Portable multi-purpose audience measurement systems, apparatus and methods

A tangible article of manufacture storing machine readable instructions which, when executed, cause a machine to:

• sense a media content signal output by a media presentation device using a portable device separate from the media presentation device, the portable device supporting media metering functionality and native functionality;
• detect whether a code is encoded in the sensed media content signal using the portable device;
• and
• generate a signature from the sensed media content signal using the portable device when the portable device is electrically coupled to an external power supply or the portable device has at least a threshold amount of local battery power, but not generate the signature when the portable device is not electrically coupled to the external power supply and the portable device does not have at least the threshold amount of local battery power.

A portable metering device comprising:

• a sensor to sense a media content signal output by a media presentation device separate from the portable device;
• a processor to execute media metering software to implement a media meter and to execute native software to implement native functionality;
• the media meter to:
• detect whether a code is encoded in the media content signal;
• and
• generate a signature from the sensed media content signal when the portable device is electrically coupled to an external power supply or the portable device has at least a threshold amount of local battery power, but to not generate the signature when the portable device is not electrically coupled to the external power supply and the portable device does not have at least the threshold amount of local battery power;
• and
• a memory to store at least one of the detected code or the generated signature.