, or 5 V swing on the output. The chip works down to DC and keeps the duty cycle in the 40%-60% window up to 250MHz (at 3.3V out). Jitter and noise is not spec'd however. To increase the noise immunity with a relatively slow 10MHz sine source I'd look at boosting the amplitude with the transformer, then clipping with balanced series resistors and back-to-back diodes so the translator sees a higher dV/dT on its inputs. Might want to look in some old Motorola ECL appnotes for other possible schemes. Bob From: jimlux jim...@earthlink.net To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wed, December 8, 2010 10:31:08 AM Subject: [time-nuts] reference oscillator input circuit I'm looking for suggestions on a general circuit that can be used to receive an external frequency reference (nominally a real clean sine wave at, say, 10 MHz, although up to 100 MHz is possible) and turn it into a real clean square wave. Galvanic isolation is a plus (a transformer or capacitor would probably do that). I was thinking about rummaging through the schematics for test equipment reference inputs (since they've already solved the problem, eh?), but any other ideas would be welcome. I've scanned the archives of time-nuts, and while we have a fair amount of discussion on how to square up the 1Hz (or 100Hz) in a phase noise/ADEV setup, not so much on what to do with the 10 MHz. Rick has commented that you don't want to use a comparator. I have the papers by Dick, et al, and Collins, as well as all the others.. they tend to be looking at the low frequency problem, although the analysis is certainly applicable. I don't know that I'm looking for the whole multiple limiting stages scheme in any case. Oh, as far as performance.. Say the need is to not horribly degrade a good quality crystal oscillator... here's a typical set of specs: 76 MHz 1Hz -90dBc 10Hz -110dBc 100Hz -120dBc 1k-100k -125dBc Adevs of the oscillator run from 5E-12 at 0.1 sec, down to 1E-12 at 10 sec, and back up to 2 E-12 at 1000sec. ___ 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] reference oscillator input circuit
One caveat with driving a CMOS gate input is that if it is overdriven so that the input protection circuit diodes conduct then the output jitter may increase substantially. At least this appears to happen when overdriving 74HC04 inverters. Once the input diodes conduct (5MHz sine wave input) the output jitter is easily measured with a 5370A/B. Just below conduction the output jitter appears to be buried in the 5370A/B noise. Bruce Rick Karlquist wrote: The document cited is full of plausible sounding but misleading information, if you want really low jitter. This type of oversimplification of the problem was present when the HP53131 series counters were designed, with the result that the Allan deviation of an external 10 MHz reference is degraded to only a part in 10^11 at 1 second. Rick Karlquist jimlux wrote: John Ackermann N8UR wrote: Wenzel has some discussion and circuits at: http://www.wenzel.com/documents/waveform.html. The Shera GPSDO made clever use of the input circuit of a 74HCT4046 PLL chip for squaring. John Doh... I was thinking that there was some vendor with ap notes on stuff like this, and I couldn't recall who it was, and I'm actually looking at a Wenzel OCXO sitting here on the desk. ___ 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.
[time-nuts] Time reference for recording...
