Re: [time-nuts] Question about samplers
Thanks a lot for this tip, i´ve already found a lot of info there. Daniel Em 29/03/2013 20:22, Ed Palmer escreveu: Yes, they're all online. Here's the link: http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/hpjindex.html The best way to find a model # would be to use google's site: command with the model # like this: site:www.hpl.hp.com/hpjournal 83481a Ed On 3/29/2013 2:09 PM, Daniel Mendes wrote: Em 29/03/2013 12:26, paul swed escreveu: If the schematics are available then you can reverse engineer a solution or adaptation. the other thing I do is hunt down the hp journal for the device that used them and when it was introduced. Often the article will give you a fair hint as to whats going on. However the real detail of sample pulse behavior and even power supply voltages are going to be a guess and gamble. Some modules have helpful markings. Like agc or +12V.. But again its a real guess. Regards Paul Here´s a short list of instruments that use these devices: 54751A 83481A 83487A 54753A 83485A E2603A 54754A 83486A Don´t know about service manuals for any of these. Are these journals available on the internet so I can hunt down for information in them? Daniel ___ 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] Photodiodes for high frequency OPLL
Moin, I'm currently reading up some stuff on optical PLLs and am stuck with some details i cannot find any data on. The goal is to make two lasers locked with about 7GHz of offset to eachother. 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. Now the question is: Do these use special made photodiodes with a very high transition frequency or do they just treat the transition frequency as a 3dB point and amplify the signal after detection? (They do not describe the detection circuit at all, so i guess it must be something readily available) If it's the former, any idea where i could get such photodiodes? If it is the later, how much damping can i assume with PIN or avalanche photodiodes per decade? Thanks in advance! 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] WWVB d-psk-r update. Seems a reasonable solution
On Thu, 28 Mar 2013 21:01:27 -0400 paul swed paulsw...@gmail.com wrote: OK it has been a while and I have promised to share results. In the next few days I will put whats on paper into a schematic and share. I won't dwell on all of the stuff from October to now. But several front end rcvrs, and several analog Costas loops were built using MC1496s and another using AD633 multipliers. Various other glue. Nothing to rave about. It may sound strange, but actually the stuff you tried and didnt work would be more interesting to me.. especially if you include the reason why it didnt work. 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] GPS usable for weather forecasting?
Hi If you go back into the papers from the early 1980's there is one where they used a high gain antenna and no knowledge of the coding scheme to pull timing off of GPS. I believe it was at White Sands, but that could be wrong. Bob On Mar 29, 2013, at 11:42 PM, Stewart Cobb stewart.c...@gmail.com wrote: I wonder if you cannot do this same work from the ground. Has anyone tried tracking single GPS satellites from the ground using very high gain tracking antenna. Many times. USAF does this each time they launch a new GPS satellite, to check out all the kit in a high-res view before they switch it on for general use. They used to use an antenna at Camp Parks in the California central valley. When that one was being overhauled a few years ago, they used Stanford's big dish for a while. It gives about 60 dB gain at L1, IIRC. Hardcore GPS researchers have used that dish and a bunch of others over the years. If you're interested, contact SRI. They used to charge a couple of hundred bucks an hour for the Stanford dish. Hard to use for weather forecasting, though, because you can only see one tiny chunk of atmosphere at a time. Cheers! --Stu ___ 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] WWVB d-psk-r update. Seems a reasonable solution
On 3/29/13 9:01 AM, Bob Camp wrote: Hi Too much tuning range is easy enough to fix. Use a pot to set it on frequency and then hook it to the rest of the stuff with a fixed resistor. The gotcha would be if the poor thing drifts so much that it *needs* the wide range to stay in lock. My guess is that you could buy a hundred VCXO's at auction for less than the cost of trying a dozen samples. wide tuning range VCOs have lower Q resonators, so the outside the loop BW noise will tend to be worse. The other problem I have found is that wide tuning range VCOs tend to drift more (that is, with a constant input voltage, their frequency changes more as they warm up or otherwise change temperature). It's a matter of sitting with the online order site open in one window, and the Vectron or whoever website open to their catalog in another and going back and forth comparing part #s.. ___ 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 usable for weather forecasting?
On 3/30/13 5:31 AM, Bob Camp wrote: Hi If you go back into the papers from the early 1980's there is one where they used a high gain antenna and no knowledge of the coding scheme to pull timing off of GPS. I believe it was at White Sands, but that could be wrong. One can just run it into a squaring circuit and recover the carrier, for instance. Recovering accurate carrier frequency isn't going to help you navigate a ICBM to a hardened target. Knowing the P-code is. ___ 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-r update. Seems a reasonable solution
Hi I think it's pretty safe to say that the Vectron part mentioned is a VCXO with a crystal as the resonator. Indeed a ceramic resonator or an L/C resonator part would have a bit more drift and lower Q than a crystal based part. I would not try something like this with anything other than a crystal based part. At least as far as the commonly available stuff goes. I'm sure you could make it work with a hydrogen maser as the frequency source and a bit of DDS magic... Bob On Mar 30, 2013, at 10:23 AM, Jim Lux jim...@earthlink.net wrote: On 3/29/13 9:01 AM, Bob Camp wrote: Hi Too much tuning range is easy enough to fix. Use a pot to set it on frequency and then hook it to the rest of the stuff with a fixed resistor. The gotcha would be if the poor thing drifts so much that it *needs* the wide range to stay in lock. My guess is that you could buy a hundred VCXO's at auction for less than the cost of trying a dozen samples. wide tuning range VCOs have lower Q resonators, so the outside the loop BW noise will tend to be worse. The other problem I have found is that wide tuning range VCOs tend to drift more (that is, with a constant input voltage, their frequency changes more as they warm up or otherwise change temperature). It's a matter of sitting with the online order site open in one window, and the Vectron or whoever website open to their catalog in another and going back and forth comparing part #s.. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS usable for weather forecasting?
Hi A, but they did recover the code in addition to the carrier frequency. Given enough gain (and thus directivity) they were able to capture the full transmission from a single bird. They could not pull the almanac data off of it, but the sat's orbital parameters are relatively easy to come up with. If I remember correctly they came up with some pretty impressive timing numbers. The paper didn't mention any navigation results (gee… I wonder why…). It was the first public paper I attended that started chipping away the value of selective availability. Bob On Mar 30, 2013, at 10:26 AM, Jim Lux jim...@earthlink.net wrote: On 3/30/13 5:31 AM, Bob Camp wrote: Hi If you go back into the papers from the early 1980's there is one where they used a high gain antenna and no knowledge of the coding scheme to pull timing off of GPS. I believe it was at White Sands, but that could be wrong. One can just run it into a squaring circuit and recover the carrier, for instance. Recovering accurate carrier frequency isn't going to help you navigate a ICBM to a hardened target. Knowing the P-code is. ___ 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
Hi Attila, The goal is to make two lasers locked with about 7GHz of offset to eachother. So far, i figured out that PIN photodiodes can go up to several 100MHz transition frequency and avalanche photodiodes are available up to 2GHz. If you need photodiode response only near 7 GHz, as seems likely, then maybe the reactance of the 2 GHz diode can be tuned out with some sort of matching circuit in the hope of getting usable response near 7 GHz. Better and simpler to get a diode with flat response all the way from DC to 7 GHz, though, of course. Depending on the application, you might be able to tolerate pretty high mixer losses, as you mention, but if you do need the best possible SNR, an I/Q configuration would give slightly lower noise at the cost of two diodes and amplifiers. Cheers, Peter ___ 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
You'll need a photodiode that can detect photons at your lasers' wavelength. You may be able to use a photodiode at a shorter than its design wavelength as long as there are not coatings (eg anti-reflection) that block the wavelength of interest. You'll need to make sure that both lasers illuminate the same photodiode area, or you won't get a signal at the difference frequency. The difference frequency power level is generally pretty low, so operating above the photodiode bandwidth is difficult. My work was at HP and Agilent, who manufactured the photodiodes we used. The photodiode frequency response is primarily limited by the depletion region's capacitance. The circuit model is simply a current source shunted by a capacitor (perhaps with bond wire inductance to the RF connector) so the RF output current falls with increasing signal frequency. I don't see much possibility of improvement thru matching--though using an amplifier with very low input impedance might help. Dave On 3/30/2013 3:48 AM, Attila Kinali wrote: Moin, I'm currently reading up some stuff on optical PLLs and am stuck with some details i cannot find any data on. The goal is to make two lasers locked with about 7GHz of offset to eachother. 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. Now the question is: Do these use special made photodiodes with a very high transition frequency or do they just treat the transition frequency as a 3dB point and amplify the signal after detection? (They do not describe the detection circuit at all, so i guess it must be something readily available) If it's the former, any idea where i could get such photodiodes? If it is the later, how much damping can i assume with PIN or avalanche photodiodes per decade? Thanks in advance! Attila Kinali -- Clear Stream Technologies ___ 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] Building a Agilent Cross Correlated Phase Noise Measurement System.
