KO4BB Wiki precision_timing

precision_timing:a_monitor_for_the_z3816a_timing_receiver

2013-01-08T19:00:00-04:00

From the Time-Nuts mailing list: ---------- Does anyone remember much about the old Motorola Oncore UT GPS receivers? I have an HP Z3816a GPS timing receiver. I've been meaning for a long time to add a display for UTC time to it for a while. Today I finally got that project built and installed, and it works as intended, but I'm seeing something that doesn't make too much sense to me.

precision_timing:about_humidity

2013-01-08T19:00:00-04:00

About Humidity From: Neville Michie Sender: time-nuts-bounces@febo.com To: richard@karlquist.com To: Time-Nuts ReplyTo: Time-Nuts Subject: Re: [time-nuts] HP 10811 Response I Replies Sent: Sep 22, 2011 8:10 PM Humidity is a confusing subject to many engineers and scientists.

precision_timing:allan_variance

2013-05-07T20:00:00-04:00

Allan Variance From the Time-Nuts mailing list: Well, I have been sort of staying out of the recent discussions regarding oscillator stability measurements, ADEV, etc., but here goes my two cents worth. I hope it doesn't muddy the waters too much and is somewhat helpful.

precision_timing:allan_variance_challenges_and_opportunities

2013-01-08T19:00:00-04:00

Allan Variance, Challenges and Opportunities The attached white paper from Symmetricom may be of interest. Among other things it explains why a common technique is largely a waste of time for tau greater than the inverse PLL bandwidth. It also indicates that using a bandpass filter centered on the beat frequency really should be used in DMTD systems.

precision_timing:bva_crystal_oscillators

2013-01-08T19:00:00-04:00

BVA Crystal Oscillators BVA is a manufacturing technique for crystals used in precision reference oscillators with improved aging characteristics. BVA stands for either “Besson Vieillissement Amélioré”, from the name of it's inventor Raymond Besson, or simply

precision_timing:cesium_clocks

2013-01-08T19:00:00-04:00

Cesium Clocks From the Time-Nuts mailing list: ---------- Having just gone through the process of finding, acquiring, and fixing an HP 5061A, here are a few pointers for qualifying one for purchase. The biggest problem you're likely to face is a beam tube that's at end-of-life. If there is an electronics failure (like mine, read on), these clocks are really fairly simple to troubleshoot and fix; almost everything is discrete components; the main circuitry is mostly analog.

precision_timing:choke_ring_antennas

2013-01-08T19:00:00-04:00

Choke Ring Antennas Hello All, Over the past couple of years I have seen several references indicating that the reason all GPS units intended for precision survey applications use a choke-ring antenna is that a properly designed GPS choke ring antenna will cut multi-path reception down very significantly. Other references I have seen indicate that using a choke-ring antenna results in a moderate improvement in GPSDO performance.

precision_timing:clock_shapers

2013-01-08T19:00:00-04:00

Clock Shapers Capacitor coupled Clock Shaper The circuit shown below has a wide bandwidth [<10KHz, > 100MHz]. Input amplitude range is [100mV - 5V]pp. Originally designed for use in a linear phase detector there are other applications for which it is suitable.

precision_timing:comparing_gps_antennas

2013-01-08T19:00:00-04:00

Comparing GPS Antennas I have tried several models, the original Trimble Bullet, the HP 58532A and several pucks, including a nice Trimble mag-mount unit. Two of the pucks are designed for marine use, with a decent waterproof case and mounting, but they are in an all plastic case. There have no part number that I could see, I need to look closer to see if there is a manufacturer's mark. They were obtained on eBay from a long forgotten vendor

precision_timing:comparing_thunderbolt_and_z3805a_gps_stabilized_crystal_oscillators

2013-01-08T19:00:00-04:00

Comparing Thunderbolt and Z3805A GPS Stabilized Crystal Oscillators From the Time-Nuts mailing list: > Hi All, > Have been thinking of getting a GPSDO and I'm looking for advice on what to choose > between the Trimble Thunderbolt and the Z3805A.

