Re: [time-nuts] WTB: HP/Agilent/Symmetricom 58517A Distribution Amplifier

[Ole Petter Rønningen]

Just a heads up, in case you’re not concious of the fact; at least my HP 
splitter (can’t recall model# off hand) is strictly L1 - many others are wide 
band and will allow L2 and whatever else you might later want.

Ole

> 18. mai 2018 kl. 16:35 skrev Clay Autery :
> 
> Gotcha  and agree
> 
> The 58516a/58517a as the main distro amp allows me to power the antenna with 
> a separate supply (for many reasons).
> Essentially, I want to replace the 4-way with an 8-way amp with same power 
> setup.
> 
> Then if I want to cascade unpowered splitters from one or more unity gain 
> ports on the distro amp, I can do that.  
> 
> For much of what I am/will be doing, I want to be able to provide "equal 
> access" to antenna signal to designated devices to control variables somewhat.
> 
> *Clay Autery
> (318) 518-1389
> *
>> On 05/18/18 08:50, Bob kb8tq wrote:
>> Hi
>> 
>> From what I have seen, it is a rare setup that requires all amplified 
>> distribution. Yes,
>> it is possible. Unless you are in that rare case, the MiniCircuits eight and 
>> sixteen port
>> splitters do a great job for *way* less money.
>> 
>> Bob
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Re: [time-nuts] nuts about position (Michael Wouters)

[Ole Petter Rønningen]

Here is a pretty good paper (as far as I can tell) from 2017 looking at ways to 
improve single frequency results: 
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5492347/

> 28. apr. 2018 kl. 06:20 skrev Jerome Blaha :
> 
> Real-time GPS <0.3m accuracy is quite possible with RTKLIB and < $35 of new 
> equipment, some patience, a laptop/android phone, and a real-time RTCM3 
> correction station stream (free) or with post-processing using ground 
> stations and actual satellite path (Ephemeris).
> 
> Disclaimer: I am neither a surveyor nor claimed GPS expert, but I play one on 
> TV with my day job, so consult a surveyor if you are having to survey in 
> WGS84 datum and convert to NAD or some other reference system, especially if 
> testing against old surveyed reference points.  For instance here in the SF 
> Bay Area, the land is moving North 28.31mm/yr and West 21.87mm/yr with 
> respect to the WGS-84 (GPS Position) datum, which uses satellites orbits and 
> the earth center as their reference.   If you were to survey your Telescope 
> position in WGS-84 in the Bay Area, wait 15 years and survey again, the 
> telescope will appear to have moved Northwest by 53.7cm and will have moved 
> down by 1.1cm (Assumptions taken from SLAC de-trended data here: 
> https://www.unavco.org/data/gps-gnss/derived-products/position-timeseries/SLAC_timeseries_cleaned_detrended.png)
> 
> This is why most surveying is performed not in WGS-84 but in a datum that 
> remains fixed to a tectonic plate as it moves, such as NAD83.  The 83 refers 
> to the date or year (epoch) when the land position or survey marker was at 
> that location, because even surveyed positions can move over time within that 
> same tectonic reference frame such as along fault-lines, etc. 
> 
> Getting back, RTKLIB is a brilliant piece of open-source software to allow 
> sub-meter (<5cm) phase-based positioning and my hat goes off to Tomoji Takasu 
> from Japan who wrote this and keeps updating it.  Very few GPS receivers can 
> measure phase shift, so this is where a specialized L1 + L2 survey receiver 
> is needed or you find a cheap L1 GPS chip capable of raw phase and code, such 
> as the u-blox M6T or M8T.
> 
> 
> RECEIVER:
> With regards to a GPS + Glonass raw receiver, the cheapest ublox M8T 
> legitimate supplier seems to be over at csgshop.com in Northern Europe.  He 
> has the real M8T GPS for $75 and I secretly believe he might also be one of 
> the test engineers for u-blox. I say real, because there are knock-offs on 
> ebay.
> 
> Why did I mention $35?  Well, you can find an M6T gps-only with raw ublox 
> output on Amazon and elsewhere called LEA-6T that should get the job done if 
> you add a metal ground plane. This little thing works surprisingly well when 
> tested for repeatable RTK fixes within 5cm and you can even do a real-time 
> RTK fixes with only an Android phone and the older RTK lib App on GooglePlay. 
> (M8T not supported)  Don't feel you have to use a newer M8T with GPS + 
> Glonass, as usually a GPS-only solution will be superior to a GPS + Gloanss, 
> because Glonass seems to have a little more noise to it. (Discussion for 
> another time) 
> 
> 
> USGS SURVEY MARKERS
> While we're at it, let's mention that there are survey points all over the 
> United States where you can test the accuracy of your newly working RTK GPS 
> system.  These are markers placed by the USGS and are typically reported in 
> NAD or other American datum format.  These must be converted to WGS-84 datum 
> for you to compare with GPS positions and there are tools out there if you do 
> a Google search for converting datums to WGS-84, just pay attention to what 
> year(epoch) you are converting to and it gets tricky to wrap your head around 
> conversion between different Ellipsoids and Geoids (ground height).
> https://www.ngs.noaa.gov/NGSDataExplorer/
> 
> 
> RTKLIB:
> RTKLIB has multiple tools to allow streaming, real-time, logging, 
> post-processing, and graphing RTK GPS fixes.  Typically raw GPS (code & phase 
> measurements) are converted to RINEX data format before post-processing.  
> RINEX is a standard and allows for raw GPS code and phase measurements 
> between different GPS manufactures into one format for processing in 
> third-party software.  
> 
> RTKLIB works in Windows and is a little tough to get started with; thankfully 
> there is another very nice guy, Tim Everett, who has written many articles at 
> rtkexplorer.com on accuracy of cheap RTK gps chips interfaced with RTKLIB as 
> well as tutorials on getting started with pretty pictures.  As a side note, 
> you may be tempted to try a newer ublox M8N; however many M8N chips are 
> firmware disabled to not give raw phase anymore without firmware hacking.  
> (The M8T still works with RTKLIB 2.4.3)
> 
> 
> SATELLITE PATH (EPHEMERIS)
> When typical GPS receivers are running in real-time, they download an 
> approximate ephemeris of where the 