There has been times in the past where I needed to make broadcast off-air recording that needed positive time indication. In those cases I would record the station's audio on one track and one of the WWV's on the other. I would start my recording early or let it run past the end of the program in order to get the top of the minute announcement of the time. For my needs this was more than adequate, as it didn't require anything more than a stereo playback contraption, and who could argue with the time! Burt At 10:50 AM 12/8/2010, someone wrote: On another list to which I subscribe, the question was asked about the suitability of recording WWV 2.5mhz audio as one track when recording off the air signals of interest as a time reference. The person who asked the question didn't really state his intentions but they seem very similar to my immediate needs. That is, simply a time reference - that is the time, the start of the minute, and periodic references (i.e. seconds) between the announcements. Burt I. Weiner Associates Broadcast Technical Services Glendale, California U.S.A. b...@att.net www.biwa.cc K6OQK ___ 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] reference oscillator input circuit
One can estimate the resultant jitter from the input slew rate and the circuit noise and bandwidth. Too much bandwidth with a slow input slew rate increases the jitter substantially over that possible with an optimal circuit. Bruce Robert LaJeunesse wrote: Assuming a transformer coupled input (with biasing via a secondary center tap) why not use a fast differential PECL to CMOS level translator? For example, the IDT ICS508 will take 0.3 to 1.0 V p-p input and give 2.5, 3.3, or 5 V swing on the output. The chip works down to DC and keeps the duty cycle in the 40%-60% window up to 250MHz (at 3.3V out). Jitter and noise is not spec'd however. To increase the noise immunity with a relatively slow 10MHz sine source I'd look at boosting the amplitude with the transformer, then clipping with balanced series resistors and back-to-back diodes so the translator sees a higher dV/dT on its inputs. Might want to look in some old Motorola ECL appnotes for other possible schemes. Bob From: jimluxjim...@earthlink.net To: Discussion of precise time and frequency measurementtime-nuts@febo.com Sent: Wed, December 8, 2010 10:31:08 AM Subject: [time-nuts] reference oscillator input circuit I'm looking for suggestions on a general circuit that can be used to receive an external frequency reference (nominally a real clean sine wave at, say, 10 MHz, although up to 100 MHz is possible) and turn it into a real clean square wave. Galvanic isolation is a plus (a transformer or capacitor would probably do that). I was thinking about rummaging through the schematics for test equipment reference inputs (since they've already solved the problem, eh?), but any other ideas would be welcome. I've scanned the archives of time-nuts, and while we have a fair amount of discussion on how to square up the 1Hz (or 100Hz) in a phase noise/ADEV setup, not so much on what to do with the 10 MHz. Rick has commented that you don't want to use a comparator. I have the papers by Dick, et al, and Collins, as well as all the others.. they tend to be looking at the low frequency problem, although the analysis is certainly applicable. I don't know that I'm looking for the whole multiple limiting stages scheme in any case. Oh, as far as performance.. Say the need is to not horribly degrade a good quality crystal oscillator... here's a typical set of specs: 76 MHz 1Hz-90dBc 10Hz-110dBc 100Hz-120dBc 1k-100k-125dBc Adevs of the oscillator run from 5E-12 at 0.1 sec, down to 1E-12 at 10 sec, and back up to 2 E-12 at 1000sec. ___ 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] Time Code generator
On 12/08/2010 02:27 PM, scmcgr...@gmail.com wrote: When audio/video time code is specified if its on a audio track its called LTC or Longitudinal Time Code and is generally IRIG-B, This is very uncommon these days as it went out of common use about the time 1 reel to reel was discontinued. Most common today on NTSC is VITC or vertical interval time code. Its encoded as a series of pulses in the vertical blanking interval. The display is generally called a 'Screen Burner' LTC (Linear Time Code) and VITC (Video Time Code) is both being part of SMPTE 12M-1-2008 which is the time-code formats for audio, film and video recordings. LTC is NOT IRIG-B, but a distinct code (I just checked the respective standards to be sure). LTC enumerate picture frames and the rate changes between 24 frames/s, 25 frames/s, 30/1,001 frames/s or 30 frames/s. IRIG-B is quite unfit for this. 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] Time Code generator
