A novel method is proposed for improving the performance of traditional laser heterodyne radiometry. The technique, which is based on the use of a wavelength modulated local oscillator laser, provides baseline-free spectra, lower limits of detection, and betteA novel method is proposed for improving the performance of traditional laser heterodyne radiometry. The technique, which is based on the use of a wavelength modulated local oscillator laser, provides baseline-free spectra, lower limits of detection, and better precision and consistency than the conventional approach. This tool could, therefore, boost the accuracy of current terrestrial and planetary atmospheric studies.[+][-]