Re: [time-nuts] 74HC4046 receiver

Pete wrote: > Bruce, > > The jitter measurements were made via the DTS PER function. > This looks only at CH1 & the reference is the DTS internal > 100MHz. OXCO. DTS-2075 jitter floor is < 3ps rms. > > The Fairchild & National parts have identical datasheets & > spec SIGin sensitivity as 133mV @ Vc

Re: [time-nuts] femtosecond jitter anyone?

> The incoming clock source (master house clock) to this box / design > of interest is in another rack mount box external to this design on > the other side of the room and is anywhere from 44.1kHz up to a 10MHz > Rubidium (see also http://www.antelopeaudio.com). This clock source > on the

Re: [time-nuts] femtosecond jitter anyone?

Chris The biggest problem with the OCXO is probably that it has a square wave output. With careful design it is possible to achieve a jitter of a few tens of femtosec for a logic level output from a limiter, but the OCXO designers are unlikely to have used such a limiter. To produce a sinewave ou

Re: [time-nuts] 74HC4046 receiver

Bruce, The jitter measurements were made via the DTS PER function. This looks only at CH1 & the reference is the DTS internal 100MHz. OXCO. DTS-2075 jitter floor is < 3ps rms. The Fairchild & National parts have identical datasheets & spec SIGin sensitivity as 133mV @ Vcc=6V. The Philips version

Re: [time-nuts] femtosecond jitter anyone?

Thanks Bruce, The 12kHz is a figure for the DSP PLL and how they measure it (starting at 12kHz usually for jitter over BW measurements) I haven't touched SONET since 1997 and this may be a SONET spec? I am using the simulator software for the LMK04000 series to see what jitter is for th

Re: [time-nuts] femtosecond jitter anyone?

Chris Now we have a more complete picture of what you are trying to do our suggestions will perhaps be a little more useful. Cleaning up a marginal OCXO is quite complex and probably more expensive than obtaining an OCXO or other reference that has lower noise. Is it in fact possible to just sub

Re: [time-nuts] femtosecond jitter anyone?

On Apr 8, 2009, at 8:50 PM, Bruce Griffiths wrote: >> > Chris > > If you divide the output down to ~38MHz using a noiseless divider then > the performance is 20dB or more worse than can be achieved with a good > ~38MHz crystal oscillator. > Ah, this would work, but there is a synchronization aspe

Re: [time-nuts] 74HC4046 receiver

Pete wrote: > Bruce, > > Quite correct, fumble fingers win again. As they say "here's > the rest of the story". > > I was able to measure just 1 part. It is a NSC MM74HC4046N, > date code 9018, presumably still available from Fairchild. The VCO > was disabled (INH=H), the COMP input was grounded &

Re: [time-nuts] 74HC4046 receiver

Bruce, Quite correct, fumble fingers win again. As they say "here's the rest of the story". I was able to measure just 1 part. It is a NSC MM74HC4046N, date code 9018, presumably still available from Fairchild. The VCO was disabled (INH=H), the COMP input was grounded & I looked at the PC1 output

Re: [time-nuts] femtosecond jitter anyone?

Chris Mack / N1SKY wrote: > On Apr 8, 2009, at 8:02 PM, Bruce Griffiths wrote: > > > >> Unless you are prepared to place the crystals in an oven with the >> temperature regulated tightly and carefully tune the filter >> periodically >> then using a crystal filter (or any passive filter with a

Re: [time-nuts] 74HC4046 receiver

Pete wrote: > A long thread was running on various ways to process a 10MHz > (or other) sinewave to reduce measured jitter (presumably limited > by slew rate). This note is a quick look at what the 74HC4046 > signal input circuit yields; since it was mentioned in 1 post as > possibly useful. > > Ji

Re: [time-nuts] femtosecond jitter anyone?

On Apr 8, 2009, at 8:02 PM, Bruce Griffiths wrote: > Unless you are prepared to place the crystals in an oven with the > temperature regulated tightly and carefully tune the filter > periodically > then using a crystal filter (or any passive filter with a sufficiently > narrow bandwidth to cle

Re: [time-nuts] femtosecond jitter anyone?

Bruce Griffiths skrev: > Chris > > Chris Mack / N1SKY wrote: This is a good idea for testing.. >>> Applying jitter frequencies for jitter tolerance testing is standard >>> stuff and needs to be done. Jitter tolerance curves match up with MTIE >>> tolerance curves very neatly. >>>

Re: [time-nuts] femtosecond jitter anyone?

