Re: [time-nuts] Photodiodes for high frequency OPLL
On Sun, 31 Mar 2013 15:27:02 +0100 David Kirkby david.kir...@onetel.net wrote: You can't modulate the sensitivity of a PIN diode by an adjustable bias like you can in an APD. For a PIN diode, at the wavelengths you are talking of, you basically get around 0.5 Amps/Watt from the diode. Right.. Forgot about that ^^' APDs are not that expensive, especially the small ones you will need for this. Well.. an APD is about 60-100USD while PIN photodiodes start from 10USD. Ok, considering that the rest will be probably in the 2000-5000USD range, this isn't much :-) But I still can't really see a solution - I was just clutching at straws. I think the gain modulated approach to downconvert the signal should work. Taking the beat signal of the two lasers and applying it to the APD will get me an approx 7GHz signal. Gain modulating the the APD with an 1-2GHz sinusoidal should downconvert it to something below 1GHz. The frequency of the modulation signal is low enough to pass trough the APD unperturbed (the APD is specified for 2.5Gbps). That the gain of an APD is an exponential function of the applied bias voltage should make the bias modulation sharp enough to approximate it with a pulse train. Ie it should nicely downconvert the beat signal to something below 1GHz. Attila Kinali -- The people on 4chan are like brilliant psychologists who also happen to be insane and gross. -- unknown ___ 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] Photodiodes for high frequency OPLL
On Sun, 31 Mar 2013 20:31:58 -0700 gary li...@lazygranch.com wrote: On 3/31/2013 5:52 AM, Attila Kinali wrote: Probably. But as steep filters for optics are kind of hard to come by, i think a super heterodyne design isn't realy going to work. I've bought optical filters from Andover. They are pretty cheap, at least compared to the rest of the industry. http://www.andovercorp.com/Web_store/index.php Yes, but the usual optical filters are not steep enough for this application. They are specified to a few nm, while we are talking here about GHz. At those wavelengths this is IIRC a factor 100'000. But thanks for the page anyways.. they might come handy as an ambient light filter for the photodiodes. Attila Kinali -- The people on 4chan are like brilliant psychologists who also happen to be insane and gross. -- unknown ___ 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] Photodiodes for high frequency OPLL
On Sun, 31 Mar 2013 10:47:29 -0400 Mike S mi...@flatsurface.com wrote: On 3/30/2013 7:48 AM, Attila Kinali wrote: So far, i figured out that PIN photodiodes can go up to several 100MHz transition frequency and avalanche photodiodes are available up to 2GHz. The only photodiodes that go higher are those for the telecom range at 1-1.5um, which is a bit low for my needs. But, i have seen descriptions of such OPLL that work with multi GHz offsets in the 700-800nm range. Maybe you can find something here: http://www.gcsincorp.com/optical_chips/GaAs%20%20InGaAs%20PIN%20Photodetectors.php They have ones which have a wavelength range of 760-860 nm, and go up to 14 GHz. Interesting! thanks! Attila Kinali -- The people on 4chan are like brilliant psychologists who also happen to be insane and gross. -- unknown ___ 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] Photodiodes for high frequency OPLL
On Mon, 01 Apr 2013 09:08:51 +1300 Bruce Griffiths bruce.griffi...@xtra.co.nz wrote: Nothing to do with laser line width. Merely indicating that the photodiode mixer can be used with a suitable LO to build an optical spectrum analyser front end. Are you refering to heterodyne spectrum analyser? Attila Kinali -- The people on 4chan are like brilliant psychologists who also happen to be insane and gross. -- unknown ___ 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] Photodiodes for high frequency OPLL
Attila Kinali wrote: On Mon, 01 Apr 2013 09:08:51 +1300 Bruce Griffithsbruce.griffi...@xtra.co.nz wrote: Nothing to do with laser line width. Merely indicating that the photodiode mixer can be used with a suitable LO to build an optical spectrum analyser front end. Are you refering to heterodyne spectrum analyser? Attila Kinali Essentially, however if the photdiode has say a 1GHz bandwidth the LO could be stepped in say 1GHz steps with subsequent circuitry providing finer resolution. Constructing an optoelectronic version of either an LSB or USB converter may be interesting. Bruce ___ 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] Photodiodes for high frequency OPLL
On Mon, 01 Apr 2013 22:32:11 +1300 Bruce Griffiths bruce.griffi...@xtra.co.nz wrote: Attila Kinali wrote: On Mon, 01 Apr 2013 09:08:51 +1300 Bruce Griffithsbruce.griffi...@xtra.co.nz wrote: Nothing to do with laser line width. Merely indicating that the photodiode mixer can be used with a suitable LO to build an optical spectrum analyser front end. Are you refering to heterodyne spectrum analyser? Essentially, however if the photdiode has say a 1GHz bandwidth the LO could be stepped in say 1GHz steps with subsequent circuitry providing finer resolution. The difficulty here is to get an LO laser that can be stepped in 1GHz steps and keep it there, stable. The only way i have seen sofar is using a mode locked laser and referencing/stabilizing the LO to one of the comb tooths. Technically seems to be relatively simple, but unfortunately a mode locked laser is financially out of the reach of a mere mortal. Constructing an optoelectronic version of either an LSB or USB converter may be interesting. Yes, an optoelectronical I/Q mixer would be very intersting. But also very difficult and fragile to build, considering that you have to keep the distances stable down to a couple of 10nm. Attila Kinali -- The people on 4chan are like brilliant psychologists who also happen to be insane and gross. -- unknown ___ 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] Photodiodes for high frequency OPLL