On 12/08/2010 07:18 PM, jimlux wrote: Chris Albertson wrote: Adding time code to video would be redundant. All video is already time coded. All *digital* video is timecoded.. No, not all digital video. The time-code is optional in many of the transfer formats. Record that video on an analog 1/2 or 3/4 deck and you need the timecode on the longitudinal audio track. Yes, primarily as you say, to support editing. It's been 12 years since I sat in an edit bay, so I'll bet that analog gear is pretty much out of the picture by now, though. Analog black-bursts is still here. But many consumer level cameras fake it by defining time = zero at the start of a tape or the first frame in memory. If absolute time needs to be record on a consumer level camera then I'd shoot a few frames of a digital clock and then later in a video editor adjust the time code That would work..(e.g. it's just like slating at the beginning of a film take) Sometimes it would be more convenient to just record an audio timecode on the audio track. Where I could see timecode being handy is when you're trying to do automated processing. I worked on a system 15 years ago where we had 100 cameras, and we did the alignment by hand, and it was pretty painful. What's easy when syncing A and B roll gets tedious when there's 100 takes you're essentially cutting together. For Cameras it is not actual time which is important, but frame and line alignment needs to be aligned. Digital video mixers has line-stores on the input, so the cameras only needs to be synced to within a few lines such that the line-store can solve the rest. If you fail syncing up you need to use a frame-store, which you try to avoid since it adds 40 ms of delay and you drop/duplicate frames. Even if you cut between the frames on the editing line, it is still a degradation you want to avoid, so syncing cameras is a good thing. Taking the effort to sync up kind of make sense when you look on the alternatives. 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] reference oscillator input circuit
ECL has a high phase noise floor in the -140s. Other than that, it works fine. Rick Karlquist Robert LaJeunesse wrote: Assuming a transformer coupled input (with biasing via a secondary center tap) why not use a fast differential PECL to CMOS level translator? For example, the IDT ICS508 will take 0.3 to 1.0 V p-p input and give 2.5, 3.3, or 5 V swing on the output. The chip works down to DC and keeps the duty cycle in the 40%-60% window up to 250MHz (at 3.3V out). Jitter and noise is not spec'd however. To increase the noise immunity with a relatively slow 10MHz sine source I'd look at boosting the amplitude with the transformer, then clipping with balanced series resistors and back-to-back diodes so the translator sees a higher dV/dT on its inputs. Might want to look in some old Motorola ECL appnotes for other possible schemes. Bob From: jimlux jim...@earthlink.net To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wed, December 8, 2010 10:31:08 AM Subject: [time-nuts] reference oscillator input circuit I'm looking for suggestions on a general circuit that can be used to receive an external frequency reference (nominally a real clean sine wave at, say, 10 MHz, although up to 100 MHz is possible) and turn it into a real clean square wave. Galvanic isolation is a plus (a transformer or capacitor would probably do that). I was thinking about rummaging through the schematics for test equipment reference inputs (since they've already solved the problem, eh?), but any other ideas would be welcome. I've scanned the archives of time-nuts, and while we have a fair amount of discussion on how to square up the 1Hz (or 100Hz) in a phase noise/ADEV setup, not so much on what to do with the 10 MHz. Rick has commented that you don't want to use a comparator. I have the papers by Dick, et al, and Collins, as well as all the others.. they tend to be looking at the low frequency problem, although the analysis is certainly applicable. I don't know that I'm looking for the whole multiple limiting stages scheme in any case. Oh, as far as performance.. Say the need is to not horribly degrade a good quality crystal oscillator... here's a typical set of specs: 76 MHz 1Hz -90dBc 10Hz -110dBc 100Hz -120dBc 1k-100k -125dBc Adevs of the oscillator run from 5E-12 at 0.1 sec, down to 1E-12 at 10 sec, and back up to 2 E-12 at 1000sec. ___ 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] reference oscillator input circuit
