Re: [time-nuts] Low cost SDR suitable for phase noise measurement?

Thank Attila.  At this point I'm mostly just collecting ideas.  I hope to put something to copper in a month or two. Bob  - AE6RV.com GFS GPSDO list: groups.yahoo.com/neo/groups/GFS-GPSDOs/info From: Attila Kinali

Re: [time-nuts] Safely getting the electrical length of a connected, antenna feedline

"The biggest variable will be the velocity factor." If you determine the length electrically, you will already have the electricallength. If you need the physical length, then multiply electrical length times the inverse of the velocity factor. -- Joe Leikhim Leikhim and Associates

Re: [time-nuts] State of the art of crystal oscillator measurements

> If the oscillator output is thru the resonator, then at large offsets, > the source impedance is reactive. It can easily have an effective > temperature less than room temperature. If this "source" is then > used with a low noise temperature preamp, it is entirely possible > to go beyond these

Re: [time-nuts] Low cost SDR suitable for phase noise measurement?

Hi In a DMTD (or in the equally useful single mixer setup) the advantage for frequency measurement comes from the downconversion process. The further you downconvert (10 Hz vs 100 Hz) the greater your potential resolution. The design approach is to push the beat note as low as you can

Re: [time-nuts] Low cost SDR suitable for phase noise measurement?

Hi Bob, If I understand the question correctly, yes.  The DMTDs that I've encountered so far use a zero-crossing detector and a TIC.  I wanted to build sort of a hybrid system that has a DMTD front end and an SDR back end.  It seemed to me that that would be sort of half way between a DMTD and

Re: [time-nuts] State of the art of crystal oscillator measurements

On 8/11/2016 3:47 PM, John Miles wrote: Right, I'm speaking specifically of L(f). The device being driven by the oscillator doesn't care about the NF of the driver stage, only what a PN analyzer would measure at the output jack. For any 50-ohm source, the practical L(f) floor is -177

Re: [time-nuts] State of the art of crystal oscillator measurements

-177dBm /Hz at 300 deg SSB phase noise is correct, not because AM/ FM but Single Sideband Energy . In my last QEX paper I showed the measured AM and FM levels and how to calculate them. 73 de Ulrich xx

Re: [time-nuts] State of the art of crystal oscillator measurements

That is interesting. We always used -174 and not -177 as it was concluded that at those low levels AM and PM noise are not discernible, so, the total noise density per Hz was -174. This must be relatively new since I worked in industry. We had a bunch of PhDs from Lincoln helping as well and

Re: [time-nuts] State of the art of crystal oscillator measurements

-177 = the -174 dBm/Hz SSB thermal noise floor at 25C, less 3 dB to account for the usual assumption that half of it is AM, half PM. dBm/Hz is obviously equivalent to dBc/Hz for a 0 dBm carrier. Anyone who claims to measure noise in a 1 Hz bandwidth below -177 dBm/Hz at room temperature

Re: [time-nuts] State of the art of crystal oscillator measurements

Good point, the 'milliwatt' part of 'dBm' takes the E^2/R part out of the math. If we were speaking of dBv/Hz, the system Zo would need to be considered to determine the power. -- john, KE5FX Miles Design LLC > -Original Message- > From: time-nuts [mailto:time-nuts-boun...@febo.com]

Re: [time-nuts] State of the art of crystal oscillator measurements

That is why I asked what the Po was. Where did the 177 come from? L(f) is single sided. This is not my first "rodeo" in these matters. 73 - Mike Mike B. Feher, EOZ Inc. 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 office 908-902-3831 cell -Original Message- From: time-nuts

Re: [time-nuts] State of the art of crystal oscillator measurements

Values of kT at 25°C (298 K) Units kT = 4.11×10−21 _J_ (https://en.wikipedia.org/wiki/Joule) kT = 4.114 pN⋅nm kT = 9.83×10−22 _cal_ (https://en.wikipedia.org/wiki/Calorie) kT = 25.7 _meV_ (https://en.wikipedia.org/wiki/Electron-volt)Related quantities kT/hc = 200 cm-1 kT/e =

Re: [time-nuts] State of the art of crystal oscillator measurements

Right, I'm speaking specifically of L(f). The device being driven by the oscillator doesn't care about the NF of the driver stage, only what a PN analyzer would measure at the output jack. For any 50-ohm source, the practical L(f) floor is -177 dBm/Hz - the carrier power in dBm. No

Re: [time-nuts] Working with SMT parts.

