Re: [time-nuts] Suspected Spam: External clock for Analog to Digital Converter in GPSRx front-end Rx front-end

Bilal, How about using one of the spread-spectrum microprocessor clock generator IC's? These add a pseudo-random jitter to the clock signal so the interference from the equipment is slightly spread causing the equipment to pass EMC testing by causing an apparent reduction in the peak due to the

Re: [time-nuts] Suspected Spam: External clock for Analog to Digital Converter in GPSRx front-end Rx front-end

How about using one of the spread-spectrum microprocessor clock generator IC's? These add a pseudo-random jitter to the clock signal so the interference from the equipment is slightly spread causing the equipment to pass EMC testing by causing an apparent reduction in the peak due to the

Re: [time-nuts] Low noise frequency multiplication

Bruce, thank you for your help! Since it is not known a priori what kind of source will serve for the 10 MHz input I must take into account that it is not the absolute state of art. Since the VCXO solution is not far away from state of the art I consider it the better general choice. I know

Re: [time-nuts] Low noise frequency multiplication

Hi Said, The DDS idea that you (and Ulrich) suggest sounds like a good plan. However, to me your predictions sound overly optimistic. Said wrote: But let's say these are as good as advertised, and for me that would mean say better than -95dBc/Hz at 10Hz offset from 1GHz carrier, then by

Re: [time-nuts] Low noise frequency multiplication

Stephan Sandenbergh wrote: Hi Said, The DDS idea that you (and Ulrich) suggest sounds like a good plan. However, to me your predictions sound overly optimistic. Said wrote: But let's say these are as good as advertised, and for me that would mean say better than -95dBc/Hz at

Re: [time-nuts] Low noise frequency multiplication

Stephan Sandenbergh wrote: Darn, the table is a mess. Here is the corrected one: LVPECL Outputs HzdBc/Hz 1 ? 10-127 100 -145 1k-153 10k -158 100k -158 1M-158 10MHz OCXO HzdBc/Hz 1 -100 10-130 100 -152 1k-160 10k -165 100k

Re: [time-nuts] Suspected Spam: External clock for Analog to Digital Converter in GPSRx front-end Rx front-end

Possibly, if the ready-made spread-spectrum clocks provide enough jitter for him. It shouldn't be hard to do it to an existing clock, though. The article by David Chu on time-interval averaging in the June '74 HP Journal issue talks a little about why phase modulation is preferable to FM when

[time-nuts] New version of EZGPIB available

Hi folks, a new version of EZGPIB can be downloaded from http://www.ulrich-bangert.de/EZGPIB.zip. The new version recognizes on startup the new switchless version of the Prologix interface and sends a ++mode 1 command to the interface in order to make it the system controller. Have fun with it

Re: [time-nuts] Low noise frequency multiplication

In a message dated 3/2/2007 03:11:25 Pacific Standard Time, [EMAIL PROTECTED] writes: Phase noise of -115dBc/Hz @ 10Hz for a 100MHz carrier sounds a bit steep when compared to one of Wenzel's ultra low noise ULN series which achieves -125dBc/Hz @ 100Hz. (these oscillators are probably the

Re: [time-nuts] External clock for Analog to Digital Converter in GPS Rx front-end

- Original Message - From: Dr Bruce Griffiths [EMAIL PROTECTED] To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Friday, March 02, 2007 6:10 PM Subject: Re: [time-nuts] External clock for Analog to Digital Converter in GPS Rx front-end Bilal Amin

Re: [time-nuts] Suspected Spam: External clock for Analog toDigital Converter in GPSRx front-end Rx front-end

Hi Robert, I need to know the quantity of jitter I am adding to the clock signal. I don't think so this idea will work for that ? Bilal - Original Message - From: Robert Atkinson [EMAIL PROTECTED] To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent:

Re: [time-nuts] External clock for Analog to Digital Converter inGPS Rx front-end

Thanks for your email.Adding noise to a sine wave is not that straight forward I guess. Do you think a comparator works for this? See my other comment (and the David Chu article). If my understanding is correct, all you should need is an LC tank circuit with a varactor diode, plus a source of

Re: [time-nuts] Suspected Spam: External clock for Analog toDigital Converter in GPSRx front-end Rx front-end

Hi John, Thank you for your email. I am also looking at the PM method to solve my problem. I have a HP signal generator and I can use it to generate an RF signal and then modulate it with noise from the modulating input of the signal generator. I need some suggestion regarding the noise

Re: [time-nuts] External clock for Analog to Digital Converter in GPS Rx front-end

Bilal Amin wrote: - Original Message - From: Dr Bruce Griffiths [EMAIL PROTECTED] To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Friday, March 02, 2007 6:10 PM Subject: Re: [time-nuts] External clock for Analog to Digital Converter in GPS Rx

Re: [time-nuts] Suspected Spam: External clock for Analog toDigital Converter in GPSRx front-end Rx front-end

Bilal Amin wrote: Hi John, Thank you for your email. I am also looking at the PM method to solve my problem. I have a HP signal generator and I can use it to generate an RF signal and then modulate it with noise from the modulating input of the signal generator. I need some suggestion