Yes, and thus if you are going to use a comparator or line receiver (not recommended), then you should use the SLOWEST one that still works, if you want to optimize jitter. This is because the noise bandwidth is less. Bruce Griffiths wrote: One can estimate the resultant jitter from the input slew rate and the circuit noise and bandwidth. Too much bandwidth with a slow input slew rate increases the jitter substantially over that possible with an optimal circuit. Bruce Robert LaJeunesse wrote: Assuming a transformer coupled input (with biasing via a secondary center tap) why not use a fast differential PECL to CMOS level translator? For example, the IDT ICS508 will take 0.3 to 1.0 V p-p input and give 2.5, 3.3, or 5 V swing on the output. The chip works down to DC and keeps the duty cycle in the 40%-60% window up to 250MHz (at 3.3V out). Jitter and noise is not spec'd however. To increase the noise immunity with a relatively slow 10MHz sine source I'd look at boosting the amplitude with the transformer, then clipping with balanced series resistors and back-to-back diodes so the translator sees a higher dV/dT on its inputs. Might want to look in some old Motorola ECL appnotes for other possible schemes. Bob From: jimluxjim...@earthlink.net To: Discussion of precise time and frequency measurementtime-nuts@febo.com Sent: Wed, December 8, 2010 10:31:08 AM Subject: [time-nuts] reference oscillator input circuit I'm looking for suggestions on a general circuit that can be used to receive an external frequency reference (nominally a real clean sine wave at, say, 10 MHz, although up to 100 MHz is possible) and turn it into a real clean square wave. Galvanic isolation is a plus (a transformer or capacitor would probably do that). I was thinking about rummaging through the schematics for test equipment reference inputs (since they've already solved the problem, eh?), but any other ideas would be welcome. I've scanned the archives of time-nuts, and while we have a fair amount of discussion on how to square up the 1Hz (or 100Hz) in a phase noise/ADEV setup, not so much on what to do with the 10 MHz. Rick has commented that you don't want to use a comparator. I have the papers by Dick, et al, and Collins, as well as all the others.. they tend to be looking at the low frequency problem, although the analysis is certainly applicable. I don't know that I'm looking for the whole multiple limiting stages scheme in any case. Oh, as far as performance.. Say the need is to not horribly degrade a good quality crystal oscillator... here's a typical set of specs: 76 MHz 1Hz-90dBc 10Hz-110dBc 100Hz-120dBc 1k-100k-125dBc Adevs of the oscillator run from 5E-12 at 0.1 sec, down to 1E-12 at 10 sec, and back up to 2 E-12 at 1000sec. ___ 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. ___ 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] reference oscillator input circuit
On 12/08/2010 06:28 PM, Rick Karlquist wrote: jimlux wrote: I'm looking for suggestions on a general circuit that can be used to receive an external frequency reference (nominally a real clean sine wave at, say, 10 MHz, although up to 100 MHz is possible) and turn it into a real clean square wave. Galvanic isolation is a plus (a transformer or capacitor would probably do that). In the 5071A at 80 MHz, we capacitively coupled a sine wave into a 74AC series logic gate, that had DC bias resistors to hold it at half the supply voltage. A feed-back resistor over an inverter and capacitive feed will self-bias such that PWM is 50%. The details of the gate being used may however prove lethal as you may end up with self-biasing into ring-modulation mode for some inverters being effectively three inverters in series. The use of a long-tailed pair on the input to gain out of the problem, prior to a gate for final squaring up would be my recommendation. It would be in the spirit of the Dick and Collins papers. The needed slew-rate gain will not be that great for 10 MHz to 100 MHz sine. You should not need to use very exotic setups to get the performance you need. 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] reference oscillator input circuit
On 12/08/2010 09:13 PM, Rick Karlquist wrote: Yes, and thus if you are going to use a comparator or line receiver (not recommended), then you should use the SLOWEST one that still works, if you want to optimize jitter. This is because the noise bandwidth is less. For optimum result you need to balance the slew-rate gain (essentially gain of the transition slew-rate) and the amount of added noise. You need a certain amount of bandwidth for a certain amount of output slew-rate, but higher bandwidth also gives more noise. A multi-stage setup use moderate gain and bandwidth in the initial stages, but it increases down the line. A few links: http://www.ko4bb.com/~bruce/CLKSHPR.html http://www.ko4bb.com/~bruce/ZeroCrossingDetectors.html As for transformer isolation, for most uses I find it fairly useless, but an RF-choke to isolate the front-end and the electronics RF-wise in common mode sense is more useful IMHO. 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] reference oscillator input circuit
