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TRSI Satellite Devkit

It´s a satellite with a launch-ready geometry which can be sent into orbit for a reasonable price. It will be open. Launch 2014/15

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This project was created on 04/30/2014 and last updated 4 days ago.

Details

In 2013, I have built a satellite (WREN) which is now in orbit. There have been many hard issues to solve on the way.

This year, I am developing a simple and affordable satellite which is ready to be sent to orbit for an affordable price compared to similar sized satellites. It´s geometry complies with the PocketQub standard which is allowed to be sent to orbit as a secondary payload.

I will provide information about the satellite including schematics and source codes during the development and make it fully open hardware/open source after launch.

<Information video will follow>

TRSI is a demoscene group consisting of creative coders, musicians, graphicians and engineers who have been making cool stuff for over 30 years now.

On the WREN satellite, we put a demo for the Commodore64 computer which was downloadable from the orbit. The video is here:

http://www.youtube.com/watch?v=NLrF_2aS_hI

This time, we will offer sceners and nerds the possibility to send a 16x16 pixel logo from space to earth. And you will need no special decoder to see it.

In fact, all you need is a DVB-T Stick and a self-made antenna, alltogether costs less than 30 USD. 

You can command the satellite with an amateur radio connected to a directional antenna.

The logos and telemetry are written directly into the frequency spectrum (Hellschreiber), so everyone including governmental organizations as well as Vulcanians and Klingons will be able to see it in the 470 MHz frequency band.

I will offer devkits and ready-to-go milled parts when you don´t want to solder yourself.

There´s  more to come and for sure it will be a fun challenge.

In addition to the project log I want to give some information how to overcome some hardware issues and how to interface some peripherals with an ARM controller, which may be useful also for earth-based projects.

Cheers, Paul

Here is some preliminary information about small satellites and the actual TRSI project.

http://www.youtube.com/watch?v=DQ8eB_FORLo&t=45m30s

PS: There is another great use for this device - which is quite earth based. The board is designed for harsh environment and able to communicate over distances more than 1000km. And it gets his power via solar cells. You can for example  put it somewhere in the forest to get pictures of some wild animals. And you will be able to receive the signal from as far as you can see.

A swarm of them can serve as a wide range communication network. Or you put it inside a model rocket or a drone, whatever your fantasy tells you.

Components
  • 1 × LPC1114FHN33 Microprocessors, Microcontrollers, DSPs / ARM, RISC-Based Microcontrollers
  • 1 × TCM8230MD Camera 640x480 RGB
  • 1 × MPU-9150 Semiconductors and Integrated Circuits / Misc. Semiconductors and Integrated Circuits
  • 1 × SI4432 mitters, Receivers and TransceiversRF, IF, RFID, ZigBee Semiconductors and ICs / Trans
  • 2 × LTC3105 Power Management ICs / Switching Regulators and Controllers
  • 1 × LPC Link Low cost JTAG for LPC Xpresso
  • 2 × IXYS SLMD 600 Solar cell
  • 1 × Chickenfood not mentioned here... See the BOM

Project logs
  • TX Frequency vs. Temperature

    5 days ago • 0 comments

    Crystals have some temperature dependent drift which results in a significant change of your TX frequency.

    It´s very important, especially in space, to stay inside your permitted frequency range.

    If you don´t take care of it, you will probably have to deactivate the satellite or you may even get problems with governmental institutions.

    Today I made measurements to determine this temperature dependence.

    The temperature drift follows a cubic curve that usually looks like this. It depends on the cut of the crystal.

    The SI4432 radio chip has a built in temperature sensor with 8 bit resolution. It is by nature placed very close to the crystal, so it should display the crystal temperature quite accurately.

    So here are the values I got:

    The graphics shows the TX frequency (Y-Axis) over the temperature as the 8 bit ADC value from the temperature sensor (X-Axis).

    X Scaling: X-40 <-> T in °F

    Y Scaling: Y*100 Hz

    It shows that the dependency in the operational temperature range is very linear.

    Without compensation, the drift range would be 5 kHz between 60°F-140°F (15°C-60°C). 

    I´ll need to go to below zero to confirm this chart.

  • Spurious Emissions Measurements

    a month ago • 0 comments

    There are strict rules for spurious emissions according to space stations (a pocketqub satellite is a space station by law).

    The unwanted emissions must be attenuated by at least 43 dB + 10*log P (TX power in Watts)

    The document of the ITU regulations can be found here: http://life.itu.int/radioclub/rr/ap03.htm

    Here is a first test with the spectrum analyzer. Note that the PCB is not covered yet, so the attenuation will be a bit better with a completely assembled satellite:

    The attenuation of the 2nd harmonic is about 50 dB, looks good :)

    The block diagram of the amplifier IC shows a build in low-pass filter, so it seems that I don´t need to append a filter before the antenna. Unfortunately there is no further information given in the datasheet. Anyway, the result is promising. Before assembling the flight model I will ask for a deeper test at the university.

  • 1000mW Power Amplifier

    a month ago • 0 comments

    Got the PA working with the radio module.

    The datasheet of the amplifier is very thin, in fact I had to guess many things how to make it work. But instead of asking the supplier, I just tried. Here is a screenshot of the application as given in the datasheet.

    Pretty simple connection and seems convenient to use.

    Pin 24 is called VREG, which implies the output of an internal voltage regulator.

    But thats not true. It is the input for the amplifier´s bias. Without setting it to a certain voltage, there will be no valuable output power at PIN5.

    It turns out, that my IO supply voltage of 2.8V gives a good bias for the amp. It sets the Q-point to a current of 30mA with no RF at input and goes over 600mA when RF is fed in.

    I connected C_TX (switches the PA to transmit mode) directly with PIN24 and it works fine.

    Unfortunately I didnt trace PIN24 on the PCB, so I had to hack it up a bit. I cut the pad for PIN24 off the PCB with a sharp knife and soldered a thin wire to the Pad of the amp before fixing it on the PCB with hot air. Luckily it worked.

    As expected, there is some ripple now on that Pin, as seen in the osci screenshot, but it´s not critical - the PA works as intended.

    Just don´t touch the tip of the antenna while in TX mode - feels funny in case you like pain - now I know why it´s called "hot end" :-D

View all 13 project logs

Discussions

Adam Fabio wrote a month ago null point

It's not often that you get to see the work of someone who already has hardware in space! Thanks for entering The Hackaday Prize! Can't wait to see where you go with this satellite devkit!

Are you sure? [yes] / [no]

movax wrote a month ago null point

Thank you. I´ll keep posting the progress. I got the new PCB produced meanwhile so there will be more information soon.

Are you sure? [yes] / [no]

Eric Evenchick wrote 3 months ago null point

Neat project, and great logs. Didn't know you could get signal from something like the Si443x in space! How much does it cost to actually take one of these to orbit?

Are you sure? [yes] / [no]

movax wrote 3 months ago null point

Thanx. For a full sized pocketqub, you will need about 15000 Euro just for the launch. But even then you have to provide all the testing and safety papers. So it´s still not really affordable.
With this project I want to break the price limit by reducing the height. This sat will have a height of max 10mm which will reduce the costs to half of this by sharing the launch slot.
Technically, you could put five of these into one slot by modifying the deployer - so if the project is succesfull it might be an affordable solution.
Regarding the radio reception: WIth a 100mW transceiever and a dipole antenna on the satellite you can get a good reception during flyby of more than 40 degrees elevation with a simple antenna (no motors). I won´t use a dipole to get rid of an antenna deployment system. Instead I will use more TX power to compensate for that by adding an 1000mW PA.

Are you sure? [yes] / [no]