Re: [time-nuts] RINEX for Android

[Ole Petter Rønningen]

I think teqc.exe can read ubx-files directly

Ole

> 12. apr. 2018 kl. 12:46 skrev jimlux :
> 
> It turns out that some of the newer Android phones support an API which 
> returns raw GNSS data and that can be logged to a file in RINEX format. 
> There's a few apps out there that do this although I've not tried it (my 
> Samsung S6 doesn't have the right hardware).
> 
> In any case, it might be interesting, if you have one of these devices, to 
> let it log for a while, with the phone in a fixed place, and then post 
> process the data.
> 
> I ran across this when looking for software to generate RINEX files from data 
> from NEO-7 GPS modules (which I'm still looking for)
> 
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Re: [time-nuts] Rinex Data Stream

[Ole Petter Rønningen]

Depending on the receiver, the manufacturer usually provides a conversion 
utility.

No such thing as a RINEX «stream» though, as far as I know. The observations 
are usually collected in a vendor specific (or sometimes neutral, like BINEX) 
format, and then converted to RINEX in batch.

Ole

> 26. nov. 2017 kl. 12:45 skrev Marco Cardelli :
> 
> Hi All,
> I've a question for all the group. Ho can I obtain a Rinex Data Stream from
> a GPS receiver? I need to convert NMEA data?
> 
> Thank you so much.
> Marco
> 
> *Best Regards,*
> *Marco Cardelli - IZ5IOW*
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Re: [time-nuts] Next upgrade

[Ole Petter Rønningen]

I guess everyone has seen this, but Linear has a nice appnote «A Standards Lab 
Grade 20-Bit DAC with 0.1ppm/°C Drift»

http://cds.linear.com/docs/en/application-note/an86f.pdf

Ole

> 26. nov. 2017 kl. 13:50 skrev Magnus Danielson :
> 
> Hi
> 
>> On 11/26/2017 02:26 PM, Attila Kinali wrote:
>> Though, if you have a decent 16bit DAC and want to get to 18bit,
>> that's fairly simple using delta-sigma modulation... if you can live
>> with a low pass fillter after the DAC. But the DNL will be the limiting
>> factor here (unless you use some special techniques) and the (absolute) INL
>> will not get better, for obvious reasons.
> 
> I needed 19 bit rather than 16 bit, so I implemented an interpolation scheme. 
> A first degree sigma-delta would also be possible, but for low ratios what I 
> did was more efficient.
> 
> A first degree sigma-delta is fairly simple thought.
> 
> The trick is that you want to push the noise high up so it becomes trivial to 
> filter, then the filter will not be hard to design and won't be low enough to 
> cause PLL instability and implementation troubles.
> 
> Cheers,
> Magnus
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Re: [time-nuts] H-Maser drift (was: Why discipline Rubidium oscillator?)

