Acoustic Modulation

Communications apparatus including an optical link, a monitoring station for receiving sensing signals previously transmitted onto the optical link, and a modulator arrangement according to any preceding claims for modulating data onto the sensor signals, wherein the sensing signals are formed by pairs of signal copies, which copies of a pair have a time delay relative to one another, and wherein the monitoring station is configured to combine the respective signals of a pair so as to extract the modulated data.

A method of using a communication arrangement which includes an optical waveguide, removable modulator means for acoustic modulating light travelling along the optical waveguide, a plurality of access points along the waveguide at which access points a respective coupling surface for coupling acoustic vibrations to the waveguide can be accessed, the fibre being inaccessible between the access points, the modulator component being releasably connectable to coupling surface an access point, wherein the method includes the steps of:

• connecting the modulator means to one access point;
• generating acoustic vibrations such that the acoustic vibration cause a modulation of light travelling along the waveguide;
• and, removing the modulator means from the access point.

A method of using a communication arrangement which includes an optical waveguide, a removable modulator for causing acoustic vibrations which modulate light travelling along the optical waveguide, a plurality of attachment points along the waveguide at which the modulator can be attached, wherein the modulator is releasably connectable at the attachment points and is not connectable between access points, the method includes the steps of:

• connecting the modulator to an access point;
• causing acoustic vibrations such that the acoustic vibration cause a modulation of light travelling along the waveguide;
• and, removing the modulator means from the attachment point.

A modulator arrangement for acoustically modulating optical radiation, the modulator arrangement comprising:

• a waveguide portion formed from a flexible material;
• a vibrator element for generating acoustic vibrations;
• and, a coupling arrangement for releasably coupling the vibrating element to the waveguide portion, the coupling arrangement including a first coupling member secured to the waveguide portion, and a second coupling member secured to the vibrator element, wherein the second coupling member is removable from the first coupling member, and wherein the first coupling member has a substantially rigid portion for retaining the shape of the waveguide when the second coupling member is removed from the first coupling member.