Attila Kinali wrote: On Mon, 01 Apr 2013 22:32:11 +1300 Bruce Griffithsbruce.griffi...@xtra.co.nz wrote: Attila Kinali wrote: On Mon, 01 Apr 2013 09:08:51 +1300 Bruce Griffithsbruce.griffi...@xtra.co.nz wrote: Nothing to do with laser line width. Merely indicating that the photodiode mixer can be used with a suitable LO to build an optical spectrum analyser front end. Are you refering to heterodyne spectrum analyser? Essentially, however if the photdiode has say a 1GHz bandwidth the LO could be stepped in say 1GHz steps with subsequent circuitry providing finer resolution. The difficulty here is to get an LO laser that can be stepped in 1GHz steps and keep it there, stable. The only way i have seen sofar is using a mode locked laser and referencing/stabilizing the LO to one of the comb tooths. Technically seems to be relatively simple, but unfortunately a mode locked laser is financially out of the reach of a mere mortal. Constructing an optoelectronic version of either an LSB or USB converter may be interesting. Yes, an optoelectronical I/Q mixer would be very intersting. But also very difficult and fragile to build, considering that you have to keep the distances stable down to a couple of 10nm. Attila Kinali Back to the original problem: An AOM could be used to generate a sideband 7GHz above (or below) the output of 1 laser which could then be mixed with the output of the other laser using a narrow bandwidth photodiode. How do ensure a suitably wide mode hop free tuning range for the lasers to be locked to the first laser? Bruce ___ 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] Photodiodes for high frequency OPLL
On 30 March 2013 11:48, Attila Kinali att...@kinali.ch wrote: So far, i figured out that PIN photodiodes can go up to several 100MHz transition frequency and avalanche photodiodes are available up to 2GHz. It might be worth Picosecond Pulsed Labs to. I can't see it on their web site, but I would not be surprised if they sell very high speed diodes - it is sort of the market they aim at. Dave ___ 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] WWVB D-PSK document
Paul, On 04/01/2013 04:17 AM, paul swed wrote: Bob and Magnus no offense taken at all good comments and thats why I shared. Needs other eyes then just mine. I captured the text in a seperate document reread tomorrow. Easy stuff first. Magnus the concerns on the channel are very real and it really does shift phase significantly. I mearly rephrased Bob's (very valid) point. I do see this sometimes at sun rise and set. When I went to the 22K instead of the 474 K that seemed to allow things to track the dynamics better. I actually do not believe 22K is the answer. I believe its at the other end actually of the possible integration solution. 1M was definitly out. One way to combat it would be to re-play the shifts from previous day, as this is a systematic shift. That way the loop bandwidth could be held lower as dynamics would be knocked down a bit to handle the diffrential. Surely these things would shift and be different from day to day, but there should be a high degree of similarity in the way that the sun goes up and alters the ionsphere from one day to another. Today memory and CPU isn't all that hard to combine, and the circular buffer of 86400 s doesn't take a masterpiece of software to create. Another thing to consider is that you might want to reach for a PII^2 loop to combat the phase-shift-range. Pre-filtering the loop is a good tool, but I don't think is gives much benefit here, a second integrator will be able to track in the higher drift rates better than a plain PI loop. bob you have numbers of comments I need to chew on. The TL072 cutoff well below the broadcast band. The other thing noted (Darn good eyes) is the arrangement of the 2 Xformers. Yes they are what they are its what was in stock at mouser. No one make IF xformers anymore. So the z is high and the other side is higher. Great choices. Is what it is. What are you going to do no one does DC anymore. The DC transformers isn't what they used to be... (had to, a day like this) Have you been able to fully recover the phase-modulated message? The one thing I haven't seen is if someone has done a modification hack to their WWVB in order to transform them into Costas-loops. It should not be too hard to do. I don't expect to hear WWVB over here without much trouble (including separating out MSF), so I am not playing this game, even if I like the challenge. I need to improve my DXing capabilities quite a bit first. 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] Photodiodes for high frequency OPLL