I was thinking about how good or how bad would result the use of an LVDS line receiver ... but it is only a though :) Regards, Javier El 08/12/2010 19:50, Robert LaJeunesse escribió: Assuming a transformer coupled input (with biasing via a secondary center tap) why not use a fast differential PECL to CMOS level translator? For example, the IDT ICS508 will take 0.3 to 1.0 V p-p input and give 2.5, 3.3, or 5 V swing on the output. The chip works down to DC and keeps the duty cycle in the 40%-60% window up to 250MHz (at 3.3V out). Jitter and noise is not spec'd however. To increase the noise immunity with a relatively slow 10MHz sine source I'd look at boosting the amplitude with the transformer, then clipping with balanced series resistors and back-to-back diodes so the translator sees a higher dV/dT on its inputs. Might want to look in some old Motorola ECL appnotes for other possible schemes. Bob From: jimluxjim...@earthlink.net To: Discussion of precise time and frequency measurementtime-nuts@febo.com Sent: Wed, December 8, 2010 10:31:08 AM Subject: [time-nuts] reference oscillator input circuit I'm looking for suggestions on a general circuit that can be used to receive an external frequency reference (nominally a real clean sine wave at, say, 10 MHz, although up to 100 MHz is possible) and turn it into a real clean square wave. Galvanic isolation is a plus (a transformer or capacitor would probably do that). I was thinking about rummaging through the schematics for test equipment reference inputs (since they've already solved the problem, eh?), but any other ideas would be welcome. I've scanned the archives of time-nuts, and while we have a fair amount of discussion on how to square up the 1Hz (or 100Hz) in a phase noise/ADEV setup, not so much on what to do with the 10 MHz. Rick has commented that you don't want to use a comparator. I have the papers by Dick, et al, and Collins, as well as all the others.. they tend to be looking at the low frequency problem, although the analysis is certainly applicable. I don't know that I'm looking for the whole multiple limiting stages scheme in any case. Oh, as far as performance.. Say the need is to not horribly degrade a good quality crystal oscillator... here's a typical set of specs: 76 MHz 1Hz-90dBc 10Hz-110dBc 100Hz-120dBc 1k-100k-125dBc Adevs of the oscillator run from 5E-12 at 0.1 sec, down to 1E-12 at 10 sec, and back up to 2 E-12 at 1000sec. ___ 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. -- Javier HerreroEMAIL: jherr...@hvsistemas.com Chief Technology Officer HV Sistemas S.L. PHONE: +34 949 336 806 Los Charcones, 17 FAX: +34 949 336 792 19170 El Casar - Guadalajara - Spain WEB: http://www.hvsistemas.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] reference oscillator input circuit
Of all the ways to square a sine wave I think the best might be to use a PLL. the raising edge of your output square wave would trigger a sample of the input sine wave. The distance from zero volts of that sample is the phase error. The goal is to have the raising edge of the square wave happen just as the sine crosses zero. But if it's not dead-on you get an error signal that can be either positive or negative and this error is low pass filtered and then applied as a correction. But my guess is that if you are using this to feed a 'scope a reference frequency the scope will have it's own PLL. -- = 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] reference oscillator input circuit
The Wenzel diff-amp circuit is OK but it will run out of steam before 100 MHz unless you use different transistors. On the other hand you really have to go out of your way to corrupt the signal at the -125 dBc/Hz level. At that level of play any decent comparator with the necessary slew rate will be fine. A 74AC gate looks good in this scenario: http://www.ke5fx.com/ac.htm ... subject to what other people have said about it being sensitive to input level. -- john, KE5FX -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com]on Behalf Of jimlux Sent: Wednesday, December 08, 2010 7:31 AM To: Discussion of precise time and frequency measurement Subject: [time-nuts] reference oscillator input circuit I'm looking