Sensor relay emitter
A sensor relay emitter was a small device that could record and send sensor data to a computer.

In 2369, Geordi La Forge modified a sensor relay emitter to transmit a subspace beacon. That way, the crew of the  could locate Commander William T. Riker in a tertiary subspace manifold to where he had been abducted by solanogen-based lifeforms. After locking on to the signal transmitted by the sensor relay emitter, the crew was able to send a coherent graviton beam to the realm of the aliens to close the spatial rupture they had opened to gain entry into the regular universe. 

The emitter was attached to Commander Riker's arm and was equipped with several red blinking lights, one of which would light up as soon as his coordinates had been locked on to. 

The emitter had nine functional buttons, labeled with the following abbreviations: 

NON TVM SW
REF SET PAD
ON  WAV OFF

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Sensor technology