We are looking into using two N/E550XA/B Phase Noise systems and the 89410A to build a Cross Correlated measurement system. I was wondering if anyone has attempted this before? Does anyone know where to find the base GPIB command codes for the 70420A system? Thanks; Thomas Knox Phase Noise Measurement Group NIST ___ 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 don't think that you can effectively directly mix two laser wavelengths in a semiconductor light detector and get a useable IF - it's hard enough just to get the tens of GHz modulation signals out above the noise floor, let alone a tiny difference signal between hundreds of THz. You need an optical interference or nonlinear device up front to do the mixing and get the wavelength discrimination, while the optical detector(s) serve as the first IF O-E transducer. My knowledge of this stuff isn't up to date - maybe nowadays there are detector devices and methods that take care of this directly, but I don't think so. Most really high speed diodes are optimized for the 1550 nm region where EDFAs work, but maybe they have usable response at other ranges. It depends on your particular application and wavelength. I think detectors are usually specified over the entire IR region, so datasheets may tell enough. Here's link to some good info, but not current state of the art: http://e-collection.library.ethz.ch/eserv/eth:28429/eth-28429-02.pdf There are various methods that use lower frequency modulation techniques so that regular detectors can be used directly. If you study up on related patents, you may find some ideas and leads to appropriate actual devices. Ed ___ 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
You lose me at damping per decade? Is damping the right word? Do you mean high frequency rolloff? Most texts on photodiodes go into bootstrapping them to reduce the effect of capacitance. But if you design fully differential amplifier circuits, they have the same effect as bootstrapping. Jerald Graeme's Photodiode Amplifiers goes into this. I'm not a fan of Gain technology as a company, but Graeme's book are good texts. The bootstrapping circuits use simpler buffers to keep the voltage potential across the diode low, while the fully differential circuits depend on gain bandwidth product to do the same. -Original Message- From: Attila Kinali att...@kinali.ch Sender: time-nuts-boun...@febo.com Date: Sat, 30 Mar 2013 12:48:01 To: time-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: [time-nuts] Photodiodes for high frequency OPLL Moin, I'm currently reading up some stuff on optical PLLs and am stuck with some details i cannot find any data on. The goal is to make two lasers locked with about 7GHz of offset to eachother. 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. Now the question is: Do these use special made photodiodes with a very high transition frequency or do they just treat the transition frequency as a 3dB point and amplify the signal after detection? (They do not describe the detection circuit at all, so i guess it must be something readily available) If it's the former, any idea where i could get such photodiodes? If it is the later, how much damping can i assume with PIN or avalanche photodiodes per decade? Thanks in advance! 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
I used UDT PIN10 photodiodes to observe the mode spacings in HeNe lasers. The typical mode spacings were around 600 MHz. John WA4WDL -- From: ed breya e...@telight.com Sent: Friday, March 29, 2013 8:20 PM To: time-nuts@febo.com Subject: Re: [time-nuts] Photodiodes for high frequency OPLL I don't think that you can effectively directly mix two laser wavelengths in a semiconductor light detector and get a useable IF - it's hard enough just to get the tens of GHz modulation signals out above the noise floor, let alone a tiny difference signal between hundreds of THz. You need an optical interference or nonlinear device up front to do the mixing and get the wavelength discrimination, while the optical detector(s) serve as the first IF O-E transducer. My knowledge of this stuff isn't up to date - maybe nowadays there are detector devices and methods that take care of this directly, but I don't think so. Most really high speed diodes are optimized for the 1550 nm region where EDFAs work, but maybe they have usable response at other ranges. It depends on your particular application and wavelength. I think detectors are usually specified over the entire IR region, so datasheets may tell enough. Here's link to some good info, but not current state of the art: http://e-collection.library.ethz.ch/eserv/eth:28429/eth-28429-02.pdf There are various methods that use lower frequency modulation techniques so that regular detectors can be used directly. If you study up on related patents, you may find some ideas and leads to appropriate actual devices. Ed ___ 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
My understanding is that you want to operate photodiodes with high reverse bias for the best frequency response. The bias widens the space charge layer, thereby reducing the capacitance of the device. The high electric fields in the SCL region also sweeps the hole-electron pairs, produced by photon injection, out faster, hence improving the response as well. Such devices are best operated with very low capacity wiring into a virtual ground. Of course, there are limits as, at some point, the device will avalanche. When that ocurrs, the device will have gain akin to a photomultiplier. Some devices are actually designed to operate in this mode, but, since the thing is so near to unstable requires careful control of temperature and oher parameters. -John You lose me at damping per decade? Is damping the right word? Do you mean high frequency rolloff? Most texts on photodiodes go into bootstrapping them to reduce the effect of capacitance. But if you design fully differential amplifier circuits, they have the same effect as bootstrapping. Jerald Graeme's Photodiode Amplifiers goes into this. I'm not a fan of Gain technology as a company, but Graeme's book are good texts. The bootstrapping circuits use simpler buffers to keep the voltage potential across the diode low, while the fully differential circuits depend on gain bandwidth product to do the same. -Original Message- From: Attila Kinali att...@kinali.ch Sender: time-nuts-boun...@febo.com Date: Sat, 30 Mar 2013 12:48:01 To: time-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: [time-nuts] Photodiodes for high frequency OPLL Moin, I'm currently reading up some stuff on optical PLLs and am stuck with some details i cannot find any data on. The goal is to make two lasers locked with about 7GHz of offset to eachother. 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. Now the question is: Do these use special made photodiodes with a very high transition frequency or do they just treat the transition frequency as a 3dB point and amplify the signal after detection? (They do not describe the detection circuit at all, so i guess it must be something readily available) If it's the former, any idea where i could get such photodiodes? If it is the later, how much damping can i assume with PIN or avalanche photodiodes per decade? Thanks in advance! 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 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 forgot to mention if you use the bootstrap technique, you can keep a negative bias on the photodiode, which improves bandwidth by reducing capacitance. That is, you drive the AC signal across the diode to zero, but not the DC bias. If you use the fully differential amplifer, then the bias voltage is zero, hence more capacitance. I've looked into transformer coupling for photodiodes as a way to go fully differential and still apply a bias. A few years ago, the idea would be silly, but RF applications have created a supply of really high frequency transformers. The UDT diodes with the BNC attached are pretty common on ebay. I think the company was bought out. -Original Message- From: jmfranke jmfra...@cox.net Sender: time-nuts-boun...@febo.com Date: Sat, 30 Mar 2013 13:46:51 To: time-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 I used UDT PIN10 photodiodes to observe the mode spacings in HeNe lasers. The typical mode spacings were around 600 MHz. John WA4WDL -- From: ed breya e...@telight.com Sent: Friday, March 29, 2013 8:20 PM To: time-nuts@febo.com Subject: Re: [time-nuts] Photodiodes for high frequency OPLL I don't think that you can effectively directly mix two laser wavelengths in a semiconductor light detector and get a useable IF - it's hard enough just to get the tens of GHz modulation signals out above the noise floor, let alone a tiny difference signal between hundreds of THz. You need an optical interference or nonlinear device up front to do the mixing and get the wavelength discrimination, while the optical detector(s) serve as the first IF O-E transducer. My knowledge of this stuff isn't up to date - maybe nowadays there are detector devices and methods that take care of this directly, but I don't think so. Most really high speed diodes are optimized for the 1550 nm region where EDFAs work, but maybe they have usable response at other ranges. It depends on your particular application and wavelength. I think detectors are usually specified over the entire IR region, so datasheets may tell enough. Here's link to some good info, but not current state of the art: http://e-collection.library.ethz.ch/eserv/eth:28429/eth-28429-02.pdf There are various methods that use lower frequency modulation techniques so that regular detectors can be used directly. If you study up on related patents, you may find some ideas and leads to appropriate actual devices. Ed ___ 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] Photodiodes for high frequency OPLL