The best type of stereo microscope to use for SMT assembly is referred to as an "Inspection Microscope." Magnification greater than 10 is not needed or desirable for normal assembly. Something in the range of 5 to 10 works well. A wide field of view and a good light source are desirable. Just as

Re: [time-nuts] Working with SMT parts.

Lots of good suggestions have already been made, but for me, a boom style stereo microscope, with a distance between the objective, and the focal point of at least 3 inches works fairly well... One other thing that may force your decision, if you are older, your eyes will likely have lots of

Re: [time-nuts] Low cost SDR suitable for phase noise measurement?

On Thu, 11 Aug 2016 19:29:08 + (UTC) Bob Stewart wrote: > It looks like I've asked a question poorly, yet again.  So, let me try > again.  I have this idea of combining a DMTD with an SDR.  So, said that > way, it looks like what I really need is a 2-channel audio SDR.  And

Re: [time-nuts] State of the art of crystal oscillator measurements

Zo doesn't matter for these purposes. dBm works just as well for 75 ohm systems. On 8/11/2016 1:22 PM, John Miles wrote: Remember that L(f) is expressed in dBc/Hz, not dBm/Hz. If it were dBm/Hz, then kT would be the limit. But in dBc/Hz terms, the limit is 177 + the DUT's output power in

Re: [time-nuts] State of the art of crystal oscillator measurements

Hi The gotcha is that you don’t *have* to have a 50 ohm system. An output stage with a narrow band tuned tank is one example of a very “not 50 ohms” system. There is also a whole debate around the “is 50 ohm source into 50 ohm load really 25 ohms”. That will give you a 3 db delta to bet

Re: [time-nuts] State of the art of crystal oscillator measurements

I am quite intrigued by two things here: 1. What improvements were made to the instruments, and 2. What were the instrument settings and test setups? Thanks. Tom Holmes, N8ZM -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of KA2WEU--- via time-nuts

Re: [time-nuts] State of the art of crystal oscillator measurements

NO, the maximum possible noise dynamic range is ( 177 + Pout) [dBm] - Transistor large signal NF ( dB), the signal to noise ration is dimensionless In a message dated 8/11/2016 5:00:43 P.M. Eastern Daylight Time, j...@miles.io writes: Or rather -(177+DUT output power in dBm).

Re: [time-nuts] State of the art of crystal oscillator measurements

Or rather -(177+DUT output power in dBm). The minus sign makes the difference between the thermal floor and a nuclear war! -- john, KE5FX Miles Design LLC > Remember that L(f) is expressed in dBc/Hz, not dBm/Hz. If it were dBm/Hz, > then kT would be the limit. But in dBc/Hz terms, the limit

Re: [time-nuts] State of the art of crystal oscillator measurements

See below In a message dated 8/11/2016 4:30:47 P.M. Eastern Daylight Time, j...@miles.io writes: Remember that L(f) is expressed in dBc/Hz, not dBm/Hz. If it were dBm/Hz, then kT would be the limit. But in dBc/Hz terms, the limit is 177 + the DUT's output power in dBm - transistor

Re: [time-nuts] Safely getting the electrical length of a connectedantenna feedline

FYI: In Didier's post below, the correct URL is: http://www.ko4bb.com/getsimple/index.php?id=coax-cable-impedance-matching I'm guessing a mobile spell checker changed his " id= " to " I'd= " (even though it was part of a URL). /tvb - Original Message - From: "Didier Juges"

Re: [time-nuts] State of the art of crystal oscillator measurements

Remember that L(f) is expressed in dBc/Hz, not dBm/Hz. If it were dBm/Hz, then kT would be the limit. But in dBc/Hz terms, the limit is 177 + the DUT's output power in dBm. Assuming a 50 ohm system, of course. -- john, KE5FX Miles Design LLC > -Original Message- > From: time-nuts

Re: [time-nuts] Low cost SDR suitable for phase noise measurement?

Hi Just to clarify: You are looking for a way to digitize the output(s) of the mixer(s) in a DMTD. The “target signal” is in the 1 to 10 Hz range. Is that correct or are you looking for something to use instead of a DMTD? Bob > On Aug 11, 2016, at 3:29 PM, Bob Stewart

Re: [time-nuts] State of the art of crystal oscillator measurements

kT is indeed relevant for a physical implementation. - Mike Mike B. Feher, EOZ Inc. 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 office 908-902-3831 cell -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Richard (Rick) Karlquist Sent: Thursday,

Re: [time-nuts] Low cost SDR suitable for phase noise measurement?

