Re: [Flexradio] Looking fo Rubidium standard
At 03:41 PM 7/11/2006, Jerry Sharp wrote: >What's the phase noise like from a HP Z3801A GPS standard? I have one >and have thought about interfacing to my SDR. Having super frequency >accuracy would be nice, but not at the expense of degrading overall >system performance. Funny you should ask.. I have one too. the phase noise is fairly good on those, because it's derived from a ovenized XO (the HP 10811A, as it happens). The problem is that when you multiply it up by 20 in the DDS's internal multiplier, you take a 20Log(N) dB hit, or 26 dB. The XO in the SDR1000 now is quieter. >Right now I use my Z3801 to discipline test equipment. Being able to >measure 10.3681 GHz to within a few 10's of Hz is nice. > >Thanks and 73, >Jerry Sharp, KD0GS ___ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ FlexRadio Homepage: http://www.flex-radio.com
Re: [Flexradio] Looking fo Rubidium standard
What's the phase noise like from a HP Z3801A GPS standard? I have one and have thought about interfacing to my SDR. Having super frequency accuracy would be nice, but not at the expense of degrading overall system performance. Right now I use my Z3801 to discipline test equipment. Being able to measure 10.3681 GHz to within a few 10's of Hz is nice. Thanks and 73, Jerry Sharp, KD0GS Jim Lux wrote: > At 12:30 PM 7/10/2006, Edward J White wrote: > >>Hi Gang: >>I am looking for a Rubidium frequency standard to run the SDR-1000 >>oscillator. I know others have done this to run 10 GHz. What is the best >>price and make model where and where should I be looking for one(I know >>the E place). > > > Just curious, why a Rb standard, and not, say, a GPS disciplined XO? > > Jim > > > > ___ > FlexRadio mailing list > FlexRadio@flex-radio.biz > http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz > Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ > FlexRadio Homepage: http://www.flex-radio.com > > > > ___ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ FlexRadio Homepage: http://www.flex-radio.com
Re: [Flexradio] Looking fo Rubidium standard
At 07:03 PM 7/10/2006, Edward J White wrote: >Hi Jim: >I guess it is the 50 foot of coax to the radio from the antenna on the >roof. I think that is the only draw back? >Help me out here ( trying to learn what is what)I am trying to move this >project along and up in freq. With a decent ocxo, you probably don't need GPS disciplining. You could periodically calibrate to WWV or something else, and just turn the mechanical adjustment screw. The advantage of an OCXO (and they turn up surplus all the time) is that you get really good phase noise AND good frequency stability. A TCXO (like in newer commercial rigs) gives you good frequency stability (but not as good as an OCXO) and not as good phase noise (because the rock has to be soft enough that the temperature compensation can work). The disadvantage of the OCXO is the power consumption: several watts. Almost all lab equipment these days uses some form of OCXO. Look for things like the HP 10811A oscillators. There is one other technology that is interesting: the MCXO (microprocessor controlled crystal oscillator). This makes use of the fact that if you measure both the first and third overtone frequency of a crystal (most crystals will simultaneously oscillate at multiple modes), you can accurately measure the crystal's temperature. The MCXO does this, and then uses the temperature to calculate what the actual frequency is vs what it should be, and either programs a DDS to generate the "right" frequency, or provides a telemetry output to the device consuming the oscillator output telling it what the frequency is. The latter is a particularly appealing way to do it for an SDR, because the radio doesn't care what the reference oscillatoro frequency is, as long as it knows what it is. I've not seen cheap or surplus MCXOs though. I think you might also be able to do this with the stock SDR1000, with a temperature probe on the XO, feeding back into the PowerSDR software. I'm waiting for the 1.7 version which splits the radio interface from the user interface to try it out, but I've tried some experiments, and it looks promising. >Ed >WA3BZT James Lux, P.E. Spacecraft Radio Frequency Subsystems Group Flight Communications Systems Section Jet Propulsion Laboratory, Mail Stop 161-213 4800 Oak Grove Drive Pasadena CA 91109 tel: (818)354-2075 fax: (818)393-6875 ___ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ FlexRadio Homepage: http://www.flex-radio.com
Re: [Flexradio] Looking fo Rubidium standard