You might take a look at these: http://www.ebay.com/itm/360601919160?ssPageName=STRK:MEWNX:IT_trksid=p3984.m1497.l2649#ht_780wt_911 They have a fiber terminated Avalanche PD and built in HV supply from 5 volts. Cheap at $5 each. Tom - Original Message - From: J. Forster j...@quikus.com To: li...@lazygranch.com; Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Saturday, March 30, 2013 1:52 PM Subject: Re: [time-nuts] Photodiodes for high frequency OPLL My understanding is that you want to operate photodiodes with high reverse bias for the best frequency response. The bias widens the space charge layer, thereby reducing the capacitance of the device. The high electric fields in the SCL region also sweeps the hole-electron pairs, produced by photon injection, out faster, hence improving the response as well. Such devices are best operated with very low capacity wiring into a virtual ground. Of course, there are limits as, at some point, the device will avalanche. When that ocurrs, the device will have gain akin to a photomultiplier. Some devices are actually designed to operate in this mode, but, since the thing is so near to unstable requires careful control of temperature and oher parameters. -John You lose me at damping per decade? Is damping the right word? Do you mean high frequency rolloff? Most texts on photodiodes go into bootstrapping them to reduce the effect of capacitance. But if you design fully differential amplifier circuits, they have the same effect as bootstrapping. Jerald Graeme's Photodiode Amplifiers goes into this. I'm not a fan of Gain technology as a company, but Graeme's book are good texts. The bootstrapping circuits use simpler buffers to keep the voltage potential across the diode low, while the fully differential circuits depend on gain bandwidth product to do the same. -Original Message- From: Attila Kinali att...@kinali.ch Sender: time-nuts-boun...@febo.com Date: Sat, 30 Mar 2013 12:48:01 To: time-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: [time-nuts] Photodiodes for high frequency OPLL Moin, I'm currently reading up some stuff on optical PLLs and am stuck with some details i cannot find any data on. The goal is to make two lasers locked with about 7GHz of offset to eachother. 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. Now the question is: Do these use special made photodiodes with a very high transition frequency or do they just treat the transition frequency as a 3dB point and amplify the signal after detection? (They do not describe the detection circuit at all, so i guess it must be something readily available) If it's the former, any idea where i could get such photodiodes? If it is the later, how much damping can i assume with PIN or avalanche photodiodes per decade? Thanks in advance! 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 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] Building a Agilent Cross Correlated Phase Noise Measurement System.
Hi Tom: I work for Agilent. Have you asked your Agilent support engineer about this? There is some internal work going on in Agilent involving cross correlation. The guy doing it had to get access to source code. I'm not sure if there is a solution available for customers, but I would like to get you in touch with the guy who was working on this. I don't remember his name, so I will have to ask around and see if I can identify him again. I work in the Measurement Research Lab, not the sales organization, so I don't normally interface with customers. However, I am always interested in helping Agilent customers, especially important ones like NIST. Are you currently working with anyone in Agilent? Rick Karlquist Tom Knox wrote: We are looking into using two N/E550XA/B Phase Noise systems and the 89410A to build a Cross Correlated measurement system. I was wondering if anyone has attempted this before? Does anyone know where to find the base GPIB command codes for the 70420A system? Thanks; Thomas Knox Phase Noise Measurement Group NIST ___ 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
Moin Peter, On Sat, 30 Mar 2013 09:47:26 -0700 Peter Monta pmo...@gmail.com wrote: The goal is to make two lasers locked with about 7GHz of offset to eachother. So far, i figured out that PIN photodiodes can go up to several 100MHz transition frequency and avalanche photodiodes are available up to 2GHz. If you need photodiode response only near 7 GHz, as seems likely, then maybe the reactance of the 2 GHz diode can be tuned out with some sort of matching circuit in the hope of getting usable response near 7 GHz. Better and simpler to get a diode with flat response all the way from DC to 7 GHz, though, of course. Yes, but they are not available. At least i have not been able to locate any in the 700-800nm range. Depending on the application, you might be able to tolerate pretty high mixer losses, as you mention, but if you do need the best possible SNR, an I/Q configuration would give slightly lower noise at the cost of two diodes and amplifiers. What do you exactly mean by I/Q mixing here? Using two beam paths with 90° out of phase onto two photodiodes? If i'm not mistaken this will still lead to 7GHz mixing signal, which i have to get out of the diodes. 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 Sat, 30 Mar 2013 10:00:08 -0800 David McQuate mcqu...@sonic.net wrote: You'll need a photodiode that can detect photons at your lasers' wavelength. Yes, of course. You may be able to use a photodiode at a shorter than its design wavelength as long as there are not coatings (eg anti-reflection) that block the wavelength of interest. The 1um photodiodes i had a look at, have all a very steep roll of above below 900nm, leading to 0 detection at 800nm. You'll need to make sure that both lasers illuminate the same photodiode area, or you won't get a signal at the difference frequency. Yes. The current plan is to have the beams aligned on the same path. The difference frequency power level is generally pretty low, so operating above the photodiode bandwidth is difficult. My work was at HP and Agilent, who manufactured the photodiodes we used. Hmm.. that makes it sound more difficult than i anticipated. Any ballpark numbers i can expect? The photodiode frequency response is primarily limited by the depletion region's capacitance. The circuit model is simply a current source shunted by a capacitor (perhaps with bond wire inductance to the RF connector) so the RF output current falls with increasing signal frequency. So, i can expect it to behave like a first order filter and assume about 20dB/decade? 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 Fri, 29 Mar 2013 17:20:35 -0700 ed breya e...@telight.com wrote: I don't think that you can effectively directly mix two laser wavelengths in a semiconductor light detector and get a useable IF - it's hard enough just to get the tens of GHz modulation signals out above the noise floor, let alone a tiny difference signal between hundreds of THz. Well, i'd like to stay at 7GHz. That should be doable. At least i have read at least a dozen papers who claim to have done that. Some even from the 80s. My knowledge of this stuff isn't up to date - maybe nowadays there are detector devices and methods that take care of this directly, but I don't think so. According to some papers i've read, just pointing two lasers at a photodiode will do that. Most of those around 800nm do offsets of a couple 10MHz to a few 100MHz at most. The ones with the larger offsets are usually in the 1-1.5um region and talk about applications for long haul highspeed communication. Most really high speed diodes are optimized for the 1550 nm region where EDFAs work, but maybe they have usable response at other ranges. It depends on your particular application and wavelength. I think detectors are usually specified over the entire IR region, so datasheets may tell enough. Wavelenght is 780-800nm which is outside of the detection range of those communcation photodiodes. Here's link to some good info, but not current state of the art: http://e-collection.library.ethz.ch/eserv/eth:28429/eth-28429-02.pdf Thanks. I have read this already. I thought about trying to contact the author, and ask him a few questions about this project. There are various methods that use lower frequency modulation techniques so that regular detectors can be used directly. If you study up on related patents, you may find some ideas and leads to appropriate actual devices. I have not come accross any that seemed simpler. Can you give me some pointers? Attila inali -- 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 Sat, 30 Mar 2013 17:29:45 + li...