A model has been developed for calculating the CO2 ladar heterodyne mixing current for an arbitrary modulation format. Six specific techniques are considered including amplitude (AM/CW), suppressed-carrier amplitude (AM/SC), phase (PM/CW), linear frequency (FM/CW), hybrid linear frequency/suppressed-carrier amplitude (FM/SC), and short pulse (PULSE) modulation. Detailed models of the different modulators and demodulator concepts are included in the analysis. Laser efficiency, signal bandwidth, detection rate, and sensitivity to speckle effects (especially phase jitter) are discussed as they affect range measurement precision and accuracy. Theoretical and preliminary experimental results indicate that a PM/CW ladar has a 3-6 dB advantage in signal-to-noise ratio over the AM-based formats. The results also indicate improved performance for a PULSE ladar compared with CW ladars if sufficient transmitter efficiencies can be achieved, and that the FM/CW and FM/SC formats are relatively unsuited for high-precision or high-accuracy range imaging.