On Saturday 30 March 2013, Attila Kinali wrote: So far, i figured out that PIN photodiodes can go up to several 100MHz transition frequency and avalanche photodiodes are available up to 2GHz. The only photodiodes that go higher are those for the telecom range at 1-1.5um, which is a bit low for my needs. Took me about 15 Seconds of googling to find this: http://search.newport.com/?x2=skuq2=818-BB-45 Biased Photodetector, 400-900nm, GaAs, 12.5 GHz, for $ 940 -Wolfgang, DL1SKY ___ 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] Photodiodes for high frequency OPLL
On Monday 01 April 2013, Bruce Griffiths wrote: Back to the original problem: An AOM could be used to generate a sideband 7GHz above (or below) the output of 1 laser which could then be mixed with the output of the other laser using a narrow bandwidth photodiode. That's going to get tough. AOMs usually stop at some hundret MHz and even if you do quad-pass (2 polarizations, 2 directions), you will have a hard time getting to 7 GHz. So you'd have to cascade several ones. You could, however, use an EOM theoretically, but again, considering price and bandwidth constraints, you will only find suitable ones for telecom wavelengths. On Monday 01 April 2013, Attila Kinali wrote: [APD...] I think the gain modulated approach to downconvert the signal should work. Anyway, each of these down-mixing approaches needs to resolve the mirror frequency problem. I.e. if you modulate your receiver with 7.1 GHz (or use an EOM to do that optically) and detect at 100 MHz, you do not know whether the input signal has an offset of 7.2 GHz or 7.0 GHz. So you might be locking on the wrong one. The AOM would not have that issue because it is single sideband. --Wolfgang, DL1SKY ___ 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] Photodiodes for high frequency OPLL
This thread has already drifted a bit, but as an aside, the sky UV filters sold for photography are a joke. (Easily verified with UV diodes and any material that reacts to UV.) The Andover 400nm long pass actually DOES filter UV. A 400nm is nearly cast free. A 420nm does have a bit of a cast, but can be useful at times. These UV filters reduce the effect of airborne water vapor in long distance photography/remote-sensing. -Original Message- From: Attila Kinali att...@kinali.ch Sender: time-nuts-boun...@febo.com Date: Mon, 1 Apr 2013 11:12:26 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: Re: [time-nuts] Photodiodes for high frequency OPLL On Sun, 31 Mar 2013 20:31:58 -0700 gary li...@lazygranch.com wrote: On 3/31/2013 5:52 AM, Attila Kinali wrote: Probably. But as steep filters for optics are kind of hard to come by, i think a super heterodyne design isn't realy going to work. I've bought optical filters from Andover. They are pretty cheap, at least compared to the rest of the industry. http://www.andovercorp.com/Web_store/index.php Yes, but the usual optical filters are not steep enough for this application. They are specified to a few nm, while we are talking here about GHz. At those wavelengths this is IIRC a factor 100'000. But thanks for the page anyways.. they might come handy as an ambient light filter for the photodiodes. Attila Kinali -- The people on 4chan are like brilliant psychologists who also happen to be insane and gross. -- unknown ___ 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] Photodiodes for high frequency OPLL
On Mon, 1 Apr 2013 14:28:49 +0100 Wolfgang timen...@triplespark.net wrote: On Saturday 30 March 2013, Attila Kinali wrote: So far, i figured out that PIN photodiodes can go up to several 100MHz transition frequency and avalanche photodiodes are available up to 2GHz. The only photodiodes that go higher are those for the telecom range at 1-1.5um, which is a bit low for my needs. Took me about 15 Seconds of googling to find this: http://search.newport.com/?x2=skuq2=818-BB-45 Biased Photodetector, 400-900nm, GaAs, 12.5 GHz, for $ 940 Yes. I found these as well. There are tons of such photodetectors, but their price is almost always above 1000USD. I'm doing this on my own and thus am a little bit constraint on money. Beside i hope to get the whole thing done for under 2000USD. Hence i hope to be able to use some of the shelf photodiodes and build the electronics myself. Attila Kinali -- The people on 4chan are like brilliant psychologists who also happen to be insane and gross. -- unknown ___ 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] Photodiodes for high frequency OPLL
On Mon, 1 Apr 2013 14:24:58 +0100 Wolfgang timen...@triplespark.net wrote: On Monday 01 April 2013, Attila Kinali wrote: [APD...] I think the gain modulated approach to downconvert the signal should work. Anyway, each of these down-mixing approaches needs to resolve the mirror frequency problem. I.e. if you modulate your receiver with 7.1 GHz (or use an EOM to do that optically) and detect at 100 MHz, you do not know whether the input signal has an offset of 7.2 GHz or 7.0 GHz. So you might be locking on the wrong one. If i'm not mistaken, this shouldn't be a problem I'm not demodulating the laser, but using a PLL to fix the difference frequency. Being on the wrong side would invert the sign on the loop gain, thus the mirror freuquency would be an unstable point. Attila Kinali -- The people on 4chan are like brilliant psychologists who also happen to be insane and gross. -- unknown ___ 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] Photodiodes for high frequency OPLL