@lazygranch.com wrote: You lose me at damping per decade? Is damping the right word? Do you mean high frequency rolloff? Er.. yes. Frequency rolloff... Sorry, my native language got the better of me. Most texts on photodiodes go into bootstrapping them to reduce the effect of capacitance. But if you design fully differential amplifier circuits, they have the same effect as bootstrapping. Jerald Graeme's Photodiode Amplifiers goes into this. I'm not a fan of Gain technology as a company, but Graeme's book are good texts. Thanks! I just ordered this book. Although i will have to build a discrete amplifier for the first stage until i can mix the signal down to something that can be handled easier. The bootstrapping circuits use simpler buffers to keep the voltage potential across the diode low, while the fully differential circuits depend on gain bandwidth product to do the same. Well, as i currently lean torwards using an avalanche photodiode, which needs an operating voltage in the range of 100V, keeping the potential accross the diode low is not really an issue :-) How do the fully differential circuits get to keep the potential low? As far as i can tell, from the circuits i've seen so far, the differential circuits just use the single ended signal from the diode take the difference to a bias voltage. 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 Sat, 30 Mar 2013 13:46:51 -0400 jmfranke jmfra...@cox.net wrote: I used UDT PIN10 photodiodes to observe the mode spacings in HeNe lasers. The typical mode spacings were around 600 MHz. This sounds interesting. According to the datasheet i've found, the PIN10D has a response time of 25ns, which would suggest a maximum frequency around 40MHz. How does your circuit look like? How much signal do you get out of the photodiode? 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 30 March 2013 11:48, Attila Kinali att...@kinali.ch wrote: Moin, I'm currently reading up some stuff on optical PLLs and am stuck with some details i cannot find any data on. The goal is to make two lasers locked with about 7GHz of offset to eachother. So far, i figured out that PIN photodiodes can go up to several 100MHz transition frequency and avalanche photodiodes are available up to 2GHz. I would contact Hammamatsu Photonics http://www.hamamatsu.com and see if they can help. They might havae something in development, that is not on the web site. If you are in a uni, they might be especially helpful - they paid my salary for a couple of years as a post-doc. I played tricks during my Ph.D. of gain-modulating an APD with a step recovery diode. I was wondering if there is anything one could do to gain modulate one at 7 GHz, but I can't think how one could achieve anything useful by changing the gain, but it might be worth thinking about. I'm just trying to think out of the box - I can't actually see how it would help. Have you considered using a photomultiplier tube? I think there are some fast PMTs around, though perhaps not fast enough. 20 years I used to know what was state of the art in this area, but not any more. 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] Photodiodes for high frequency OPLL
On Sat, 30 Mar 2013 10:52:54 -0700 (PDT) J. Forster j...@quikus.com wrote: My understanding is that you want to operate photodiodes with high reverse bias for the best frequency response. The bias widens the space charge layer, thereby reducing the capacitance of the device. The high electric fields in the SCL region also sweeps the hole-electron pairs, produced by photon injection, out faster, hence improving the response as well. Such devices are best operated with very low capacity wiring into a virtual ground. Could you elaborate on this circuit a little bit? Some terms i could google for or pointers to books/papers to read? Of course, there are limits as, at some point, the device will avalanche. When that ocurrs, the device will have gain akin to a photomultiplier. Some devices are actually designed to operate in this mode, but, since the thing is so near to unstable requires careful control of temperature and oher parameters. Yes, the avalanche photodiodes are meant for this operation. Yes, there are kind of sensitive. But i think that's managable. 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
Maybe I'm jaded a bit, but in this town the sub-10GHz optical stuff is considered kinda slow. The guys down the street, Picometrix, have been doing 40+GHz optical receivers for over 15 years. They claim 1.5G to 100G and from 400nm to 1650nm so probably they can help. http://www.picometrix.com/ As background info they are a spinoff of the University of Michigan Center for Ultrafast Optical Science. http://www.engin.umich.edu/research/cuos/ Bob L. ___ 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 Sat, 30 Mar 2013 18:43:03 + David Kirkby david.kir...@onetel.net wrote: I would contact Hammamatsu Photonics http://www.hamamatsu.com and see if they can help. They might havae something in development, that is not on the web site. If you are in a uni, they might be especially helpful - they paid my salary for a couple of years as a post-doc. This might be a good idea. Thanks! I played tricks during my Ph.D. of gain-modulating an APD with a step recovery diode. I was wondering if there is anything one could do to gain modulate one at 7 GHz, but I can't think how one could achieve anything useful by changing the gain, but it might be worth thinking about. I'm just trying to think out of the box - I can't actually see how it would help. You mean pulsing the bias voltage at about 7GHz and see whether i can get a something out of that? There has been a similar idea around, using a third laser that is pulsed with the desired offset frequency. Using this and the non-linear intensity response of the photodiode one can get a low frequency correlation signal out of the system. A Japanese group did something like this to acheive offset frequencies of 160GHz[1] and later of 1THz[2]. In [3] Aljunid describes how to build such a correlator for fs pulses using a simple LED. (yes, i came across some really weird stuff when i started digging into this) Have you considered using a photomultiplier tube? I think there are some fast PMTs around, though perhaps not fast enough. 20 years I used to know what was state of the art in this area, but not any more. Not really. I am mostly looking at stuff i can easily get my hands on. If possible without using ebay (other should be able to build the system as well). Attila Kinali [1] External Synchronization of 160-GHz Optical Beat Signal by Optical Phase-Locked Loop Technique by Shigehiro et al, 2006 http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=4012083 [2] Development of an Optical Phase-Locked Loop for 1-THz Optical Beat Signal Generation by Shigehiro et al, 2008 http://www.furukawa.co.jp/review/fr033/fr33_02.pdf [3] Optical Autocorrelation using Non-Linearity in a Simple Photodiode by Aljunid, 2007 http://qolah.org/thesis/thesis-syed.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] Photodiodes for high frequency OPLL
On Sat, 30 Mar 2013 12:45:52 -0700 (PDT) Robert LaJeunesse rlajeune...@sbcglobal.net wrote: Maybe I'm jaded a bit, but in this town the sub-10GHz optical stuff is considered kinda slow. The guys down the street, Picometrix, have been doing 40+GHz optical receivers for over 15 years. They claim 1.5G to 100G and from 400nm to 1650nm so probably they can help. http://www.picometrix.com/ I stumbled over picometrix, but did not get much from their webside, beside that they are claiming to acheive GHz frequencies with PIN photodiodes. But nothing specific. I will contact them and see what they say. As background info they are a spinoff of the University of Michigan Center for Ultrafast Optical Science. http://www.engin.umich.edu/research/cuos/ 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
A photodiode is in fact a nonlinear device for optical fields as it is essentially a linear optical power detector. The output is proportional to the incident optical power not the field amplitude. Photomixers are routinely used in wide range of diverse application such as translating the frequency fluctuations of the (Mie) scattered light due to Brownian motion of the colloidal particle sizes to baseband. The size of the scattering particles can be inferred from the shape of the resultant frequency spectrum. An interferometer of itself (without a detector) is a linear device that merely superimposes optical fields and will of itself produce no difference frequency output. Bruce ed breya wrote: I don't think that you can effectively directly mix two laser wavelengths in a semiconductor light detector and get a useable IF - it's hard enough just to get the tens of GHz modulation signals out above the noise floor, let alone a tiny difference signal between hundreds of THz. You need an optical interference or nonlinear device up front to do the mixing and get the wavelength discrimination, while the optical detector(s) serve as the first IF O-E transducer. My knowledge of this stuff isn't up to date - maybe nowadays there are detector devices and methods that take care of this directly, but I don't think so. Most really high speed diodes are optimized for the 1550 nm region where EDFAs work, but maybe they have usable response at other ranges. It depends on your particular application and wavelength. I think detectors are usually specified over the entire IR region, so datasheets may tell enough. Here's link to some good info, but not current state of the art: http://e-collection.library.ethz.ch/eserv/eth:28429/eth-28429-02.pdf There are various methods that use lower frequency modulation techniques so that regular detectors can be used directly. If you study up on related patents, you may find some ideas and leads to appropriate actual devices. Ed ___ 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
