A method for distributed sensing of one or more measurable parameters of an optical fiber (232; 524; 702; 712; 722; 732; 802), comprising: generating (52, 602) a first pump light wave having a frequency centered at ω 0; modulating (58, 608) the first pump light wave thereby obtaining a first modulated pump light wave; generating (54, 614 and 618) a second modulated light wave having a frequency centered at ω 1, wherein ω 1 is controllably tunable and shifted from ω 0 by approximately Ω B, Ω B being a Brillouin frequency shift of the optical fiber; transmitting (60, 612) the first modulated pump light wave into the optical fiber through a first end thereof (236; 522; 704; 714; 724; 734; 824); transmitting (62, 622) the second modulated light wave into the optical fiber through a second end thereof (238; 538; 706; 716; 726; 736; 830); receiving (64, 630) at an end of the optical fiber a scattered light wave signal with a frequency approximately equal to ω 0 + Ω B + ω bir or ω 0 + Ω B - ω bir or ω 0 - Ω B + ω bir or ω 0 - Ω B - ω bir, wherein Ω B is a Brillouin frequency shift of the optical fiber, and ω bir is a birefringence frequency difference in the optical fiber; monitoring at least the frequency of the received light wave signal at an end of the optical fiber; and calculating from at least the monitored frequency of the received light wave signal a magnitude of a sensed measureable parameter of the optical fiber; characterized in that the method further comprises generating (56, 604) a generic random signal; further characterized in that the first modulated pump light wave is phase modulated or frequency modulated by a first random signal, and further characterized in that the second modulated light wave is phase modulated or frequency modulated by a second random signal, wherein at least one of the first random signal and the second random signal are obtained from the generic random signal delayed by a time delay Δ T 1 ≥ 0 and Δ T 2 ≥ 0, respectively. generating (52, 602) a first pump light wave having a frequency centered at ω 0; modulating (58, 608) the first pump light wave thereby obtaining a first modulated pump light wave; generating (54, 614 and 618) a second modulated light wave having a frequency centered at ω 1, wherein ω 1 is controllably tunable and shifted from ω 0 by approximately Ω B, Ω B being a Brillouin frequency shift of the optical fiber; transmitting (60, 612) the first modulated pump light wave into the optical fiber through a first end thereof (236; 522; 704; 714; 724; 734; 824); transmitting (62, 622) the second modulated light wave into the optical fiber through a second end thereof (238; 538; 706; 716; 726; 736; 830); receiving (64, 630) at an end of the optical fiber a scattered light wave signal with a frequency approximately equal to ω 0 + Ω B + ω bir or ω 0 + Ω B - ω bir or ω 0 - Ω B + ω bir or ω 0 - Ω B - ω bir, wherein Ω B is a Brillouin frequency shift of the optical fiber, and ω bir is a birefringence frequency difference in the optical fiber; monitoring at least the frequency of the received light wave signal at an end of the optical fiber; and calculating from at least the monitored frequency of the received light wave signal a magnitude of a sensed measureable parameter of the optical fiber;