Unless you are going to use a different OCXO, there is nothing to do except
perhaps tell it to save the self-survey results and set your "foilage mode"
if desired. They are plug and play.
-5 V/Hz is the correct kvco parameter; any changes will either degrade the
phase margin and give you a "hump"
Anyone got a .PDF of the 5062C op/service manual, before I fall back to
Manuals Plus?
-- john, KE5FX
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and follow the instructi
Along the same lines (and this may have come up before), is there a good
Allan-deviation application for Windows that talks to the 5370B?
-- john, KE5FX
> -Original Message-
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> Behalf Of Heinzmann, Stefan (ALC NetworX GmbH)
> Sent: Friday
Couple of (somewhat naive) questions here:
> It's similar to asynchronous switching inside a digital computer.
> You can
> add levels of flip flops to synchronize across two asynchronous
> time-domains,
> but all you are doing is decreasing the possibility of a
> meta-stable failure to
> make it
> > I can't find much fundamental research on this at all; and if
> even Mr. Vig
> > says the phenomenon is not well understood.. But there are
> (propriatary) ways
> > to probe for the susceptibility of a particular unit to do this.
>
> John told me once that an easy way to deal with many classe
> A high-quality crystal oscillator's broadband floor will be
> sufficiently quiet (typically better than -160 dBc/Hz) that it won't
> matter
> much whether
> you integrate out to 100 kHz or to 1 MHz. The difference will be on
> the order of attoseconds.
Sorry, should have said "femtoseconds" he
Javier Serrano wrote:
> Dear nuts,
>
> I would like to know if there is a clear explanation somewhere with
> considerations on how to choose an upper frequency limit when
> integrating phase noise to find jitter. Let's say I'm interested in
> the raw jitter measurement which comes from integrating
Sounds like you're doing everything right. 9390s are plug-and-play by
nature, so I'd have to wonder if there's some front-end damage to the GPS
receiver.
-- john, KE5FX
> -Original Message-
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> Behalf Of Myers, Charlie
> Sent: Monday, Oct
You don't normally listen to a CW signal at zero beat, so many receivers
apply a BFO offset to make the CW tone audible at a comfortable frequency.
This is usually more like 800 Hz than 4 kHz, though, so you could still have
a calibration error somewhere.
-- john, KE5FX
> -Original Message---
> It (LTSpice) has some severe limitations for most of the simulations I
have done.
You might bring those up with Mike Engelhardt (the author). He doesn't miss
many tricks.
> These need to be supplemented with on board filtering as they aren't
> quite as quiet as you need.
> Either the NIST sty
>
> > How's the filament voltage at the 7587 socket, by the way? A shorted
> > turn in your power transformer might account for some lack of
> > enthusiasm on the Nuvistor's part.
>
> I'd expect a shorted turn on a power transformer to let the smoke out.
>
Depends on a lot of things, but yes,
> >Still don't understand why probing with a 10Meg, 1pF load kills the
> >oscillation stone dead until the next power cycle.
>
> That says that the circuit had just enough gain and positive feed back to
> oscillate but just barely. I'd have to see the circuit to
> recommend changes.
> The root ca
> Following the good advice I received about increasing the value of the
> trimmer capacitor, I replaced the trimmer which was originally
> 3-12pF, with
> another one which was 2-22pF.
>
> This has given the additional adjustment range to allow me to pull the
> crystal to meet the specification.
>
What do you have in mind? I have an 8640 cavity that was removed from
service with a noisy transistor. What limits the noise floor on these
units -- the cavity or the transistor?
The dividers bottom out at around -150 dBc/Hz, so there's no point improving
the cavity oscillator much beyond that u
Is this a double-oven cubicle, or the less-stable single-oven model with the
bang-bang controller (i.e., the boss holding a gun to your head)?
Seriously, that's great that not all of the old guard has retired. The 8640
came along in the early 70s, so I'd bet that guy has seen a lot.
