GSTaTS Project

Ground Station Tracking and Telemetry System

I'm a Microsoft "Dare to Dream Different" Semifinalist !!

This blog will track my progress building an tracking antenna array for my UAV.  

PNI Sensor Corporation  has provided a Really Really Accurate Heading Module for me to use in this project - A TCM3 - Wow I had no idea how good this thing was until I started playing with it - Seriously - WOW!  I cant thank them enough!  Go Buy their sensors!  Deanna@PNI just told me that two of their team are from McKinney TX too - small world.

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Aug 21 - Project Completion

The project is completed now and I;m happy I participated.  Though I didnt win the Microsoft contest, I learned more about embedded components and how they can simple meet a technical goal. Ohh and I had fun too! And I got to meet a number of smart people on the net from around the globe This was definitely a fulfilling experience.  Maybe I'll try for another design contest in 2010.

I can;t wait to the system to track a High Altitude Ballon (you listening Earl? :-) )

May 15 - Propeller Platform Swap

My development on the platform has gone well, though this hobby doesn't get the time it deserves :-).  In fact I've ported the project to my Propeller based platform as I didn't have time to finish it on the Tahoe-II. Disappointing, but realistic. I may even port further to run on the Ardupilot hardware that Chris and Jordi built. Why not reuse a solid platform! But baby steps first...

On the Propeller I have the PNI Sensor working thanks to Earl Foster.  I had an underpower issue (4v not 5v) being supplied to the TCM3 and as a result data was corrupted.  It's odd because the sensor is spec'd for 3-5v operation -- maybe its one or the other? --  In any case my error corrected, it work really accurately!

The accellerometer (MEMSIC 2125) for measuring verticle angle works great and I added a mount to the tilt arm.

Finally I've put all the serial devices into one cog (debug, GPS, & PNI compass) to cut down overhead, though I have not added the modem code to the mix yet. I might have to pull TV out to get an extra cog . I'm up to 6 of 8. 


April 14 - Motor Demo

I've posted a video demonstrating the motor controller using an L293D chip and inverter.  I'm using PWM to drive the motors which causes both a high pitch whine from the motors and is less powerful than just applying power to the motor.  Speed seems to be affected, but then again I am using a small battery rather than the 12 or 24v normal supply.  The motors can really move under full power.

Pan-Tilt Demo

March 19 Telemetry and Pointing

I also got the basic data telemetry link to work! Hooray!  I'm using the audio channel of my AV transmitter (Blackwidow AV Tx if anyone is interested) to send data.  How is such a wonder accomplished?  It's an ancient technology called a "MoDem".  Instead of buying one, I built a pair of Terminal Network Connectors ("TNCs") to convert the digital data to tones - an audio signmal that the channel can carry - and convert it back to digital at the groundstation.  Phil Pilgrim wrote a great software implementation of the Bell 202 FSK modem for the props that I am using.  Nothin' beats 1200 baud! Thats 0.0012 mbps for the kids...

I also shot a short on the device mounts I designed. They are simple three point mounts, but quite necessary to align all the sensors. I use a laser to align the three (so far) devices).

Adjustable Camera Mounts

I spent the last two weeks earning a living, so I don't have much to report on the C# front.  However, I did tryout a nifty paint job for the project mechanism. The coloring was suggested by my pal Bob who asked, "Well, what color paints to youhave?" So its Day Glow Orange and yellow reflector tape.  No I don't think the moving arm is THAT dangerous... ;-)

Feb 11 Motor Driver bread boarded

Here's the driver for the Pan and Tilt motors. I am using an L298 Dual H-Bridge which can driver 2 motors bidirectionally. Input is 6 digital lines (CC,CCW,Enable) and (UP,DN,Enable) and output is the proper voltage on the 2 pairs of motor wires.  The 5V chip can control up to 30V and 1 amp - way more than I'll use. I'm using 12V LiPos for test, but will probably use a 24V source for the final as the motors can move much faster :-) The PNI Compass and Accelerometer sensors will indicate the driver needs to be actuated until the sensor readings are acceptable in this closed loop system. ie "Turn CW until 58 degrees".

Feb 01 Adjustable Camera Mounts & Counterweight

I spent some time last night and designed a few smaller camera mounts out of 1/4"plastic I had in the shop. They allow for the base to be squarely connected to the mounting beam, but then allow individual fine adjustment of the pan and tilt. In the case of my Aiptek AHD camera, there is a large skew from parallel to correct. Next, I made a clamp mount for the Yagi antenna which was pretty straightforward. I think I'll add a laser pointer mount to help me align all the devices on the beam. I also added an arm counterweight to balance the beam load and reduce stress on the motors depending on what is mounted.

Jan 29 - Tahoe-II and Mechanical

I'm brushing up on using C# with the Tahoe-II. Some problems like making sure to add proper references for the HW, etc and that the micro kit doesn't quite include all the same components as full C# and the differences between hardware and pure software development and ... well you get the idea - but I'll get there!

I have a few old and heavy pan/tilt motor assemblies to hack into controllable units.  There is a lot of extra analog switching controls inside, but I'll gut these and use a motor controller chip to drive them. I also machined up an extension brace to let me add a several items to the tracking arm at once. Mmmm...Welding...  I put the telescope on it to test the load. it moves pretty freely. "Up" takes a little bit longer than "Down". Need a counterbalance. 

Jan 23 Unboxing PNI and Device Solutions

I received both the PNI module and the Tahoe-II development kit this afternoon. Here are the parts that I'll use to create the fun! 

I also have the rest of the RC parts and pieces for the plane and antenna out in the garage shop. Pictures will come...

Jan 15 I'm a Microsoft "Dare to Dream Different" Semifinalist !!

Fueled by the fun I am having with my PNAV project and my ADD-like inability to focus on just a single item(!), I won a slot in the Microsoft Dare to Dream Different (shouldn't that be Differently?) embedded micro controller design contest.  Cool already right? I know!!   So I am building GSTaTS - a tracking system to follow my aircraft or other sky-ward object (balloons, satellites, planets, stars, etc) and receive data if there is any available from the far end. Think of it as a Lilliputian NASA :-)

PNI Corporation has agreed to help me out in the Really Really Accurate Compass department by sending me a TCM3 Tilt Compensated Heading Module.  In order to maintain accuracy pointing, I needed a compass capable of tight and repeatable heading information. The TCM3 data will couple with the GPS data from the tracked device or calculated heading in the case of a star or satellite's location, and let me point at it.

What am I pointing? Well, I will probably have an array of pointable elements including:

  • Antenna:
    o Flat panel 2.4 GHz antenna with ~90 deg beamwidth
    o Yagi 2.4GHx antenna with ~20deg beamwidth
    o 1m parabolic 2.4GHx dish with a ~3deg beamwidth 
  • Optical (I Might combine these)
    o Digital camera
    o Aiptek AHD Video Camera 
    o Telescope - ~1.3 deg (optical) beamwidth for comparison
  • Astronomy Laserpointer ? Why not!

And I'll hope to have a few cool features using the accelerometers and touchscreen built into the development board too for manual control.