Telecon tomorrow (Thursday) @ 5 pm Eastern time

Hi all!

Telecon tomorrow (Mar. 24 in North America, Mar. 25 in Australia) at the regular time: 5 pm Eastern (2 pm Pacific, 11 am Hawaii, 22.00 European, 8 am Eastern Australia). Andrew Macdonald now has good clock signals with proper timing being generated for the ALTAIR photodiode readout / transimpedance amplifier boards, and he's currently set up to begin to get readout data from the first of those three boards with photodiode (and also with picoamp source pulse) input. I have some new results on simulation of integrating sphere output using MEEP (https://meep.readthedocs.io/en/latest/), and also some more progress has been made with operation of the two Raveon M8S 144 MHz transceiver boards. 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 the progress report and plots 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

-- Justin Albert - 2022-03-23

Hi all,

My apologies for the delay! -- here's the update on recent ALTAIR balloon work, minutes of the meeting 2 weeks ago on Mar. 10 (attendees Liviu Ivanescu [Sherbrooke] and me -- Arnold was away then, but will likely be back today!), and a reminder of the telecon in 20 minutes(!) from now:

First, a quick reference to a non-ALTAIR, but related, brief paper -- Dima Budker (Mainz), Hossein Sadeghpour (CfA), and I published a short invited "Research Highlight" in the new Natural Sciences journal:

https://onlinelibrary.wiley.com/doi/full/10.1002/ntls.20220003

on the related topic of a future laser photometric ratio star (LPRS) utilizing excitations of sodium atoms in the upper atmosphere to produce a light source at both 589 nm and 820 nm, having a very precise 1:1 ratio between the 589 nm and 820 nm light due to the fact that a single cascade de-excitation produces both of the two wavelengths. Natural Sciences has chosen this as their cover article for their upcoming April issue, and created this nice cover illustration for it:

The April issue should be out by the end of the next week.

Now, on to ALTAIR: Andrew Macdonald has made good progress over the past couple of weeks with our three fabricated ALTAIR photodiode readout / transimpedance amplifier boards and their clock generation/distribution mini-board. Here's an oscilloscope screen capture from Andrew at the end of this past week showing the clock signal (working basically as it should, but with a little more ringing than Andrew would have liked, and which he has since reduced) of the clock signal from the clock mini-board:

and here's Andrew's setup for doing combined testing of the clock board and the photodiode readout board itself, now that the former is producing good clock signals:

Andrew is now working on getting actual readout data from the photodiode readout board, with photodiode (and also with picoamp source pulse) input -- and he hopes to have some plots of that (and some info on linearity and noise) by next week!

I've done a bit of work on MEEP (https://meep.readthedocs.io/en/latest/) finite-difference time domain (FDTD) simulation of integrating sphere output. The following animated GIF:

shows the z-component of the electric field in a tiny "integrating sphere" (with reflective aluminum walls -- I haven't figured out yet how to make rough surfaces that would simulate the approximately-Lambertian interior surface of an integrating sphere) with 638 nm light within it and a single exit port at the bottom (there is no entrance port for the light here -- the laser light is "magically" generated within the interior of this sphere). The diameter of this simulated sphere is only 8 microns (i.e. about 62500 times smaller than the 2" ID spheres that we use). The first question is why not make the sphere larger -- i.e. more similar to the spheres that we use? Unfortunately, this tiny 8 um sphere is already fairly computationally expensive to simulate -- and nominally, simulating a 2" integrating sphere in MEEP would be totally hopeless. But, even simulating a teeny sphere may give us useful info -- e.g. I still need to plot the output distribution in the far field from this simulated teeny sphere to see if it is perfectly cosine, or if it deviates from that at all. And there may also be ways that we can extrapolate the sphere to larger sizes (and somewhat more complex geometries). Hopefully I'll have some more on that in 2 weeks! Anyway, here are a few more nice images and animations of the tiny sphere simulation:

The two 144 MHz Raveon M8S data modem transceivers are still here in my office (together with the LiPoly batteries that power them), and hopefully this weekend I will get a chance to test Colton Broughton's most recent code updates for them, which can be found in:

https://particle.phys.uvic.ca/~jalbert/ALTAIR_M8S_Colton8dec21/

(as compared with his older code within https://particle.phys.uvic.ca/~jalbert/ALTAIR_M8S_Colton17nov21/ ).

Colton Broughton, Sarah Alshamaily, and Will Stokes have also completed installing AIFCOMSS ( https://github.com/ProjectALTAIR/AIFCOMSSwithCUPredictorTest ) on their laptops. I've updated AIFCOMSS to work with the recent Cesium v1.83, as well as the instructions, and they all report success with this update and those instructions. The next two things that we know most definitely will need updating (or, rather, creating) are the station-keeping software for AIFCOMSS, and the online command-handling within the onboard Arduino software -- and I'll also be working on those over the next 2 weeks.

Regarding the latest news on our four Radiometrix SHX1 144 MHz transceiver modules that were returned to us from Radiometrix (following their firmware update to fix the BUSY output):

and the problems that Colton found with them (i.e., that of the 12 radio TX to radio RX permutations between those 4 boards, only 3 of the 12 permutations work, 3 of the other permutations give spotty connections -- e.g. only around 1 out of every 5 characters gets successfully transmitted -- as if one is transmitting and the other is receiving on neighbouring channels, but not the same channel..., and the remaining 6 permutations do not successfully receive any transmitted characters) -- we sent an e-mail to Radiometrix to ask about this about 6 months ago. They then sent back an e-mail a week later asking for more information, and Colton replied to them the next day providing the info (just a query about what logic voltages we were using -- we've being using 5V TTL from our Arduino Megas). Radiometrix has not replied to us since that e-mail reply sent to them 24 weeks ago, and thus I pinged them 22 weeks ago to follow up, and again 17 weeks ago -- and Radiometrix hasn't replied to those yet either. I will be pinging Radiometrix on this yet again next week.

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

-- Justin Albert - 2022-03-24