-- john, KE5
I'm not familiar with any GPIB bugs on the 5370A, but I moved your code over
to C and ran it on my 5370B via a GPIB-LAN adapter. The test app failed
after ~6 hours with a Winsock timeout error. I'm thinking that was caused
by a power glitch, though, because I actually had to power-cycle the count
The elevation mask might also come into play. Ordinarily you don't want to
consider input from satellites too near the horizon, as terrestrial features
can distort the signal's timing.
I think it can be stated with confidence that there's nothing wrong with a
(normally functioning) Thunderbolt's
>
> I just got one of the new networked GPIB controllers, and I've been
> having some issues. I'm not sure if it's the Prologix or the
> instruments, or both.
>
> With the 5370A, I can get samples for some period of time ranging from
> about 2 to 4 hours before the GPIB controller stops responding.
That's really cool. A steampunk phase-noise analyzer!
-- john
>
> I've posted some General Radio notes and specifications on their Model
> 1115-B oscillator, hoping there might be some relevance to the Model 1120.
>
> Product specific information starts on page 8.
>
> http://www.ni6e.com/genrad
LO phase noise is almost always what limits the noise floor at close-in
offsets, because of the narrow RBW (either analog or digital) typically used
at those offsets to keep the carrier out of the measurement.
Occasionally a high degree of RF attenuation might raise the equivalent
front-end noise
> Most synthesizers regardless of technology still end up with broadband
> floors in the -150 dBc/Hz neighborhood, so now you're back to circa -120
> dBc/Hz inband... which is what the PSA-series spec sheets show.
I didn't phrase that very well; I meant to say that the broadband floor of
your pha
> The R+S FMU36 has a phase noise floor of around -143dBc/Hz (offset >
> 10kHz) with a 10MHz input.
> Whereas the R+S FSU67 has a phase noise floor of around -133dBcdBc/Hz
> (offset = 10kHz) with a 640Mhz input.
>
> There is a definite improvement at lower frequencies but not quite as
> much as on
> Perhaps the local oscillator isn't the limiting factor for the low
> frequency analysers.
> The claimed noise floor is in the vicinity (within 10dB) of -120dBc/Hz
> for the analysers for which I checked the specs.
>
> If the 10MHz reference has a phase noise floor of around -160dBc/Hz
> this is
> Yes, but kind of puzzles me a bit since I would
> be expecting phase noises more than 10x worst on a
> SA covering DC to 1GHz (+/-)
> (since the LO for this is an YIG oscillator circa 3GHz locked to a
> reference)
> comparing with an FFT analyzer that uses a few tens MHz sample rate.
Phase nois
If you don't want pushbutton convenience, you can measure the close-in phase
noise with not much more than a $5 mixer and $2 opamp. It will take a lot
of "sweat equity," and you will need to build two of whatever you're
measuring, or buy/borrow a known-cleaner source at the same frequency.
TSC an
It's sort of a religious matter, but if you are looking for an easy-to-use
part with great, free C/C++ support, you'd most likely be happy with the
AtMEGA series.
-- john, KE5FX
> -Original Message-
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> Behalf Of Jim Palfreyman
> Sent: Tue
> Hi John,
>
> On Sat, 2008-08-09 at 17:48 -0400, John Ackermann N8UR wrote:
>
> > The longer tau readings are interesting mainly to see how the GPS loop
> > kicks in; tau below about 1000 seconds seem related to OCXO performance
> > on the TBolts, while the Z3801A seems to have a longer time con
These tests were made with the GPS antenna connected? At t >> 100 seconds,
they should all look about the same, because that's where GPS disciplining
comes in, no? They should not be uncorrelated in the long run.
To the extent one Z3801 looks worse than the other at large values of tau,
I'd expe
> -Original Message-
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> Behalf Of [EMAIL PROTECTED]
> Sent: Friday, August 08, 2008 4:17 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Double-Oven Thunderbolt on Ebay
>
>
> I was actually talking
> Tom or JohnA, have either of you run any Allan plots on a
> 10811-60268? I'd
> be curious to see how they do.
