[psas-avionics] Airframe launch electronics path.

fpmathew fpmathew at comcast.net
Thu Aug 28 12:44:58 PDT 2008


We had a good discussion last night, and came up with avionics options for
the airframe flight.  Which we pursue depends on time available, necessity,
and verifying actual hardware.

Maria has ordering information to buy a solid state (SD or SDHC card) DVR
(Digital Video Recorder) which we can use in-flight or on the ground.

Levels of development.

1.  ARTS2 flight computer.  This is a given.  We will use the ARTS 2 from
Ozark Aerospace for our flight computer.  It has built in accelerometer and
barometric altimeter.  We can program it to release the drogue parachute
after apogee.  We can specify how many seconds after apogee.  Apogee is
determined from the accelerometer.  The main parachute can be released after
descending to our specified altitude.  Release will be based on descent,
(not just the altitude).

The ARTS2 also logs events, acceleration and altitude into on-board Flash
which can be read into a computer serial port after the flight.  FWIW, the
unit also has a beeper that indicates status when you power it on, and after
landing.  I think it can be used as a beacon from the ground; it continues
beeping until the battery runs down.

        A.  The ARTS2.  We have two.  It needs to be tested, so we can be
confident that it will do the job.
        B.  Power requirements:
              The ARTS2 is powered by a 9V battery, It has a second battery
dedicated to powering the electric 

2.  Add a camera an on-board DVR with text overlay time stamp.  In this
addition, a camera solid state DVR are added and are independent of the
flight computer.  The DVR can record on-screen date and time overlay, plus
frame count (it's made for PIs, lawyers and Police to capture evidence.  The
camera's microphone would record the ARTS2 beeps, as well as outside sounds.

        A.  LawMate PV700 Pocket DVR.  We have one DVR in the pipeline to
                This may take a while according to Maria.
            Power:  built-in 3.7 V 1800 mAH LiIon battery.  It can supply 5V
or 12V to a camera.  
        B.  Camera.  We have two cameras, with great looking images.
            Power:  12 VDC at 250 mA.  Likely can be supplied by PV700 DVR.

3.  Add video overlay of acceleration and altitude.  This bumps up the
hardware to include am LPC2148 prototype board and the BOB4 text overlay
board.  The LPC would read flight data from the ARTS2 in real time, format
it and send it to the text overlay board.  The ARTS2 manufacturer assures me
that we can get the data -- he will send me information when he returns from
a trip.


        A.  LPC-H2148?
              Power: USB power (5VDC < 500 mA).
        B.  BOB4 -- We have two, and have demonstrated its ease of
              Power:  5 VDC at < 150 mA.

4.  Add GPS information to video text overlay.  This would use the LPC to
read data from a COTS GPS unit, and add it to the other flight data.


        A.  Select and purchase the GPS unit.
        B.  Design and build the Circular Patch Antenna for the GPS unit.
        C.  Design and build the glue electronics.
        D.  Power -- depends on the electronics.

I think we can work our way toward level 4, but launch at whatever level is
ready.  Maybe we can make several launches in pretty short order.


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