Hej Bruce, Bruce Griffiths skrev: > Magnus > > Magnus Danielson wrote: >> Bruce Griffiths skrev: >> >>> Magnus >>> >>> For examples of the use of crystals in filters for cleaning up the >>> output of a crystal oscillator look at the circuit schematics for some >>> of the early crystal frequenc

[time-nuts] 74HC4046 receiver

A long thread was running on various ways to process a 10MHz (or other) sinewave to reduce measured jitter (presumably limited by slew rate). This note is a quick look at what the 74HC4046 signal input circuit yields; since it was mentioned in 1 post as possibly useful. Jitter was measured on a DT

Re: [time-nuts] femtosecond jitter anyone?

Chris Chris Mack / N1SKY wrote: >>> This is a good idea for testing.. >>> >> Applying jitter frequencies for jitter tolerance testing is standard >> stuff and needs to be done. Jitter tolerance curves match up with MTIE >> tolerance curves very neatly. >> >> > > Of course, here is the

Re: [time-nuts] Hadamard variance

Tom Van Baak skrev: >> According to Wikipedia, this is insensitive to drift and so seems like >> a better tool for measuring oscillators, like ocxo. I don't think I've >> seen this being used by anyone on the list and wonder why? > > Hi Steve, > > I use it sometimes when I need to. But note that

Re: [time-nuts] femtosecond jitter anyone?

>> This is a good idea for testing.. > > Applying jitter frequencies for jitter tolerance testing is standard > stuff and needs to be done. Jitter tolerance curves match up with MTIE > tolerance curves very neatly. > Of course, here is the weird part... It's not SONET; but it is a chip that can

Re: [time-nuts] femtosecond jitter anyone?

Magnus Magnus Danielson wrote: > Bruce Griffiths skrev: > >> Magnus >> >> For examples of the use of crystals in filters for cleaning up the >> output of a crystal oscillator look at the circuit schematics for some >> of the early crystal frequency standards. >> Crystal filters were used quite

Re: [time-nuts] femtosecond jitter anyone?

Bruce Griffiths skrev: > Magnus > > For examples of the use of crystals in filters for cleaning up the > output of a crystal oscillator look at the circuit schematics for some > of the early crystal frequency standards. > Crystal filters were used quite liberally in some of these to clean up > the

Re: [time-nuts] Hadamard variance

> According to Wikipedia, this is insensitive to drift and so seems like > a better tool for measuring oscillators, like ocxo. I don't think I've > seen this being used by anyone on the list and wonder why? Hi Steve, I use it sometimes when I need to. But note that in most cases you do NOT want t

Re: [time-nuts] femtosecond jitter anyone?

Magnus For examples of the use of crystals in filters for cleaning up the output of a crystal oscillator look at the circuit schematics for some of the early crystal frequency standards. Crystal filters were used quite liberally in some of these to clean up the outputs. However it may be necessary

Re: [time-nuts] femtosecond jitter anyone?

Chris, Chris Mack / N1SKY skrev: > Hey Magnus, > > This is a good idea for testing.. Applying jitter frequencies for jitter tolerance testing is standard stuff and needs to be done. Jitter tolerance curves match up with MTIE tolerance curves very neatly. > I have Howard Johnson's book for

Re: [time-nuts] femtosecond jitter anyone?

Hey Magnus, This is a good idea for testing.. I have Howard Johnson's book for "high speed digital design (a handbook of black magic)" which shows some circuits with varactors on the transmission line with some ECL gates creating a variable delay based on an analogue voltage... maybe that

Re: [time-nuts] Characterising frequency standards

> But how does that explain the output of Tom's adev1 program which > still seems to give a a good measurement at tau = 1s? The first argument to the adev1 program is the sampling interval t0. The program doesn't know how far apart the input file samples are taken so it is your job to specify this

Re: [time-nuts] femtosecond jitter anyone?

