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Telecon tomorrow (Thursday) @ 5 pm Eastern time

Hi all!

Telecon tomorrow (Aug. 23 in North America, Aug. 24 in Australia) at the regular time: 5 pm Eastern (2 pm Pacific, noon Hawaii, 23.00 European, 7 am Eastern Australia). More progress on the photodiode precision amplifier board construction, updates on station-keeping prediction and simulation software, on the pre- and post-flight cross-calibration integrating sphere, and on the windowless photodiode orders from Hamamatsu and OSI Optoelectronics -- I'll post a summary shortly. More discussion items for tomorrow's telecon include: flight/telescope plans and tests; construction, drop testing, and other tests of the new gondolas/payloads; light sources and light source modelling; goniometric and pre- and post-flight calibration; propulsion work; nanosat bus and payload solid models; computing / website / TWiki forums and e-mails; grant applications; and recap of schedules.

Here's how to connect:

1) Open Skype on your computer (note that of course, you should first install Skype, http://www.skype.com, on your machine if you haven't already).

2) In the "Contacts" menu, add me ( jalbertuvic ) as a contact, if you haven't already.

3) Just wait for me to Skype-call you at the usual time (5 pm Eastern, 2 pm Pacific, etc).

4) If there is any trouble, or if you don't get a Skype-call for some reason and would like to join, please just send me an e-mail (jalbert@uvicNOSPAMPLEASE.ca).

Here's the tentative agenda:

I) Flight & telescope plans, and upcoming tests

II) Construction, drop tests, and other forms of tests of the new gondolas and payloads here in Victoria

III) Diffused light source and its modelling, pre- and post-flight calibration, and goniometric calibrations

IV) Solid modelling

V) Computing/website, including recent flight control and simulation progress

VI) Grant applications


Talk to you all tomorrow, thanks!!!


-- jalbert - 2018-08-22

Hi all!

Here's a quick progress report on ALTAIR balloon work done over the past two weeks, plus the minutes of our last telecon (attended by Arnold Gaertner (NRC) and me) -- my apologies for the delay! -- please just reply with (or let me know) any corrections -- thanks! :

We have more updates on the design of our inflight precision photodiode amplifier board from Andrew Macdonald in the UVic phys & astro electronics shop -- a version 4 of his design can be found at

His schematic is definitely both improving and converging, but we also want to A) add the ability to choose between 1) no reverse bias voltage on the photodiode (i.e. the current fixed configuration) and 2) a reverse bias voltage of 5 V; and also B) have a second (version B) of the circuit with a precision PGA as the second amplifier, rather than implementing this ourselves as in the present design with a solid-state analog switch between gain resistors on that amplifier. Andrew will be implementing those updates, and at that point I'll send around his circuit design to George Eppeldauer and other NIST folks for their views.

Our 11 windowless Hamamatsu S2386-8K photodiodes should be arriving at the Stubbs Lab at Harvard in late September, and then I'll carry our share of them up to Canada at the end of the year. We still haven't gotten a quote for our windowless UV-015 photodiodes (as the secondary cross-check photodiode on the integrating sphere) from OSI Optoelectronics, but I will continue to keep after them for that.

Mark Lenckowski and I affixed together the two hemispheres of the fully-coated pre- and post-flight photometry cross-check integrating sphere:

with electrical tape and then duct tape -- that should be (and appears to be) both strong and stable enough to serve as a permanent connection between the two halves, but be removable if for whatever reason we ever need to take them apart again. The legs of ALTAIR payload, if the wheels are removed, fit nicely into the upper flange on top of the sphere, and the payload rests gently on top of the sphere just as it should, ready for its photometry cross-check...:

In order to be able to get the wheels off (and on) quickly, right before and after flight, for this photometry cross-check, I replaced the long (and bent) M3 screws and lock-nuts holding on the wheels with simple stainless-steel pins and very-easy-removal Tygon tubing so that the wheels can very quickly and simply be put on and taken off. (At some point it might even be better to replace the clear Tygon tubing with black silicone tubing, as the latter is even more flexible [and would avoid any light reflection], but that is most certainly not urgent.) The next steps are to 1) add some fine ALTAIR-legs-positioning-registration tabs to the upper flange on top of the sphere:

and to use a long Q-tip to add some Avian-B white coating to the internal seam in the integrating sphere (which you can see in the above image), just in order to white-out that seam.

The version 2.3 of the API for the Windy (https://www.windy.com) 2-D map viewer that we use in the upper left of AIFCOMSS:

has been deprecated and will no longer be supported or usable at the end of this calendar year, so I've begun to update for version 4 of the Windy API (https://api4.windy.com). A simple update to v4 unfortunately loses the ability to zoom in to street-map scale (i.e., zoom in beyond the level below), or to add the "Wind altitude" control bar that you can see in the image above, or to interpolate to find the wind speed and angle at ALTAIR's present elevation and location -- so the below screenshot is all one gets at present with Windy API v4:

I'll continue to work on this, and hopefully also Windy API v4 will continue to improve over the next months, so that those little issues can be fixed. Fortunately, upgrading to v4 does appear to fix a longstanding bug with their API v2.3 in that the wind provided by v2.3 is not correct for the present time zone time. So hopefully those issues with API v4 will get fixed soon, so that everything there will be working as it should be.