[Ole Petter Rønningen]

Hi, Dana.

> What does 'EFOS' mean?  I hadn't heard the term before.

EFOS was a series of masers made by Oscilloquartz in Switzerland, there is a 
little information on my website www.efos3.com under «about».

The manuals for those masers are also available, lots of good info for the 
interested: 
http://www.leapsecond.com/museum/efos/

> I do hear mixed reports about where the conversion to atomic H
> occurs, and consider the jury to still be out on that question.

Well, I think that jury is in.. :) plenty of information in old papers on that 
part.

Ole

> I had thought that the volume of the storage bulb was much
> smaller in out maser, perhaps in the pint to quart range.  For a
> frequency of ~1420 MHz, I guess it would take a cavity that is
> operating in a somewhat higher than fundamental mode if the
> volume is in the gallon regime as you suggest.  But with the
> narrow gain profile width of this transition, I supposed there'd
> be no risk of the thing running in the wrong mode.
> 
> Dana
> 
> 
> On Tue, Nov 21, 2017 at 8:14 AM, Ole Petter Ronningen > wrote:
> 
>>> On Tue, Nov 21, 2017 at 2:50 PM, Attila Kinali  wrote:
>>> 
>>> [...] The advantage of the platinum valve
>>> system is that it "generates" single atom Hydrogen, as required
>>> by the maser.
>> 
>> 
>> Picking nits here.. It was my understanding that the splitting of molecular
>> hydrogen into atomic hydrogen happens using RF in the dissociator - not in
>> the platinum leak valve. Is my understanding incorrect?
>> 
>> 
>>> Within the cavity there is a small glass bulb that keeps the atoms
>>> in the right position of the cavity field.
>> 
>> 
>> 4.5 liters in EFOS type masers - so not *that* small. I believe other
>> masers are the same order of magnitude.
>> 
>> 
>>> Yes, IIRC normal numbers are several 10s to 100s of wall collisions
>>> before the atom loses its state due to wall colisions and without
>>> contributing to the signal.
>>> 
>> 
>> Lifetime ~1 second I think
>> 
>> 
 I've long wondered what causes the slow frequency drift, typically
>>> amounting
 to about 3E-14 over a time span of several months.
>>> 
>>> Mostly changes in the wall coating leading to a different wall collision
>>> shift and mechanical changes of the cavity dimension (think air pressure
>>> and creep) leading to a different cavity pulling. To a lesser extend
>>> it's the changes in the quality of the vacuum and number of Hydrogen
>> atoms
>>> in the cavity.
>> 
>> 
>> Also aging of electronic components - coarse tuning of the cavity is done
>> by temperature, and any drift if the temperature-sensor/amplifiers etc will
>> result in drift. At least for EFOS type masers.
>> 
>> Ole
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Re: [time-nuts] Time and frequency practical exercise 2018 late quarter; precision measure of 432mhz band Sat in Lunar Orbit

[Ole Petter Rønningen]

Pat,

I am not a ham, but would be interested in participating if there is someone in 
my neck of the woods that needs access to timing gear. I am in western norway, 
near stavanger. I have a hydrogen maser and many other precision oscillators.