Hi Brooke, It looks like I've asked a question poorly, yet again.  So, let me try again.  I have this idea of combining a DMTD with an SDR.  So, said that way, it looks like what I really need is a 2-channel audio SDR.  And having said that, maybe what I'm looking for is an external USB sound

Re: [time-nuts] Shera revisted

Hoi Bert, On Wed, 10 Aug 2016 09:33:30 -0400 Bert Kehren via time-nuts wrote: > I get repeated requests for info on Shera mainly for Rb applications. Shera > has a successful history controlling Rb's. Two things are a problem. The > AD 1861 is not only unavailable but

Re: [time-nuts] Safely getting the electrical length of a connected antenna feedline

Why is velocity factor an issue?  Aren't we only interested in the electrical time from one end of the coax to the other? Bob  - AE6RV.com GFS GPSDO list: groups.yahoo.com/neo/groups/GFS-GPSDOs/info From: Didier Juges

Re: [time-nuts] Working with SMT parts.

I use a Nikon and a Meiji that I picked up surplus on the cheap. Lighting matters. Fostec ring illuminators are okay, but I prefer something with gooseneck arms so I actually do have shadows. Light from a particular angle can help rather than nice uniform illumination. #1 recommendation I have

Re: [time-nuts] Working with SMT parts.

Hi Bob: I don't think it's so much the stereo microscope as the related equipment. I have a Bausch & Lomb StereoZoom 4 and the dial is always at the lowest setting (0.7dial * 10X objective = 7 power). For another reason I got a Nikon SMZ-U microscope and discovered that it's so tall that it

Re: [time-nuts] Working with SMT parts.

Hi Didier: Another option is to send the free ExpressPCB files to FAR Circuits for production. This can be very cost effective if you only need a simple circuit. Vias not supported. www.farcircuits.net/EXPRESS%20PCB%20DOC.doc -- Have Fun, Brooke Clarke http://www.PRC68.com

Re: [time-nuts] Working with SMT parts.

Hi Bob, You want to get something along the lines of ebay item 272331719376 or 262202931320.  The boom is pretty important, otherwise how do you get your boards under the microscope if they're not very small?  Some time ago, I got a Bausch & Lomb Stereo 3 with 10X oculars and a 0.5 barlow.  The

Re: [time-nuts] Low cost SDR suitable for phase noise measurement?

Hi Bob: The SDR-IQ has a lower frequency limit of 500 Hz. http://www.prc68.com/I/Bats.shtml#SDRIQ There is a mod that replaces the on board 66 MHz oscillator with one locked to 10 MHz. -- Have Fun, Brooke Clarke, N6GCE http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html

Re: [time-nuts] Safely getting the electrical length of a connected antenna feedline

I used the PPS from a Thunderbolt (fast rise lime, low rep frequency, was handy) and a digital storage scope and a couple of resistors to make a reflectometer based on this experiment: www.ko4bb.com/getsimple/index.php?I'd=coax-cable-impedance-matching You can very clearly see a 50 ohm/75 ohm

Re: [time-nuts] Working with SMT parts.

What are the important parameters regarding purchase of a stereo microscope?  I see some on ebay for around $50; are those good? Bob On Thursday, August 11, 2016 10:00 AM, Didier Juges wrote: I concur. I have been using ExpressPCB extensively over the last 2 years

[time-nuts] Low cost SDR suitable for phase noise measurement?

A number of posts have appeared about Zynq SDRs on the "Shera revisited" thread.  So, I'd like to ask the more general question: Are there any low cost SDRs that are suitable for measuring phase noise when coupled with a DMTD?  I believe what I'm looking for is something with enough bits to

Re: [time-nuts] State of the art of crystal oscillator measurements

On 8/11/2016 5:01 AM, Mike Feher wrote: This may be a naive question, but, how can you achieve results that are so close to, and sometimes at further out are below kT? Thanks & 73 - Mike Mike B. Feher, EOZ Inc. kT per see is not the relevant parameter. It is the ratio between kT and

Re: [time-nuts] Working with SMT parts.

