GPSDL Data Set
Karl Upton May 2009
It took me about a dozen launches to create a procedure to prep the rocket and datalogger to successfully record data. Of course, this all didn't take place in one day.
The g forces involved are greater than 4.5 gs during liftoff. To put this into perspective, an F-16 fighter pilot experiences about 5 gs at takeoff. These tremendous forces will momentarily disconnect the JST power supply plug, which would give me anywhere from 0 to 5 seconds of data before momentarily disconnecting which resets the micro-controller and no useful data would be recorded from that point on. I didn't know this was the problem initially, but after a little figuring I decided to epoxy the positive and negative wires where they enter the JST connectors on the battery end and the PCB end. This seems to have solved the problem for now, but a better power supply connection is on the drawing table.
The g forces involved are greater than 4.5 gs during liftoff. To put this into perspective, an F-16 fighter pilot experiences about 5 gs at takeoff. These tremendous forces will momentarily disconnect the JST power supply plug, which would give me anywhere from 0 to 5 seconds of data before momentarily disconnecting which resets the micro-controller and no useful data would be recorded from that point on. I didn't know this was the problem initially, but after a little figuring I decided to epoxy the positive and negative wires where they enter the JST connectors on the battery end and the PCB end. This seems to have solved the problem for now, but a better power supply connection is on the drawing table.
Now that I had the hang of recording some data, I could interpret which would be useful or not. It seems the only reliable data recorded is the latitude, longitude and bearing data points. The speed and altitude are not reliable,--GPS data is notorious for this. The latitude, longitude and bearing data points alone are an awesome addition to a rockets dataset. There are other more reliable methods for speed and altitude.
First 15 seconds of data:
UTCtime, knots, altitudeMeters, numSats, bearing, latitude, longitude
19:12:40, 0.0, 1, 7, 43.5, 4002.3267, -7838.2576
19:12:41, 2.0, 1, 5, 42.3, 4002.3269, -7838.2571
19:12:42, 2.0, 11, 4, 23.6, 4002.3282, -7838.2568
19:12:43, 2.0, 3, 5, 71.5, 4002.3287, -7838.2505
19:12:44, 2.0, 1, 6, 77.6, 4002.3292, -7838.2448
19:12:45, 2.0, 1, 4, 69.2, 4002.3303, -7838.2435
19:12:46, 2.0, 1, 6, 54.4, 4002.3349, -7838.2376
19:12:47, 2.0, 1, 7, 29.4, 4002.3412, -7838.2381
19:12:48, 2.0, 1, 7, 17.0, 4002.3445, -7838.2398
19:12:49, 2.0, 1, 7, 357.3, 4002.3488, -7838.2450
19:12:50, 2.0, 1, 7, 347.4, 4002.3546, -7838.2496
19:12:51, 4.9, 1, 7, 27.2, 4002.3582, -7838.2536
19:12:52, 6.3, 1, 6, 36.2, 4002.3639, -7838.2529
19:12:53, 6.3, 1, 7, 55.2, 4002.3643, -7838.2499
19:12:54, 6.3, 1, 7, 58.5, 4002.3654, -7838.2469
19:12:55, 6.3, 1, 7, 75.0, 4002.3647, -7838.2450
The entire 2 minute and 22 second flight dataset is listed below as an Open Office .ods spreadsheet for download. There is also a .csv file which is specifically formatted so all the datapoints can be mapped out for free at www.gpsvisualizer.com
First 15 seconds of data:
UTCtime, knots, altitudeMeters, numSats, bearing, latitude, longitude
19:12:40, 0.0, 1, 7, 43.5, 4002.3267, -7838.2576
19:12:41, 2.0, 1, 5, 42.3, 4002.3269, -7838.2571
19:12:42, 2.0, 11, 4, 23.6, 4002.3282, -7838.2568
19:12:43, 2.0, 3, 5, 71.5, 4002.3287, -7838.2505
19:12:44, 2.0, 1, 6, 77.6, 4002.3292, -7838.2448
19:12:45, 2.0, 1, 4, 69.2, 4002.3303, -7838.2435
19:12:46, 2.0, 1, 6, 54.4, 4002.3349, -7838.2376
19:12:47, 2.0, 1, 7, 29.4, 4002.3412, -7838.2381
19:12:48, 2.0, 1, 7, 17.0, 4002.3445, -7838.2398
19:12:49, 2.0, 1, 7, 357.3, 4002.3488, -7838.2450
19:12:50, 2.0, 1, 7, 347.4, 4002.3546, -7838.2496
19:12:51, 4.9, 1, 7, 27.2, 4002.3582, -7838.2536
19:12:52, 6.3, 1, 6, 36.2, 4002.3639, -7838.2529
19:12:53, 6.3, 1, 7, 55.2, 4002.3643, -7838.2499
19:12:54, 6.3, 1, 7, 58.5, 4002.3654, -7838.2469
19:12:55, 6.3, 1, 7, 75.0, 4002.3647, -7838.2450
The entire 2 minute and 22 second flight dataset is listed below as an Open Office .ods spreadsheet for download. There is also a .csv file which is specifically formatted so all the datapoints can be mapped out for free at www.gpsvisualizer.com
I am working on an inertial altitude formula which will sum the FPS traveled every second taking into account the slope of the rockets flight via its heading data points. I will need a pressure gauge to verify the accuracy of my formula, but so far so good.
In rocketry, you have to extract every gram of performance out of every part. I have only parsed two sentences available from the mighty GPS satellites; GPRMC and GPGGA. There are 2 other NEMA sentences available for this receiver to parse from, which will be looked into later this month. Off the top of my head, I think the only useful data left to extract is the HDOP and VDOP (horizontal/vertical degree of precision) which just indicates the degree of accuracy on a scale from 1 to 30, the lower the number the greater the latitude and longitude accuracy.
In rocketry, you have to extract every gram of performance out of every part. I have only parsed two sentences available from the mighty GPS satellites; GPRMC and GPGGA. There are 2 other NEMA sentences available for this receiver to parse from, which will be looked into later this month. Off the top of my head, I think the only useful data left to extract is the HDOP and VDOP (horizontal/vertical degree of precision) which just indicates the degree of accuracy on a scale from 1 to 30, the lower the number the greater the latitude and longitude accuracy.
As I started this project I assumed that GPS data would be the “know all” of data that could be collected from a rockets flight, but the reality is somewhat different.--In fact the latitude, longitude and bearing points are the basis from which the other data points within the GPS sentence are derived. For example, the speed is calculated by how much time passes between each latitude/longitude point collected during flight. This is a good example of data fusion. The next step for my datalogger will be the addition of a temperature and humidity gauge and I hope to replace the $17 accelerometer switch that only trips the datalogger to record data and nothing else, with a $5 single axis 50g accelerometer that will not only replace the accelerometer switches purpose, but also reliably record the rockets speed and g forces throughout the flight. A digital barometric air pressure gauge is also being ordered to record accurate altitude data. This should keep me busy for awhile!
gpsvisualizer6may09launch6.csv | |
File Size: | 7 kb |
File Type: | csv |
6may09launch6.ods | |
File Size: | 16 kb |
File Type: | ods |