[Ground-station] Please vote - Ambasat sensor

Sat Sep 28 13:10:07 PDT 2019

Hi Douglas --

OK, that makes sense as a neat experiment, but "ultra-stable" implies something a lot more complex and sent me off into the weeds.  I think the biggest challenge, as someone else pointed out, is that getting a transmitter authorized, even at very low power, probably creates a bunch of bureaucratic hurdles.

On Sep 28, 2019, 2:52 PM, at 2:52 PM, Douglas Quagliana <dquagliana at gmail.com> wrote:
>Hi John,
>
>The idea was to have a very simple crystal oscillator (perhaps a very
>small milliwatt class amplifier) and an antenna
>such that the oscillator's signal (with Doppler) can be detected on
>the ground.  No data, just a carrier that a
>ground station with a simple antenna and perhaps a FunCube or RTLSDR
>dongle can detect.
>
>The overriding principle is "keep it simple."  Generate just enough RF
>output so that the oscillator's signal can be
>detected on the ground -- and detection can be done at MUCH lower
>signal levels than are needed to demodulate
>a data signal. Ground stations know the frequency to listen at.  This
>experiment would be placed on a short lived
>LEO so that as the orbit decays and the spacecraft slowly spirals in
>(over several months/years) the changing
>orbit can be observed by watching the signal and it's Doppler
>characteristics change over time.  It's not a very
>interesting experiment at GEO where the orbit really never changes.
>
>The whole experiment (except the antenna) should fit on postage stamp
>sized circuit board, weigh only a few
>grams, and pull just a couple of milliamps.  The frequency could be
>any frequency in any amateur band
>authorized for satellite downlinks.
>
>I'm not sure what the specifications should be except that the
>oscillator should be as stable as reasonably
>possible within whatever the budget it, but if someone can help out
>then let me know and we can
>write the specification and propose it to be included as an experiment
>on some future satellite.  The
>experiment also needs a cool name.
>
>Perhaps we should move this to another thread...  if anyone is
>interested, please let me know.
>
>73,
>Douglas KA2UPW/5
>
>On Fri, Sep 27, 2019 at 7:37 AM John Ackermann. N8UR <jra at febo.com>
>wrote:
>>
>> In this context, what does "Ultra Stable" mean?  There are a bunch of
>interesting challenges with crystals in space because of the launch
>shock, the huge temperature swings, and the thermal insulating
>properties of vacuum.
>>
>> I know people who know about these things and would be glad to help
>if we wanted to do this, but a spec is the first requirement.  It would
>need to include (at a minimum) nominal frequency,  short-term
>stability,
>> phase noise, drift/aging, temperature response, and absolute
>frequency accuracy, along with mechanical things like shock rating,
>physical dimensions, and power budget.  There would have to be
>consideration
>> of thermal management as well, given the likely need for an oven.
>>
>> (Note: I've never done spacecraft design, but I've picked up on these
>issues from conversations with those who have worked on space-borne
>USOs.)
>>
>> 73,
>> John
>> On Sep 27, 2019, at 1:32 AM, Michelle Thompson via Ground-Station
><ground-station at lists.openresearch.institute> wrote:
>>>
>>> We can design our own sensor. There's a blurb about it on the site
>and specs for the footprint and interface.
>>>
>>> If someone commits to build and test, I can work with Ambasat to see
>if we can get it on there.
>>>
>>> On Thu, Sep 26, 2019, 22:27 Douglas Quagliana <
>dquagliana at gmail.com> wrote:
>>>>
>>>> Rather than a sensor, could we get an ulta stable oscillator (USO)
>for some frequency in an amateur satellite band? We would just need the
>USO, a small amplifier and an antenna. Even an inefficient antenna.
>Even if we’re only radiating a few milliwatts. There’s still a lot of
>good science we can do from an unmodulated carrier with Doppler.
>>>>
>>>> Regards,
>>>> Douglas
>>>>
>>>> On Sep 26, 2019, at 6:24 PM, Michelle Thompson via Ground-Station <