Ole

> 17. nov. 2017 kl. 22:26 skrev Patrick Barthelow :
> 
> From me, Pat a newbie, second post:
> 
> A new project, STEM opportunity.   A STEM/CitizenScience/Ham Space Science
> project. Kids welcome.
> In formative stages so this is for internal discussion, not for public
> announcements yet.
> Will do a frequency measurement of a Cubesat at about 437 mhz that will
> orbit the Moon in 2018.
> Can be received by modest yagi antennas while orbiting the moon.
> Challenge is to get/use/build precision frequency references and counters,
> and measure the carrier frequency.Cesium, Rubidium,  MASER, GPS based,
> commercial standards, and their derivations all welcome.
> Have found 4 (and More)  more hydrogen line masers in diverse locations
> around the world, who wish to participate.
> USA, Netherlands, South Africa, Australia, Mexico, and other locations have
> expressed interest.
> 
> I am a member of  Team Alpha Cubesat.  We and some other teams are in the
> NASA CUBEQUEST challenge.  Launching next year a 6u  cubesat to lunar
> orbit.  I am not an expert at the freq measurement aspect of this, so, I am
> a Newbie. With tons of questions, but  I was surprised how quickly a check
> of the world's Hydrogen line MASERS got many to offer to come on board.
> MASER is overkill, but that is OK.  The Chief Scientist of the project is
> in the USA and wants to make measurements to the HZ level, at 437 mhz so
> with MASERS and Cesium, Rubidium we are overkill but it could generate
> STEM/Citizen Science participation.  That is what we are doing.  So the
> satellite will be on 437.5 mhz  plus  minus doppler.  We have to measure
> its received freq to 1 HZ or less.   So I talked to the chief scientist,
> and we decided to go with a public STEM related program  with it. [PLEASE
> DO NOT GO PUBLIC YET this is confidential for now.] Announcement of a
> competition for anyone to measure the frequency of the sat as it is in moon
> orbit.  So I decided to check with  about 5 geographically diverse located
> MASERS. ( Australia,  South Africa, UK, Holland, Mexico and USA,  and got
> or am getting buy-in from them to make the measurement.  I was surprised
> they did not just say go away... a half million dollar MASER is, or should
> be busy with similar but necessary measurements from paying customers.
> Overkill, I admit, but it is a chance for Citizen Science publicity,
> Popular Science, STEM, etc..
> 
> 
> Anyway I got a bunch of MASERS  to participate and will develop a website
> for people to measure the freq and send in their "answer".  We will have
> (are looking for) sponsors that will pay prizes or wall paper awards,  for
> very close accurate measurements.
> This is like a modern day Frequency Measurement Test that ARRL did years
> ago.  I will in fact call ARRL to see if they want to play in this.  I will
> CC others to see if they want to play.  Other frequency references used may
> be commercial variations of
> Cesium Beam and Rubidium references.  But the King Kong in accuracy is the
> MASER.  I got to learn a bit about the MASER they had at Arecibo when I was
> there.   And now know a school in Europe a Technical Instrumentation
> school, that offers a project to build a Hydrogen Line Maser using modern
> simpler, cheaper methods and hardware.
> 
> Arecibo may play on this event next year.   So, you only need modest yagis
> to pick up the Sat at moon distances  on 437.5 mhz  should be fun...
> ​The Goldstone MASER; above:
> 
>> 
>> https://www.nist.gov/pml/time-and-frequency-division
>> https://www.nist.gov/pml/time-and-frequency-division/radio-stations/wwv
>> http://tf.nist.gov/stations/wwvtimecode.htm
>> https://www.nist.gov/pml/time-and-frequency-division/time-se
>> rvices/history-radio-station-wwv
>> 
>> https://www.nist.gov/pml/time-and-frequency-division/time-se
>> rvices/wwv-and-wwvh-digital-time-code-and-broadcast-format
>> 
>> http://tf.nist.gov/phase/Properties/main.htm
> 
> ​See/Search Also:
> ​Precise Time and Time Interval Clocks Time Frames and Frequency, James R.
> Clynch  Navy Postgraduate School.
> ​Introduction to Frequency Standards  by Lindon Lewis
> 
> 
> ​Interested?   Get back to me to start planning for the 2018 launch, and
> cubesat in lunar orbit,  exact date not known.​
> 
> Best, 73,   Pat Barthelow AA6EG
> apol lo...@gmail.com
> 
> 
> *"The most exciting phrase to hear in Science, the one that heraldsnew
> discoveries,  is not "Eureka, I have found it!"but:*
> "That's funny..."  Isaac Asimov
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Re: [time-nuts] a link to a explanation of Rb vs Cs?

[Ole Petter Rønningen]

A little of the thinking, and a bit of the history of the rb v cs is in "CESIUM 
AND RUBIDIUM FREQUENCY STANDARDS STATUS AND PERFORMANCE ON THE GPS PROGRAM"

http://www.stanson.ch/files/GPS/Vol%2027_14.pdf

Ole

> Den 12. apr. 2017 kl. 08.41 skrev Hal Murray :
> 
> 
> jim...@earthlink.net said:
>> If there's nothing folks are aware of, I'll probably see if I can find  some
>> nice schematic pictures of a Cs Beam, a gas cell, and an Hg ion  trap, and
>> then a AVAR plot or something. 
> 
> I think the GPS satellites have 3 Cs and 2 Rbs.  There might be an 
> interesting story about why they decided to split their eggs into two baskets.
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
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Re: [time-nuts] Thermal effects on cables --> ADEV

[Ole Petter Rønningen]

That IS interesting.. It reads to me that the advice is to keep a "moving 300 
pt ADEV" when continously monitoring a (pair of) frequency source in e.g a VLBI 
site - the reason for limiting it to 300 pts being that much more than that is 
likely to average out potential issues.. 

