Optical time domain reflectometer with heterodyne reception

Details Optical time domain reflectometer with heterodyne reception Optical time domain reflectometer with heterodyne reception

1987-03-17

1988-12-27

Nelms, David C.

Radiant energy

Photocells; circuits and apparatus

Optical or pre-photocell system

356 731, H01J 516

Patent

active

047942495

ABSTRACT:
The invention relates to an optical time domain reflectometer (OTDR) with heterodyne reception for determining the attentuation of an optical waveguide (measuring waveguide) by measuring the back-scattered portion of light pulses sent into the measuring waveguide. This structure is comprised of a modulated laser light source sending a send beam into the measuring waveguide and a laser light source which constitutes a local oscillator and transmits continuous light, on whose light of a wavelength differing by an intermediate-frequency from the back-scattered light from the transmission light source is superposed and is applied to a photodetector having an intermediate-frequency electric output signal which is filtered and evaluated. To improve the signal-to-noise ratio it is provided that the transmission light source is a transmission laser 1 whose light is influenced in consecutive time intervals (t.sub.1 to t.sub.2) such that the light frequency varies between two cut-off frequencies f.sub.L1 and f.sub.L2 and that the light source forming the local oscillator is a laser transmitting light at a frequency f.sub.LO, which is located outside the range between the cut-off frequencies f.sub.L1 and f.sub.L2 and differs from a frequency value (f.sub.LM), located between the frequencies f.sub.L1 and f.sub.L2, by the intermediate frequency (F.sub.ZF).

REFERENCES:
patent: 4708471 (1987-11-01), Beckmann et al.

Affiliated with

Also associated with

Rating

Optical time domain reflectometer with heterodyne reception does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Optical time domain reflectometer with heterodyne reception, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Optical time domain reflectometer with heterodyne reception will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-869222