Er, -60168, that is.
-- john, KE5FX
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I don't have any of the 10811-60158s, but I did buy two of the 10811-60168s
that were up for auction recently. The -60168s seem to be really good
performers (from memory, -106 dBc/Hz at 1 Hz, -139 at 10, -155 at 100, -164
at 1000, when I measured them against each other.) I have never seen any
sp
> > Modern ECL parts aren't necessarily that bad compared to the old MECL
> > stuff.
>
> My experience goes all the way back to the MECL 1000 series that was
> discontinued 30 years ago. I designed many synthesizers around them
> for Zeta Labs. Every newer family of ECL line receivers has been fa
>
> I do agree with Richard, comparators are quite bad...
>
> Having played with interfacing signals to FPGA 'ad nausea'
> I found that the only simple scheme that works
> better than biased (or feedback) cmos gates and of
> course much better than ECL line receivers or comparators
> (even cmos ga
> In any event, if you actually test real comparators, you will
> find them to be universally lousy. I will be happy to be proven
> wrong if someone is aware of a good comparator. It's just that
> I have never met I comparator I liked :-)
I think you're right about that. About the best thing y
I've played with the Hittite chips before and obtained PN results in the
same ballpark (see http://www.ke5fx.com/hpll.htm ), but at 8 GHz rather than
6 GHz. To save further head-scratching, the figure of merit on these chips
works like this:
In-band phase noise in dBc/Hz = FOM + 10*log(Fcomp) + 2
Yeah, those Noritake parts are very nice. I wouldn't expect trouble from
one.
There is a slight possibility of additional EMI versus an LCD, obviously
nothing that would cause trouble at the end of an RS232 cable.
-- john, KE5FX
> -Original Message-
> From: [EMAIL PROTECTED] [mailto:[EM
quency divider design critique request
>
>
> John,
>
> This is just DC selection of which MUX line is active.
>
> Am I missing something here?
>
> Dave
>
> -Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
> Behalf Of John Mi
I don't know about sending edges that slow into a CMOS chip. Is that
considered kosher for HC-series logic?
-- john, KE5FX
> -Original Message-
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] Behalf Of David C. Partridge
> Sent: Tuesday, July 15, 2008 10:16 AM
> To: 'Discussion of
eBay has partitioned itself lately into items with excessive starting bids,
and items which are real bargains. But yeah, I already paid for all the
Cs/Rb sources flying around overhead, damned if I'm not going to use 'em!
-- john
> -Original Message-
> From: [EMAIL PROTECTED] [mailto:[EM
I believe the Allan variance graph in Trimble's data sheet was taken before
Selective Availability was turned off. I'm not sure what impact this would
have; I wouldn't expect any at all at tau << 100s.
A pronounced hump in the ADEV plot could suggest that the disciplining loop
is underdamped. Id
I am not a big fan of BNC connectors on the PC board itself, because I am
not a big fan of attaching PC boards directly to panels in most cases.
There are usually some BNC bulkhead connectors on eBay that terminate in
SMA/SMB/SMC pigtails, which are great for panel mounting.
http://cgi.ebay.com/eB
> >
> Just watch for the odd error in those references.
> eg in the first reference (.../498.pdf) the captions for figure 2 and
> figure 3 should be swapped.
>
> If anyone wants to try it, I have an even quieter, lower distortion 3
> transistor isolation amplifier design that runs from a 12V suppl
There is nothing special about the 5087A's amplifier cards. The 5087A
design is not especially quiet; in fact, it will degrade the broadband floor
of a Thunderbolt by a good 7 or 8 dB from what I have seen.
I'd say grab some PCB prototyping stock and a Dremel tool, and surf through
Bruce's notes
Nigel --
Can you send it to the upload page at http://www.ko4bb.com/cgi-bin/upload.pl
(user 'manuals', password 'manuals', without the quotes)? I could use that
one myself...
