Telemetry systems normally comprise a transmitter for transmitting electromagnetic signals, e.g. from a measurement, and a receiver for receiving the electromagnetic signals from the transmitter. The transmitters transmit messages that are as short as feasible and with the interval between the transmissions as long as feasible. This minimizes the average current drain in the transmitters, which are typically battery operated. In addition, short and infrequent transmissions lower the probability that data is lost as a result of collisions that occur when two or more transmitters transmit at the same time. Remote telemetry is a technique by which telemetry data collected at a remote location is collected in a central repository (e.g., a host computer) for analysis and archival purposes. The telemetry data might be any physical measurement, such as a liquid level, weight, pH, chlorine concentration, temperature, pressure, proximity, etc., and is sensed by a remote telemetry unit (RTU). In a telemetry system analog or digital metering data is captured at a remote location by a telemetry computer and is then transmitted to a central computer facility via a telecommunication device. In radio telemetry the telecommunication device is a radio modem that transmits the metering data between the telemetry computer and the central computer facility via radio frequency waves, thus eliminating the need for land-line wiring, such as a telephone line. RF based telemetry systems provide an additional advantage in that the data acquisition device can work with data collection systems which are mobile. Radio based systems often employ a mobile reader device, carried either by a person on foot or by a vehicle, to periodically travel throughout a utility's service area and read the endpoints. A typical radio telemetry system employs one of several different modulation methods, and one of several different multiplexing techniques, in order to transmit information produced by multiple sensors to a user's location remote from the sensors. Well known methods of modulating a carrier frequency to convey information include amplitude modulation, frequency modulation, phase modulation, and pulse modulation. Wireless telemetry systems (e.g., burglar alarms, fire alarms, power utility meters, leak detectors, environmental monitoring, temperature control, etc.) comprise many transmitters that periodically or sporadically transmit messages to one or more receivers. In these systems, each transmitter is located at a different place and transmits messages that indicate the status of sensors associated with the transmitter. A centrally located receiver receives messages from each transmitter. Digital electronic telemetry systems are used to send information over a significant distance in the form of an electrical signal which comprises electrical voltage levels corresponding to binary numbers. Binary numbers are typically used in digital telemetry because they are composed entirely of ones and zeroes. Automated meter reading (AMR) systems are designed to retrieve consumption data from utility meters, such as gas, water, and electric meters. AMR systems employ a variety of techniques for collecting data from transceivers installed at the meters, commonly referred to as "endpoints", including telephone connections, radio signals, optical signals, inductive probes, and direct electrical connections. An AMR system may utilize multiple data collection modules that may receive a transmission from the same telemetry device, in an effort to enhance reliability of data transmissions. An arbitration scheme may be utilized to determine which data collection module receiving data from the same telemetry device forwards the data to the central data collection facility.

Patient monitoring with telemetry system gets more and more popular in many medical areas. Monitoring by telemetry has some advantages over conventionally monitoring especially for patients who need not necessarily stay in their bed but nevertheless must be monitored continuously. Telemetry transmitters provide a convenient means for remotely monitoring the medical condition of a patient, i.e., monitoring heart related electrical signals, such as electrocardiogram (EKG) and cardiac pacemaker signals. Implantable devices such as heart pacemakers ordinarily accumulate data indicating the condition of the pacemaker's internal parameters, as well as a log of pacing activity and of the heart's condition. Periodically, this accumulated data is transmitted via telemetry to an external device, called a programmer. Most patient monitoring systems that permit patients to ambulate through a care unit use telemetry-based communication schemes. Medical telemetry systems that allow the physiologic data of multiple, remotely-located patients to be monitored from a central location typically comprise remote telemeters that remotely collect the physiologic data of respective patients and transmit the data over a wireless link to a centralized monitoring station. The telemetry transmitter is connected to the patient by electrodes and wires. The telemetry transmitter includes terminals for receiving the EKG and pacemaker signals from the wires, and a wireless transmitter that comprises, for example, a radio frequency (RF) link. Additional circuitry may be provided in the transmitter device for amplifying, filtering and multiplexing the received EKG and pacemaker signals. In one common form, the patient wears a telemetry transmitter attached to the patient using ECG electrodes. The telemetry transmitter acquires an ECG signal, conducts a nominal amount of filtering on the ECG signal, and transmits a telemetry data signal to an antenna array. The telemetry signal is conducted through the antenna array to a telemetry receiver, which in turn, is connected to a central station that analyzes and displays the ECG information for viewing and evaluation by the clinicians staffing the care units. From the centralized monitoring station, a clinician can visually monitor the physiologic status, in real time, of many different patients. The central station may also run automated monitoring software for alerting the clinician whenever a predetermined physiologic event occurs, such as a cardiac arrythmia condition. Remote telemeters of medical telemetry systems are generally of two types: instrument remote telemeters and ambulatory remote telemeters. Instrument remote telemeters operate in a similar manner, but receive the patient's physiologic data from a bedside monitor ver a hardwired link. Instrument remote telemeters that transfer the physiologic data to the central station over a hardwired connection are also common. An ambulatory remote telemeter is a portable, battery-powered device which permits the patient to be monitored while the patient is ambulatory. The ambulatory telemeter attaches to the patient by a strap or other attachment device, and receives the patient's physiologic data via ECG leads which attach to the patient's body. The physiologic data is continuously transmitted to the central monitoring station by the telemeter's radio frequency transmitter to permit real-time monitoring.

The control of oil and gas production wells constitutes an on-going concern of the petroleum industry due to the enormous monetary expense involved as well as the risks associated with environmental and safety issues. Production well control has become particularly important and more complex in view of the industry wide recognition that wells having multiple branches will be increasingly important and commonplace. Measurements of drilling parameters and logs to measure properties of the surrounding strata are common while drilling wells. These measurements are taken by various instruments mounted within the drill string. Measurements of the direction of the drill bit have become particularly important in recent years with the growth in number of directional and horizontal wells. Modern petroleum drilling and production operations demand a great quantity of information relating to parameters and conditions downhole. Such information typically includes characteristics of the earth formations traversed by the wellbore, along with data relating to the size and configuration of the borehole itself. The collection of information relating to conditions downhole is commonly is referred to as "logging". Well-logging is the measurement of characteristics of different earth formations traversed by a borehole, usually an oil or gas well using one or more measuring instruments or tools. The tools are typically stacked in a tool string attached to a logging cable which supports the tool string, provides power to the tool or tools and provides a communication medium for the transmission of data from the tool or tools to data acquisition and processing equipment on the surface. Modern well drilling techniques involve the use of several different measurement and telemetry systems to provide petrophysical data and data regarding drilling mechanics during the drilling process. Designs for measuring conditions downhole including the movement and location of the drilling assembly contemporaneously with the drilling of the well have come to be known as measurement-while-drilling techniques, or MWD. Data is acquired by sensors located in the drill string near the bit and either stored in downhole memory or transmitted to the surface using measurement-while-drilling (MWD) telemetry devices. In measurement-while-drilling (MWD) tools, data is acquired by sensors located in the drill string near the bit. Data transmitted in a well-logging digital telemetry system are typically first transmitted over a bus within the tool string to a downhole modem. The downhole modem then uses that data to modulate a carrier signal suitable for transmission over the logging cable to the surface. This data is either stored in downhole memory or transmitted to the surface using a telemetry means, such as mud flow telemetry devices.