I think that you should be able to take the signal right out of the backbiased diode and run it straight into a microwave mixer w/ a fixed 7 GHz LO and frequency discrimitate the IF output from the mixer to generate a control signal for your LASER. In theory, if your LASERS were very, very, very good, you might be able to achieve phase lock, but I'd not hold my breath. A discriminator can give you frequency lock. YMMV, -John = On Mon, 1 Apr 2013 14:24:58 +0100 Wolfgang timen...@triplespark.net wrote: On Monday 01 April 2013, Attila Kinali wrote: [APD...] I think the gain modulated approach to downconvert the signal should work. Anyway, each of these down-mixing approaches needs to resolve the mirror frequency problem. I.e. if you modulate your receiver with 7.1 GHz (or use an EOM to do that optically) and detect at 100 MHz, you do not know whether the input signal has an offset of 7.2 GHz or 7.0 GHz. So you might be locking on the wrong one. If i'm not mistaken, this shouldn't be a problem I'm not demodulating the laser, but using a PLL to fix the difference frequency. Being on the wrong side would invert the sign on the loop gain, thus the mirror freuquency would be an unstable point. Attila Kinali -- The people on 4chan are like brilliant psychologists who also happen to be insane and gross. -- unknown ___ 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] FE-5680 frequency jump
I’ve been running an FE-5680 for maybe a total of 50 hours over the last several months. I found that an offset setting of 180 made it track GPS and (previously-set) LPRO-101 10 MHz signals. Even with power cycling, after about 1/2 hour, with an offset setting of 180 the FE-5680 was stable. The last time I turned on the FE-5680, it drifted with a setting of 180 and needed a new setting of –415 to track the other signals. That’s a change of 595 counts and with a resolution of 6.8 uHz per count, a frequency change of 4 mHz (0.004 Hz) and 0.4 ppb. Operation at the new setting is stable for now. The lock signal indicates lock and the power supply voltage is still 15V. I haven’t checked lamp voltage or VCXO voltage as that requires opening the case. Before I start poking around, thought I’d ask if anyone has seen a similar symptom. Time to open it up? Thanks, Bob ___ 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] FE-5680 frequency jump
Hi Bob, On 04/01/2013 10:06 PM, Bob Quenelle wrote: I’ve been running an FE-5680 for maybe a total of 50 hours over the last several months. I found that an offset setting of 180 made it track GPS and (previously-set) LPRO-101 10 MHz signals. Even with power cycling, after about 1/2 hour, with an offset setting of 180 the FE-5680 was stable. The last time I turned on the FE-5680, it drifted with a setting of 180 and needed a new setting of –415 to track the other signals. That’s a change of 595 counts and with a resolution of 6.8 uHz per count, a frequency change of 4 mHz (0.004 Hz) and 0.4 ppb. Operation at the new setting is stable for now. The lock signal indicates lock and the power supply voltage is still 15V. I haven’t checked lamp voltage or VCXO voltage as that requires opening the case. Before I start poking around, thought I’d ask if anyone has seen a similar symptom. Time to open it up? How long have it been turned on since last power-up? Let it sit for a day at least. I've found that it is easy to be in too much hurry to judge the situation and trim things efter power-up. The crystal oscillator just doesn't get the time to settle in. When triming up caesiums, I did this mistake myself, altered my ways and got a much better result. 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] Time shown as two horizontal bars
Looking for a long, thin horizontal clock display for use above or below a flat screen TV. Tried searching for bar clock and got a lot of useless hits. What I'd like is a display that is about half an inch (12 mm) high by 12-18 inches long (30-50 cm) that is just two rows of 60 or 120 leds. One row is labeled 0 to 59 (or 60) and the other is labeled 0 to 12. The display does not stay at 12 or 60 but jumps back to zero. Power line frequency is an adequate reference, as long as it always has the same 86,400 seconds per day, except for added leap seconds. There should not be a clock frequency adjustment. 60 seconds worth of line cycles bumps the minute bar (30 if it has 120 leds), and 5 minutes bumps the hour bar (150 seconds for 120 leds). The clock is set (after startup and power outages) by four buttons on the back - minutes, increment, decrement, hours. Have any of you connoisseurs of time seen such a clock? How about a bar of leds that could be used to make a clock? Bill Hawkins P.S. Currently re-reading Terry Pratchett's Thief of Time - a whole new way to look at time in a funny and perceptive story. ___ 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] Photodiodes for high frequency OPLL