Chris Mack / N1SKY skrev: > Hello fellow time nuts, > > Have a project here with an OCXO from Vectron at 38.88MHz being the > "jitter reference" for a DSP based PLL. > > The Vectron part has a little bit of close-in phase noise below 12kHz > of BW. Is there a way to filter this, say by driv

Re: [time-nuts] looking at creative ways to route GPS signals through a home to a Thunderbolt

Hi Scott, Looking at your proposed implementation below, you may like to look at one of my kit products - a distribution amplifier which will split a GPS antenna signal up to 4 ways, and will act as the power source for the antenna. There is no need to disable the 5v feeds in the receivers, si

Re: [time-nuts] looking at creative ways to route GPS signals through a home to a Thunderbolt

This is an unused coax run, so there's no AC or DC on this line to be a problem. I do carry feeds from 4 security cameras via a 4 channel modulator on other coax runs to elsewhere in the house, but I can't see trying to mix this application with GPS to this room -- I should really just digitize

Re: [time-nuts] looking at creative ways to route GPS signals through a home to a Thunderbolt

Hi Scott Most GPS antennas have some amount of gain and that varies from none to over 50 dB, with about 20 to 30 dB the most common. The idea is for the system noise figure to be established by the antenna and not the coax loss getting to the receiver. To have gain requires DC power to the anten

Re: [time-nuts] looking at creative ways to route GPS signals through a home to a Thunderbolt

In message <49dcc283.4010...@gmail.com>, Scott Burris writes: >So the dedicated time-nuts may laugh at plan C. This is to mount an >antenna on roof near the garage >and connect to the RG6 CATV run from the garage to this room. I'd guess >it's about 60-70ft of RG6. >Can RG6 pass the 1.5Ghz sign

Re: [time-nuts] looking at creative ways to route GPS signals through a home to a Thunderbolt

Oh how embarrassing -- I have that exact message sitting in my inbox not yet read! OK, good to know it works, I'll go with Plan C. Scott Ralph Smith wrote: > This was discussed just yesterday. > > > The short answer is that Plan C

Re: [time-nuts] looking at creative ways to route GPS signals through a home to a Thunderbolt

This was discussed just yesterday. The short answer is that Plan C is just what Trimble recommends, with RG-59. I have about 110 feet of RG-6 and it works wonderfully. Ralph On Wed, April 8, 2009 11:28 am, Scott Burris wrote: > I

[time-nuts] looking at creative ways to route GPS signals through a home to a Thunderbolt

I have a Thunderbolt (thanks TAPR!) located in a second floor room of my house which has only an obstructed view of the sky. There's no easy way to get to that room, short of putting an antenna on the roof and punching a hole in the wall to get inside. For some reason, my wife takes a dim view

[time-nuts] femtosecond jitter anyone?

Hello fellow time nuts, Have a project here with an OCXO from Vectron at 38.88MHz being the "jitter reference" for a DSP based PLL. The Vectron part has a little bit of close-in phase noise below 12kHz of BW. Is there a way to filter this, say by driving an external (temperature stabilize

Re: [time-nuts] Hadamard variance

Steve Rooke wrote: > Bruce, > > 2009/4/9 Bruce Griffiths : > >> But at least some of us do use it. >> Ulrich includes estimators (both the non overlapping and overlapping >> estimators) for it in Plotter. >> Plotter is a Windows program so you will have to use VMware, Wine or >> another Virtual

Re: [time-nuts] Characterising frequency standards

Steve Rooke wrote: > 2009/4/9 Bruce Griffiths : > >> The sampling interval is indeed 1sec in the original data. >> However, if you delete every second sample the sampling interval in the >> resultant data is then 2 sec. >> > > Doesn't that imply that the data point should correspond to the

Re: [time-nuts] Hadamard variance

Bruce, 2009/4/9 Bruce Griffiths : > But at least some of us do use it. > Ulrich includes estimators (both the non overlapping and overlapping > estimators) for it in Plotter. > Plotter is a Windows program so you will have to use VMware, Wine or > another Virtual machine to run it in Linux. Do yo

Re: [time-nuts] Characterising frequency standards

2009/4/9 Bruce Griffiths : > The sampling interval is indeed 1sec in the original data. > However, if you delete every second sample the sampling interval in the > resultant data is then 2 sec. Doesn't that imply that the data point should correspond to the whole sampling period and not just half

Re: [time-nuts] Characterising frequency standards

Yes, it compiles cleanly with "gcc -o adev1 -lm adev1.c" and works just like a bought one, thanks. 73, Steve 2009/4/9 John Ackermann N8UR : > I've compiled adev1 under Linux with no changes required; don't recall > the exact gcc line I used but it was pretty much the obvious one. > > Steve, one o