for suggestions on a general circuit that can be used to receive an external frequency reference (nominally a real clean sine wave at, say, 10 MHz, although up to 100 MHz is possible) and turn it into a real clean square wave. Galvanic isolation is a plus (a transformer or capacitor would probably do that). I was thinking about rummaging through the schematics for test equipment reference inputs (since they've already solved the problem, eh?), but any other ideas would be welcome. I've scanned the archives of time-nuts, and while we have a fair amount of discussion on how to square up the 1Hz (or 100Hz) in a phase noise/ADEV setup, not so much on what to do with the 10 MHz. Rick has commented that you don't want to use a comparator. I have the papers by Dick, et al, and Collins, as well as all the others.. they tend to be looking at the low frequency problem, although the analysis is certainly applicable. I don't know that I'm looking for the whole multiple limiting stages scheme in any case. Oh, as far as performance.. Say the need is to not horribly degrade a good quality crystal oscillator... here's a typical set of specs: 76 MHz 1Hz -90dBc 10Hz -110dBc 100Hz -120dBc 1k-100k -125dBc Adevs of the oscillator run from 5E-12 at 0.1 sec, down to 1E-12 at 10 sec, and back up to 2 E-12 at 1000sec. ___ 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] MBD /B
Hello The Net: I estimate /B MBD to be in DM79lt, in Westminster, CO. Just NW of Denver. Since I am in FN41sr, my LOB to is: 277.5 degrees ref true North at a distance of 2,907.5 Km or 1806.4 miles. I got the LOB and DX info from the BD2004 software at the www.w1ghz.org site. It would be a long shot for me to hear it from Cape Cod FN41sr Stan,W1LE ___ 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] MBD /B
umm u lost me any help? On Wed, Dec 8, 2010 at 6:05 PM, Stan, W1LE stanw...@verizon.net wrote: Hello The Net: I estimate /B MBD to be in DM79lt, in Westminster, CO. Just NW of Denver. Since I am in FN41sr, my LOB to is: 277.5 degrees ref true North at a distance of 2,907.5 Km or 1806.4 miles. I got the LOB and DX info from the BD2004 software at the www.w1ghz.org site. It would be a long shot for me to hear it from Cape Cod FN41sr Stan,W1LE ___ 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] MBD /B
Hi I assume we're talking about a NDB (non directional beacon). This time of year is pretty good for low frequency stuff. The thunderstorms die down and you can really hear a *long* ways. The path you are talking about is quite possible. Bob On Dec 8, 2010, at 6:05 PM, Stan, W1LE wrote: Hello The Net: I estimate /B MBD to be in DM79lt, in Westminster, CO. Just NW of Denver. Since I am in FN41sr, my LOB to is: 277.5 degrees ref true North at a distance of 2,907.5 Km or 1806.4 miles. I got the LOB and DX info from the BD2004 software at the www.w1ghz.org site. It would be a long shot for me to hear it from Cape Cod FN41sr Stan,W1LE ___ 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] MBD /B
Sorry for the confusion, Not a non directional beacon (NDB) , but rather a part 15 beacon on 137 KHz. some recent posts include : On 12/8/2010 3:55 PM, C. Turner wrote: I tried detecting MBD/QRSS30 from Utah - but nothing heard/seen. Beacon MBD is on now, at 187.517 khz, QRSS30 mode. 0400 - 0700 UTC ( 9pm MST to 12 am MST ) 73 Mark AB0CW Thanks Stan, W1LECape Cod ___ 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] MBD /B
I figured out what I did wrong. I cross posted from the lowfer reflector. Please disregard. I will be more careful in the future. Stan, W1LE Cape Cod ___ 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] MBD /B
Hi And take away all the fun of guessing what's going on If you can indeed track a 1W signal from ~ Colorado, there might indeed be some timing use for the system. Bob On Dec 8, 2010, at 8:32 PM, Stan, W1LE wrote: I figured out what I did wrong. I cross posted from the lowfer reflector. Please disregard. I will be more careful in the future. Stan, W1LE Cape Cod ___ 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] MBD /B
Darn, I was sure that was a coded message to space saying it was safe to bring the Mother Ship in because we were all distracted by tax cuts for the rich. Bill Hawkins -Original Message- From: Stan, W1LE Sent: Wednesday, December 08, 2010 7:32 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] MBD /B I figured out what I did wrong. I cross posted from the lowfer reflector. Please disregard. I will be more careful in the future. Stan, W1LE Cape Cod ** You are assuming that you have a future. ** ___ 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] Got 60HZ?
