The present invention relates to a system and a method of measuring a physiological variable in a body. A basic idea of the present invention is to measure a physiological variable in a body by means of employing a sensor (314) which is arranged to be disposed in the body for measuring the physiological variable. The sensor must be provided with a supply voltage in order to be operable. Therefore, a control unit (322) disposed outside the body provides this supply voltage to the sensor. The control unit also receives, from the sensor, via a wired connection (311), signals that represent the physiological variables that are measured. The control unit is arranged with a communication interface (401, 701) and a modulator (301) for wireless spread spectrum communication of the measured physiological variables for presentation purposes.