Abstract: A portable audio device having reduced sensitivity to RF interference over a predetermined frequency range from an adjacent mobile wireless communications device may include a portable housing, a battery carried thereby, a recharging power input connected to the battery, a digital signal input, and an audio analog signal output. A digital-to-analog converter (DAC) may be carried by the portable housing and powered by the battery for converting a selected digital audio file from a memory into an analog audio signal. An audio analog amplifier may be connected between the DAC and the audio analog signal output. A first RF filter(s) may be connected to the recharging power input, and a second RF filter(s) may be connected to the audio analog signal output, both for reducing RF interference over the predetermined frequency range from the adjacent mobile wireless communications device.

Abstract: A portable audio device having reduced sensitivity to RF interference over a predetermined frequency range from an adjacent mobile wireless communications device may include a portable housing, a battery carried thereby, a recharging power input connected to the battery, a digital signal input, and an audio analog signal output. A digital-to-analog converter (DAC) may be carried by the portable housing and powered by the battery for converting a selected digital audio file from a memory into an analog audio signal. An audio analog amplifier may be connected between the DAC and the audio analog signal output. A first RF filter(s) may be connected to the recharging power input, and a second RF filter(s) may be connected to the audio analog signal output, both for reducing RF interference over the predetermined frequency range from the adjacent mobile wireless communications device.

Abstract: A telephone to be connected to a wireline having reduced sensitivity to RF interference over a predetermined frequency range from an adjacent mobile wireless communications device may include a transmit amplifier, a receive amplifier, an audio input transducer connected to the transmit amplifier, and an audio output transducer connected to the receive amplifier. The telephone may further include an RF shield(s) surrounding the audio input transducer and the audio output transducer for reducing RF interference over the predetermined frequency range from the adjacent mobile wireless communications device. Moreover, the telephone may also include at least one RF audio input filter element connected to the audio input transducer and at least one RF audio output filter element connected to the audio output transducer, both of which are also for reducing RF interference over the predetermined frequency range from the adjacent mobile wireless communications device.

Abstract: A portable audio device having reduced sensitivity to RF interference over a predetermined frequency range from an adjacent mobile wireless communications device may include a portable housing, a battery carried thereby, a recharging power input connected to the battery, a digital signal input, and an audio analog signal output. A digital-to-analog converter (DAC) may be carried by the portable housing and powered by the battery for converting a selected digital audio file from a memory into an analog audio signal. An audio analog amplifier may be connected between the DAC and the audio analog signal output. A first RF filter(s) may be connected to the recharging power input, and a second RF filter(s) may be connected to the audio analog signal output, both for reducing RF interference over the predetermined frequency range from the adjacent mobile wireless communications device.

Abstract: A telephone to be connected to a wireline having reduced sensitivity to RF interference over a predetermined frequency range from an adjacent mobile wireless communications device may include a transmit amplifier, a receive amplifier, an audio input transducer connected to the transmit amplifier, and an audio output transducer connected to the receive amplifier. The telephone may further include an RF shield(s) surrounding the audio input transducer and the audio output transducer for reducing RF interference over the predetermined frequency range from the adjacent mobile wireless communications device. Moreover, the telephone may also include at least one RF audio input filter element connected to the audio input transducer and at least one RF audio output filter element connected to the audio output transducer, both of which are also for reducing RF interference over the predetermined frequency range from the adjacent mobile wireless communications device.

Abstract: A distributed intercom system including a centralized interconnection unit with a central control device for receiving, processing and transmitting signals, a power distribution device for transmitting a power signal for distribution and at least one cable connection port for receiving a cable connection therein. The system includes a cable with a cable connection element for connection to the cable connection port, and the cable transmits a control signal, a line-level, analog audio signal and the power signal. One or more remote user interface units are connected to and in communication with the centralized interconnection unit through the cable, and the remote user interface unit includes an amplifier, a speaker device and a microphone device. At least one component of the remote user interface unit is powered by the power signal transmitted by the power distribution device.

Abstract: A telephone to be connected to a wireline having reduced sensitivity to RF interference over a predetermined frequency range from an adjacent mobile wireless communications device may include a transmit amplifier, a receive amplifier, an audio input transducer connected to the transmit amplifier, and an audio output transducer connected to the receive amplifier. The telephone may further include an RF shield(s) surrounding the audio input transducer and the audio output transducer for reducing RF interference over the predetermined frequency range from the adjacent mobile wireless communications device. Moreover, the telephone may also include at least one RF audio input filter element connected to the audio input transducer and at least one RF audio output filter element connected to the audio output transducer, both of which are also for reducing RF interference over the predetermined frequency range from the adjacent mobile wireless communications device.

Abstract: An intercom system for a building or apartment house includes at least one main entrance station 1 which is installed at an entrance or the like of a building or an apartment house, a plurality of residential master stations 2 which are respectively installed inside a plurality of residences in the building or apartment house for receiving calls and talking with the main entrance station 1, a common line 3 which connects the main entrance station 1 and respective residential master stations 2 in parallel, a line power supply 4 which supplies direct current power, for example, DC 24 V to the main entrance station 1 and respective residential master stations 2 through the common line 3, an electronic door lock 5 which is connected to the main entrance station 1 for locking and releasing an entrance door of a main entrance, and a plurality of call switches 6 connected to respective residential master stations 2 and mounted on front doors of respective residences for operation by a visitor.