Passive location of mobile cellular telephone terminals

The strengths and weaknesses are discussed of various elements of possible methods for determining the location of cellular telephones using the North American AMPS (Advance Mobile Phone System) analog cellular telephone standard which require no modifications or assistance from the mobile units. Each element suffers from multipath effects and requires different levels of hardware addition at the cell sites. It is found that the combined use of interferometric and SAT (supervisory audio tone) tone ranging techniques may be useful for inferring the locations of mobile cellular telephones. The use of contours of constant field strength is less desirable because of variations between mobile units, variations in emissions from mobile units, and ambient environmental considerations. As with most UHF communications systems, multipath effects will afflict each of the location techniques discussed. Interference from mobile telephones operating in nearby cells on the same frequency as the target mobile telephone will be sources of corruption to the various measurements