The invention relates to digital scanning imaging by electromagnetic radiation. A sampling method and apparatus that utilize one or more of the following to advantage is provided: restricting deformation of the packers during inflation using an annular bracing assembly; actively retracting the packers using ambient borehole pressure; and substantially centralizing the mandrel intermediate the packers so as to resist buckling of the mandrel. The processor is arranged to control the audio output device andor display to convey the historical information as an audio andor visual output in response to the processor determining from the locator that the navigation device is in the vicinity of the location identified by the location identifier. The second inductor can function as a source inductor for and cancel an input parasitic capacitance of the LNA. The present invention can be used to provide statistically unbiased random data for writing to the power calibration area of an optical disc. The intermediate portion of each of the connecting terminals has a weakened region so that the first end portion is separated from the second end portion along a weakened line in the weakened region upon relative movement between the first and second end portions in a give direction.