The 40340-01 (North American version) Voice Frequency Measurement Module consists of a transmitter and receiver operating in the audio frequency range for use in testing telephone transmission lines. The transmitter can operate in single tone or sweep modes. The receiver is capable of tone level & frequency as well as noise measurements. A notch filter can be used to measure the signal to noise ratio. The receiver can receive, store, and output the channel characteristics to the Data Sentry 10 printer.