precision_timing:converting_datum_ts2100_to_gps

2013-01-08T19:00:00-04:00

Converting a Datum TS2100 timing unit to GPS " I have recently acquired a Datum TS2100-IRIG NTP time server. Nice unit, and I do have IRIG-B to feed it, however, reading the manual I notice that there is a GPS version as well. Upon taking the top of

precision_timing:crystal_aging

2013-01-08T19:00:00-04:00

Crystal Aging There have been a number of threads on the Time Nuts Mailing List about crystal aging, what affects it and how to predict/compensate for it. Here are a few posts from October 2007: ---------- I was the person who posted the original comments. My comments were based on discussions with notable crystal guru, Jack Kusters, who was merely an inventor of the SC cut. He didn't have much confidence in the various FCS papers Jeffrey was referring to.

precision_timing:dual_mixer_time_difference_systems

2013-02-05T19:00:00-04:00

Dual Mixer systems REFERENCES Offset Sources Sometimes it is possible to tune a low phase noise high stability OCXO to the desired offset frequency. A frequency synthesizer can sometimes be used however it may have lowest noise and spurs at some weird offset frequency like 13.3333 Hz which may not be convenient. The highest perfor…

precision_timing:ebay_cheap_ds3231_modules_have_a_bug

2019-02-18T20:09:00-04:00

From the [time-nuts] mailing list: Achim Gratz Stromeko@------.de via [time-nuts] 4:01 PM (3 hours ago) " What manufacture or brand DS3231 do you have?" There are two modules you can get easily from the usual places, prices and delivery times vary wildly. The first and larger variant used to be called ZS-042, but now generally has

precision_timing:fe5680a_faq

2013-01-08T19:00:00-04:00

FE-5680A Rubidium Frequency Standard FAQ culled from the time-nuts mailing list, and various related web sites. Jan. 31 2012 v0.2 initial compilation by John Beale What is a FE-5680A and why would I want one? The FE-5680A is a Rubidium Frequency Reference made by FEI (Frequency Electronics, Inc)

precision_timing:fe5680a_pin-out

2015-03-07T09:36:42-04:00

FE5680A Connector Pin-Out On 2/21/2015, Bob Camp wrote: Just so it goes into the archives. Here’s the pinout for the FE-5680B with a 15 pin connector on it. Marking shows as part number 2616000-51604 Pin Function 1 >= +15V power in (likely the same

precision_timing:fe5860a_faq

2013-01-08T19:00:00-04:00

FE-5680A Rubidium Frequency Standard FAQ This page was incorrectly named (digits transposed). Please update your links. The correct page is:

precision_timing:fe_series_oscillators

2014-11-17T15:59:42-04:00

Notes on FE Series oscillators On 2014-11-10 1:24 AM, Skip Withrow posted the following on time-nuts: Hello time-nuts, I have spent a lot of time recently with Frequency Electronics, Inc. (FEI) oscillators including the FE-5680A, FE-5680B, FE-5650A, and FE405B and just wanted to pass on some of my findings. Not everything I am including here is new, but figured I would include the informattion for the sake of completeness.

precision_timing:fractional_dividers_in_a_pld

2013-01-08T19:00:00-04:00

Fractional Dividers in a PLD From the Time Nuts mailing list: " A 10 MHz clock into a PIC gives a 400 ns/instruction time. To produce 32.768 kHz you flip an output pin put every 38 instructions, except that 9632 times per second you make it 39

precision_timing:fts_2000a_connector_pin-out

2013-01-08T19:00:00-04:00

FTS 2000A OCXO pinouts Mark Sims Fri, 20 Jun 2008 17:35:30 -0700 Here are the pinouts of the FTS 2000A OCXO jumper board in my 4060M/S24 cesium beam unit. This board makes the 2000A look like a Datum 1000 OCXO. Datum 1000 pinouts and definitions are from Brooke Clark's PRC68.COM web site. The FTS-2000A coax connects to an SMB connector.

precision_timing:gps_monitor

2016-12-15T16:32:16-04:00

GPS Monitor This is the “News” page of the GPS Monitor project (it's easier for me to frequently update pages via the Wiki.) The GPS Monitor project page is at The most recent version of the source code is at Please note that the code version used in these devices does not allow you to change the time zone, which is fixed at US Central Time (Chic…

precision_timing:how_to_check_an_hp5061a_cesium_standard

2013-01-08T19:00:00-04:00

How to check an HP5061A Cesium Standard? from the [Time-Nuts] mailing list: ---------- The best place to start is to look at the 5061B manual, the operating portion of which can be found on the internet. Simple things would be to put the Mode switch in the CS Off position, plug it in, and then watch the meter indications.