At 02:57 PM 7/10/2006, Robert McGwier wrote: >I completely agree. Ed, the Gibraltar project from HPSDR or the >Reflock II project from TAPR (which are about to coalesce), taming an >external oscillator is what you want. The inexpensive rubidiums "FM" >to find the line. JUST SAY NO. > >Bob Or, for that matter, a brand new $200 low phase noise OCXO from Wenzel that you turn the screw to calibrate once a year. 5ppb frequency stability from 0 to 50C, 0.5ppb aging/day after the first 30 days. At 30 MHz, that's 0.15 Hz stability, which should be good enough.. The aging works out to about 0.2ppm/yr. If you'd rather spend time than money, I would imagine that one could build a OCXO using a nice quiet oscillator (like the Valpey Fisher one on the SDR1000) with a decent enclosure, etc. Put the oscillator inside a bunch of foam with a temperature sensor and a heater and a little DC proportional controller and run it at, say, about 50 C. Let it age for a while and run your cal. The goal on Rb standards is to use them to provide an absolute frequency reference that you can use to calibrate a nice quiet XO. For that purpose, FMing them doesn't make any difference in the output of the system. >Jim Lux wrote: > > At 12:30 PM 7/10/2006, Edward J White wrote: > > > >> Hi Gang: > >> I am looking for a Rubidium frequency standard to run the SDR-1000 > >> oscillator. I know others have done this to run 10 GHz. What is the best > >> price and make model where and where should I be looking for one(I know > >> the E place). > >> > > > > Just curious, why a Rb standard, and not, say, a GPS disciplined XO? > > > > Jim > > > > > > > > ___ > > FlexRadio mailing list > > FlexRadio@flex-radio.biz > > http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz > > Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ > > FlexRadio Homepage: http://www.flex-radio.com > > > > > > >-- >AMSAT VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats, >NJQRP/AMQRP, QRP ARCI, QCWA, FRC. ARRL SDR Wrk Grp Chairman >"An expert is a man who has made all the mistakes which can be >made in a very narrow field." Niels Bohr > > >___ >FlexRadio mailing list >FlexRadio@flex-radio.biz >http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz >Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ >FlexRadio Homepage: http://www.flex-radio.com James Lux, P.E. Spacecraft Radio Frequency Subsystems Group Flight Communications Systems Section Jet Propulsion Laboratory, Mail Stop 161-213 4800 Oak Grove Drive Pasadena CA 91109 tel: (818)354-2075 fax: (818)393-6875 ___ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ FlexRadio Homepage: http://www.flex-radio.com
Re: [Flexradio] Looking fo Rubidium standard
I completely agree. Ed, the Gibraltar project from HPSDR or the Reflock II project from TAPR (which are about to coalesce), taming an external oscillator is what you want. The inexpensive rubidiums "FM" to find the line. JUST SAY NO. Bob Jim Lux wrote: > At 12:30 PM 7/10/2006, Edward J White wrote: > >> Hi Gang: >> I am looking for a Rubidium frequency standard to run the SDR-1000 >> oscillator. I know others have done this to run 10 GHz. What is the best >> price and make model where and where should I be looking for one(I know >> the E place). >> > > Just curious, why a Rb standard, and not, say, a GPS disciplined XO? > > Jim > > > > ___ > FlexRadio mailing list > FlexRadio@flex-radio.biz > http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz > Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ > FlexRadio Homepage: http://www.flex-radio.com > > -- AMSAT VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats, NJQRP/AMQRP, QRP ARCI, QCWA, FRC. ARRL SDR Wrk Grp Chairman "An expert is a man who has made all the mistakes which can be made in a very narrow field." Niels Bohr ___ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ FlexRadio Homepage: http://www.flex-radio.com
Re: [Flexradio] Looking fo Rubidium standard
At 12:30 PM 7/10/2006, Edward J White wrote: >Hi Gang: >I am looking for a Rubidium frequency standard to run the SDR-1000 >oscillator. I know others have done this to run 10 GHz. What is the best >price and make model where and where should I be looking for one(I know >the E place). Just curious, why a Rb standard, and not, say, a GPS disciplined XO? Jim ___ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ FlexRadio Homepage: http://www.flex-radio.com
Re: [Flexradio] Looking fo Rubidium standard
Edward J White wrote: > Hi Gang: > I am looking for a Rubidium frequency standard to run the SDR-1000 > oscillator. I know others have done this to run 10 GHz. What is the best > price and make model where and where should I be looking for one(I know the E > place). > Ed > WA3BZT You may want to be careful about using one of the small Rb standards (like the Efratom FRS or FRK) for this application. They tend to have fairly bad phase noise because the reference frequency is FM'd as part of the lock system. An HP5065A Rb doesn't have this problem, but is a much bigger and more expensive beast. 73, John ___ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ FlexRadio Homepage: http://www.flex-radio.com
[Flexradio] Looking fo Rubidium standard
Hi Gang: I am looking for a Rubidium frequency standard to run the SDR-1000 oscillator. I know others have done this to run 10 GHz. What is the best price and make model where and where should I be looking for one(I know the E place). Ed WA3BZT -- next part -- An HTML attachment was scrubbed... URL: /pipermail/flexradio_flex-radio.biz/attachments/20060710/b8b05282/attachment.html ___ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ FlexRadio Homepage: http://www.flex-radio.com