Our ALTAIR summer undergraduate student Patrick Ryan and I have been working together on code to simulate station-keeping over a region of land, and also reasonable values for air drag, propulsive thrust, battery power (as well as some battery recharging with future lightweight solar panels), etc. In that vein, we have written, and added to AIFCOMSS, an interface (pred_src/state/ALTAIR_state.hh , and other files in the https://github.com/ProjectALTAIR/AIFCOMSSwithCUPredictorTest/tree/master/pred_src/state directory) for accessing (in both real operation and in simulation) and modifying (just in simulation) the present state of the ALTAIR balloon, gondola, and payload, as well as its external environment. We've utilized that in a calculation of the present thrust of the ALTAIR propulsion system (in pred_src/util/ThrustCalcMethods.hh and .cc), drag (in pred_src/util/DragCalcMethods.hh and .cc), and torque (in pred_src/util/TorqueCalcMethods.hh and .cc) and will continue to expand and utilize that interface in order to start simulating station-keeping.

Mark Lenckowski has completed the stabilized pole for the new 10-meter-high drop test setup at Victoria:

As you can see (faintly), he affixed side-struts and guy wire to the PVC pole, to prevent it from bending in either of the two transverse directions, so it can now be raised to vertical, from horizontal, without bending or breaking.

The survey-tripod-mounted device to cross-check yaw-pitch-roll information from the gondola (e.g., on days before/after flights) is constructed now, thanks to Mark Lenckowski -- photo at:

and all that remains to be done is to finish the small fitting between the device and the bottom of the payload. The purchased hardware in it includes both the survey tripod (http://www.cpotools.com/cst-berger-60-alwi20-o-aluminum-tripod-with-quick-release--orange-/cstn60-alwi20-o,default,pd.html), two adjustable angle mounts (http://www.thorlabs.com/thorproduct.cfm?partnumber=AP180), and a rotation mount (https://www.thorlabs.com/thorproduct.cfm?partnumber=RP01). That last fitting to attach (temporarily, pre- or post-flight) the upper adjustable angle mount to the payload landing gear has been started and will be completed here in the next couple weeks.

We're currently revising the draft initial contractual agreement from our colleagues at Globalstar Canada regarding 2 initial SPOT Trace devices (and their service plans) for the educational side-project for the upcoming NATO SPS application, in which classrooms in elementary and high schools could launch company-donated SPOT Traces using party balloons (or a more environmentally-friendly version thereof), and track them to learn more about winds at different levels in Earth's atmosphere.

Another next step, software-wise, is to add a bunch of additional data information to the telemetry communication between ALTAIR-Victoria:

and the Capella ground station:

and to update the control and monitoring software to incorporate the telemetered info, and also implement onboard SD card data storage, as well as storage of the telemetered info.

Houman will send Cordell and/or us updated sections of his master's thesis soon -- that information will be extremely useful to us going forward. Also, Susana and Nathan, it would be very helpful for us all to get the JHU students' final writeup when you have a chance.

Our next grant applications will be a NATO "Science for Peace and Security" application, together with Australian colleague partners.

That's all I remember, please send things that I forgot. Next telecon * NOW!!! *, at our usual 5:00 pm Eastern time.

Cheers, talk to you all now -- thanks all!!!!!


-- jalbert - 2018-08-23

Title Telecon tomorrow (Thursday) @ 5 pm Eastern time
Forum ForumGeneral
Topic attachments
I Attachment History Action Size Date Who Comment
PNGpng AIFCOMSSWindyAPIv4IntitialStatusScreenshot.png r1 manage 2357.3 K 2018-08-23 - 22:36 JustinAlbert AIFCOMSS screenshot with initial status of Windy API v4
JPEGjpg ALTAIREasyWheelRemovalTubes.JPG r1 manage 1653.3 K 2018-08-23 - 21:07 JustinAlbert Easy removal Tygon tubing for quick removal of wheels before putting payload onto integrating sphere
JPEGjpg ALTAIRPrePostFlightIntSphereFlange.JPG r1 manage 1639.2 K 2018-08-23 - 21:04 JustinAlbert Pre- and post-flight integrating sphere top flange
JPEGjpg ALTAIRPrePostFlightIntSphereMated.JPG r1 manage 2113.7 K 2018-08-23 - 21:03 JustinAlbert Pre- and post-flight integrating sphere with hemispheres mated together
JPEGjpg ALTAIRPrePostFlightIntSphereWithPayload.JPG r1 manage 2135.8 K 2018-08-23 - 21:05 JustinAlbert Pre- and post-flight integrating sphere with payload resting on top flange
PNGpng NISTTransimpedanceAmplifierCircuit.png r1 manage 297.0 K 2018-08-27 - 20:59 JustinAlbert NIST transimpedance amplifier circuit (with hand switch)
PDFpdf PDAnalogFrontendV4.pdf r1 manage 66.0 K 2018-08-23 - 20:46 JustinAlbert Version 4 of the precision photodiode amplifier board circuit
PDFpdf PDAnalogFrontendV4a.pdf r1 manage 69.2 K 2018-08-27 - 20:55 JustinAlbert Version 4a of the precision photodiode amplifier board circuit
PDFpdf PD_Analog_Frontend_V4b.pdf r1 manage 73.1 K 2018-08-27 - 20:56 JustinAlbert Version 4b of the precision photodiode amplifier board circuit
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Topic revision: r4 - 2018-08-27 - JustinAlbert
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