The Sony GPS-CS1 is a very simple GPS device - it records your
position everywhere you go. It has no screen display, no controls,
and you can't get it to tell you where you are right now. So why
pay so much for such a seemingly less-than-useful device?
"Geotagging photographs" is the main reason. This means recording where you were when you took each photo. If you know where each photo was taken you can plot them on Google Earth, you can search geographically. If you have every wanted to say "show me all the photos I took in Glasgow" then you will like geotagging/geocoding. (OK, maybe substitute Italy for Glasgow ;-))
The principal works like this: leave your GPS switched on all day, recording the position every 15 seconds or so. Take photos as often as you like. Then when you get home you can "tag" each photo with the location it was taken. This can be done completely automatically by software which knows exactly what time the photo was taken (this is done by the camera), and compares it with the location from the GPS at that time.
Example: at 12:00 I am at the bottom of my road and switch on the GPS. At 12:05 I am half-way up my road and take a photograph; the camera writes 12:05 into a hidden part of the image file. At 12:10 I am at the top of my road and the GPS records my position. Software can read the time 12:05 from the inside the image, work out from the GPS exactly where I was at 12:05 and write the location into a hidden part of the image file. The hidden parts are known as meta-data.
Why the Sony? You can use any GPS device for the same purpose. The software is useful but the same result can be achieved with other (free) software. A Bluetooth GPS is just as small and unobtrusive. PDAs are not much larger. Regular GPS units (eg. eTrex) are better. And so on.
The reasons I chose this device are:
For the types of trips and holidays I like this makes it ideal for me. If you're going to be in a hotel each night and not likely to lose, drop, damage, or have a GPS stolen you might think differently!
It seems to take quite a while to lock up and can be quite picky about reception during this period. But when locked up its reception is fairly reasonable. The manual says it can be covered by textiles so I am hoping it can be kept in a rucksack pocket for example.
Cold start: if you turn on the GPS after travelling a long distance it can take quite some time to get a fix but this is quite normal. I've yet to measure the time it takes.
Having tried it in the top pocket of a rucksack I can say I'm pleased with the performance, it kept locked on whilst cycling and going in/out of shops (not on the bike!) and the track matched the route very closely on MemoryMap; very well in fact considering it only takes a reading every 15 seconds.
See the map to the right: the red line is the GPS track and it seems to be on the road most of the time and no more than 15 to 20m off at worst.
Details to follow... contact me for more information.
Or see a review.
You don't need a Sony camera in order to make full use of this device.
It doesn't appear to work in aeroplanes, much to my disappointment. It works on the ground but right after take-off it stops working. This is only mentioned in a short sentence in the manual after you have bought the product. "The unit may not track when you are moving at the speed of about 500 km/hour (300 miles/hour) or faster".
Sony and Other Hardware
Here I've used RoboGeo to create a Google-Earth file from my recent flight from Tokyo to London. It has plotted the route in red:
Zoom in: you can see where we flew over the Øresund Bridge (Sweden - Denmark) and I took a photo of the bridge from the window.
How did I do it? I used GPSBabel to convert the output from my GPS into a so-called GPX file, then used RoboGeo to create a so-called KMZ file for Google Earth. Easy!
To answer these questions:
The device stores plain text files whose names are WG followed by the date and time, eg. WG20061208143736.log. The file format is NMEA but with a single-line header @sonygps/ver1.0/wgs-84. The NMEA sentences are as follows:
$GPGGA,133542,3352.7159,S,01902.9092,E,1,08,01.1,00215.0,M,032.2,M,,*55 $GPGSA,A,3,05,09,14,18,22,25,30,31,,,,,01.9,01.1,01.5*08 $GPGSV,3,1,11,01,24,244,00,05,37,114,34,09,09,130,47,11,02,226,00*79 $GPGSV,3,2,11,12,21,131,00,14,59,195,35,18,37,035,46,22,76,019,36*7C $GPGSV,3,3,11,25,27,296,34,30,50,066,38,31,37,300,45,,,,*48 $GPRMC,133542,A,3352.7159,S,01902.9092,E,050.7,279.0,041206,,,A*65 $GPVTG,279.0,T,,M,050.7,N,094.0,K,A*0E
An NMEA reference from Glenn Baddeley suggests that:
All lines end with a checksum, calculated as the 8-bit exclusive OR of all characters in the sentence, including the "," delimiters, between the $ and * delimiters, then the hexadecimal value of the most significant and least significant 4 bits of the result are converted to two ASCII characters.
The memory is about 32 MB. I've had log files reach 900 KB, which would indicate that it should be able to hold at least 32 days worth of data. However I don't leave it turned on all day so you're files may be larger in which case you would get less days.
The data files can of course be renamed if you don't like .log, and the first line can be deleted to turn the file into plain NMEA sentences. The file can then be used in any program which accepts NMEA, for example MemoryMap has an import option. Probably the best thing is to run the file through GPSBabel which accepts it without any complaint (even with the header), and produces any other format (GPX being pretty standard these days).