Re: [time-nuts] Cesium Oscialltors and Low Phase Noise Frequency Standard
Cambridge University Press, which is a non-profit company. I am unsure of the relevance of the above statement but, being pedantic (as befits time-nuts): Cambridge University Press is part of the University of Cambridge [see http://www.admin.cam.ac.uk/univ/so/so_statj.pdf], and the University of Cambridge is a common law corporation, being a corporation by prescription consisting of a Chancellor, Masters, and Scholars who from time out of mind have had the government of their members and enjoyed the privileges of such a corporation. ... The University is now authorized by the Lord Chancellor to act in relation to charitable, ecclesiastical, and public trusts as a trust corporation. [http://www.admin.cam.ac.uk/univ/so/so_prelims.pdf] Chris G3RSE ___ 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] Super stable BVA Quartz resonators... BVA??
Hal Murray wrote: [EMAIL PROTECTED] said: The key points which yield the BVA's improved aging are, that - the whole resonator package is made from quartz, consisting of the resonationg quartz plate in the middle section and the two mounting sealing plaates on top and bottem - you may call it a Hamburger style ;-) - the resonating plate is held through quartz bridges rather than metal suspensions, thus reducing mounting stress. Neat. Thanks. Why is the top domed? I assume flat would be easier to manufacture. Why is it not symmetrical? If the top is domed, why not the bottom too? One surface is convex to facilitate suppression of unwanted harmonics. Its actually quicker and easier to make a planoconvex lens than a biconvex one. 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] Super stable BVA Quartz resonators... BVA??
[EMAIL PROTECTED] said: The key points which yield the BVA's improved aging are, that - the whole resonator package is made from quartz, consisting of the resonationg quartz plate in the middle section and the two mounting sealing plaates on top and bottem - you may call it a Hamburger style ;-) - the resonating plate is held through quartz bridges rather than metal suspensions, thus reducing mounting stress. Neat. Thanks. Why is the top domed? I assume flat would be easier to manufacture. Why is it not symmetrical? If the top is domed, why not the bottom too? -- These are my opinions, not necessarily my employer's. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Symmetricon 58534A manual / setup
- Original Message - From: Didier Juges [EMAIL PROTECTED] To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com Sent: Saturday, December 08, 2007 10:01 AM Subject: Re: [time-nuts] Symmetricon 58534A manual / setup Sometimes, the answer comes from the most unexpected places: the 58534 data sheet (not sure there is a manual) is on the Symmetricom web site: http://ngn.symmetricom.com/products/Subsystems_Components/58534A.asp (it's on my web site too now) Didier KO4BB Didier, I Do appreciate that but that is just the data sheet. I need the pin-outs and cable configuration as well. I have the factory cable but without the manual I'm lost. It is my understanding it is available for free to download from Symmetricom if you have an account or you are a Symmetricom customer. Unfortunately I don't have an account, that's why I tried this board. I've scoured Google and the data sheet is as close as I have found. Many Thanks, Phil ___ 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] Super stable BVA Quartz resonators... BVA??
Thanks for the description, it is very interesting. I have a follow up question if you don't mind. How does crystal aging look on a graph of temp versus frequency. This graph has some temperature point where the slope of frequency variation goes to zero and the crystal is quite stable around this temperature. What does this graph look like as a crystal ages? Does the optimal operating temperature change over time, that is, does the graph tend to move left and right, or does aging tend to move the graph vertically (the optimal freq stays the same, but the optimal operating temperature changes as a result of aging). I hope this makes sense... jeff Bernd T-Online wrote: Hi all, For explanation how the BVA works, please see the attached slide which shows schematically its internal construction. (The explaning text is in German, as it is from my periodically given crystal seminar.) The key points which yield the BVA's improved aging are, that - the whole resonator package is made from quartz, consisting of the resonationg quartz plate in the middle section and the two mounting sealing plaates on top and bottem - you may call it a Hamburger style ;-) - the resonating plate is held through quartz bridges rather than metal suspensions, thus reducing mounting stress. - the BVA is electrodeless, as the electrodes are evaporated on the inner side of the upper and lower mounting plates. Therefore no stress between the quartz surface and the metal eletrode. - Therefore the energizing electrical field is applied through an airgap, which represents two small load capacitors in series to the resonator, thus making the resonator electrically stiffer and less sensitive to circuit influences. On the other side you may imagine the main problems associated with such a construction: - The difficulty to manufacture the convex and concave shaped parts with such a precision, that the curvature yields a constant and very small airgap. - To realize the fine adjustment to frequency, because the unit cannot be tuned in the conventional way, i.e. by plating some metal on the electrode. - The frequency accuracy to which the resonator has to manufactured, because the resonator frequency cannot be pulled with the external circuit elements by more than some hundred ppb. It may be interesting to note, that there was a company BVA Industries, which wanted to generate their income solely from making BVA - which failed. Maybe because of the cost could not be covered by the revenues from the rather limited market. Bernd DK1AG __ AXTAL GmbH Co. KG Facility MOS Wasemweg 5 D-74821 Mosbach / Germany fon: +49 (6261) 939834 fax: +49 (6261) 939836 www.axtal.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ 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] Super stable BVA Quartz resonators... BVA??