Re: [time-nuts] External clock for Analog to Digital Converter in GPS Rx front-end

You can easily add noise to a sinewave, for example a hybrid combiner can be used to combine the output of a sinewave generator and a noise source. That's just going to create AM noise, isn't it? He wants jitter (phase modulation), I believe. -- john, KE5FX

Re: [time-nuts] External clock for Analog to Digital Converter in GPS Rx front-end

John Miles wrote: You can easily add noise to a sinewave, for example a hybrid combiner can be used to combine the output of a sinewave generator and a noise source. That's just going to create AM noise, isn't it? He wants jitter (phase modulation), I believe. -- john, KE5FX

Re: [time-nuts] External clock for Analog to Digital Converter in GPS Rx front-end

Well, sure, but it also causes all kinds of secondary distortion effects (such as potential clipping at the rails of whatever you're feeding the signal into). I don't think AM'ing the signal when you want PM is a good idea, when it's so easy to apply PM by itself. -- john, KE5FX John Since

Re: [time-nuts] External clock for Analog to Digital Converter in GPS Rx front-end

John Miles wrote: Well, sure, but it also causes all kinds of secondary distortion effects (such as potential clipping at the rails of whatever you're feeding the signal into). I don't think AM'ing the signal when you want PM is a good idea, when it's so easy to apply PM by itself. -- john,

Re: [time-nuts] External clock for Analog to Digital Converter in GPS Rx front-end

Well, sure, but it also causes all kinds of secondary distortion effects (such as potential clipping at the rails of whatever you're feeding the signal into). I don't think AM'ing the signal when you want PM is a good idea, when it's so easy to apply PM by itself. He's feeding a digital

Re: [time-nuts] Suspected Spam: External clock for Analog toDigital Converter in GPSRx front-end Rx front-end

I bought a nice little noise source, flat from DC to 2 GHz, a Noise/Com model (www.noisecom.com), on eBay for $30 a year ago. You might want to try your luck there. A noise source is very handy. Didier KO4BB Bilal Amin wrote: Hi John, Thank you for your email. I am also looking at the PM

[time-nuts] Prologix GPIB-USB news

Below is news from from Prologix. Abdul, if you haven't met Ulrich Bangert yet, please exchange email; he's done excellent work with your controller. Also, you're welcome to join the time-nuts list. For details, please see: http://www.leapsecond.com/time-nuts.htm and/or

[time-nuts] Setting Osc Frequencies

HI All , first time request. I wish to know how I can accurately set some oscillators on frequency. I have 3 Sulzer oscillators .. 1 x 2.5A and 2 x 2.5C's and 1 matching P/S with dead nicads. My main reference is a Trimble Thunderbird which was the second source to the HP unit was used in

Re: [time-nuts] Dana Racal 1996 Questions

To also support my theory the racal counters will resolve 1X10 -11 using 99 (100s) second gate time. when I activate the mean average mode this extends the gate time two more decimal places (1 second gate) wouldn't you assume a resultt of 2 more digits in accuracy ? Things are

Re: [time-nuts] Setting Osc Frequencies

HI All , first time request. I wish to know how I can accurately set some oscillators on frequency. I have 3 Sulzer oscillators .. 1 x 2.5A and 2 x 2.5C's and 1 matching P/S with dead nicads. My main reference is a Trimble Thunderbird which was the second source to the HP unit was used

Re: [time-nuts] Setting Osc Frequencies

HI Tom, I realised when I read your reply that I had not said how I was observing the result. I am feeding these signals into a 100 MHZ CRO not a counter and visually observing the 2 signals in relationship to each other. 1 being the Trimble which I believe to be good to 3 parts in10^12 and the

Re: [time-nuts] External clock for Analog to Digital Converter in GPS Rx front-end

Yep, that's great as long as the comparator's already there or can be easily added. I was mainly wrinkling my nose at the idea of adding hybrid combiners and the like, just to introduce some jitter. -- john, KE5FX Well, sure, but it also causes all kinds of secondary distortion effects

Re: [time-nuts] Setting Osc Frequencies

Don, Yes, using an oscilloscope in this way is a time-honored trick to observe slow changes in relative phase over time. It gets even better if you have access to a storage 'scope or variable persistence because then you can get a rough sense of short-term jitter as well. Either way, the math

Re: [time-nuts] External clock for Analog to Digital Converter inGPS Rx front-end

Hi John and Bruce, Thank you for your ideas. Now I have a much better picture for the experiment using the comparator. Now, my only concern is a noise generator. I have searched and found out that all the commercially available now generators are very expensive and some what out of my price

Re: [time-nuts] External clock for Analog to Digital Converter inGPS Rx front-end

Bilal Amin wrote: Hi John and Bruce, Thank you for your ideas. Now I have a much better picture for the experiment using the comparator. Now, my only concern is a noise generator. I have searched and found out that all the commercially available now generators are very expensive and some

Re: [time-nuts] External clock for Analog to Digital Converter inGPS Rx front-end

Bilal Amin wrote: Hi John and Bruce, Thank you for your ideas. Now I have a much better picture for the experiment using the comparator. Now, my only concern is a noise generator. I have searched and found out that all the commercially available now generators are very expensive and some