Abstract: Luggage that is easy to transport and easy to store is provided with security tags to enable the passenger and terminal security officers to determine the last person to seal the luggage, enabling a passenger to determine if the luggage was searched, and enabling security personal to determine whether the luggage was previously searched.

Abstract: A circuit arrangement reduces the time necessary for a voltage-to-frequency converter to provide a new output frequency in response to a change in input voltage levels. A current source provides additional input current to the input integrating node of the v/f before a conversion is requested. When a conversion is requested, the additional input current effectively provides operation of the v/f at an increased frequency, thus speeding the settling process therefor. When the integrator of the v/f is at a predetermined voltage level in a predetermined operating cycle, the current source is removed, thus terminating the increased frequency of operation.

Abstract: A bipolar analog voltage is converted into a digital signal by sensing the polarity of the voltage and selectively supplying a bias voltage to an analog-to-digital converter, which can preferably be a charge balanced voltage to frequency converter, as a function of the sensed polarity. The voltage to frequency converter has a double valued variable frequency output with a discontinuity at zero volt such that the converter derives a maximum output frequency for a maximum positive voltage and also for a negative value slightly displaced from zero; the voltage to the frequency converter minimum output frequency is derived from positive voltages slightly greater than zero and for maximum negative voltages. The converter output frequency and the sensed polarity are supplied to a frequency to digital converter which derives an output signal having a bit representing the polarity of the analog voltage and additional bits indicative of the magnitude of the analog voltage.