>ground-station at lists.openresearch.institute> wrote:
>>>>
>>>> There are solar panels.
>>>>
>>>> From  https://ambasat.com/ambasat-2/ambasat-1/
>>>>
>>>> "AmbaSats are just a little bigger than the size of a couple of
>postage stamps but have solar cells, a LoRaWAN radio transceiver..."
>>>>
>>>> For the dashboard, there's a big hint here:
>>>> "Your AmbaSat-1 is fully TTN compliant so as well as viewing data
>in your Dashboard, you can sign-up for a TTN account and access your
>satellite’s sensor data directly using a range of different TTN
>extensions."
>>>>
>>>> I think the dashboard is essentially The Things Network. I'll see
>what I can find out about the dashboard availability.
>>>>
>>>> Interesting question about HABs! I think several people on this
>list are much more active than I am in designing and building payloads,
>and might be able to give an evaluation based on what's on the
>ambasat.com website.
>>>>
>>>> -Michelle W5NYV
>>>>
>>>>
>>>>
>>>>
>>>> On Thu, Sep 26, 2019 at 11:56 AM KC9SGV < kc9sgv at gmail.com> wrote:
>>>>>
>>>>> The "three months in space" bit, makes me wonder.
>>>>> Maybe out of power by then ?
>>>>> (Don't see any solar panels on the board.)
>>>>> What would the possibility be to use the board as payload on a HAB
>(high altitude balloon).
>>>>> Maybe a Mylar balloon cluster achieving float, like the current
>Miami effort ?
>>>>> Then the environmental modules would make sense.
>>>>> Could you get the dashboard and web based tracking without buying
>the launch ?
>>>>>
>>>>> Bernard,
>>>>> KC9SGV
>>>>> Sent from my iPad
>>>>>
>>>>> On Sep 26, 2019, at 1:11 PM, Howie DeFelice via Ground-Station <
>ground-station at lists.openresearch.institute> wrote:
>>>>>
>>>>> It has a LoRA radio on board which is really cool. I always
>thought that LoRA on a LEO would make a great Store  and Forward
>messaging sat. The chirp spread spectrum modulation handles doppler
>quite well and LoRA chips on carrier boards are easy to find to make
>ground stations.  Unfortunately there is little chance we could license
>it since the FCC decided that anything smaller than a 1U cubesat is too
>small to track.
>>>>>
>>>>> Howie
>>>>> AB2S
>>>>> ________________________________
>>>>> From: Ground-Station
><ground-station-bounces at lists.openresearch.institute> on behalf of
>Michelle Thompson via Ground-Station
><ground-station at lists.openresearch.institute>
>>>>> Sent: Thursday, September 26, 2019 11:26 AM
>>>>> To: Michelle Thompson via Ground-Station
><ground-station at lists.openresearch.institute>
>>>>> Subject: [Ground-station] Please vote - Ambasat sensor
>>>>>
>>>>> I bought into the Kickstarter for Ambasat.
>>>>> https://ambasat.com/
>>>>>
>>>>> I’d like you all to help choose the sensor!
>>>>>
>>>>> Choices here:
>>>>> https://ambasat.com/ambasat-2/sensor-options/
>>>>>
>>>>> Disclaimer:
>>>>> This has nothing to do with our project. I acknowledge that
>Ambasat is controversial. No project funds are involved.
>>>>>
>>>>> Why post this here?
>>>>>
>>>>> Details:
>>>>> I asked Ambasat about a custom amateur radio payload, so we could
>test something for us. The kickstarter had that option. The lead of
>Ambasat said yes, amateur payload ok, several people I asked at
>Virginia Tech said go for it, and a small group looked at the specs and
>tried to design something useful for us. But, the very compact size and
>power budget was quite daunting. And the time frame was very short. We
>don’t have enough miniaturization or time. Instead of a custom board,
>we have a standard flight and a ground version.
>>>>>
>>>>> Instead of quietly sending this up, I wanted to share it with the
>team as something fun. I just received the survey for the sensors, so
>we easily have a week at least to vote. It includes some sensors
>already. The free choice is an additional sensor slot.
>>>>>
>>>>> -Michelle W5NYV
>>>>>
>>>>>
>>>>> --
>>>>> -Michelle W5NYV
>>>>>
>>>>> "Potestatem obscuri lateris nescis."
>>>>>
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