Reverse biased diodes are not very low impedance. You can't really drive a low impedance with them. In fact, the high impedance of the photodiode leads to all sorts of ugliness in noise analysis. This is well documented in Graeme's book. I think TI also has an app note on feedback networks for the best SNR, though Graeme has a technique to get optimal bandwidth and noise performance. A lot of people make a living just designing front ends for high impedance devices. They are really hard to do optimally since high impedance is bad for bandwidth, noise, and all things nice. There is also a book by Hobbs on photodiode interfaces. Much of the book is unfortunately filler, though parts are very good. I found a pirated copy online and decided not to buy the real thing. Graeme's book is much more detailed. The derivations of the equations are shown in painful detail. [My dislike of Gain Technology comes from dealing with the company. I have no personal knowledge of Graeme other than buying his books.] You might want to track down the pirated version of Hobbs before spending $150. I did, then deleted it since I already owned Graeme's book. Building Electro-Optical Systems: Making It all Work On 4/1/2013 10:30 AM, J. Forster wrote: I think that you should be able to take the signal right out of the backbiased diode and run it straight into a microwave mixer w/ a fixed 7 GHz LO and frequency discrimitate the IF output from the mixer to generate a control signal for your LASER. In theory, if your LASERS were very, very, very good, you might be able to achieve phase lock, but I'd not hold my breath. A discriminator can give you frequency lock. YMMV, -John ___ 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 shown as two horizontal bars
Hi Should be easy enough to build one, if one does not already exist. Great big piece of perf board and a bunch of wire. Put a piece of colored Lexan in front of it, simple wood box around it. Run with your favorite CPU board. Bob On Apr 1, 2013, at 6:06 PM, Bill Hawkins b...@iaxs.net wrote: Looking for a long, thin horizontal clock display for use above or below a flat screen TV. Tried searching for bar clock and got a lot of useless hits. What I'd like is a display that is about half an inch (12 mm) high by 12-18 inches long (30-50 cm) that is just two rows of 60 or 120 leds. One row is labeled 0 to 59 (or 60) and the other is labeled 0 to 12. The display does not stay at 12 or 60 but jumps back to zero. Power line frequency is an adequate reference, as long as it always has the same 86,400 seconds per day, except for added leap seconds. There should not be a clock frequency adjustment. 60 seconds worth of line cycles bumps the minute bar (30 if it has 120 leds), and 5 minutes bumps the hour bar (150 seconds for 120 leds). The clock is set (after startup and power outages) by four buttons on the back - minutes, increment, decrement, hours. Have any of you connoisseurs of time seen such a clock? How about a bar of leds that could be used to make a clock? Bill Hawkins P.S. Currently re-reading Terry Pratchett's Thief of Time - a whole new way to look at time in a funny and perceptive story. ___ 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] FE-5680 frequency jump
On Mon, 01 Apr 2013 23:57:48 +0200 Magnus Danielson mag...@rubidium.dyndns.org wrote: On 04/01/2013 10:06 PM, Bob Quenelle wrote: I’ve been running an FE-5680 for maybe a total of 50 hours over the last several months. I found that an offset setting of 180 made it track GPS and (previously-set) LPRO-101 10 MHz signals. Even with power cycling, after about 1/2 hour, with an offset setting of 180 the FE-5680 was stable. The last time I turned on the FE-5680, it drifted with a setting of 180 and needed a new setting of –415 to track the other signals. That’s a change of 595 counts and with a resolution of 6.8 uHz per count, a frequency change of 4 mHz (0.004 Hz) and 0.4 ppb. Operation at the new setting is stable for now. The lock signal indicates lock and the power supply voltage is still 15V. I haven’t checked lamp voltage or VCXO voltage as that requires opening the case. How long have it been turned on since last power-up? Let it sit for a day at least. I've found that it is easy to be in too much hurry to judge the situation and trim things efter power-up. The crystal oscillator just doesn't get the time to settle in. That might be indeed the case. Figure 3 in [1] gives quite high frequency aging differences after switch on and long run time. Attila Kinali [1] http://www.pi5.uni-stuttgart.de/common/show_file.php/lectures/100/blaetter/The%20Rubidium%20Clock%20and%20Basic%20Research.pdf -- The people on 4chan are like brilliant psychologists who also happen to be insane and gross. -- unknown ___ 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 shown as two horizontal bars
Hi Bill, Before you go digital consider a retro solution -- use two loops of 1/4 inch tape (as in magnetic recording tape, or even dymo label tape). Put a tension pulley on one end and a small stepper drive on the other. Step at the appropriate rotation rate to create the desired snail's pace linear velocity. You can imprint numbers or just a color line on the tape. Sort of like a strip-chart flip-clock. If you use LEDs it might be easier to use a collection of LED bars (as in the .1x10 in DIP package). Google for LED bar graph. For driving, look at the MAX7219 if you want far fewer wires (and your eyes can tolerate multiplexed LED's). Finally, see http://www.primeled.com/ /tvb - Original Message - From: Bill Hawkins b...