This paper provides an overview of work undertaken over the last three years to improve the accuracy and reliability of positions provided by low-cost GPS receivers when used for tracking and navigation. The techniques developed are also effective when used with hand held receivers used on footpaths. There is great potential to adapt the methods described this paper for use in mobile phone positioning. Either directly where handsets contain a GPS receiver, or when the positioning method used is based on ranges from handset to a number of transmitters. For example, using methods for handset positioning such as Uplink Time of Arrival (TOA), Enhanced Observed Time Difference (E-OTD). A number of experiments are described, and significant results presented. Ongoing work and further research projects are also discussed.