We did a lot of characterization of crystal temp vs freq in the E1938 development and never observed any aging of these curves. Even on green crystals with zero run time. Rick Karlquist N6RK Jeff Mock wrote: Thanks for the description, it is very interesting. I have a follow up question if you don't mind. How does crystal aging look on a graph of temp versus frequency. This graph has some temperature point where the slope of frequency variation goes to zero and the crystal is quite stable around this temperature. What does this graph look like as a crystal ages? Does the optimal operating temperature change over time, that is, does the graph tend to move left and right, or does aging tend to move the graph vertically (the optimal freq stays the same, but the optimal operating temperature changes as a result of aging). I hope this makes sense... jeff ___ 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] Symmetricon 58534A manual / setup
I also purchased two of these units. Although I could not find a spec. It appears that it has the same Pinout as the: ONCORE Remote GPS Antenna Receiver ACUTIME 2000 Trimble Palisade The Provided cable only brings out pins 1-5, 9, 11, 12 These Correspond to Pin 01Red Vcc (+8 - 36 VDC) Pin 02Purple Port B Recv- Pin 03Orange Port B Recv+ Pin 04Gray Port B Transmit- Pin 05White Port B Transmit+ Pin 09Black Ground Pin 11Green 1PPS Transmit+ Pin 12Blue 1PPS Transmit- I connected +12VDC to Pin 1 and Goind to Pin 9 and after about 20 Minutes I got good 1PPS from Pin 11 with 50% Duty Cycle (500ms). I have not connected the RS422 Yet but on the scope it looked like it was transmiting something. I do not know if the protocol is: NMEA ONCORE Binary Trimble TSIP Trimble TIAP or some other Protocol. As I learn more I will let you know. I have PDF's for both the ACUTIME 2000 and the ONCORE Remote which I can send to you. There is information on www.leapsecond.com about the Trimble Palisade. Previous Message: Date: Sat, 8 Dec 2007 08:53:47 -0500 From: phil [EMAIL PROTECTED] Subject: Re: [time-nuts] Symmetricon 58534A manual / setup To: Discussion of precise time and frequency measurement time-nuts@febo.com Message-ID: [EMAIL PROTECTED] Content-Type: text/plain; charset=iso-8859-1 Hello Time Nuts, Would anyone have a PDF manual and/or the configuration software or links to it for a Symmetricon 58534A GPS Timing Antenna they would be willing to share ? Many Thanks, Phil Harwood - Looking for last minute shopping deals? Find them fast with Yahoo! Search. ___ 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] Symmetricon 58534A manual / setup
Tom You are correct; it is a complete unit with a 1pps and RS422 output for time and setup/control. I wanted to try to use 3 of them in/for time stamps for triangulating lightning strike data. With a 100 ns timing accuracy I would think it may work for my application. The manual is available for free (download) from Symetricon if you have an account or are an existing customer. Unfortunately I have neither. Should no one in the time-nuts group help I'll go to Symmetricon next week and I'll be happy to share the manual with you. Don, Interesting on what you discovered on pin outs. I have some units with just wires out and two that came with RJ45's on the end. I'll compare wire colors and hope they match. Thanks for giving me a starting place with the wiring. They have a simple setup program for that series of units but again I don't have it. Protocol, who knows, I have heard it is a variation on nmea, but that remains to be seen. Phil ___ 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.