@iaxs.net To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com Sent: Monday, April 01, 2013 3:06 PM Subject: [time-nuts] Time shown as two horizontal bars Looking for a long, thin horizontal clock display for use above or below a flat screen TV. Tried searching for bar clock and got a lot of useless hits. What I'd like is a display that is about half an inch (12 mm) high by 12-18 inches long (30-50 cm) that is just two rows of 60 or 120 leds. One row is labeled 0 to 59 (or 60) and the other is labeled 0 to 12. The display does not stay at 12 or 60 but jumps back to zero. Power line frequency is an adequate reference, as long as it always has the same 86,400 seconds per day, except for added leap seconds. There should not be a clock frequency adjustment. 60 seconds worth of line cycles bumps the minute bar (30 if it has 120 leds), and 5 minutes bumps the hour bar (150 seconds for 120 leds). The clock is set (after startup and power outages) by four buttons on the back - minutes, increment, decrement, hours. Have any of you connoisseurs of time seen such a clock? How about a bar of leds that could be used to make a clock? Bill Hawkins P.S. Currently re-reading Terry Pratchett's Thief of Time - a whole new way to look at time in a funny and perceptive story. ___ 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 shown as two horizontal bars
A more fun design would be a projector. Scan a laser pointer by spinning it fast and modulate the beam so that it looks like a few red dots on whatever screen it is aimed at. Maybe salvage the scanner mirror from an old laser printer. The LED based design would be easier but less interesting, just some 7400 series chips, some LEDs and a small uP. On Mon, Apr 1, 2013 at 3:54 PM, Bob Camp li...@rtty.us wrote: Hi Should be easy enough to build one, if one does not already exist. Great big piece of perf board and a bunch of wire. Put a piece of colored Lexan in front of it, simple wood box around it. Run with your favorite CPU board. -- 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] FE-5680 frequency jump
On 04/02/2013 01:12 AM, Attila Kinali wrote: On Mon, 01 Apr 2013 23:57:48 +0200 Magnus Danielsonmag...@rubidium.dyndns.org wrote: On 04/01/2013 10:06 PM, Bob Quenelle wrote: I’ve been running an FE-5680 for maybe a total of 50 hours over the last several months. I found that an offset setting of 180 made it track GPS and (previously-set) LPRO-101 10 MHz signals. Even with power cycling, after about 1/2 hour, with an offset setting of 180 the FE-5680 was stable. The last time I turned on the FE-5680, it drifted with a setting of 180 and needed a new setting of –415 to track the other signals. That’s a change of 595 counts and with a resolution of 6.8 uHz per count, a frequency change of 4 mHz (0.004 Hz) and 0.4 ppb. Operation at the new setting is stable for now. The lock signal indicates lock and the power supply voltage is still 15V. I haven’t checked lamp voltage or VCXO voltage as that requires opening the case. How long have it been turned on since last power-up? Let it sit for a day at least. I've found that it is easy to be in too much hurry to judge the situation and trim things efter power-up. The crystal oscillator just doesn't get the time to settle in. That might be indeed the case. Figure 3 in [1] gives quite high frequency aging differences after switch on and long run time. Attila Kinali [1] http://www.pi5.uni-stuttgart.de/common/show_file.php/lectures/100/blaetter/The%20Rubidium%20Clock%20and%20Basic%20Research.pdf You are confusing the VCXOs frequency drift with that of the rubidiums (which is the result of the FLL locking of the VCXO to the rubidium resonance). If the VCXO still has a fair distance to drift, then false locking can occur while compating the initially quite vigorous drift rate. The only real way to handle that is to sit and wait for it to settle down. Only after that may trimming of the oscillator be done to zeroize the integrator state. A small commercial rubidium doesn't need very long to get a feel if it is in good condition or not, but sitting on your hands and let it warm up gives you a fair idea of just how skewed situation it is. That's also true for caesium clocks. So, sit on your hands and let it settle. Better yet, leave on while you do other things. Just recall to put enought cooling on it! 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] Link for WWVB PSK Remover by Paul WB8TSL and group folder
I set up a folder on my PogoPlug device which can be used by Time-Nuts members to upload and download files and documents. It is suggested that users zip project files with descriptive names. As long as there are no bandwidth issues I will leave this link up for the groups use. Please do not put any files there that you want to keep private or files that you do not have a right to post for public access. Please file this link away for future use. http://ppl.ug/ysoCRmlPKuY/ Best regards, Sam W3OHM Owner and Moderator LeCroy_Owners_Group on Yahoo! Groups ___ 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] Link for WWVB PSK Remover by Paul WB8TSL and group folder
Thanks Sam looks easy to get to. Regards Paul WB8TSL On Mon, Apr 1, 2013 at 7:44 PM, Sam Reaves sam.rea...@gmail.com wrote: I set up a folder on my PogoPlug device which can be used by Time-Nuts members to upload and download files and documents. It is suggested that users zip project files with descriptive names. As long as there are no bandwidth issues I will leave this link up for the groups use. Please do not put any files there that you want to keep private or files that you do not have a right to post for public access. Please file this link away for future use. http://ppl.ug/ysoCRmlPKuY/ Best regards, Sam W3OHM Owner and Moderator LeCroy_Owners_Group on Yahoo! Groups ___ 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 shown as two horizontal bars
