H - Electricity – 04 – B
Patent
H - Electricity
04
B
H04B 10/08 (2006.01) G01J 9/00 (2006.01) G01J 9/02 (2006.01) G01M 11/00 (2006.01)
Patent
CA 2303602
In order to avoid errors inherent in the measurement of electrical phase or pulse arrival time in relative group delay measurements, different optical signals have their intensity modulated at a common high frequency, different permutations are selected, their amplitudes detected, and phase differences between the signals are computed on the basis of trigonometrical relationships between amplitude and phase. In one embodiment, two optical signals are provided with continuous wave modulation at the same high frequency, transmitted along different optical paths, and detected individually and in combination. Following conversion to corresponding electrical signals, the amplitudes corresponding to the individual signals and combined signals, are measured and used to compute phase differences between the two optical signals. The computation relies upon trigonometrical relationships to extract the phase differences. Because the frequency of the modulation is known, the time differences can be deduced. Conveniently, apparatus for measuring the phase differences comprises a slotted wheel or other selection device which passes different selections of the optical signals, the first signal alone, the second signal alone, and both together. One of the optical signals may be split to produce a third signal, and a known propagation delay, preferably corresponding to about 90 degrees at the modulation frequency, introduced into the path taken by the third optical signal. The amplitudes of seven possible permutations of the three optical signals then are used to compute the phase difference. The phase difference measurements may be made for a plurality of different physical variables of one or more of the optical signals or the paths taken thereby, and used to compute, for example, chromatic dispersion, polarization mode dispersion, elongation, and so on.
Pour éviter les erreurs inhérentes aux mesures de différences de phase électrique ou de temps d'arrivée d'impulsion dans les mesures du temps de propagation de groupe relatif, on module en intensité différents signaux optiques à une fréquence commune élevée et on sélectionne différentes permutations. Les amplitudes des signaux électriques correspondants sont décelées et les différences de phase sont calculées sur la base de relations trigonométriques. La fréquence de modulation étant connue, on peut déduire les différences de temps. Le dispositif utilisé pour les mesures de différence de phase comprend avantageusement une roue à fentes laissant passer l'un ou l'autre des deux signaux optiques, selon le choix, ou les deux à la fois. On peut diviser l'un des signaux optiques pour établir un troisième signal à décalage de phase préétabli, soit environ 90 degrés à la fréquence de modulation, et l'on utilise les amplitudes de certaines permutations possibles des trois signaux optiques pour calculer la différence de phase. On peut utiliser les mesures pour calculer la dispersion chromatique, la dispersion en mode de polarisation, l'élongation, etc.
Babin Francois
Cyr Normand
Adams Thomas
Babin Francois
Cyr Normand
Exfo Inc.
LandOfFree
Method and apparatus for measuring phase differences between... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for measuring phase differences between..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for measuring phase differences between... will most certainly appreciate the feedback.
Profile ID: LFCA-PAI-O-1866126