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AMSAT CubeSat Simulator Hack Chat

Making sure your bird will fly

Wednesday, December 4, 2019 12:00 pm PST Local time zone:
Hack Chat
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Alan Johnston will join us for the Hack Chat on Wednesday, December 4 at noon PST.

Time zones got you down? Here's a handy time converter!

Join Hack ChatFor all the lip service the world's governments pay to "space belonging to the people", they did a pretty good job keeping access to it pretty much to themselves for the first 50 years of the Space Age. Oh sure, private-sector corporations could spend their investors' money on lengthy approval processes and pay for a ride into space, but with a few exceptions, if you wanted your own satellite, you needed to have the resources of a nation-state.

All that began to change about 20 years ago when the CubeSat concept was born. Conceived as a way to get engineering students involved in the satellite industry, the 10-cm cube form-factor that evolved has become the standard around which students, amateur radio operators, non-governmental organizations, and even private citizens have designed and flown satellites to do everything from relaying ham radio messages to monitoring the status of the environment.

But before any of that can happen, CubeSat builders need to know that their little chunk of hardware is going to do its job. That's where Alan Johnston, a teaching professor in electrical and computer engineering at Villanova University, comes in. As a member of AMSAT, the Radio Amateur Satellite Corporation, he has built a CubeSat simulator. Built for about $300 using mostly off-the-shelf and 3D-printed parts, the simulator lets satellite builders work the bugs out of their designs before committing them to the Final Frontier.

Dr. Johnston will stop by the Hack Chat to discuss his CubeSat simulator and all things nanosatellite. Come along to learn what it takes to make sure a satellite is up to snuff, find out his motivations for getting involved in AMSAT and CubeSat testing, and what alternative uses people are finding the platform. Hint: think high-altitude ballooning.

  • Hack Chat Transcript, Part 2

    Lutetium3 days ago 0 comments

    alan.b.johnston12:33 PM
    FSK is a Fox-1 emulation mode, also known as Data Under Voice or DUV

    alan.b.johnston12:34 PM
    The BPSK mode is for Fox-1E (to be launched in 2020) and HuskySat-1 1200 bps

    J12:34 PM
    ah yeh can see the frequency jump now

    J12:34 PM
    (must be lagging a tad)

    Casey Halverson12:35 PM
    This LoRa FossaSat-1 will be interesting.

    Casey Halverson12:35 PM
    not to talk about another satellite ;)

    alan.b.johnston12:35 PM
    Here's the waterfall with the 3 different modes

    steve.bossert12:35 PM
    i am looking forward to FossaSat-1 more than you know :)

    alan.b.johnston12:35 PM

    Joe Latrell12:35 PM
    @steve.bossert - me too!

    alan.b.johnston12:35 PM
    Yes, LoRA is cool!

    Casey Halverson12:35 PM
    I have my 1 watt LoRa radio waiting for it ... with a Yagi ;)

    Joe Latrell12:36 PM
    @alan.b.johnston - how did you go about building out the ground station you are using?

    steve.bossert12:37 PM
    An SDR I feed into spyserver is set to default to 911.25 Mhz and let others near my experiment with decoding Lora and other bursts down in 70cm.... back on subject now :) I would be interested to see the sim run Lora if possible (not today, some other time)

    alan.b.johnston12:37 PM
    My Web SDR ground station is an old Ubuntu laptop, running openwebrx with an RTL-SDR plugged into it

    steve.bossert12:37 PM
    antenna alan?

    J12:37 PM
    What is good about LoRa FossaSat-1? (first I've heard of it)

    alan.b.johnston12:37 PM
    I use remote.it to open a port to 7300 so that it is accessible outside my network, just while I do this demo

    alan.b.johnston12:38 PM
    My antenna for this demo is just a rubber duck!

    alan.b.johnston12:38 PM
    I also have a tape measure Yagi hanging out my office window

    alan.b.johnston12:38 PM
    I'm helping the CubeSat Club members here build a Lindenblad - it is almost finished!

    steve.bossert12:39 PM
    i bet your sim could also be helpful for those looking to test payloads for balloons.

    alan.b.johnston12:39 PM
    LoRA modulation is spread spectrum, so requires radically lower power levels or simpler ground stations. Could be a game changer for future satellite low bit rate communication

    alan.b.johnston12:39 PM
    Yes, it could be used with balloons.

    J12:40 PM
    Ah I see

    alan.b.johnston12:40 PM
    If you look at the Voltage tab on this graph https://docs.google.com/spreadsheets/d/1LB44eiODrIT9o9FA2rvRszA-hIo7iovx9XdL21Ge1vI/edit#gid=1311478884 you can see how the voltage dropped before

    alan.b.johnston12:40 PM
    When it went below 8V, the Pi automatically shut down

    alan.b.johnston12:41 PM
    Here's a screenshot of the voltage telemetry from before

    alan.b.johnston12:41 PM

    alan.b.johnston12:42 PM
    Here's the current graphs

    J12:42 PM
    8V... is there a regulator there dropping below 5v?

    alan.b.johnston12:42 PM

    alan.b.johnston12:42 PM
    Anyone receiving the satellite? ;-)

    J12:42 PM
    (probs a daft question I only wondered since I have my zero on a 5v usb

    alan.b.johnston12:43 PM
    Yes, I use a 9V NiMH battery

    alan.b.johnston12:43 PM
    So it isn't good to discharge it all the way down to 5V

