A gatekeeper electronic signal can be generated by a patient sensor and/or in an intermediate device, such as an electrical cable, that is separate from a patient's physiological information electronic signal. The gatekeeper signal can be generated to indicate to a computer monitor that the sensor and/or cable is of the type that is compatible with, and/or usable with, such computer monitor, and/or that the sensor and/or cable is properly attached to the computer monitor. The gatekeeper signal can be created by an ambient temperature sensor on, or in electrical communication with, the patient monitor, and/or the gatekeeper signal can be created by a gatekeeper electronic signal generator to simulate an ambient temperature value. The gatekeeper signal can be separate from an electronic signal or plurality of signals that include patient physiological information, and the gatekeeper signal may not include any patient physiological information.