I concur. I have been using ExpressPCB extensively over the last 2 years with great satisfaction now that it is possible to get Gerber files from them. I typically use the mini board pro service (3 bare boards, 2 sided with solder mask and silk screen) for prototypes and then buy the Gerbers to

Re: [time-nuts] PRS10

> Le 11 août 2016 à 12:15, Martyn Smith a écrit : > > Hello, > > I have a strange fault on a PRS10. Wondered if anyone had seen it. > > I am running a PRS10 and at the same time monitoring its FC (the frequency > control value) and Status byte data values. > > So

[time-nuts] Looking to find an antenna for a TrueTime XL-DC

Here is the Manual for the True Time XL-DC (circa 1997-1999) http://glacier.lbl.gov/gtp/DOM/Support/xl-dc-manual.pdf gb Sent from iPad Air ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to

Re: [time-nuts] Shera revisted

There are also some nice cypresses semiconductor parts that are similar and have a really nice dev environment. Basically a core surrounded by programmable logic. Code in C ore close to it. > On Aug 11, 2016, at 07:06, Bob Camp wrote: > > Hi > > To your earlier point,

[time-nuts] KO4BB Manuals

Thank you to those who let me know of an issue with my Manuals site last week and this week. It turns out that the primary issue was not lack of disk space (even though that was going to be an issue very soon, so that has been fixed preemptively) but an issue with the download app. In the

Re: [time-nuts] State of the art of crystal oscillator measurements

Ulrich - This may be a naive question, but, how can you achieve results that are so close to, and sometimes at further out are below kT? Thanks & 73 - Mike Mike B. Feher, EOZ Inc. === .. by reducing T? David -- SatSignal Software - Quality software

Re: [time-nuts] Heathkit clock available

On 8/10/16 8:03 PM, Chris Albertson wrote: But for sure a GPS module, a handful of buttons, 7 7-seg LEDs (I’d display a 10 Hz digit), a little phototransistor dimming circuit and an ATMega… $99 retail? Certainly doable. Almost everyone one Earth already owns a GPS sync'd alarm clock. My

Re: [time-nuts] Shera revisted

On 8/10/16 8:18 PM, Chris Albertson wrote: Thanks for pointing out the Zynq. Wow you get a dual core ARM and an FPGA all in one package. It seems overkill for a GPSDO but not the type you are making as you can transferring the time out of the GPSDO using PTP. The Zyng looks to the the

Re: [time-nuts] Shera revisted

Hi To your earlier point, there are a number of fairly low cost boards with Zynq’s on them. They aren’t into the $5 range, but they are not that much more than one of the Beagle boards. Bob > On Aug 10, 2016, at 11:18 PM, Chris Albertson > wrote: > > Thanks

Re: [time-nuts] State of the art of crystal oscillator measurements

Ulrich - This may be a naive question, but, how can you achieve results that are so close to, and sometimes at further out are below kT? Thanks & 73 - Mike Mike B. Feher, EOZ Inc. 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 office 908-902-3831 cell From: ka2...@aol.com

Re: [time-nuts] State of the art of crystal oscillator measurements

Good morning, the difference between the two phase noise FWSP systems is the lower noise internal 10 MHz reference crystal oscillator (optimized ) as well as also some of the internal FSWP circuits custom optimized . The output power was 17 dBm, but we also have build one oscillator

[time-nuts] PRS10

Hello, I have a strange fault on a PRS10. Wondered if anyone had seen it. I am running a PRS10 and at the same time monitoring its FC (the frequency control value) and Status byte data values. So normally, the Status shows are all zeros, except 2nd from last is a 1, showing the unit is not

Re: [time-nuts] Shera revisted

You are so right, Chris. The Zynq is absolutely an overkill for an ordinary GPSDO. What I think is attractive with the Zynq are the possibilities to experiment with different implementations of counters and gates without soldering and that you can get pretty fast counters well integrated with

Re: [time-nuts] Shera revisted

The Red Pitaya uses a Zynq, and there's an (unofficial) SDR application available to experiment with. Cheers Michael On Thursday, 11 August 2016, Chris Albertson wrote: > Thanks for pointing out the Zynq. Wow you get a dual core ARM and an > FPGA all in one package.

Re: [time-nuts] Heathkit clock available

On Thu, Aug 11, 2016 at 4:03 AM, Chris Albertson wrote: > Digital clocks are just not the amazing technical wonders they once > were. > > No, but it's interesting that they've considered the interface rather than using the common one supported by generic clock chips.

Re: [time-nuts] Heathkit clock available

> > But for sure a GPS module, a handful of buttons, 7 7-seg LEDs (I’d display a > 10 Hz digit), a little phototransistor dimming circuit and an ATMega… $99 > retail? Certainly doable. Almost everyone one Earth already owns a GPS sync'd alarm clock. My iPhone does all I need, pretty decent