    Desu Ravi Kumar joined  the room.12:43 PM

    J12:43 PM
    ah gotcha

    alan.b.johnston12:44 PM
    I have a battery charging board made by MoPower that handles the charging

    nitinvaishya000 joined  the room.12:44 PM

    alan.b.johnston12:44 PM
    So AMSAT has built 4 loaners that can be shipped to a classroom anywhere

    Joe Latrell12:44 PM
    Not seeing the sat via the proxy. Keep getting a timeout.

    alan.b.johnston12:45 PM
    Message me offline if you are a teacher or know a teacher who would like to show it off in the classroom

    nitinvaishya00012:45 PM
    Hello

    alan.b.johnston12:45 PM
    Here's the web sdr link http://proxy22.rt3.io:38006

    alan.b.johnston12:45 PM
    Make sure it isn't trying https - that won't work!

    alan.b.johnston12:45 PM
    Oh, and SatNOGS has a Dashboard for the Simulator, too! :-)

    nitinvaishya00012:45 PM
    I need help

    alan.b.johnston12:46 PM
    SatNOGS Dashboard: https://dashboard.satnogs.org/d/VesVjq6mk/amsat-cubesat-simulator?orgId=1&from=1563974788355&to=1563976686873

    alan.b.johnston...

    Read more »

  • Hack Chat Transcript, Part 1

    Lutetium3 days ago 0 comments

    alan.b.johnston11:58 AM
    Hi everyone!

    Josh11:58 AM
    Hi Alan

    RoGeorge11:58 AM
    You guys don't have audio?

    :o)

    Dan Maloney11:58 AM
    Hi @alan.b.johnston! We'll kick off in just a minute or two

    Applied Ion Systems11:59 AM
    hi alan, looking forward to the chat!

    Spehro joined  the room.11:59 AM

    Joe Latrell joined  the room.12:00 PM

    Joe Latrell12:00 PM
    Good Afternoon everyone.

    Dan Maloney12:01 PM
    OK everyone, let's get started! Thanks for your patience with the lack of Hack Chats during the Supercon break. But we're back today with a great one - @alan.b.johnston is here to tell us all about simulations for CubeSats.

    Alan - can you tell us a little about your background and how you came to the CubeSat world?

    JamesDavid joined  the room.12:01 PM

    Dan Maloney12:01 PM
    And welcome, BTW!

    alan.b.johnston12:01 PM
    Thanks, Dan. Sure! Welcome everyone! Thanks for joining

    alan.b.johnston12:02 PM
    I got my start in electronics and radio as a teenager when he got his ham radio extra class license, call sign KU2Y. He built satellite antennas, and tracked satellites, and communicated using the AMSAT OSCAR-8 satellite. Since 2018 he has served as AMSAT’s Vice President for Educational Relations. I am also an Associate Teaching Professor of Electrical and Computer Engineering at Villanova, University.

    alan.b.johnston12:02 PM
    The AMSAT CubeSat Simulator is a functional model of a satellite for use in education and demonstrations. A proof-of-concept prototype was shown at the 2018 AMSAT Space Symposium, and the CubeSat Simulator program was officially “launched” at the AMSAT Update Forum at Hamvention 2019 in Dayton, OH.

    alan.b.johnston12:02 PM
    It is Raspberry Pi Zero W-based, 3D-printed frame structure, functional model of a “1U” CubeSat and is designed to act, as reasonably as possible, as though in Low Earth Orbit (LEO).

    alan.b.johnston12:03 PM
    Runs on rechargeable “flight” NiMH battery power and body-mounted solar cell panels.

    alan.b.johnston12:03 PM
    Transmits housekeeping telemetry on the 70 cm band using AO-7 format using AFSK AX.25 modulation

    steve.bossert joined  the room.12:03 PM

    alan.b.johnston12:03 PM
    Lots of info at http://cubesatsim.org

    alan.b.johnston12:03 PM
    I have a live demo running in my office right now

    alan.b.johnston12:03 PM
    I'll try pasting a photo, see if it works

    RoGeorge12:04 PM
    you need to click the image button first

    Dan Maloney12:04 PM
    So that's interesting - do flight-qualified CubeSats used NiMH batteries routinely? Guess I always assumed something more "modern" like LiPo

    alan.b.johnston12:05 PM

    alan.b.johnston12:05 PM
    Lets see if that worked!

    alan.b.johnston12:05 PM
    Yes, the battery design choice always generates questions :-)

    Paul E Wogg joined  the room.12:06 PM

    Joe Latrell12:06 PM
    So what battery did you use and what is the total system power usage?

    alan.b.johnston12:06 PM
    Most CubeSats today use LiPO, yes, and they provide much higher capacity than nickel metal hydride

    alan.b.johnston12:06 PM
    I chose the NiMH for two reasons:

    alan.b.johnston12:06 PM
    1. The simulator was designed to be easy to ship to classrooms and events. So being able to answer "No" to the LiPO question when shipping is big benefit

    Chinna12:06 PM
    Hi Alan, great introduction. I am relatively new into the satellite things. Your Cubesat simulator looks great. I would like to build a even simpler cube sat. Is it possible to build one with just some kind of Arduino (I mean one Uno, not too many like Ardusat) and an antenna that is connected to RX and TX ports of the Arduino??

    Josh12:07 PM
    Is it possible to purchase 1U frame are there instructions(?) for a more realistic 1U frame if I don't want to 3D print?

    alan.b.johnston12:07 PM
    2. I like to show the battery discharging and charging during demos, and LiPO batteries take too long! With a low capacity NiMH battery, you can see it change voltage over a few minutes

    alan.b.johnston12:08 PM
    Which is great for demos....

    Read more »

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