Abstract: An RF matrix switch has a first set of card slots at selected locations on the chassis and a second set of card slots at different selected locations on the chassis as well as input cards and output cards. The input cards, the output cards, the first set of card slots and the second set of card slots are all configured so that the input cards and the output cards fit into all of these slots. Reroute cards can be provided for any unused card slots. The RF matrix switch also may have an active power management system in which there is a power control switch connected to each amplifier that turns the amplifier off when the amplifier is not being used.

Abstract: A trunking protocol for a two-way radio communication system designates an available channel as a parking channel for radios on standby. The parking channel is converted to an active voice channel upon request for a voice call, and non-called radios are then moved from the newly-designated voice channel to a newly-designated parking channel. Upon completion of the voice call, the participating radios are moved to the then-existing parking channel, and the channel of the just-completed voice call becomes available. If all channels are busy such that no parking channel is available, the radios in standby mode convert to operate in scan mode until a channel becomes available to serve as the parking channel.

Abstract: A radio information system operating at low power transmits in the AM broadcast band. A message to be broadcast is digitized and stored in a random access memory. It is retrieved from the memory, converted to analog form, and used to modulate a carrier signal. The message is continuously repeated, allowing nearby persons with AM radio sets to receive the message. In order to extend the useful range of the information system, an impedance matching circuit with a high-Q inductor is located between the antenna and the output circuitry of the transmitter.