Its schedule outlines plans to open a tender process in April 2005 following meter tests between October 2004 and March 2005 that will test three different electronic measurement systems.
A new contract to measure radio audiences will be handed to a research company in September 2005. However, the earliest date that data from electronic measurement will be published is January 2007, and then only in parallel with the diary system.
Rajar has attracted criticism from radio companies including Kelvin MacKenzie's The Wireless Group and Virgin Radio for moving too slowly to introduce electronic measurement and for the size and shape of its listener panel.
The project, which Rajar has dubbed its "roadmap to change", has been agreed by the Rajar board, which includes BBC Radio, commercial radio companies, the IPA and ISBA.
Sally de la Bedoyere, the managing director of Rajar, said: "We are optimistic that by 2007 we will be heralding the introduction of an audio-meter-based methodology, which measures analogue, digital, digital TV and internet listening."
Rajar has already carried out a series of tests, lasting 15 months, on electronic measurement systems. This research has cost £800,000 but it claimed the results raised questions about the accuracy of the meters.
The Wireless Group, which now conducts its own electronic tests through the research company Gfk, accused Rajar of wasting four years to get to this stage.
A statement from TWG said: "(This is) hardly cause for celebration. Delay is built into every tortuous step along this long and winding road of more tests, more evaluations and more consultations."