Does that make sense?

> Den 13. jan. 2017 kl. 17.04 skrev Bob Camp :
> 
> Hi
> 
> There’s an interesting comment buried down in that paper about limiting ADEV 
> to 
> < 300 samples per point. Their objective is apparently to better highlight 
> “systematic 
> errors”. I certainly agree that big datasets will swamp this sort of thing. 
> I’m not quite
> sure that I’d recommend ADEV to find these things in the first place. My 
> guess is that
> it’s the only spec they have to call the device good or bad in this case 
> …They don’t seem
> to have Hadamard in their list of variances. If I was going after systematics 
> with a deviation,
> that’s the one I’d use. Of course I probably would not use a something-dev in 
> the first place. 
> 
> Bob
> 
> 
>> On Jan 13, 2017, at 1:52 AM, Ole Petter Ronningen  
>> wrote:
>> 
>> Hi, all
>> 
>> The question of phase shifts in cables pops up every now and then on this
>> list - I stumbled across a good table of measured phase shifts with
>> temperature in different cable types in this paper:
>> http://www.ira.inaf.it/eratec/gothenburg/presentations/ERATEC_2014_PresentationWSchaefer.pdf
>> that I though would be of interest to others.
>> 
>> A quick summary given below, see pdf for full details. Lots of other
>> interesting stuff in there also.
>> 
>> Values in ppm/K, for 10 Mhz except when otherwise stated. (The paper gives
>> values for 5, 10 and 100Mhz)
>> 
>> Huber-Suhner Multiflex 141: -6
>> RG-223: -131.9
>> Semiflex Cable: -11.5
>> Huber-Suhner: -8.6
>> Times Microwave LMR-240: -3.4
>> Times Microwave SFT-205: 7.7
>> Meggitt 2T693 SiO2: 30.6
>> Andrew FSJ-1 (@5Mhz): 25
>> Andrew FSJ-4 (@5Mhz): 10
>> Andrew LDF-1P-50-42: 2.8
>> Andrew LDF4-50A: 4.7
>> Times Microwave TF4FLEX (@100Mhz):6.4
>> Phasetrack PT210 (@100Mhz): 2
>> 
>> Ole
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Re: [time-nuts] hm H Maser

[Ole Petter Rønningen]

"The European Commission and the European Space Agency have approved the 
Galileo GNSS programme. Two experimental satellites will be launched in late 
2005 or early 2006. Atomic clocks are critical for satellite navigation. After 
more than ten years of development and an overall budget of € 30M, two onboard 
clock technologies have been qualified. The author considers their current 
status and performance."

