Telecon tomorrow (Thursday) @ 5 pm Eastern time

Hi all,

Telecon tomorrow (Aug. 6 in North America, Aug. 7 in Australia) at the regular time: 5 pm Eastern (2 pm Pacific, 11 am Hawaii, 23.00 European, 7 am Eastern Australia). Further updates on the design of our further-improved (lower noise) transimpedance amplifier board for the photodiodes (which will be sent out for fabrication next week), on updates of AIFCOMSS, and on the 144 MHz transceivers (Raveon and Radiometrix). 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 - 2020-08-06

Hi all,

Apologies for the delay! -- here's an update on recent ALTAIR balloon work, minutes of the meeting two weeks ago (attendees Arnold Gaertner [NRC] and me), and a reminder of the telecon in 20 minutes(!) from now:

We have further important updates from electrical engineering student Evan Moore on his updated version of the lower-noise transimpedance amplifier circuit for both ALTAIR and ORCASat (to further reduce noise -- last year's version ended up with quite a bit too much noise in the pre-amplifier stage, which was traced, via picoammeter, to the "ultra-low-noise" proton pump negative voltage supply DC-DC converter IC for the pre-amplifier op amp. It turns out that all room temperature negative voltage supply ICs, even the lowest-possible-available-noise ones, have unavoidable noise. This version uses only a positive supply and ground to feed its ADA4522-1 [last year's used an ADA4530-1] pre-amplifier op amp -- no negative rail. Very important info for designing lowest-possible-noise room temperature amplifiers that I had not previously known.) Evan added temperature monitoring thermistors to the front-end photodiode modules, which requires modifying the short shielded cables from the amplifier board to the photodiodes on their front-end modules from single-conductor(+ground) SMA to 4-conductor(+ground) shielded mini-USB connectors and cables. (I had preferred using these mini-M5 4-conductor shielded screw-in connectors+cables: https://www.norcomp.net/series/m5-series-circular-connector , but Evan for some reason really prefers pull-in/out mini-USB-B, so we're going with his choice, since that shouldn't matter so much as long as they are properly shielded.) Here are Evan's latest renderings:

and his design document for this new board:

He's now finishing up the layout of the little cut-out boards for the photodiode front-end modules, and will send all this out for fab next week (and then of course comes the testing). And next week I'll also hand off Evan's board design to Andrew Macdonald, so that Andrew can make ALTAIR versions of these ORCASat boards (i.e. just a slight form-factor change, and importantly also adding the additional relays to switch between gain settings: ALTAIR needs the ability to have further-dimmed light sources with resulting higher PD gain, since it is only ~20 km above telescopes-to-be-calibrated, whereas ORCASat is ~400 km up, and has resultingly only the relatively brighter source settings and thus lower PD gain.)

I've now added the Python 3.8 version of the code and instructions to the AIFCOMSS Github site: https://github.com/ProjectALTAIR/AIFCOMSSwithCUPredictorTest , and student Dhwani Sutariya is now working on station-keeping algorithms for AIFCOMSS.

Radiometrix has our four SHX1-144 transceiver modules (they arrived there on Apr. 6) and is doing their firmware update that solves the BUSY output issue. They'll then test them out and send them back to us. Due to the COVID-19 situation in the UK, they've been taking a while. Very fortunately, the COVID situation is slowly starting to improve in the UK (although everyone is of course very wary of a likely second wave). I asked them about the status a few days ago, and they replied that they will hopefully be able to do this next week. We've also been doing more connecting up and testing out of our two new 144 MHz Raveon M8S data modem transceivers here in Victoria:

After checking them out with Raveon's Windows-based Radio Manager software, I've started to connect the radios up to Arduino Megas -- in the next few weeks I'm planning to get them talking to one another, and then I'll check out their effective ranges.

Once we get those 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:

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 - 2020-08-06