Telecon tomorrow (Thursday) @ 5 pm Eastern time

Hi all,

Telecon tomorrow (Jun. 24 in North America, Jun. 25 in Australia) at the regular time: 5 pm Eastern (2 pm Pacific, 11 am Hawaii, 23.00 European, 7 am Eastern Australia). We now have our three new Hamamatsu G10899-03K InGaAs photodiodes -- our first InGaAs calibration photodiodes (all of our many many others are silicon) -- here for testing. We also have some more recent updates on AIFCOMSS, and Andrew Macdonald is still working on the layout for the new ALTAIR form-factor version of the ORCASat transimpedance amp board. Progress also continues to be made on optical simulation and on measuring electrical characteristics of the photodiode readout. More discussion items for tomorrow's telecon include: flight/telescope plans and tests; construction and lab 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. I'll send a progress report 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
VII) AOB

Talk to you all tomorrow, thanks!!!
justin

-- jalbert - 2021-06-24

Hi all,

My apologies for the delay! -- here's an update on recent ALTAIR balloon work, minutes of the last meeting on June 10 (attendees Arnold Gaertner [NRC], Liviu Ivanesu [Sherbrooke], and me), and a reminder of the telecon in 20 minutes(!) from now:

Evan Moore provided Andrew Macdonald and me the schematic showing how the 14.2 kHz notch filter, to reject the bit of noise from the chopper in the AD8638 op amp that forms the heart of the transimpedance amplifier circuit, should be implemented. You can see it on the left-hand side of the 4th (last) page of the schematic here:

as compared with the 4th page of the no-notch-filter ORCASat board schematic here:

However, on both ALTAIR and ORCASat, the default circuit will indeed have the land pattern for the notch filter on the board, but the notch filter itself will intentionally not be implemented -- specifically, the inductor and the capacitor for the notch filter will nominally be do-not-place (DNP), and the 620 mOhm resistor will instead be a 0 Ohm jumper-resistor. Why? This is because the 14.2 kHz noise from the chopper on the AD8638 ends up being a transient for the nominal pulsed operation of the ORCASat, and of the ALTAIR, light sources: while the noise element ends up being regular at 14.2 kHz, the actual noise artifact is a wiggle of only a few hundred nanoseconds in length (because the switching in our nominal pulsed light source operation on both ORCASat and on ALTAIR happens very quickly). Thus, we only want to have the ability to actually implement the noise filter on the ALTAIR and the ORCASat boards for testing purposes (and, thus, all the spots for it on the boards -- but with the notch filter itself -- i.e. with its inductor and capacitor -- nominally not filled/implemented in the default circuits).

Andrew Macdonald is presently updating the schematic, and making the layout, for the ALTAIR version of the board per the above -- and he'll have layout files for us for the next telecon.

Summer students Colton Broughton, Sarah Alshamaily, and Will Stokes are working on installing AIFCOMSS ( https://github.com/ProjectALTAIR/AIFCOMSSwithCUPredictorTest ) on their laptops, and seeing what updates need to be made on it. Two things that we know most definitely need updating (or, rather, creating) are the station-keeping software for AIFCOMSS, and the online command-handling within the onboard Arduino software -- but right now the students are seeing if there are any other issues needing fixing with AIFCOMSS on any of the 3 platforms (MacOS, Windows, Linux).

I still need to test out out Radiometrix SHX1 144 MHz transceiver modules that were returned to us last month from Radiometrix (following their firmware update to fix the BUSY output):

as well as our two 144 MHz Raveon M8S data modem transceivers:

Once we get our 144 MHz transceivers settled and back into the ALTAIR gondola, we'll do some outdoor drop testing of the actual gondola. (We've done all the outdoor drop tests I can think of doing with our dummy gondola.)

And we also still need to test out our new DFRobot SEN0177 payload aerosol monitors that we have here:

I've begun to look some more at MEEP (https://meep.readthedocs.io/en/latest/) for finite-difference time domain (FDTD) simulation of integrating sphere output, but I haven't yet had time to make any significant progress there -- I'm hoping to do that in the next couple of weeks. It will be interesting to compare that with ray tracing simulations, when I can get a chance to do that!

Engineering students Josh Gage and Evan Moore found that the "wings" that Josh had found in the laser diode light output distributions:

were due to how the diode was mounted in the heat sink. When the diode is mounted properly and carefully, the wings go away.

We also have our 10 Hamamatsu S12698-01 photodiodes and 3 Thorlabs FDS100-NOCAN photodiodes (those Thorlabs ones have their windows removed) here in Victoria:

I've given them to Evan to try out -- he's taking a few weeks to ramp up, and will produce some linearity, etc., plots from them soon.

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 application will be a NATO "Science for Peace and Security" application (together with Australian colleague partners).

Our next telecon is in 20 minutes from now -- see below for Skype instructions.

Cheers, talk in 20 mins (!) from now -- thanks all!

justin

-- jalbert - 2021-06-27