A new method to measure the internal magnetic field in a plasma, based oncross-correlation of ordinary (O) mode and extraordinary (X) modereflectometer signals originating from naturally occurring turbulence, isinvestigated. This method relies on identifying the O- and X-mode frequencypair (fo, fx) where cross-correlation is maximum. Maximumcross-correlation is found to occur at an X-mode frequency slightly lower thanthe right-hand cut-off frequency. It is shown that the magnetic field strengthcan be determined from reflectometer data interpreted via a one-dimensionalmodel, given estimates of the k-spectral width of the electrostatic plasmaturbulence, and the electron density gradient scale length.