Discussion Forum » General »

Telecon tomorrow (Thursday) @ 5 pm Eastern time

Hi all,

Telecon tomorrow (Apr. 18 in North America, Apr. 19 in Australia) at the regular time: 5 pm Eastern (2 pm Pacific, 11 am Hawaii, 23.00 European, 7 am Eastern Australia). More progress from Andrew in fixing the voltage supply noise issues with the new photodiode precision amplifier boards; a quick study done on ways to remove the windows from the OSI Optoelectronics UV-015 photodiodes (the Thorlabs "can opener" device tends to mangle these PDs, but it appears that carefully knocking the window out might possibly be more promising); plus lots more new updates on AIFCOMSS station-keeping prediction/simulation software; and in readying for outdoor drop testing. More discussion items for tomorrow's telecon include: flight/telescope plans and tests; construction and lab tests of the new gondola/payload; 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. I'll send an update with a bunch of recent photos, etc, before the telecon tomorrow.

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 tests of the new gondola and payload

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 - 2019-04-17

Hi all!

Apologies for the delay! -- here's the quick progress report on ALTAIR balloon work over the past 2 weeks (+ meeting minutes of our telecon 2 weeks ago, as well as the telecon we just had today -- attendees both times were Arnold Gaerner [NRC] & me):

I installed 4 of the OSI UV-015 photodiodes in the pre- and post-flight cross-check integrating sphere:

Those OSI photodiodes do not (yet) have their windows removed. They're mechanically mounted (using the new Thorlabs mounts) but not yet electrically mounted/connected to a connector or to an amplifier board.

I then experimented with window removal on the OSI UV-015 photodiodes, using the Thorlabs WR1 "can opener" device. That was initially not very successful: the UV-015 "can" is rather thick metal, and thus tends to bend and deform, rather than cutting nicely, with the WR1 "can opener". Here is a photo:

and this is what happens when one pushes the can opening to completion:

The latter photo is even worse than it looks, because the can opening can't avoid at least a very small level of contact, or crushed-window impact, with the active surface of the interior photodiode itself (even when done upside-down, so that the crushed window falls out due to gravity). So, although we'll check the resulting PDs to see if they read out values consistent with untouched PDs -- even if they do, the procedure is just a little more violent than what I would want on the internals of such a delicate device. A possibly better option appears to be holding the photodiode upside-down in a vice, and very very carefully knocking out the window with an awl and small hammer, per this photo:

Those results are certainly more aesthetic -- but we'll need to see if the photodiodes retain nominal functionality following that procedure. The best thing, of course, would be for OSI Optoelectronics to just supply us with windowless photodiodes (as Hamamatsu has done with theirs), but OSI found that to be impossible (or at least bureaucratically too difficult for OSI) when we asked OSI (many times) last year.

Andrew Macdonald in the UVic phys & astro electronics shop found and is fixing an issue with the voltage supply in his daughterboards:

Previously the supply to the LM27762 was 5 volts (datasheet says it requires between 5 V and 5.5 V), but Andrew found that apparently it actually requires between about 5.1 V and 5.5 V, because its +-5 V output is not in fact quite rail-to-rail with its input voltage. So here's his revised schematic for that same physical daughtercard:

He's now testing that new update/fix of his.

Some separate progress on preparing for outdoor drop testing this summer, in the backyard of my new house. Here's the diagram (overlayed on a photo) of how drop testing will be set up there (the clothes-drying line, crossed out in red, will be removed):

and the opposite view (the small chain-link fence, crossed out in red, will also be removed):

As you can see in the following photos, I've now (just this week) successfully removed both the chain link fence (although the fence posts still need to be removed) plus the clothes-drying line -- thus some progress:

And I'll remove those fence posts this weekend. The indoor work still all needs to be done, however: here's an indoor view -- the base of the drop-testing pole will be fixed on the floor (inside the window) by a pole-base-holder which I will make from some lumber:

This outdoor drop testing setup will, of course, use the 10-meter stabilized pole that Mark Lenckowski made a while ago:

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 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 also 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.

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.

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

Next telecon is in 2 weeks from now, on Thurs. May 2.

Cheers, talk then -- thanks all!


-- jalbert - 2019-04-18

Title Telecon tomorrow (Thursday) @ 5 pm Eastern time
Forum ForumGeneral
Topic attachments
I Attachment History Action Size Date Who Comment
JPEGjpg ALTAIRBackyardChainLinkFenceRemoval17Apr2019.JPG r1 manage 2921.1 K 2019-04-18 - 22:14 JustinAlbert Removal of chain link fencing in my backyard for ALTAIR drop testing.
JPEGjpg ALTAIRBackyardChainLinkFenceRemoval17Apr2019_2.JPG r1 manage 3113.2 K 2019-04-18 - 22:15 JustinAlbert Removal (second view) of chain link fencing in my backyard for ALTAIR drop testing.
JPEGjpg ALTAIROSIPDImprovedWindowRemovalAwl16Apr2019.JPG r1 manage 2063.0 K 2019-04-18 - 22:48 JustinAlbert Possibly improved window removal for the OSI Optoelectronics UV-015 photodiodes using an awl and small hammer.
JPEGjpg ALTAIROSIPDWindowRemovalCanOpenerDamage16Apr2019.JPG r1 manage 2038.1 K 2019-04-18 - 22:11 JustinAlbert Photo showing how the Thorlabs WR1 "can opener" device damages the OSI Optoelectronics UV-015 photodiodes when window removal is attempted.
JPEGjpg ALTAIROSIPDWindowRemovalCanOpenerDamage16Apr2019_2.JPG r1 manage 1793.7 K 2019-04-18 - 22:13 JustinAlbert Photo showing completion of destructive window removal using the Thorlabs WR1 "can opener" device on an OSI Optoelectronics UV-015 photodiode.
JPEGjpg ALTAIRPrePostFlightIntSphereOSIPDswWindowsInstalled5Apr2019.JPG r1 manage 2070.2 K 2019-04-18 - 22:10 JustinAlbert OSI UV-015 photodiodes installed in the pre- and post-flight check integrating sphere. These OSI photodiodes do not (yet) have their windows removed.
PDFpdf DC-DCMODSCHEMATIC1.pdf r1 manage 73.3 K 2019-04-18 - 23:19 JustinAlbert Updated schematic for the daughterboard for the precision photodiode amplifier board (to solve power supply noise issues).
Edit | Attach | Watch | Print version | History: r2 < r1 | Backlinks | Raw View | WYSIWYG | More topic actions
Topic revision: r2 - 2019-04-18 - JustinAlbert
    • Cern Search Icon Cern Search
    • TWiki Search Icon TWiki Search
    • Google Search Icon Google Search

    Altair/Forum All webs login

This site is powered by the TWiki collaboration platform Powered by PerlCopyright & 2008-2023 by the contributing authors. All material on this collaboration platform is the property of the contributing authors.
or Ideas, requests, problems regarding TWiki? use Discourse or Send feedback