A portable transponder device including a receiver having an input frequency range of either but not both of 20 kHz-300 kHz and 3 MHz-30 MHz, the receiver having a plurality of signal input channels, the input frequency range not including an infra-red frequency range, and infra-red frequency range receiving circuitry receiving infra-red frequency range signals modulated by at least one signal in the input frequency range, and providing the infra-red frequency range signals to the receiver through at least one signal input channel of the plurality of signal input channels.