  The range resolution in conventional continuous time frequency modulation
(CTFM) is inversely proportional to the signal bandwidth. The dual-demodulator
continuous time frequency modulation (DD-CTFM) processing technique was
proposed by Gough et al [1] as a method to increase the range resolution by
making the output of DD-CTFM truly continuous. However, it has been found that
in practice the range resolution is still limited by the signal bandwidth. The
limitation of DD-CTFM has been explained using simulations and mathematically
in this paper.
