Neil Pickford and Mapping

Over the years through my involvement with the Communications Laboratory I have used the Global Positioning Satellite system (GPS) and Differential GPS (DGPS) system to record data with spatial location tags. These techniques were first applied at the laboratory with the Digital Audio Broadcasting field survey where a mobile GPS receiver was used to locate the start and finish of measurement runs, typically 200m.

In 1999 I had the opportunity to purchase personally a Magellan Meridian XL GPS receiver which I have been experimenting with since.

After the abolition of the Communications Lab the focus of our work turned to mapping using MapInfo 5.5 and 6.0. I soon realised that there was a wealth of geographic data available that could be used in real time to present absolute position information to the mobile user. I have been using a software tool for MapInfo called SmartImage to register 10000ft photographs of the Belconnen area in Canberra to the AGD66 street layout. I have found that using real image data for real time mapping increases the user acuity over that of standard cartographic representations.

In the last few months I have been experimenting with linking Geographic Information System (GIS) mapping to live GPS data. The latest version of MapInfo (Version 6.0) comes with a tool called Geographic Tracker. This allows information from a GPS receiver to feed into the mapping application to be rendered as a point or track. The received data can also be logged to a file for later off-line playback. Poly-lines of the track can be entered, providing an automatic method of entering spatial data.

The current system has three main limitations:

  1. There is a significant delay (20 seconds) between movement on the ground and the reporting/mapping of the GIS data.
  2. Even though Selective Availability (SA) was switched off on the GPS system as of the 2nd May 2000, the typical errors encountered while moving equate to around 20-30 metres. Information from stationary stations indicates that accuracy should be better than 10m. It is possible that the accuracy of the system degrades when the receiver is moving relative to the ground.
  3. When the receiver comes to rest the error reduces to within the 10m region withn a few minutes.

I have been trying to get information that would allow the geotracker tool to read the Sony IPS GPS data format unfortunately I have not had the time to build a protocol converter. The standard format used by most receivers today appears to be either NMEA 0183 or Trimble. Sony have produced a number od OEM GPS subsystems (receiver only - no display) that provide data output. I have obtained one of these GPS receivers IPS-2010 (Similar to a IPS-3000) which I would like to integrate into my experimental system.

Recently I purchased a ALTINA GPS Mouse GGM308 (PS2) and have found it's performance most impressive, it even works indoors and is very responsive. I am about to interface an old Epson EHT-10 hand held touchscreen computer to the GPS mouse as a lightweight terminal to turn the GPS mouse into a type of portable GPS.
I am collecting the development information for the EHT-10 so I can write the required code in Basic.
I have a suite of DOS interface programs for the EHT-10 including FILINK.EXE.

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This page was last updated on 28/03/2005