OCCAMS Feedback bits

[joshnelson_MNSGC]

In Minnesota, we've had trouble getting our OCCAMS boards to work in-flight.  We suspect that this is due to poor Iridium connection.  Is there any way to tell if the cutdown command is reaching the Iridium modem/OCCAMS board remotely?  For example, is the a sequence of bits received by the OCCAMS board that we could look for?  

Thanks

[David MSGC]

I am not as familiar with occams as some other folks and would have to look in the documentation or the arduino code to see how many pins the arduino is watching, I think it is 3. There are the output pins from the iridium modem that the arduino is watching that go high and low depending on what command was received by the modem. You could add some serial output or text out put to a file depending on what pins went high and low to see if the iridium modem received the command. When I say arduino I am talking about the microcontroller on occams, it is programmed in arduino and the arduino code for them should be in the documentation somewhere.
What other electronics do you have in the same payload as the Iridium? I saw your guys' flight last week and there were several Iridium packets missing. If you are trying to send commands at the same time iridium is not receiving packets from the modem, iridium wont be able to send commands TO your modem.

[joshnelson_MNSGC]

Thanks for the help! I'll try to play around with the arduino in the next few days, and I'll post if I have any success.

All we have in our Iridium payloads are the iridium modem, the OCCAMS control board, the antenna and the GPS (and sometimes a siren for recovery). Do you have any advice for mounting the iridium antenna? Missing packets has been a growing issue, and it definitely could have something to do with the cutdown failures we've had.

[David MSGC]

I would mount the antenna on the 3D printed mount that was part of the July kit and as shown in the July documentation. Also with cutdown make sure you are following the reset instructions per the July documentation. If it is not reset cutdown will not run. The missing packets would not have anything to do with commands getting through but it indicates there was no connection with the Iridium network, if there is poor connection with the network your commands will not go through.
Can you get cutdown to work on the ground and not during a flight?

[joshnelson_MNSGC]

I've figured out why one of our OCCAMS wasn't working, I was sending commands that were configured with the wrong IMEI. I'll fix that and give it another try.

Does the orientation of the antenna matter? Right now we have both the GPS and Iridium antennae inside of a foam box. Also do you know which of the antennae is for the GPS and which is for Iridium? (one is larger and squarer, and the other is smaller and rounded)

To answer your question, we've been able to get OCCAMS to work on the ground, but only very sporadically. We have a hard time getting a strong and lasting Iridium connection in the cities.

Dr. Flaten suggested to me that there is some website (similar to 153.90.202.26) where you can view the raw packets that are transmitted over the iridium network. Is there anything like this to your knowledge, and if so, do you think it could be used to see whether OCCAMS commands had been sent successfully?

[leviw]

Please correct me if any of this is incorrect.

Both of those antennas should point towards the sky.

When you send iridium the email with the command file attached, they send you a response like:

The following mobile-terminated message was queued for delivery:

IMEI: 300234064802840
Time: Sat Feb 11 21:33:21 2017

Attachment Filename: cutdown_100.sbd
Attachment Size: 15

The MTMSN is 22, and the message is number 1 in the queue.

If you don't get emails like that back, make sure you're sending them to the right email address.  I send them to [e-mail] with my IMEI number as the subject and the command file as an attachment.  I named my files cutdown and idle, but I don't think the name matters.

On the last line it's telling you how many messages you've sent total, and how many have not been sent through yet.  So if you send several files back-to-back or they aren't getting through, you'll see the position in the queue go up.

As far as I can tell, the position in the queue number only goes down when the payload has received the message.  Maybe someone can confirm if that's true or not, we've only sent.. well, I guess about 22 of these during tests.

[joshnelson_MNSGC]

I ran another test of our OCCAMS units yesterday and had some mixed success. I sent emails to [e-mail] as leviw described for both of our units (with the different IMEIs in the subject line, and different commands created for each IMEIs). I got back those same emails for each unit, and saw the queue remain at 1 as I continued to send emails, but only one of our OCCAMS actually spun its servo. The working unit performed flawlessly; the servo would respond to commands within 30 seconds every time. The other unit didn't respond at all (the servo would spin when I pressed the "motor" button, but when I sent commands, the servo didn't spin and the "cut" LED didn't come on). Its worth noting that I managed to find high ground where I had pretty consistently good Iridium connection. I'm going to try swapping Iridium modems with OCCAMS boards to see if I can pinpoint where the command gets lost for that unit.

[leviw]

Feb 15, 2017 13:47:12 GMT -7 David MSGC said:

Also with cutdown make sure you are following the reset instructions per the July documentation. If it is not reset cutdown will not run.

Can you provide a link to the reset documentation?  Are those pdfs on the main eclipse.montana.edu website somewhere?

I still have the usb slides on those thumb drives somewhere, and my notes from the workshop, but I want to make sure I'm not missing anything.

Edit: I looked at the pdf section for resetting the timer but I'm still not sure what it actually does.  We have never reset the timer, but we can still activate/deactivate the cutdown by sending messages to iridium.

I see a section at the bottom of the Iridium Satellite Tracker Payload pdf that says: When the switch or shunt jumper return to their safe positions, the timer begins and increments every second until the timer overflows and triggers cutdown.

Is the timer a built-in timed cutdown then, and if so, how long until it triggers?  We have never seen it trigger and I don't want our lack of understanding to accidentally cut down our payload.