The circuit is something like the instrumentation amplifier. The description starts on page 207 with a schematic on page 208. I can scan it later, but the circuit is easy to describe. Think of two op amps in the classic current multiplication (I to V) circuit, that is positive input to ground and a resistor from output to negative input. Now place the diode between the two negative inputs. The current flow will cause the outputs of the op amp to move differentially, which can then be made single ended with an op amp circuit. But the thing to keep in mind is that the voltage potential across the photodiode has been kept to zero, so the capacitance doesn't matter. But it is only held to zero as long as the amplifier has loop gain, that is create the virtual ground, hence you need a high GBP for the capacitance to be neutralized. Now I haven't seen this published, but it seems to me if you wanted a negative bias across the diode, you could just use a transformer. I ran into a patent on transformer coupled photodiode circuitry. It was for high speed flash detection. (Amazing was common sense obvious design technique can be patented.) The bootstrap technique basically takes the virtual ground signal of the current multiplier circuit and replicates the AC portion of the virtual ground on the other side of the photodiode, keeping the AC signal across the diode at zero volts, but letting the current flow into the circuit to be multiplied by the op ampresistor. Since the bootstrap needs to sample the virtual ground, it itself can't steal any current from that point, so it usually employs a JFET. These amplifier circuits usually go down to DC, so they will also have response to ambient light, which could eat into the dynamic range of the circuit. Linear Technology app notes use the bootstrap often. They use a common low noise JFET from NXP. Noise from the bootstrap adds right to the diode, so the bootstrap components need to be low noise. The fully differential circuit doesn't have the bootstrap noise source, but it has two amplifiers on the front end, hence two uncorrelated noise sources. Going back to the fully differential circuit, you could bias the diode by placing the positive inputs of the I to V circuits at different potentials, then reject the DC components at the double ended to single ended converter by capacitive coupling. You would probably want to meditate on start up issues if the DC bias is large, that is use clamping diodes on the double ended to single ended converter if it looks like something will be stressed on start up. When you read the photodiode literature, bandwidth is stated into an impedance, so I think they just treat the capacitance as the limiting factor. Maybe that is real life, or maybe it is oversimplified. At that point this is a solid state physics problem and not a circuit design issue. (I'd have to crack a book on the physics.) --Original Message-- From: Attila Kinali To: li...@lazygranch.com To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Photodiodes for high frequency OPLL Sent: Mar 30, 2013 12:03 PM On Sat, 30 Mar 2013 17:29:45 + li...@lazygranch.com wrote: You lose me at damping per decade? Is damping the right word? Do you mean high frequency rolloff? Er.. yes. Frequency rolloff... Sorry, my native language got the better of me. Most texts on photodiodes go into bootstrapping them to reduce the effect of capacitance. But if you design fully differential amplifier circuits, they have the same effect as bootstrapping. Jerald Graeme's Photodiode Amplifiers goes into this. I'm not a fan of Gain technology as a company, but Graeme's book are good texts. Thanks! I just ordered this book. Although i will have to build a discrete amplifier for the first stage until i can mix the signal down to something that can be handled easier. The bootstrapping circuits use simpler buffers to keep the voltage potential across the diode low, while the fully differential circuits depend on gain bandwidth product to do the same. Well, as i currently lean torwards using an avalanche photodiode, which needs an operating voltage in the range of 100V, keeping the potential accross the diode low is not really an issue :-) How do the fully differential circuits get to keep the potential low? As far as i can tell, from the circuits i've seen so far, the differential circuits just use the single ended signal from the diode take the difference to a bias voltage. 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] WWVB d-psk-r update. Seems a reasonable solution
The reciever is now drawn up in expressPC. Will add in the dividers to another drawing I simply could not get it all in the same schematic. Not that there is a lot expressPC has sizing limitations. I know there is better... Just no time to tinker. Its going to be interesting getting the schematics into a word or pdf doc. Will repond to other comments. But for Atilla the issue with simple stuff like doubler dividers is simply noise and competition from MSF. Regards Paul On Sat, Mar 30, 2013 at 11:12 AM, Bob Camp li...@rtty.us wrote: Hi I think it's pretty safe to say that the Vectron part mentioned is a VCXO with a crystal as the resonator. Indeed a ceramic resonator or an L/C resonator part would have a bit more drift and lower Q than a crystal based part. I would not try something like this with anything other than a crystal based part. At least as far as the commonly available stuff goes. I'm sure you could make it work with a hydrogen maser as the frequency source and a bit of DDS magic... Bob On Mar 30, 2013, at 10:23 AM, Jim Lux jim...@earthlink.net wrote: On 3/29/13 9:01 AM, Bob Camp wrote: Hi Too much tuning range is easy enough to fix. Use a pot to set it on frequency and then hook it to the rest of the stuff with a fixed resistor. The gotcha would be if the poor thing drifts so much that it *needs* the wide range to stay in lock. My guess is that you could buy a hundred VCXO's at auction for less than the cost of trying a dozen samples. wide tuning range VCOs have lower Q resonators, so the outside the loop BW noise will tend to be worse. The other problem I have found is that wide tuning range VCOs tend to drift more (that is, with a constant input voltage, their frequency changes more as they warm up or otherwise change temperature). It's a matter of sitting with the online order site open in one window, and the Vectron or whoever website open to their catalog in another and going back and forth comparing part #s.. ___ 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] Releasing sources (was Re: Brooks Shera)
What a bunch of hooey. Another so called expert wasted hours of my time because he can't be bothered to either note that code is buggy or just can't be bothered.. If you don't want to release it, then don't. If you do and it's a POS, Expect emails. On Thu, Mar 28, 2013 at 2:16 PM, NeonJohn j...@neon-john.com wrote: On 03/25/2013 09:36 AM, Jim Lux wrote: One reason is that if one DOES release source, one will wind up supporting it, because generally, we all nice people and helpful, and it's hard to tell someone no when they send an email asking how to get it to compile on Version N+3 when you used version N, etc. This can be a real distraction from whatever else you are doing. Boy, you can say that again. And open source hardware is even worse. A couple of years ago I put up an open source induction heater on my site. Everything included - schematics, board layouts, CAD files, theory of operation, how to wind the transformer - in short, everything I could think of. There's even a kit available from Fluxeon.com. Yet I probably spend an hour a day responding to emails about that project. Approximately 100% of the questions are either answered on my site or by a little googling. It's getting to be enough of a burden that I'm considering taking the page down. I'm a dedicated supporter of Open Source but this experience has tempered my enthusiasm a bit. And then there's the folks who argue with you about your implementation or coding style. Or electrical design style. I think that the people who want to argue design, especially what if I did this? type arguments are more tiresome than the software know-it-alls. People need to really think and do their Google homework before hitting the email button on a project site. John -- John DeArmond Tellico Plains, Occupied TN http://www.fluxeon.com -- THE source for induction heaters http://www.neon-john.com-- email from here http://www.johndearmond.com -- Best damned Blog on the net PGP key: wwwkeys.pgp.net: BCB68D77 ___ 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] WWVB d-psk-r update. Seems a reasonable solution