-- john, KE5FX
> -
> Hi Jack
>
> I've got the manual for the 9390-52054, don't know how similar it is but
>
dwin B. Walker
> Sent: Tuesday, June 24, 2008 2:24 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Thunderbolt control software
>
>
> My copy of Adobe will not open this
>
> Ed WA4DFS
> ----- Original Message -
> From: "
Thanks for throwing that one over the wall, Mark. Could be useful. Here's
a native Win32 port that can be built with the free Visual Studio tools:
http://www.ke5fx.com/tbolt_win.zip (120 KB)
This version will work with any COM port, e.g., tbolt /12 will use COM12
instead of the default COM1 por
Hmm, sounds like a handshaking problem of some sort. Are you using the MR
command to synchronize your readings?
This code is from my 5370B console app that reads a single frequency value:
snip
void main(S32 argc, C8 **argv)
{
if (argc < 2)
{
printf("Usage: 5370
> John Ackermann N8UR wrote:
> > Hello!
> >
> > We're happy to announce that TAPR is now accepting orders from time-nuts
> > subscribers for the Trimble Thunderbolt GPSDO units.
>
> Great news. :-)
>
> Thank you to all that have made this possible, I've just placed my order.
John A. won't say thi
That is an RS-232 port; there's no "locked" line on it (although I agree
there should have been.) You'll need to run TBoltMon.exe to monitor its
status, or talk to Mark Sims about the dedicated Thunderbolt controller he
mentioned he was developing.
-- john, KE5FX
> -Original Message-
> F
Maybe try
hp (5071a,5061a,5061b)
... to start with.
The 5071as seem more desirable but they're also usually more expensive, and
(the really scary part, true of all of them): how do you tell how much tube
life is left?
-- john, KE5FX
> -Original Message-
> From: [EMAIL PROTECTE
> I would suggest you go through the detailed alignment procedures even
> though the unit passes the operational checks. These units almost always
> have drifted out of alignment in the analog front-end unless you were
> lucky enough to get a freshly-calibrated one. You can usually
> significantly
It would be nice to have a graphical display of the 10 MHz offset, PPS
offset, and/or DAC values from the periodic 8F AC packets. I've got a
hacked breadboard that allows me to plug 10811s into my old (pre-TAPR)
Thunderbolt. Was thinking of implementing a graphical monitor on the
Chumby, thereby
e potential for error that
> entails).
>
> I suppose I should have expected such a level of 'quality' from a
> Windows based program. Glad the software is largely optional to use
> the T'bolt.
>
> Tom Frank, KA2CDK
>
>
> On Jun 14, 2008, at 12:06 AM, John
You can also just look yourself up on Google Earth and enter the coordinates
by hand.
-- john, KE5FX
> -Original Message-
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> Behalf Of Mark Sims
> Sent: Friday, June 13, 2008 9:00 PM
> To: time-nuts@febo.com
> Subject: [time-nuts] Tboltmo
I don't believe the Thunderbolt is a carrier-phase receiver, is it? If it's
not, I'd be surprised if reflections make any difference.
They don't seem to have gone out of their way to match either 50 or 75 ohms
(see S11 plot of TAPR unit's antenna jack attached), unless the input Z changes
when
There's a lot about 5370s in the archive. Common problems seem to be
intermittent sockets for the ROM chips, and (in my own experience) dirty
polarity/impedance/attenuator switches. The manual has a good self-check
procedure for the internal circuitry, but you need to be careful to ensure
that th
That's a good way to do it, but be careful soldering chip capacitors and
resistors. Reliability can be a problem when SMD parts are installed this
way. They are not meant to be hand-soldered (even to a proper PC board),
and it's easy to ruin them by tearing off their end plating. You won't
alway
> From: "Matt Ettus" <[EMAIL PROTECTED]>
> Subject: Re: [time-nuts] low-g OCXO GPSDO
> Date: Thu, 5 Jun 2008 10:25:43 -0700
> Message-ID: <[EMAIL PROTECTED]>
>
> > > A "normal" OCXO would drift significantly when being turned
> around in any
> > > direction.