https://www.gim-international.com/content/article/onboard-galileo-atomic-clocks

Ole

> Den 10. jan. 2017 kl. 14.18 skrev ewkehren via time-nuts :
> 
> Do we know what the PHM development for Galileo cost?
> 
> 
> 
> 
> Sent from Samsung tabletBob Camp  wrote:Hi
> 
>> On Jan 10, 2017, at 2:45 AM, Dr. David Kirkby (Kirkby Microwave Ltd) 
>>  wrote:
>> 
>> Once 9 Jan 2017 12:59, "Bob Camp"  wrote:
>>> 
>>> Hi
>>> 
>>> Ok here are some rough numbers:
>>> 
 On Jan 9, 2017, at 4:35 AM, Dr. David Kirkby (Kirkby Microwave Ltd) <
>> drkir...@kirkbymicrowave.co.uk> wrote:
>> 
 It would be interesting to see your breakdown of the costs and man hours
 for an H2 maser. I suspect that others would find cheaper/faster
>> solutions.
>>> 
>>> $100M for the H2
>>> 
>>> $25M for the Rb
>> 
>> With all due respect,  and I apprectiate you have a good knowledge of this
>> field, but that's not a breakdown of costs or man hours I wanted to see,
>> but a cost which appears to be plucked from the air.
> 
> Hardly plucked from the air. The last Rb design that I was involved with was 
> roughly 5X that expensive. 
> 
>> 
>> There's a BIG difference between a volunteer effort where
>> 
>> * Salaries are not paid
>> * Items of test equipment are likely to be borrowed or people provide
>> access to them for no charge etc,
>> * Academics are likely to provide consultancy for free, in return for being
>> on papers published.
>> * Software licenses could probably be obtained free,  or enough people get
>> trials.
> 
> That’s where the 5:1 cost reduction comes from. 
> 
>> 
>> compared to a commercial company building a maser where
>> 
>> * Salaries are paid
>> * All equipment is purchased new
>> * Bench power supplies with 3.5 digit displays are sent out for calibration
>> each year.
>> *  No outside body will do anything except at a commercial rate.
>> * Flights are booked for meetings which could be done over the Internet.
>> * High end software licenses are huge.
>> 
>>> $500M for the fountain.
>> 
>> But on what basis do you arrive at that figure?
> 
> The numbers that the people who have done it come up with when you talk to 
> them. 
> 
>> 
>>> To get sponsorship for anything remotely close to those numbers, you
>>> need to have some massively good credentials.
>>> 
>>> Bob
>> 
>> Yes agreed at $500M. But someone like Tom, who does have massively good
>> credentials, could perhaps get $500,000, and perhaps that wisely spent
>> could get a fountain built.  Without knowing how you arrive at $500M, it is
>> not possible for anyone to look at ways of shaving that cost.
> 
> 
> This is *not* a cheap field to be doing things in ….
> 
> Bob
> 
>> 
>> The Lovell Telescope at Jodrell Bank in the UK was built on a shoestring
>> budget. It was at the time the world's  largest steerable radio telephone.
>> Half a century later only 2 larger ones have been built.
>> 
>> Maybe I am too nieve.
>> 
>> Dave.
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Re: [time-nuts] hm H Maser

[Ole Petter Rønningen]

... having said that, I for one think I'm with Bob on this one. The thing about 
masers are that they are big. At least active masers. And they require a 
substantial volume be kept at ultra high vacuum - which is not trivial, 
especially not in a homeshop. The cavity needs to be kept at a temperature 
stable to 0.001 degree C. With 4-5 magnetic shields. Add to this costly pumps 
to keep the vacuum this low even if you succeed at reaching that vacuum.. 
There's easily 1-2KUSD running cost per year just to keep the maser running.

Granted, I've never built a maser, but personally I think the problems that 
would need to solving (and lead to learning) would be much more on the 
vacuum-systems, shielding and temperature long before electronics becomes a 
major factor. And the chance of  actually get a result comparable to a 
commercial maser (or even just better than what you could realistically pick up 
from ebay for a few K) are pretty slim. And LOT of time and cash would be 
burned before you are even close to getting some sort of oscillation.

A rubidium does look like a more realistic project.. 

Dont get me wrong - it would be beyond cool if someone built a homemade maser. 
The first ones were built by regular people in regular labs, so sure it can be 
done.