Hi The easy way to get to pdf is normal a pdf translator loaded as if it's a printer. Anything that will print can (at least in theory) be translated to a pdf by this approach. In real life, nothing is ever perfect, but I've had good luck with them. Bob On Mar 30, 2013, at 5:41 PM, paul swed paulsw...@gmail.com wrote: The reciever is now drawn up in expressPC. Will add in the dividers to another drawing I simply could not get it all in the same schematic. Not that there is a lot expressPC has sizing limitations. I know there is better... Just no time to tinker. Its going to be interesting getting the schematics into a word or pdf doc. Will repond to other comments. But for Atilla the issue with simple stuff like doubler dividers is simply noise and competition from MSF. Regards Paul On Sat, Mar 30, 2013 at 11:12 AM, Bob Camp li...@rtty.us wrote: Hi I think it's pretty safe to say that the Vectron part mentioned is a VCXO with a crystal as the resonator. Indeed a ceramic resonator or an L/C resonator part would have a bit more drift and lower Q than a crystal based part. I would not try something like this with anything other than a crystal based part. At least as far as the commonly available stuff goes. I'm sure you could make it work with a hydrogen maser as the frequency source and a bit of DDS magic... Bob On Mar 30, 2013, at 10:23 AM, Jim Lux jim...@earthlink.net wrote: On 3/29/13 9:01 AM, Bob Camp wrote: Hi Too much tuning range is easy enough to fix. Use a pot to set it on frequency and then hook it to the rest of the stuff with a fixed resistor. The gotcha would be if the poor thing drifts so much that it *needs* the wide range to stay in lock. My guess is that you could buy a hundred VCXO's at auction for less than the cost of trying a dozen samples. wide tuning range VCOs have lower Q resonators, so the outside the loop BW noise will tend to be worse. The other problem I have found is that wide tuning range VCOs tend to drift more (that is, with a constant input voltage, their frequency changes more as they warm up or otherwise change temperature). It's a matter of sitting with the online order site open in one window, and the Vectron or whoever website open to their catalog in another and going back and forth comparing part #s.. ___ 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] Photodiodes for high frequency OPLL
Ooops - never mind. I wrote before my memory was updated. My experience in E-O stuff was years ago using AM at relatively low frequency, and nowhere near the lasers and microwave/gigabit/sec stuff - I didn't think the detectors were fast enough to actually keep up with the optical carrier frequency. I was also picturing wavelength/spatial separation with interference in order to allow relatively slow detectors to see it, or mixing in nonlinear optical materials. Ed Bruce Griffiths wrote: A photodiode is in fact a nonlinear device for optical fields as it is essentially a linear optical power detector. The output is proportional to the incident optical power not the field amplitude. Photomixers are routinely used in wide range of diverse application such as translating the frequency fluctuations of the (Mie) scattered light due to Brownian motion of the colloidal particle sizes to baseband. The size of the scattering particles can be inferred from the shape of the resultant frequency spectrum. An interferometer of itself (without a detector) is a linear device that merely superimposes optical fields and will of itself produce no difference frequency output. Bruce ed breya wrote: I don't think that you can effectively directly mix two laser wavelengths in a semiconductor light detector and get a useable IF - it's hard enough just to get the tens of GHz modulation signals out above the noise floor, let alone a tiny difference signal between hundreds of THz. You need an optical interference or nonlinear device up front to do the mixing and get the wavelength discrimination, while the optical detector(s) serve as the first IF O-E transducer. My knowledge of this stuff isn't up to date - maybe nowadays there are detector devices and methods that take care of this directly, but I don't think so. ___ 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
The circuit I've seen is: |--||--- +Vb---o--| amp |--||-o- Vb gnd--| The diode is reverse biased by 50 to several hundred volts. The two caps are DC bypass caps w/ very short leads. The output is a 50 Ohm coax to a broadband amp w/ 50 Ohm input. In the limit, the amp is put right at the detector and has near-zero input Z. Best, -John = On Sat, 30 Mar 2013 10:52:54 -0700 (PDT) J. Forster j...@quikus.com wrote: My understanding is that you want to operate photodiodes with high reverse bias for the best frequency response. The bias widens the space charge layer, thereby reducing the capacitance of the device. The high electric fields in the SCL region also sweeps the hole-electron pairs, produced by photon injection, out faster, hence improving the response as well. Such devices are best operated with very low capacity wiring into a virtual ground. Could you elaborate on this circuit a little bit? Some terms i could google for or pointers to books/papers to read? Of course, there are limits as, at some point, the device will avalanche. When that ocurrs, the device will have gain akin to a photomultiplier. Some devices are actually designed to operate in this mode, but, since the thing is so near to unstable requires careful control of temperature and oher parameters. Yes, the avalanche photodiodes are meant for this operation. Yes, there are kind of sensitive. But i think that's managable. 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
The detectors don't have to be fast enough to keep up with optical carrier frequency as long as the incident optical power has a component at a much lower frequency. Bruce ed breya wrote: Ooops - never mind. I wrote before my memory was updated. My experience in E-O stuff was years ago using AM at relatively low frequency, and nowhere near the lasers and microwave/gigabit/sec stuff - I didn't think the detectors were fast enough to actually keep up with the optical carrier frequency. I was also picturing wavelength/spatial separation with interference in order to allow relatively slow detectors to see it, or mixing in nonlinear optical materials. Ed Bruce Griffiths wrote: A photodiode is in fact a nonlinear device for optical fields as it is essentially a linear optical power detector. The output is proportional to the incident optical power not the field amplitude. Photomixers are routinely used in wide range of diverse application such as translating the frequency fluctuations of the (Mie) scattered light due to Brownian motion of the colloidal particle sizes to baseband. The size of the scattering particles can be inferred from the shape of the resultant frequency spectrum. An interferometer of itself (without a detector) is a linear device that merely superimposes optical fields and will of itself produce no difference frequency output. Bruce ed breya wrote: I don't think that you can effectively directly mix two laser wavelengths in a semiconductor light detector and get a useable IF - it's hard enough just to get the tens of GHz modulation signals out above the noise floor, let alone a tiny difference signal between hundreds of THz. You need an optical interference or nonlinear device up front to do the mixing and get the wavelength discrimination, while the optical detector(s) serve as the first IF O-E transducer. My knowledge of this stuff isn't up to date - maybe nowadays there are detector devices and methods that take care of this directly, but I don't think so. ___ 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
If I can rephrase that it it, the diode needs to see the difference signal of the mixer? -Original Message- From: Bruce Griffiths bruce.griffi...@xtra.co.nz Sender: time-nuts-boun...@febo.com Date: Sun, 31 Mar 2013 11:43:48 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 The detectors don't have to be fast enough to keep up with optical carrier frequency as long as the incident optical power has a component at a much lower frequency. Bruce ed breya wrote: Ooops - never mind. I wrote before my memory was updated. My experience in E-O stuff was years ago using AM at relatively low frequency, and nowhere near the lasers and microwave/gigabit/sec stuff - I didn't think the detectors were fast enough to actually keep up with the optical carrier frequency. I was also picturing wavelength/spatial separation with interference in order to allow relatively slow detectors to see it, or mixing in nonlinear optical materials. Ed Bruce Griffiths wrote: A photodiode is in fact a nonlinear device for optical fields as it is essentially a linear optical power detector. The output is proportional to the incident optical power not the field amplitude. Photomixers are routinely used in wide range of diverse application such as translating the frequency fluctuations of the (Mie) scattered light due to Brownian motion of the colloidal particle sizes to baseband. The size of the scattering particles can be inferred from the shape of the resultant frequency spectrum. An interferometer of itself (without a detector) is a linear device that merely superimposes optical fields and will of itself produce no difference frequency output. Bruce ed breya wrote: I don't think that you can effectively directly mix two laser wavelengths in a semiconductor light detector and get a useable IF - it's hard enough just to get the tens of GHz modulation signals out above the noise floor, let alone a tiny difference signal between hundreds of THz. You need an optical interference or nonlinear device up front to do the mixing and get the wavelength discrimination, while the optical detector(s) serve as the first IF O-E transducer. My knowledge of this stuff isn't up to date - maybe nowadays there are detector devices and methods that take care of this directly, but I don't think so. ___ 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] Building a Agilent Cross Correlated Phase Noise Measurement System.