precision_timing:jitter_what_is_it

2013-01-08T19:00:00-04:00

Jitter, what is it? from the [time-nuts] mailing list: " Magnus Danielson magnus@rubidium.dyndns.org via febo.com 4:46 PM (3 hours ago) to Discussion" Fellow time-nuts, In a private discussion, I got somewhat inspired, so I wrote this relating to what jitter is. It's the pre-breakfast, won't get out of bed version. Since it was enjoyed by a fellow time-nut, I share it with a little larger audience.

precision_timing:links

2013-01-08T19:00:00-04:00

Precision Timing Links * Modifying an HP 5370A Time Interval Counter to use 5370B firmware, by Mike Sauve, 18Oct09:

precision_timing:low_noise_mixer_preamp

2013-04-24T20:00:00-04:00

Low noise mixer preamp The circuit uses a low flicker noise SSM2220 pnp input stage with an OP27 output stage and an AD820 dc servo stage. It has a gain of 60dB and a <1Hz to >300kHz 3dB frequency response. It can accommodate mixer IF port dc offsets of up to 40 millivolts. It is suitable for use with PC sound cards and low frequency spectrum analysers for measuring phase noise. The offset frequency range is [20Hz, 20kHz] when using a sound card.

precision_timing:low_noise_power_supplies

2013-01-08T19:00:00-04:00

Low Noise Power Supply Often a low noise power supply is required to power a VCO an OCXO or an isolation amplifier. These are not usually off the shelf items so you may have to build your own. Here are some guidelines: ---------- Low noise voltage regulators

precision_timing:lpro_disciplining_with_thunderbolt

2013-01-08T19:00:00-04:00

LPRO disciplining with Thunderbolt From the Time Nuts Mailing List: In response to request on how I set up my Tbolt with a long time constant to directly discipline a LPRO 101 Rubidium; I use a standard LPRO 101 Rb as an external replacement for the Tbolt's internal OCXO, and connect the LPRO's external C_Field adjustment input to the Tbolt's Dac out thru a 1K ohm resistor (added as protection for the Tbolt.)

precision_timing:m12_-_difference_between_m12_and_m12_t

2013-01-08T19:00:00-04:00

Differences between Oncore M12 and M12+T (useful when buying online) From the [time-nuts] mailing list ---------- In case anyone else is shopping online for a used Motorola Oncore M12+T timing GPS, it's probably useful to know what I just learned:

precision_timing:minimizing_noise_bandwidth

2013-01-08T19:00:00-04:00

Minimizing Noise Bandwidth in Closed Loop Systems Subject: GPSDO time constant " " " Magnus Danielson wrote: For ThunderBolt owners it is pretty straightforward to separately adjust the Time Constant and damping, which is very nice. Use this opportunity!

precision_timing:mouse_interference_with_serial_port

2013-01-08T19:00:00-04:00

Mouse Interference with Serial Port From the Time Nuts Mailing List: " I am running XP Pro with a USB laser mouse and a USB to serial adapter to the T'Bolt. The USB to serial adapter drivers are on hand and they loaded nicely, with the computer setting the USB port to COM10.

precision_timing:multiple_time_interval_capture

2013-01-08T19:00:00-04:00

Muyltiple Time Interval Capture To measure the stability of an oscillator, you normally run a Time Interval Counter between the Oscillator Under Test and a Reference Oscillator. What do you do when you do not have a Reference Oscillator that you know is better than the one you want to measure?

precision_timing:outliers_how_to_identify_and_eliminate_them

2013-01-08T19:00:00-04:00

Outliers, how to Identify and Eliminate them ---------- From Ulrich Bangert, on the Time-Nuts mailing list Discarding outliers in two dimensions > " Suppose I want to average a bunch of samples. Sometimes it helps to discard the outliers. I think that helps when there are two noise

precision_timing:phase_frequency_measurement_methods

2013-01-08T19:00:00-04:00

Phase/Frequency Measurement Methods There was a thread about the Tight PLL method on the Time-Nuts mailing list. One useful outcome was this post by Tom Van Baak: ---------- Here are a couple of really good articles that describe many methods of phase/frequency measurement, including TPLL.