> >
> > I've actually been wondering ab
Non-option 100, but options 002 or 003 are preferred. 10811-60209 also OK.
Interested in non-working units as well. Thanks; please reply offlist to
[EMAIL PROTECTED]
-- john, KE5FX
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> Quoth Bruce Griffiths at 2008-06-03 09:50...
>
> > How do you cope with SMT parts (eg high frequency ADCs) with metal
> > thermal transfer /ground connections under the package itself?
>
> Haven't done it myself, but interested to hear others experiences. I'm
> guessing that this would be a job
>
> These are the ones we've used. I am sure there are many others.
> Prototypes -- www.pcbfabexpress.com
> Production -- www.pcbnet.com
>
> >> Is there a way to split the layers of an old board apart to study them?
>
> An assembly shop can x-ray them for you.
Also, as a group, dentists are bigge
For one-off PCBs, I've had good luck with www.batchpcb.com . They work by
panelizing different orders together, so it can sometimes take a month or
more to get your board back. That's especially true of 4-layer boards,
since it takes longer for them to accumulate enough 4-layer orders to make a
p
These antennas work very well with the Thunderbolt:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=280228924879
Pyrojoseph is a great seller. I've bought a lot of stuff from him over the
years.
This antenna will need a BNC-male/SMA-female adapter for use with the BNC-F
adapter packaged with
> "I have never had a piece of equipment rejected because a reading was
> 1.99 for a spec of 2 max"
>
> The statements were made with regard to instrument
> resolution/accuracy/precision. Clearly, measuring 2.01 (or 1.99) on an
> instrument with an accuracy of 1 does not allow compliance with a
>
> >>
> >>
> > Download the 5087A manual from the Agilent website.
> >
> > Bruce
> >
> >
> Oops thats only a supplement.
> I thought I had downloaded the 5087A manual from there, obviously it was
> from elsewhere that seems to have disappeared since.
>
> Bruce
QService on eBay sells a nice .PDF sc
Chumby is the brainchild of Andrew 'Bunnie' Huang, who's a stellar engineer
and all-around boddhisatva of hacking. He's most well-known for the book
"Hacking the Xbox", probably the best (if not the only) popularly-accessible
volume on reverse engineering.
I don't follow many blogs, but Bunnie's
> I'm very pleased to announce that TAPR is going to stock
> these Thunderbolts for us and handle ordering and payment
> issues. Note that TAPR is non-profit and our time-nuts
> list has a non-commercial, amateur and hobby focus. So
> you will get these Thunderbolts at cost.
>
> The group price is
> Probably impractical as the sampling noise is so high that it will
> require tens of thousands of measurements to get the noise down to the
> required level and meanwhile the temperature etc will have changed
> significantly.
Heh, that's a good point, you can't just sit there and trigger the t
> Not quite so easy. First of all, this type of transient response
> signal is not
> well suited for FFT. Then, I am not sure the repeatability of the
> signal is
> valid to such a degree that an accurate curve is achieved.
If the chirp is just the startup behavior of an ordinary crystal oscillat
> The quickest and easiest way to achieve the required resolution is to
> buy a high speed (~100MHz) sampling ADC evaluation kit from Analog
> Devices, Linear Technology etc, use a low phase noise crystal oscillator
> (eg Wenzel ULN or equivalent performance device) or equivalent bandpass
> filter
> So to summarise : To make a synthesiser`s phase noise low :
>
> - Apply the KIS principle [Keep It Simple]
> - Use high speed [non-saturating?] logic rather than low
CMOS is actually among the cleanest logic families for digital PLLs these
days. ECL has always been among the worst. It was u
Usually bricks are good for at least a few MHz either side of the sweet
spot. There's little incentive for the manufacturer to install an expensive
crystal filter. I'd just sweep it by hand with an 8640B or something like
that, to verify the frequency and power levels it wants to see.