Hi, Tom -- A paper in the 2010 EFTF described the use of a pair of 11848A boxes from the 3048A system, which is similar to the E5500 hardware ( http://www.congrex.nl/EFTF_Proceedings/Papers/Session_14_Oscillators_and_Noi se/14_04_Bale.pdf ). You could ping those authors if you haven't already. Also, have you talked with Craig Nelson about his work with the NI digitizers and T/H amps? The 70820A GPIB documentation is part of the overall 71500A reference guide at http://cp.literature.agilent.com/litweb/pdf/70820-90051.pdf . -- john, KE5FX Miles Design LLC -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts- boun...@febo.com] On Behalf Of Tom Knox Sent: Saturday, March 30, 2013 10:17 AM To: Time-Nuts Subject: [time-nuts] Building a Agilent Cross Correlated Phase Noise Measurement System. We are looking into using two N/E550XA/B Phase Noise systems and the 89410A to build a Cross Correlated measurement system. I was wondering if anyone has attempted this before? Does anyone know where to find the base GPIB command codes for the 70420A system? Thanks; Thomas Knox Phase Noise Measurement Group NIST ___ 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
Yes, the beat (difference) frequency of the 2 lasers has to lie within the photodiode electrical passband. With a suitable low noise tunable LO (laser) the frequency spectrum beyond the photodiode electrical bandwidth can be explored. Bruce li...@lazygranch.com wrote: If I can rephrase that it it, the diode needs to see the difference signal of the mixer? -Original Message- From: Bruce Griffithsbruce.griffi...@xtra.co.nz Sender: time-nuts-boun...@febo.com Date: Sun, 31 Mar 2013 11:43:48 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 The detectors don't have to be fast enough to keep up with optical carrier frequency as long as the incident optical power has a component at a much lower frequency. Bruce ed breya wrote: Ooops - never mind. I wrote before my memory was updated. My experience in E-O stuff was years ago using AM at relatively low frequency, and nowhere near the lasers and microwave/gigabit/sec stuff - I didn't think the detectors were fast enough to actually keep up with the optical carrier frequency. I was also picturing wavelength/spatial separation with interference in order to allow relatively slow detectors to see it, or mixing in nonlinear optical materials. Ed Bruce Griffiths wrote: A photodiode is in fact a nonlinear device for optical fields as it is essentially a linear optical power detector. The output is proportional to the incident optical power not the field amplitude. Photomixers are routinely used in wide range of diverse application such as translating the frequency fluctuations of the (Mie) scattered light due to Brownian motion of the colloidal particle sizes to baseband. The size of the scattering particles can be inferred from the shape of the resultant frequency spectrum. An interferometer of itself (without a detector) is a linear device that merely superimposes optical fields and will of itself produce no difference frequency output. Bruce ed breya wrote: I don't think that you can effectively directly mix two laser wavelengths in a semiconductor light detector and get a useable IF - it's hard enough just to get the tens of GHz modulation signals out above the noise floor, let alone a tiny difference signal between hundreds of THz. You need an optical interference or nonlinear device up front to do the mixing and get the wavelength discrimination, while the optical detector(s) serve as the first IF O-E transducer. My knowledge of this stuff isn't up to date - maybe nowadays there are detector devices and methods that take care of this directly, but I don't think so. ___ 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] Building a Agilent Cross Correlated Phase Noise Measurement System.
Oops, sorry, I read 70820 for 70420, disregard that last link. -- john, KE5FX Miles Design LLC -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts- boun...@febo.com] On Behalf Of John Miles Sent: Saturday, March 30, 2013 4:10 PM To: 'Discussion of precise time and frequency measurement' Subject: Re: [time-nuts] Building a Agilent Cross Correlated Phase Noise Measurement System. Hi, Tom -- A paper in the 2010 EFTF described the use of a pair of 11848A boxes from the 3048A system, which is similar to the E5500 hardware ( http://www.congrex.nl/EFTF_Proceedings/Papers/Session_14_Oscillators_a nd_Noi se/14_04_Bale.pdf ). You could ping those authors if you haven't already. Also, have you talked with Craig Nelson about his work with the NI digitizers and T/H amps? The 70820A GPIB documentation is part of the overall 71500A reference guide at http://cp.literature.agilent.com/litweb/pdf/70820-90051.pdf . -- john, KE5FX Miles Design LLC -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts- boun...@febo.com] On Behalf Of Tom Knox Sent: Saturday, March 30, 2013 10:17 AM To: Time-Nuts Subject: [time-nuts] Building a Agilent Cross Correlated Phase Noise Measurement System. We are looking into using two N/E550XA/B Phase Noise systems and the 89410A to build a Cross Correlated measurement system. I was wondering if anyone has attempted this before? Does anyone know where to find the base GPIB command codes for the 70420A system? Thanks; Thomas Knox Phase Noise Measurement Group NIST ___ 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] Releasing sources (was Re: Brooks Shera)
On Sat, Mar 30, 2013 at 2:58 PM, Lizeth Norman normanliz...@gmail.com wrote: If you don't want to release it, then don't. If you do and it's a POS, Expect emails. Some I know use a dedicated email address when they post things intended as open source. They then set up an auto-respond message such as: *Thanks for taking interest in my [contribution]. I have made it freely available for your use, but unfortunately I am not able to answer email about it, or to assist in adapting it to your application. I suggest you look online for Yahoo forums or other discussion sites for answers.* They then have a filter that deletes the incoming email. 73, Todd K7TFC / Medford, Oregon, USA / CN82ni / UTC-8 QRP (CW SSB) / EmComm / SOTA / Homebrew / Design ___ 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 19:50, Attila Kinali att...@kinali.ch wrote: On Sat, 30 Mar 2013 18:43:03 + David Kirkby david.kir...@onetel.net wrote: I would contact Hammamatsu Photonics http://www.hamamatsu.com This might be a good idea. Thanks! I played tricks during my Ph.D. of gain-modulating an APD with a step recovery diode. You mean pulsing the bias voltage at about 7GHz and see whether i can get a something out of that? I did not really have anything in mind specifically. I was just wondering if there was anything could do modulating the gain of a detector so forming a non-linear detector. I pulsed the voltage on an APD to buid a cross correlator. By doing that I was able to get better temporal resolution than the basic APD. Quick summary here: http://www.medphys.ucl.ac.uk/research/borl/research/phd_projects/davek_phd.htm Fulll thesis here http://www.medphys.ucl.ac.uk/research/borl/docs/dkirkby.pdf I have seen systems where one sinusoidally modulates the voltage of a photomultipler tube. You could do the same with an APD. Then it acts a a mixer. Essentially 1) Modulate laser at 100 MHz 2) Modlulate the APD bias voltage at 100.01 MHz 3) Detect light from laser on an APD. 4) Output of the APD is a sine wave at 10 kHz. There has been a similar idea around, using a third laser that is pulsed with the desired offset frequency. I was wondering if it could be done in more than one stage. A bit like a superhetrodyne receiver. I've had quite a few beers tonight (OK, I am ed) so my mind is not thinking too straight. Have you considered using a photomultiplier tube? I think there are some fast PMTs around, though perhaps not fast enough. 20 years I used to know what was state of the art in this area, but not any more. Not really. I am mostly looking at stuff i can easily get my hands on. If possible without using ebay (other should be able to build the system as well). PMTs are available new. Hamamatsu has almost 100 different types. http://www.hamamatsu.com/eu/en/product/category/3100/3003/index.html so there is no need to trawl ebay. Using PMTs you can easily get sub ns temporal response. 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] Photodiodes for high frequency OPLL
