Abstract: A meter for use in a radio frequency remote metering system comprises an antenna; a transmitter for transmitting meter signals via the antenna; a receiver connected to the antenna for receiving and filtering an incoming radio frequency signal; and a carrier signal detect circuit which is connected to receive the filtered radio frequency signal and which is operable to detect the presence or absence of a carrier signal, and to prevent activation of the transmitter in response to the presence of the carrier signal, to activate the transmitter in response to the absence of the said carrier signal.

Abstract: A fixed network AMR system that has a range from the meter (4) to the node (6) of up to 5 km uses a common reference source (2) for the frequency reference of the meter transmitter (12) and the system receiver (18). By using a publicly available reference frequency the necessary frequency stability can be obtained in order to provide a signal to noise bandwidth of the order of 32 Hz.