BTW, I hav
Given the low prices Thunderbolts have been selling for lately, I believe
most people are better off with one of those, or a similar high-quality GPS
slock. If you expect very poor GPS coverage with lots of complete signal
dropouts, then perhaps an Rb-based standard makes more sense.
-- john, KE5
If you haven't seen this yet:
http://www.ke5fx.com/HP_PN_seminar.pdf (7 MB)
... I'd strongly encourage you to check it out. The early part of the
document answers some of those questions pretty well.
-- john, KE5FX
> -Original Message-
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
A man with one watch knows what time it is.
A man with two watches is never sure.
A man with THIS watch has transcended such earthly concerns:
http://snurl.com/antitime
-- john, KE5FX
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rom: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> Behalf Of John Ackermann N8UR
> Sent: Thursday, April 24, 2008 5:21 AM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Disciplining Rubidium
>
>
> John Miles wrote:
> > Phase noise general
Mostly that labelling is required because of the unfortunate events that
ensue if the stuff gets wet. They're both alkali metals, in the same column
as sodium and potassium.
-- john, KE5FX
> Hi Bruce,
>
> last chemistry/physics class is a while back :) I guess a half
> life of 50
> Billion years
> The actual FRS-C is quite a bit cleaner but still nowhere near as good as
> the Thunderbolt.
>
> Also worth noting is that the Datum's output is quite a bit
> noisier than it
> was several months ago when I measured it with (very) different
> hardware. I
> wouldn't take the green trace in this
> > 11) Short-term phase noise; the GPS-Rb sources don't seem to
> > be as clean as the better GPS-OCXO packages.
>
> And EXACTLY THIS was what the OP was asking after!
More quantitatively: in this file, the red trace is from my Thunderbolt, the
green trace is from a Datum 9390 Rb-GPS standard's 1
collected, statically averaged over a long period (at least 1
> month), and the calculated average used to adjust the OCXO frequency.
>
> Tom
> Tom Duckworth
> 510-886-1396
>
>
> -Original Message-
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
> Behalf O
No idea, really. It may not even be a universal principle but it sure seems
that way.
Something in the Datum 9390 I have also degrades the noise quite a bit,
relative to what comes out of the FRS-C Rb module.
-- john, KE5FX
> -Original Message-
> From: [EMAIL PROTECTED] [mailto:[EMAIL P
Adding to Tom's worthy list:
11) Short-term phase noise; the GPS-Rb sources don't seem to be as clean as
the better GPS-OCXO packages.
-- john, KE5FX
> > More precisely, if I had two black boxes, one containing
> > a GPS-Rb-XTAL setup and another containing GPS-XTAL,
> > what measurement would y
> I took a closer look at this board. It has a lot to offer over the older
> Digilent 2 boards that I've used a fair bit.
>
> If there was interest, we could do some aux interface boards for the
> Nexsys-2 -- either simple I or O boards for the 2x6 connectors or a bigger
> multi-function I/O boar
> Reflock II is not bad, but I am sure we could spin a board that work even
> better for general time-nut nuttiness(*) without a lot of difficulty.
Has anyone tried out one of the Digilent Nexys-2 boards?
http://snurl.com/nexys2 (product page)
http://digilentinc.com/Data/Products/NEXYS/Nexys_rm
Thanks! How'd you find that option?
-- john, KE5FX
> -Original Message-
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> Behalf Of Stephen Tompsett
> Sent: Friday, March 28, 2008 1:12 AM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Tboltmon S
> Most, but not all, sound cards have a low frequency cutoff of 20Hz or so.
> Some (but not all) sound card ADCs can dc coupled.