OK, so if you just need to detect the mixer difference, the band limiting of the photodiode is a feature. ;-) -Original Message- From: Bruce Griffiths bruce.griffi...@xtra.co.nz Date: Sun, 31 Mar 2013 12:28:59 To: li...@lazygranch.com; Discussion of precise time and frequency measurementtime-nuts@febo.com Subject: Re: [time-nuts] Photodiodes for high frequency OPLL Yes, the beat (difference) frequency of the 2 lasers has to lie within the photodiode electrical passband. With a suitable low noise tunable LO (laser) the frequency spectrum beyond the photodiode electrical bandwidth can be explored. Bruce li...@lazygranch.com wrote: If I can rephrase that it it, the diode needs to see the difference signal of the mixer? -Original Message- From: Bruce Griffithsbruce.griffi...@xtra.co.nz Sender: time-nuts-boun...@febo.com Date: Sun, 31 Mar 2013 11:43:48 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 The detectors don't have to be fast enough to keep up with optical carrier frequency as long as the incident optical power has a component at a much lower frequency. Bruce ed breya wrote: Ooops - never mind. I wrote before my memory was updated. My experience in E-O stuff was years ago using AM at relatively low frequency, and nowhere near the lasers and microwave/gigabit/sec stuff - I didn't think the detectors were fast enough to actually keep up with the optical carrier frequency. I was also picturing wavelength/spatial separation with interference in order to allow relatively slow detectors to see it, or mixing in nonlinear optical materials. Ed Bruce Griffiths wrote: A photodiode is in fact a nonlinear device for optical fields as it is essentially a linear optical power detector. The output is proportional to the incident optical power not the field amplitude. Photomixers are routinely used in wide range of diverse application such as translating the frequency fluctuations of the (Mie) scattered light due to Brownian motion of the colloidal particle sizes to baseband. The size of the scattering particles can be inferred from the shape of the resultant frequency spectrum. An interferometer of itself (without a detector) is a linear device that merely superimposes optical fields and will of itself produce no difference frequency output. Bruce ed breya wrote: I don't think that you can effectively directly mix two laser wavelengths in a semiconductor light detector and get a useable IF - it's hard enough just to get the tens of GHz modulation signals out above the noise floor, let alone a tiny difference signal between hundreds of THz. You need an optical interference or nonlinear device up front to do the mixing and get the wavelength discrimination, while the optical detector(s) serve as the first IF O-E transducer. My knowledge of this stuff isn't up to date - maybe nowadays there are detector devices and methods that take care of this directly, but I don't think so. ___ 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] Releasing sources (was Re: Brooks Shera)
k7...@arrl.net said: Some I know use a dedicated email address when they post things intended as open source. They then set up an auto-respond message such as: Auto-responders are evil. The problem is that spammer's forge the return address. The response to any spam that gets past your filters will go back to an innocent victim. To the victim, it looks like spam. Don't be surprised if you get added to black lists. http://en.wikipedia.org/wiki/Backscatter_%28e-mail%29 http://en.wikipedia.org/wiki/Bounce_message#Bouncing_vs._rejecting It's much better to put that message out where people are finding the email address. If you didn't plan ahead that far, most mail systems will let you reject mail with some error text you provide which could include a URL. That does require cooperation from the people running the mail server so it probably won't work if you use gmail, hotmail, comcast or similar services. It's easy if you or a friend run the mail server. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Releasing sources (was Re: Brooks Shera)
If you write something and want to publish it. Put it one Source Forge and then you get Subversion system to host the code, an email list people can join and a forum that is linked to it and bug tracking and so on and so on. You can keep up with the forum that is tied to your code or not. Users can join it if they like or not. The tools are all there for free. The bug tracker is us full and everything lives on THEIR server for free. On Sat, Mar 30, 2013 at 5:40 PM, Hal Murray hmur...@megapathdsl.net wrote: k7...@arrl.net said: Some I know use a dedicated email address when they post things intended as open source. They then set up an auto-respond message such as: Auto-responders are evil. The problem is that spammer's forge the return address. The response to any spam that gets past your filters will go back to an innocent victim. To the victim, it looks like spam. Don't be surprised if you get added to black lists. http://en.wikipedia.org/wiki/Backscatter_%28e-mail%29 http://en.wikipedia.org/wiki/Bounce_message#Bouncing_vs._rejecting It's much better to put that message out where people are finding the email address. If you didn't plan ahead that far, most mail systems will let you reject mail with some error text you provide which could include a URL. That does require cooperation from the people running the mail server so it probably won't work if you use gmail, hotmail, comcast or similar services. It's easy if you or a friend run the mail server. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- 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] Building a Agilent Cross Correlated Phase Noise Measurement System.
Hi Miles; Thanks for the paper. Craig is actually the one taking the lead on this project. I will keep the group updated on the project. Thomas Knox From: jmi...@pop.net To: time-nuts@febo.com Date: Sat, 30 Mar 2013 16:10:21 -0700 Subject: Re: [time-nuts] Building a Agilent Cross Correlated PhaseNoise Measurement System. Hi, Tom -- A paper in the 2010 EFTF described the use of a pair of 11848A boxes from the 3048A system, which is similar to the E5500 hardware ( http://www.congrex.nl/EFTF_Proceedings/Papers/Session_14_Oscillators_and_Noi se/14_04_Bale.pdf ). You could ping those authors if you haven't already. Also, have you talked with Craig Nelson about his work with the NI digitizers and T/H amps? The 70820A GPIB documentation is part of the overall 71500A reference guide at http://cp.literature.agilent.com/litweb/pdf/70820-90051.pdf . -- john, KE5FX Miles Design LLC -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts- boun...@febo.com] On Behalf Of Tom Knox Sent: Saturday, March 30, 2013 10:17 AM To: Time-Nuts Subject: [time-nuts] Building a Agilent Cross Correlated Phase Noise Measurement System. We are looking into using two N/E550XA/B Phase Noise systems and the 89410A to build a Cross Correlated measurement system. I was wondering if anyone has attempted this before? Does anyone know where to find the base GPIB command codes for the 70420A system? Thanks; Thomas Knox Phase Noise Measurement Group NIST ___ 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.