Hi Bill, Interesting idea. One of the problems you are going to have with normal available displays is being able to distinguishing the individual elements as you get further away from the clock. So it sounds like you may have to construct your own display area so that the elements are further apart. Doing so would allow for some embellishments, such as using a different colors for the 10 and 30 minute LEDs. Equally so, you could use 24 LEDs for hour marks using two different colors for day and night. Likewise, you could reduce the number of LEDs by using 9 for the minutes in one row. A second row would have 5 for the 10 minute marks. The third row would be the hours with just the 12 LEDs but by using dual color LEDs you could cover day and night. Just thought I would complicate your project BillWB6BNQ Bill Hawkins wrote: Looking for a long, thin horizontal clock display for use above or below a flat screen TV. Tried searching for bar clock and got a lot of useless hits. What I'd like is a display that is about half an inch (12 mm) high by 12-18 inches long (30-50 cm) that is just two rows of 60 or 120 leds. One row is labeled 0 to 59 (or 60) and the other is labeled 0 to 12. The display does not stay at 12 or 60 but jumps back to zero. Power line frequency is an adequate reference, as long as it always has the same 86,400 seconds per day, except for added leap seconds. There should not be a clock frequency adjustment. 60 seconds worth of line cycles bumps the minute bar (30 if it has 120 leds), and 5 minutes bumps the hour bar (150 seconds for 120 leds). The clock is set (after startup and power outages) by four buttons on the back - minutes, increment, decrement, hours. Have any of you connoisseurs of time seen such a clock? How about a bar of leds that could be used to make a clock? Bill Hawkins P.S. Currently re-reading Terry Pratchett's Thief of Time - a whole new way to look at time in a funny and perceptive story. ___ 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] Photodiodes for high frequency OPLL
On Monday 01 April 2013, Attila Kinali wrote: On Mon, 1 Apr 2013 14:24:58 +0100 Wolfgang timen...@triplespark.net wrote: Anyway, each of these down-mixing approaches needs to resolve the mirror frequency problem. I.e. if you modulate your receiver with 7.1 GHz (or use an EOM to do that optically) and detect at 100 MHz, you do not know whether the input signal has an offset of 7.2 GHz or 7.0 GHz. So you might be locking on the wrong one. If i'm not mistaken, this shouldn't be a problem I'm not demodulating the laser, but using a PLL to fix the difference frequency. Being on the wrong side would invert the sign on the loop gain, thus the mirror freuquency would be an unstable point. Without too much of thinking it seems to me that there are 4 cases that show up as 100 MHz. Only 2 of them without the RF mixing. 2 will have the same loop sign (only 1 without RF mixing). A-B = 7.2 GHz A-B = 7.0 GHz A-B = -7.0 GHz A-B = -7.2 GHz BTW, what's the linewidth of your lasers? -Wolfgang DL1SKY ___ 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 shown as two horizontal bars
Bill, And if google gives too many hits, also try eBay: LED segment bar graph For $10 and up you get beautiful, almost irresistible hits like: http://www.ebay.com/itm/160986263849 http://www.ebay.com/itm/160996095451 http://www.ebay.com/itm/151007627810 http://www.ebay.com/itm/160996948941 http://www.ebay.com/itm/160996949241 /tvb - Original Message - From: Tom Van Baak t...@leapsecond.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Monday, April 01, 2013 4:45 PM Subject: Re: [time-nuts] Time shown as two horizontal bars Hi Bill, Before you go digital consider a retro solution -- use two loops of 1/4 inch tape (as in magnetic recording tape, or even dymo label tape). Put a tension pulley on one end and a small stepper drive on the other. Step at the appropriate rotation rate to create the desired snail's pace linear velocity. You can imprint numbers or just a color line on the tape. Sort of like a strip-chart flip-clock. If you use LEDs it might be easier to use a collection of LED bars (as in the .1x10 in DIP package). Google for LED bar graph. For driving, look at the MAX7219 if you want far fewer wires (and your eyes can tolerate multiplexed LED's). Finally, see http://www.primeled.com/ /tvb - Original Message - From: Bill Hawkins b...@iaxs.net To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com Sent: Monday, April 01, 2013 3:06 PM Subject: [time-nuts] Time shown as two horizontal bars Looking for a long, thin horizontal clock display for use above or below a flat screen TV. Tried searching for bar clock and got a lot of useless hits. What I'd like is a display that is about half an inch (12 mm) high by 12-18 inches long (30-50 cm) that is just two rows of 60 or 120 leds. One row is labeled 0 to 59 (or 60) and the other is labeled 0 to 12. The display does not stay at 12 or 60 but jumps back to zero. Power line frequency is an adequate reference, as long as it always has the same 86,400 seconds per day, except for added leap seconds. There should not be a clock frequency adjustment. 60 seconds worth of line cycles bumps the minute bar (30 if it has 120 leds), and 5 minutes bumps the hour bar (150 seconds for 120 leds). The clock is set (after startup and power outages) by four buttons on the back - minutes, increment, decrement, hours. Have any of you connoisseurs of time seen such a clock? How about a bar of leds that could be used to make a clock? Bill Hawkins P.S. Currently re-reading Terry Pratchett's Thief of Time - a whole new way to look at time in a funny and perceptive story. ___ 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 shown as two horizontal bars
