HAB Data From a Recent Flight

DCIM100GOPROHAB Data from 37km Flight

Recently I published a story on a High Altitude Balloon (HAB) flight I help with for my friend Andy from Melbourne. I was asked about the data collected.

The flight data was only stored from transmissions from the Payloads on the balloon. The payload did not carry a recording device for such data. There were two sets of data returned. RTTY on UHF frequencies and HAM radio APRS. APRS relies, like RTTY, on a number of stations picking up the transmissions and sending the resulting data to the network for storage and display (maps) on a server via the Internet.

Simply this post is to display the data collected and help decode the data. I have not cleaned up the results. They are simply in Text and Word (Docx) format.

Andy Flight 20140208 Text File

Sorry about the formatting in the above file. I will try and fix that shortly, but it does not matter. The formatting is only in the legend for the data.

Andy Flight 20140208  Word File (docx)

This from the data file:

This is the breakdown of the raw HAM Radio APRS data strings. I have chosen the first line of APRS data as an example:

Server Date                             2014-02-08

Server Time                             00:43:06 UTC

Call-sign of the balloon:          VK3YT-11>APRS,WIDE1-1,WIDE2-1,qAR,VK3YT-7    (including the APRS data and call sign of the relay station if applicable)

Beacon TX time                       004300h (time of transmission from the payload)

Latitude and Longitude           3532.44S/14456.90E

Course                                    O052/    Note “O” + course in degrees “052”

Speed                                      000/   knots

Altitude                                     A=000314   feet above sea level

Packet number                        143  – starts at “1” with the first packet of data and increases with each packet.

After this point, the data strings are determined by the user / builder of the tracking unit and spaced by commas. This unit is configured with the following:

Number of satellites                   9

GPS lock (3D)                            3

Navigation Mode                        6     Will work over 60,000 feet

Not used                                    0.0,0.0,

Volts (mV) of Battery                  3296   Note, the battery voltage falls over time and with temperature. The voltage increases as the battery warms before landing

The first few APRS packets of data transmitted every 36 seconds by the tracker:

2014-02-08 00:43:06 UTC: VK3YT-11>APRS,WIDE1-1,WIDE2-1,qAR,VK3YT-7:/004300h3532.44S/14456.90EO052/000/A=000314,143,9,3,6,0.0,0.0,3296
2014-02-08 00:43:42 UTC: VK3YT-11>APRS,WIDE1-1,WIDE2-1,qAR,VK3YT-7:/004336h3532.44S/14456.90EO052/000/A=000318,144,10,3,6,0.0,0.0,3296
2014-02-08 00:44:18 UTC: VK3YT-11>APRS,WIDE1-1,WIDE2-1,qAR,VK3YT-7:/004412h3532.44S/14456.90EO052/000/A=000318,145,9,3,6,0.0,0.0,3296
2014-02-08 00:44:54 UTC: VK3YT-11>APRS,WIDE1-1,WIDE2-1,qAR,VK3YT-7:/004448h3532.44S/14456.90EO052/000/A=000318,146,9,3,6,0.0,0.0,3296
2014-02-08 00:45:30 UTC: VK3YT-11>APRS,WIDE1-1,WIDE2-1,qAR,VK3YT-7:/004524h3532.44S/14456.90EO052/000/A=000318,147,9,3,6,0.0,0.0,3296  (launch)
etc

 

UpLift-1 Raw Data 28th Dec 2011 (Archives)

WotzUp_Black_logo.135x100.jpg*** Retrieved from Archives ***

UpLift-1 Flight Data 2011-12-28

I have already detailed the top level science that is easily seen from the data returned by radio telemetry from the flight. The radio link returns data approximately every 20 seconds and it has a variety of information as described previously. There are a few plots missing from the start and end of the flight as the tracking system only 863worked when the receivers could see the balloon. We were effectively over the radio horizon due to the distance from the receivers – much like a light house cannot light the ocean around it unless it is on a high headland. There are also 3 plots missing during the 2.5 hour flight. I have added these in to smooth out the plots, but the estimations are all in red. I have not tried to extrapolate data from the landing as I was not present to see the course it took.

The Database information is available in metric form and not imperial. You will need to convert that yourself, but that is very easy.

You can download the database here for educational purposed and similarly any photos are available for education purposes, but are copyright – Robert Brand 2011

CLICK HERE to DOWNLOAD the DATABASE

The file contains both flight data and graphs as used in the posts on this website re UpLift-1′s flight. There is also a list of photograph numbers. Many were unusable due to sun, glare, direction of the photo, etc. All photos indicated with a “1′ are available on this website in subsequent posts.

As far as position accuracy is concerned, the data from the telemetry also contain a parameter called HDOP. Firstly let’s look at DOP:

The following information is from http://gpsinformation.net/main/dopnontech.htm

Dilution of Precision

The DOP factor is used in a very simple equation:

SD(position) = DOP * SD(inputs)

This means that the standard deviation of the position is simply the standard deviation of the inputs multiplied times the DOP factor. Of course, this formula isn’t as simple as it looks, since for GPS a multidimensional solution is required, and therefore matrix mathematics is used. But the idea is good.

One interesting thing about DOP is that it does not depend on the anything that cannot be predicted in advance. It only depends on the positions of the GPS satellites relative to the GPS receiver’s location. The satellite positions can be calculated in advance, so you can determine the quality of your GPS position fix in advance, without even using the GPS system.

Satellite geometry

DOP only depends on the position of the satellites: how many satellites you can see, how high they are in the sky, and the bearing towards them. This is often refered to as the geometry. The satellites move, so the geometry varies with time, but it is very predictable.

HDOP = Horizontal Dilution of Position

HDOP is horizontal DOP. It is one component of the total DOP. Others are VHOP for Vertical DOP, PDOP for 3D positions, TDOP for time, and GDOP for geometic DOP. Altogether they =DOP.

UpLift-1  was outdoors and the receiver facing the sky with only a layer of bubble-wrap and Styrofoam that had already been tested for GPS integrity. It offered no apparent impediment to GPS signals. In fact the entire flight was a DOP=1. This is the lowest error estimate and means the horizontal position information was estimated to be very accurate. It has not been included with the figures. The vertical position also appears to be accurate with the repetition of the data and the expected rates of slowing on descent. The smoothness of the curves attests to the quality of the results.