Abstract: An encoder/decoder for an emergency alert system to enable broadcasters to receive, store, re-broadcast and originate emergency alert messages. Multiple emergency alert signals are received by the encoder/decoder. A digital signal processor of the encoder/decoder scans the reception of the multiple emergency alert messages to determine the presence of an incoming emergency alert signal. The digital signal processor provides digital implementation of a frequency shift key modulation and a frequency shift key demodulation to encode and decode emergency alert messages. Additionally, the digital signal processor functions as a central processing unit to control input/output ports over a digital signal processor bus for performing all encoding and decoding functions and to control all encoding and decoding functions.

Abstract: An emergency alert communication system comprising a radio frequency receiver. The radio frequency receiver decodes incoming emergency alert signals and demodulates data header signals and emergency alert voice message signals of the emergency alert signals. Included in the data header signals are event and location code signals, which are followed by the emergency alert voice message signals. The demodulated data header signals in the form of digital data header signals are applied to a microcontroller. A telephone keypad of a telephone device is actuated to enter into the microcontroller event and location code signals. Should the event and location code signals demodulated by the receiver and applied to the microcontroller match the event and location code signals entered into the microcontroller by the telephone keypad, the microcontroller routes through an audio switching circuit the emergency alert voice message signals to a speaker, a recording device and a telephone handset of a telephone device.

Abstract: A frequency modulated radio frequency broadcast network in which re-transmitting stations employ a synchronous frequency modulated booster system. Included in the frequency modulated booster system is a synchronous frequency modulated exciter for converting a frequency modulated intermediate frequency into a frequency modulated broadcast signal. The synchronous frequency modulated exciter includes phase locked loop circuits for synchronizing the re-transmitted frequency modulated broadcast signal with the frequency modulated intermediate frequency signal by detecting reference signals in the composite baseband of the intermediate frequency signal and in the composite signal frequency modulated broadcast signal.

Abstract: A frequency modulated radio frequency broadcast network in which re-transmitting stations employ a synchronous frequency modulated booster system. Included in the frequency modulated booster system is a synchronous frequency modualted exciter for converting a frequency modulated intermediate frequency into a frequency modulated broadcast signal. The synchronous frequency modulated exicter includes phase locked loop circuits for synchronizing the re-transmitted frequency modulated broadcast signal with the frequency modulated intermediate frequency signal by detecting reference signals in the composite baseband of the intermediate frequency signal and in the composite signal frequency modulated broadcast signal.

Abstract: A UHF transmission frequency oscillator generates a UHF radio signal that is frequency modulated by a program signal. The voltage applied to a control voltage input of the UHF transmission frequency oscillator controls the transmission frequency. A sample of the UHF transmission frequency signal is heterodyned with the output of a crystal controlled reference frequency oscillator to generate a frequency difference signal. A voltage controlled VHF radio signal generator produces a VHF signal frequency modulated by the program signal. A phase detector receives the frequency difference signal and the VHF signal frequency modulated by the program signal and therefrom applies a voltage to the control voltage input of the UHF transmission frequency oscillator for the transmission of a UHF radio frequency signal frequency modulated by the program signal. The VHF voltage controlled generator has VHF programmable frequency dividers, which are pre-settable, to establish the VHF radio transmission frequency.

Abstract: A frequency modulated radio frequency broadcast network in which re-transmitting stations employ a synchronous frequency modulated booster system. Included in the frequency modulated booster system is a synchronous frequency .[.modualted.]. .Iadd.modulated .Iaddend.exciter for converting a frequency modulated intermediate frequency into a frequency modulated broadcast signal. The synchronous frequency modulated .[.exicter.]. .Iadd.exciter .Iaddend.includes phase locked loop circuits for synchronizing the re-transmitted frequency modulated broadcast signal with the frequency modulated intermediate frequency signal by detecting reference signals in the composite baseband of the intermediate frequency signal and in the composite signal frequency modulated broadcast signal.

Abstract: A frequency modulated ratio frequency broadcast network in which re-transmitting stations employ a synchronous frequency modulated booster system. Included in the frequency modulated booster system is a synchronous frequency modulated exciter for converting a frequency modulated intermediate frequency into a frequency modulated broadcast signal. The synchronous frequency modulated exciter includes phase locked loop circuits for synchronizing the re-transmitted frequency modulated broadcast signal with the frequency modulated intermediate frequency signal by detecting reference signals in the composite baseband of the intermediate frequency signal and in the composite signal frequency modulated broadcast signal.