On 4/1/13 3:06 PM, Bill Hawkins wrote: Looking for a long, thin horizontal clock display for use above or below a flat screen TV. Tried searching for bar clock and got a lot of useless hits. If you're bulding it.. Arduino is your friend.. there's tons of LED displays of all shapes and sizes that people have written interface libraries for the Arduino.. ___ 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 shown as two horizontal bars
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 On 02/04/2013 04:31, Jim Lux wrote: On 4/1/13 3:06 PM, Bill Hawkins wrote: Looking for a long, thin horizontal clock display for use above or below a flat screen TV. Tried searching for bar clock and got a lot of useless hits. If you're bulding it.. Arduino is your friend.. there's tons of LED displays of all shapes and sizes that people have written interface libraries for the Arduino.. +1 for Arduino for quickly hacking stuff like this together - http://www.bliptronics.com/ do some great LED modules that are pre-wired individually addressable serial controlled RGB LEDs. There's plenty of realtime clocks available for Arduino (the DS1302 and DS1307 are common, eg https://www.sparkfun.com/products/99 ), and if you go with the Arduino Ethernet you can just talk NTP to your local time server: http://arduino.cc/en/Tutorial/UdpNtpClient . Very convenient! Cheers, James Harrison -BEGIN PGP SIGNATURE- Version: GnuPG v2.0.17 (MingW32) iEYEARECAAYFAlFaVLEACgkQ22kkGnnJQAyJVACeNeai8Fn9lTAlANJhFkarq3Ug Yo0An10vfKHHd1GGEr00YKBeYVBGyOT2 =sPJ9 -END PGP SIGNATURE- ___ 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 shown as two horizontal bars
I still like my laser pointer design. I've been thinking about it and the parts count is lower than I first thought. Here is how it works Aim a laser pointer as a spinning hexagonal scanner mirror. These look like the head of a large size bolt, but with mirrored sides. The moter turns the mirror and there is a contact switch that closes once per face or six times per revolution. The contact swich interrupts an Arduino. Then inside the interrupt the software toggle sthe power to the laser. The delays between the interrupt and toggle depend on the time of day. So all you need is the spinning scanner assembly, a laser pointer a transistor to drive it and one Arduino. The size of the display can be adjusted by changing the delay between the toggles and it can be a front or rear projection system. Unlike the fixed LEDS my projecter can have moving dots. Maybe they can look lie a metronome and count off seconds. Or the dot can crawl across the screen.Or you couldspell the numbers on mose code with dots and dashes. Or you make it change the presentation every day and confuse people On Mon, Apr 1, 2013 at 3:38 PM, WB6BNQ wb6...@cox.net wrote: Hi Bill, Interesting idea. One of the problems you are going to have with normal available displays is being able to distinguishing the individual elements as you get further away from the clock. So it sounds like you may have to construct your own display area so that the elements are further apart. Doing so would allow for some embellishments, such as using a different colors for the 10 and 30 minute LEDs. Equally so, you could use 24 LEDs for hour marks using two different colors for day and night. Likewise, you could reduce the number of LEDs by using 9 for the minutes in one row. A second row would have 5 for the 10 minute marks. The third row would be the hours with just the 12 LEDs but by using dual color LEDs you could cover day and night. Just thought I would complicate your project BillWB6BNQ Bill Hawkins wrote: Looking for a long, thin horizontal clock display for use above or below a flat screen TV. Tried searching for bar clock and got a lot of useless hits. What I'd like is a display that is about half an inch (12 mm) high by 12-18 inches long (30-50 cm) that is just two rows of 60 or 120 leds. One row is labeled 0 to 59 (or 60) and the other is labeled 0 to 12. The display does not stay at 12 or 60 but jumps back to zero. Power line frequency is an adequate reference, as long as it always has the same 86,400 seconds per day, except for added leap seconds. There should not be a clock frequency adjustment. 60 seconds worth of line cycles bumps the minute bar (30 if it has 120 leds), and 5 minutes bumps the hour bar (150 seconds for 120 leds). The clock is set (after startup and power outages) by four buttons on the back - minutes, increment, decrement, hours. Have any of you connoisseurs of time seen such a clock? How about a bar of leds that could be used to make a clock? Bill Hawkins P.S. Currently re-reading Terry Pratchett's Thief of Time - a whole new way to look at time in a funny and perceptive story. ___ 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.