precision_timing:pictic

2013-01-08T19:00:00-04:00

Simple PICTIC 250ps time interval counter Are you an amateur bit by the Time-Nut bug but can’t afford a commercial time interval counter with sub nanosecond resolution and a GPIB interface? Did you find a universal counter on eBay with good time interval resolution but became frustrated figuring out the GPIB interface and writing a command script to get the counter data into your PC so you could analyze it? Are you an experienced Time-Nut tired of tying up multiple expensive commercial counter…

precision_timing:reset_hp53131a_security_code

2015-01-11T16:24:13-04:00

Reset the HP53131A Security Code On December 23, 2014, Ulli posted the following on time-nuts: " Hi, I got a used HP 53131A to which I added a stability option board (ocxo). In order to calibrate the device, a security code is needed - I don't

precision_timing:rubidium_oscillators

2013-01-08T19:00:00-04:00

FEI Rubidium Oscillators This posting from Mark Sims on the Time-Nuts mailing list: ---------- I recently purchased some FEI FE-5650A option 58 rubidium oscillators. They are basically the same as the 5680A unit, but in a different (3x3x1.4 inch) form factor. The following applies to the oscillator versions with the Direct Digital Synthesis board that has the Analog Devices AD9830A DDS chip.

precision_timing:setting_clocks_100_years_ago

2013-01-08T19:00:00-04:00

Setting Clocks 100 Years Ago from the Time-Nuts mailing list (Nov 4, 2010): ----Original Message---- Subject: [time-nuts] Setting clocks 100 years ago This evening I happened to hear the nearby church's bell tolling 10 pm, and thought that 100+ years ago this could have been the

precision_timing:states_modes_and_alarms

2013-01-08T19:00:00-04:00

====== ThunderBolt States, Modes and Alarms ======! Receiver Mode * 0 Automatic (2D/3D) * 1 Single Satellite (Time) * 2 Not used * 3 Horizontal (2D) * 4 Full Position (3D) * 5 DGPS Reference * 6 Clock Hold (2D) * 7 Overdetermined Clock

precision_timing:store_position_on

2013-01-08T19:00:00-04:00

For example is there a way to change the “Stored Position” from a yellow to green dot? Setup menu > Position, fill in your known location and hit “save segment”. that should change that dot.

precision_timing:store_position_on_trimble_thunderbolt

2013-01-08T19:00:00-04:00

Store Position On Trimble Thunderbolt John Miles, jmiles at pop.net Wed Feb 6 23:05:00 EST 2008 ---------- Message: [time-nuts] Setting Trimble Thunderbolt Stored Position Short answer: go to Setup->Self-Survey, make sure the Enable and Save buttons are clicked, then hit

precision_timing:thunderbolt_damping

2013-01-08T19:00:00-04:00

Trimble Thunderbolt Damping Tbolt users, One of the questions I often hear is what should the Tbolt's Damping be set to? Assuming the Dac_Gain and TC_Sec are correctly set, then Damping is the easy one; 1) If your concerns are freq accuracy and you don't care about Phase accuracy, Set the damping from 1 to 1.5 with the Factory default of 1.2 being a good Nominal Value.

precision_timing:thunderbolt_temperature_sensor

2013-01-08T19:00:00-04:00

Thunderbolt Temperature Sensor Re: [time-nuts] Thunderbolt performance vs temperature sensor ---------- Mark Sims Fri, 06 Mar 2009 09:57:39 -0800 I did some testing on a Thunderbolt with the new revision E2 (low resolution, flat line) and old revision D1 (high resolution, curvy line) DS1620 temperature sensor chips. The only thing that changed was the temperature sensor chip.

precision_timing:ticpic

2013-01-08T19:00:00-04:00

precision_timing:time_interval_measurement_techniques

2013-01-08T19:00:00-04:00

Time Interval Measurement Techniques From the Time-Nuts mailing list: Trevor Higgins wrote: " Hello! Just a couple of backslashes probing the world of insanely accurate time. My first question, which will doubtlessly lead to many more, is where

precision_timing:time_nuts_mailing_list

2013-01-08T19:00:00-04:00

Time-Nuts Mailing List The Time-Nuts mailing list is a high signal-to-noise ratio mailing list for those interested in precision timing. The list is operated and maintained by John Ackerman.

precision_timing:timing_links

2013-01-08T19:00:00-04:00

Timing Links Here you can add links to your favorite Precision Timing sites: Here are my own pages: * Tom Van Baak's Leapsecond site: * John Ackermann's febo.com site *