Well, my $0.02 has been spent..
Ole

> Den 10. jan. 2017 kl. 15.15 skrev Ole Petter Ronningen 
> :
> 
> Not sure how relevant that particular example is. PHM on Galileo was new 
> science (at least the sapphire loaded cavity), and *very* different 
> reliability engineering.
> 
> AHM's are nothing new, the science hace been done, the construction is known, 
> down to exact drawings and circuit diagrams. There are numbers from 1982 that 
> can possibly be used as a startingpoint for estimating an amateur project in 
> https://library.nrao.edu/public/memos/vlba/main/VLBA_65.pdf
> 
> As a side note, I am also not convinced that sourcing the fused quartz teflon 
> coated bulbs would be a show stopper for a limited number (<5) of masers, I 
> for one have one on my shelf. It is quite possible that old bulbs for 
> previous designs exists with the current manufacturers that they might be 
> willing to part with.
> 
> They are also still manufactured, Vremya or one of the others might be 
> willing to sell them - although I have no idea about the cost.
> 
> As another side note, on a trip to Switzerland I was allowed a glimpse of a 
> couple of the PHM's for Galileo in person. Impressive. 
> 
> Ole
> 
>> On Tue, Jan 10, 2017 at 2:18 PM, ewkehren via time-nuts  
>> wrote:
>> Do we know what the PHM development for Galileo cost?
>> 
>> 
>> 
>> 
>> Sent from Samsung tabletBob Camp  wrote:Hi
>> 
>> > On Jan 10, 2017, at 2:45 AM, Dr. David Kirkby (Kirkby Microwave Ltd) 
>> >  wrote:
>> >
>> > Once 9 Jan 2017 12:59, "Bob Camp"  wrote:
>> >>
>> >> Hi
>> >>
>> >> Ok here are some rough numbers:
>> >>
>> >>> On Jan 9, 2017, at 4:35 AM, Dr. David Kirkby (Kirkby Microwave Ltd) <
>> > drkir...@kirkbymicrowave.co.uk> wrote:
>> >
>> >>> It would be interesting to see your breakdown of the costs and man hours
>> >>> for an H2 maser. I suspect that others would find cheaper/faster
>> > solutions.
>> >>
>> >> $100M for the H2
>> >>
>> >> $25M for the Rb
>> >
>> > With all due respect,  and I apprectiate you have a good knowledge of this
>> > field, but that's not a breakdown of costs or man hours I wanted to see,
>> > but a cost which appears to be plucked from the air.
>> 
>> Hardly plucked from the air. The last Rb design that I was involved with was
>> roughly 5X that expensive.
>> 
>> >
>> > There's a BIG difference between a volunteer effort where
>> >
>> > * Salaries are not paid
>> > * Items of test equipment are likely to be borrowed or people provide
>> > access to them for no charge etc,
>> > * Academics are likely to provide consultancy for free, in return for being
>> > on papers published.
>> > * Software licenses could probably be obtained free,  or enough people get
>> > trials.
>> 
>> That’s where the 5:1 cost reduction comes from.
>> 
>> >
>> > compared to a commercial company building a maser where
>> >
>> > * Salaries are paid
>> > * All equipment is purchased new
>> > * Bench power supplies with 3.5 digit displays are sent out for calibration
>> > each year.
>> > *  No outside body will do anything except at a commercial rate.
>> > * Flights are booked for meetings which could be done over the Internet.
>> > * High end software licenses are huge.
>> >
>> >> $500M for the fountain.
>> >
>> > But on what basis do you arrive at that figure?
>> 
>> The numbers that the people who have done it come up with when you talk to 
>> them.
>> 
>> >
>> >> To get sponsorship for anything remotely close to those numbers, you
>> >> need to have some massively good credentials.
>> >>
>> >> Bob
>> >
>> > Yes agreed at $500M. But someone like Tom, who does have 

Re: [time-nuts] NCOCXO anyone?

[Ole Petter Rønningen]

SpectraDynamics HROG 5/10

http://www.spectradynamics.com/products/hrog-10-high-resolution-phase-and-frequency-offset-generator/

On 22. jul. 2016, at 09.49, Anders Wallin  wrote:

>> rich...@karlquist.com said:
>>> Also in 1996, phase microsteppers were already legacy technology and
>> didn't
>>> have a good reputation for spectral purity.  Another non-panacea.
>> 
>> What is a phase microstepper and/or how does it compare to a DDS?
>> 
>> (Google gets lots of hits, but they all refer to motors.)
> 
> 
> H-maser aging is typically compensated by something like
> spectratime femto-stepper
> http://www.spectratime.com/products/itest/clock-instruments/FemtoStepper/
> microsemi AOG
> http://www.microsemi.com/products/timing-synchronization-systems/time-frequency-references/active-hydrogen-maser/aog-110
> (there are probably others, please post if you know about them!)
> 
> afaik they contain a OCXO/BVA that is steered based on a DMTD measurement
> against the input reference.
> 
> 
> AW
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Re: [time-nuts] MicroPulse L1/L2 Surveying Antenna

[Ole Petter Rønningen]

I recently also searched for details on a Micro Pulse antenna - I finally got a 
datasheet from PCTEL support, who (presumably) took over the Micro Pulse range 
at some point. 

> On 30. jan. 2016, at 19.17, Dan Rae  wrote:
> 
> Does anyone have any details on the above antenna?  Part Number is: 
> 90LL122300-2 and it has a sticker on it saying it is a Global Hawk Asset, it 
> has a big set of choke rings (about 35 cm across) and looks as though it 
> might have been designed to be mounted flush on an aircraft body.
> 
> I'm doing a LH survey at present with it perched temporarily on a wall at the 
> back of my house and it seems healthy at 5V supply.
> 
> Dan
> 
> ac6ao
> 
> 
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