[time-nuts] Time and frequency practical exercise 2018 late quarter; precision measure of 432mhz band Sat in Lunar Orbit
Bob kb8tq
kb8tq at n1k.org
Fri Nov 17 18:54:11 EST 2017
Hi
> On Nov 17, 2017, at 4:26 PM, Patrick Barthelow <apolloeme at gmail.com> wrote:
>
> 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.
That sounds like a pretty high ERP … Of course your definition of a modest antenna
may not be quite the same as mine :) Consider that there *are* SNR implications
when you get into your accuracy requirements below.
> 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 MASER is a cute device. It is not an accurate device by it’s self. It is a
very *stable* device. Yes, that is a subtle distinction. In this case I think it is
a pretty important one.
> 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.
Ok, 1 Hz at 437.5 MHZ is roughly 2 ppb. That is pretty much “slam dunk” accuracy
with a GPSDO. Much easier to obtain and set up in a school environment. The
key will be orbit estimation for the +/- doppler part of it. Orbit estimation is not
quite a slam dunk sort of thing. The GPSDO would also give accurate location.
Even with good orbit data, the solution still requires a good location estimate.
> So I talked to the chief scientist,
> and we decided to go with a public STEM related program
I’ve been down the road (from scratch to running) on STEM competitions. The
KISS principle is one to keep in mind. At the same time you *do* want a topic
that presents a challenge.
> with it. [PLEASE
> DO NOT GO PUBLIC YET
This *is* a public list, it’s “out” now.
> 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 <apolloeme at gmail.com>loeme at gmail.com
>
Bob
>
> *"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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