Sample text running on the Nokia 5110 LCD screen that's connected to a Raspberry Pi

I purchased a cheap Nokia 5110 from Deal Extreme it can display around 5 lines at 14 characters per line, as well as graphics.  I based my program on Andre's C code to write lines of info to the display. Here it is running sample code:

It's pretty much wired up as per his instructions.

I have connected the Adafruit Ultimate GPS to the Raspberry Pi using Gordon's WiringPi software. There is a seperate blog post with more detail on this.

The Nokia 5110 LCD screen is written to via some C code.  See my seperate blog post on this.

I have divided the GPS data into 5 sections of 757 sequential data points and given a colour to each segment (see legend).  This high lights the chrono-spacial nature of the data.  Some segments have more points/dots than others, because a lot of readings are identical and therefore lay on top of each other.

This is a GIS plot of around 9216 stationary GPS readings.  The full average was some 14m from the actual GPS position.  By just averaging GPS readings with a HDOP of less than 1.24, the average moves a bit, but not much. 

Just as a comparison, I set my iPhone 4 on the same West facing window sill and took a GPS reading (using the LogGPS App), when the error rate had dropped to +/- 5m.  I have plotted the result out in the empty block.  It too was around 14m away. 

This graph is just a graph displaying the second data run with possible Satellite counts and the number of satellites the GPS is actually using with a resultant distance error.  The distance error was worked out with using a HDOP error of 1 equalling a distance error of +/- 5m.  At around reading 1065, the large olive line spikes with a reading of +/-37.5m, when the usable satellite count gets down to 5.  A few seconds later the satellite count is back to 7 and the distance error has dropped back to +/- 5.6m.

This is plot shows the actual difference between two sequential Lat/Long readings over 9216 readings.  The Top graph shows the difference after the data from the bottom graph has been averaged out over a running 60 second period.  The bottom graph shows how much a stationary GPS reading can appear to jump around.

This is a GIS plot of some 3785 readings and slightly colour coded to show the HDOP.  Dark Green is low and light Green is a high HDOP value.  I also show where the actual GPS is located and where the everage of the reads says thinks it was.  The light blob on the right is my house, there is an empty block, then my neighbours house.  The average GPS reading is approximatly 37m from where the actual GPS sits.  I think the error is a result of it sitting in a West facing window.  North is up.

This graph is a count of the different HDOP errors.  I have used Unix CLI commands to extract the HDOP data from the text file, sort it, and then count the number of each HDOP error type.  This was collated from a small run of 3785 records(seconds) of GPS data and after the GPS unit had been up and running for quite some time.  Looking at the graph, if you said that a HDOP of 1 is equal to an error of around 5m, then a HDOP of 1.23 is equal to around 6.15m and if that accuracy was good enough for you, them around 76% of the data is equal or under that value.  See one of

The red-orange-yellow data points are the differences in metres from previous sequential lat/long reading.  Deep red is good (0m - 0.15m) to yellow, (0.67m - 0.78m).  Superimposed on top is a display of histogramed GPS HDOP with dark purple (best: 0.76 - 0.80), to light purple (worse: 0.94 - 0.99).

This also shows an outside iPhone test, where I placed it out on the fence top (green diamond) and plotted the resultant reading (lower black diamond) some 3m south of the iPhone.