  In this paper we investigate the problem of locating multiple non-cooperative
radio frequency (RF) emitters using only received signal strength (RSS) data.
We assume that the number of emitters is unknown and that individual emitters
cannot be distinguished in the RSS data. Moreover, we assume that the
environment in which the data has been collected has not been mapped or
"fingerprinted" by the prior collection of RSS data. Our primary interest is
the limiting resolution that can be obtained by this type of data, and the
lowest power emitters that can be detected, as a function of noise level,
sensor geometry, and other variables. We formulate the recovery problem as one
of sparse approximation or compressed sensing, and investigate an appropriate
recovery algorithm for this setting, and use it to illustrate our conclusions.
We also include a reconstruction based on sampled data we collected, to
illustrate the reasonableness of our parameter choices and conclusions.