> A high resolution dc coupled ADC may be more effective for frequencies
> below 20Hz.
True; I'm assuming that anyone using a sound card for these purposes is
either goi
> I am continuing my phase noise measurement quest. I gathered
> equipment (HP 8662a/11729C/8568B/multipliers) to measure
> 100Hz+ from the carrier. I now need to get a grip on the
> 0.1-100Hz range, which is where most of my applications are.
>
> What is the suggested measurement methodology for
> I just bought a book called "making things talk" from O'Reilly. I just
> started reading it. The book looks fine but it appears that most of the
> projects are based on the Arduino line of microcontroller modules and
> they use the processing/wiring language. I am not crazy about learning
> anot
> It's surprising what kind of performance can be achieved with the 10KHz
> locking the OCXO through an Exor gate. Then again that design
> get's to compare
> phase 10.000 times more often per second than all of the other
> 1PPS based PLL's
> :)
Which, as Bruce has noted, is not really an advanta
That's an OEM unit. Plenty of people have been using those with legacy
12-volt RS-232 ports, so I wouldn't worry about it.
-- john, KE5FX
> -Original Message-
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> Behalf Of Darrell Robinson
> Sent: Tuesday, February 12, 2008 9:49 PM
> To:
> To me, the interesting part is that both the Thunderbolt and the Miller
> designs appear to degrade the performance of the OCXO in locked mode at
> short Tau compared to unlocked. The Z3801 does very well < 300sec, but
> degrades the ADEV at Tau farther out. The Fury does best, never
> worse loc
Short answer: go to Setup->Self-Survey, make sure the Enable and Save
buttons are clicked, then hit "Set Survey," "Save Segment," and "Close."
After that, do a Control->Restart Self-Survey. The alarm indication should
go away once the survey process finishes.
You do not need to copy anything manu
equency
> section, on the
> other hand, are quite different as this hardware differs
> considerably from
> the 11848A. However, I have been working on a program to control
> both units
> and have decoded the register assigments for the 11848a interface. If you
> are interested in t
Question -- was the HP 3048A software ever made available as a
human-readable BASIC program, as the 3047A software was?
It looks like any attempt to write code for the 11848A is going to require
a lot of reverse engineering to discover the GPIB commands. It could save
me a lot of time if there's
Kind of a dumb question, but you rebooted the PC, right? Maybe the GPIB
device driver's receive buffers aren't being flushed properly by the Python
interface.
Are there any powered-down devices on the GPIB bus?
-- john, KE5FX
> -Original Message-
> From: [EMAIL PROTECTED] [mailto:[EMAIL
1 versus ST2 in the last three characters of the command,
to see if that makes a difference.
-- john, KE5FX
> -Original Message-
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> Behalf Of John Miles
> Sent: Wednesday, January 30, 2008 5:38 PM
> To: Discussion of precise time a
Sounds like a handshaking issue. It may not be related, but you might take
a look at the 5345a.cpp example. The 5345A is kind of nonstandard in that
it terminates responses with CR (ASCII 13) rather than CR/LF and/or EOI. I
have to set the EOS character to 13 in 5345a.cpp to receive any data fro
As unhappy as you may be to hear it, Mike, you're done upgrading, at least
for now. Thunderbolts are about as good as they get. Yes, some units like
the HP and Jackson Labs clocks can do somewhat better, and with
entirely-different equipment, you might be able to tell. Not with the 49xP
analyzer
That looks like a classical underdamped PLL response. You usually see this
sort of hump in a phase-noise plot when your PLL is about to break into
oscillation. :)
Either someone at HP was careless with the loop-filter constants and came
close to running out of phase margin, the Z3801A is not conf
> One option is to use just the programmable divider part of a PLL IC,
> such as those from National Semiconductors or Analog Devices. Or, use a
> Hittite HMC394 programmable counter preceded by a fast /2 flip flop.
> The PLLs will need serial programming via a micro-controller or other
> logic d
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