Re: [time-nuts] Characterising frequency standards

Steve Rooke wrote: > Bruce, > > But the sampling interval is still 1 sec and you can see by my notes > that I explicitly give this on the command line for adev1.exe. > > The sampling interval is indeed 1sec in the original data. However, if you delete every second sample the sampling interval in

Re: [time-nuts] Characterising frequency standards

John, OK, I see what you mean if I re-run with a 2 second period:- C:\Documents and Settings\Steve Rooke\Desktop>adev1.exe 2 : > I've compiled adev1 under Linux with no changes required; don't recall > the exact gcc line I used but it was pretty much the obvious one. > > Steve, one other point --

Re: [time-nuts] Hadamard variance

Steve Rooke wrote: > According to Wikipedia, this is insensitive to drift and so seems like > a better tool for measuring oscillators, like ocxo. I don't think I've > seen this being used by anyone on the list and wonder why? > > 73, > Steve > Steve But at least some of us do use it. Ulrich inc

Re: [time-nuts] Characterising frequency standards

Bruce, But the sampling interval is still 1 sec and you can see by my notes that I explicitly give this on the command line for adev1.exe. OK, I'll have a go at compiling it as it is just a command line program. 73, Steve 2009/4/9 Bruce Griffiths : > Steve > > Therein lies your problem. > adev1

Re: [time-nuts] Characterising frequency standards

I've compiled adev1 under Linux with no changes required; don't recall the exact gcc line I used but it was pretty much the obvious one. Steve, one other point -- your results with every sample versus every-other-sample aren't hugely different because ADEV doesn't usually change dramatically ov

[time-nuts] Hadamard variance

According to Wikipedia, this is insensitive to drift and so seems like a better tool for measuring oscillators, like ocxo. I don't think I've seen this being used by anyone on the list and wonder why? 73, Steve -- Steve Rooke - ZL3TUV & G8KVD & JAKDTTNW Omnium finis imminet _

Re: [time-nuts] Characterising frequency standards

Steve Therein lies your problem. adev1 defaults to a sampling interval of 1 sec. (read the C source code). TvB's documentation explicitly states that you should supply the sampling interval. (its a command line argument for adev1.c). adev1.c is a simple command line program that uses stdin and s

Re: [time-nuts] Characterising frequency standards

Bruce, I set nothing, as indicated in my text, I just delete data points, IE. a file of 40 records now becomes 20. I'm trying to get my head round this as the absolute requirement for continuous data seems unneeded. What you have to remember here is that the data set I'm working with consi

Re: [time-nuts] Characterising frequency standards

Steve The data file doesn't include the time interval between samples so do you set this in some way? If so you need to set it to 1s for the unaltered data, to 2s when you take every 2nd sample, and 1s when you take the first 200,000 samples. In principle you could use CANVAS (available on reques

Re: [time-nuts] Characterising frequency standards

Bruce, I hear what you say but the results seem to correlate quite well:- 1 tau, 3.0127e-009 adev(n=38), 3.0127e-009 oadev(n=38) 1 tau, 3.0257e-009 adev(n=18), 3.0257e-009 oadev(n=18) And using the first half of the data:- 1 tau, 3.0411e-009 adev(n=18), 3.0411e-009 oad

Re: [time-nuts] Characterising frequency standards

Steve It cant, it must be a matter of interpretation. Perhaps it means something like: 1 tau means tau = 1x the interval between consecutive measurements. 2 tau means tau = 2x the interval between consecutive measurements 10 tau means tau = 100,000 x the interval between consecutive measur

Re: [time-nuts] Characterising frequency standards

Bruce, But how does that explain the output of Tom's adev1 program which still seems to give a a good measurement at tau = 1s? 73, Steve 2009/4/8 Bruce Griffiths : > Steve > > If you delete every second measurement then your effective minimum > sampling time is now 2s and you can no longer calcu

Re: [time-nuts] Characterising frequency standards

Steve If you delete every second measurement then your effective minimum sampling time is now 2s and you can no longer calculate ADEV for tau< 2s. You can still calculate ADEV for tau = 100,000 sec. If you delete all but the first 200,000 lines then you can calculated ADEV for tau=1sec and up to

Re: [time-nuts] Characterising frequency standards

Tom, I understand fully the points that you have made but I have obviously not made my point clear to all and i apologise for my poor communication skills. This is what I'm getting at: Using your adev1.exe from http://www.leapsecond.com/tools/adev1.htm and processing various forms of gps.dat fro