Recently I bought a Efratom Ru frequency standard from eBay and a frequency divider chip that makes 1MHZ,100KHZ,25KHZ,10KHZ,100HZ and a 1HZ output. Today I thought of a way to make a nice 60HZ so you can use a mains-powered clock for the display (using amplifier and transformer wired backwards). But, now you'll need 60HZ. A European has it easy with 50HZ as you use a BASIC Stamp or Arduino to divide the 100HZ output. But for 60HZ I came up with a solution: You set up the Arduino to take the 10KHZ from the divider chip and program it to count off 83 pulses to flip an output. But wait! Unless you add a leap count every 3 flips of the output, it'll run fast. Assume at the start the Arduino output starts high then turns low: (83+83+84+83+83+84)*20 = 10,000 pulses = one second H__L__H__L__H__L Every output cycle and a half the voltage swing is a little over 1 percent longer because of the leap count. This means that the distortion adds a slight inaccuracy, not enough to upset New Year's revelers. But if you want a better 60HZ, try using the 100KHZ: (833+833+834+833+833+834)*20 = one second You see where this is going with leap counts. The ultimate of course is one really good Arduino and (after a hex inverter to amplify it) take the straight 10MHZ and apply this leap count technique: (8+8+83334+8+8+83334)*20 = one really accurately made 60HZ = one nice second, just the thing for a Nixie clock. :) Now, what is a good hex inverter to take the 10 million HZ of my rubidiom movement to feed a frequency divider chip (and later Arduino)? It needs to take the .5 of a volt sinewave and squarewave it and in a normal 14 pin DIP (breadboardable) package. ___ 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] GPS antenna info needed
My magnetic base hockey puck amplified GPS antenna for my Lucent receiver died. I had purchased it at the Dayton Hamvention so I don’t remember the dealer. I’ve found quite a few sellers on Amazon that are in the USA and their prices are all about the same. Does anyone have a recommendation? I’d rather spend a few dollars more for a quality unit but I don’t know if they are all from the same supplier in china and they only difference is the dealers price. TIA Perrier ___ 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 antenna info needed
On Wed, Dec 8, 2010 at 6:16 PM, Perry Sandeen sandee...@yahoo.com wrote: My magnetic base hockey puck amplified GPS antenna for my Lucent receiver died. I had purchased it at the Dayton Hamvention so I don’t remember the dealer. I’ve found quite a few sellers on Amazon that are in the USA and their prices are all about the same. Does anyone have a recommendation? I’d rather spend a few dollars more for a quality unit but I don’t know if they are all from the same supplier in china and they only difference is the dealers price. I really like the Antenna Factor GPS-SH: http://tinyurl.com/2fxm6n7 I've bought them from Mouser but it looks like you might be able to order direct from the manufacturer. They seem to outperform the China clones by several dB, and have a relatively narrow (~60MHz) bandpass filter at the antenna that reduces out-of-band noise. Don't forget to use a ground plane. Henry ___ 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] Got 60HZ?
Recently I bought a Efratom Ru frequency standard from eBay and a frequency divider chip that makes 1MHZ,100KHZ,25KHZ,10KHZ,100HZ and a 1HZ output. Today I thought of a way to make a nice 60HZ so you can use a mains-powered clock for the display (using amplifier and transformer wired backwards). But, now you'll need 60HZ. A European has it easy with 50HZ as you use a BASIC Stamp or Arduino to divide the 100HZ output. But for 60HZ I came up with a solution: You set up the Arduino to take the 10KHZ from the divider chip and program it to count off 83 pulses to flip an output. But wait! Unless you add a leap count every 3 flips of the output, it'll run fast. Assume at the start the Arduino output starts high then turns low: (83+83+84+83+83+84)*20 = 10,000 pulses = one second H__L__H__L__H__L Every output cycle and a half the voltage swing is a little over 1 percent longer because of the leap count. This means that the distortion adds a slight inaccuracy, not enough to upset New Year's revelers. True -- it's a common technique in synthesizers. Now, what is a good hex inverter to take the 10 million HZ of my rubidiom movement to feed a frequency divider chip (and later Arduino)? It needs to take the .5 of a volt sinewave and squarewave it and in a normal 14 pin DIP (breadboardable) package. The LPro-101 manual offers some advice of uneven quality on that subject, but I think you'd be fine with either a two-transistor differential amp (http://www.wenzel.com/documents/waveform.html) or a 74AC-series gate (http://www.ke5fx.com/ac.htm). See the other thread on reference-oscillator input circuits as well. -- john, KE5FX ___ 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.
