Short range radio information system
First Claim
Patent Images
1. A low power AM band broadcast station, comprising:
- an antenna;
a transmitter;
a tuning circuit coupled to said antenna and to said transmitter, wherein said tuning circuit has an inductor and a capacitor in parallel, wherein said tuning circuit matches the impedance of the transmitter with that of the antenna, and wherein the inductor is formed on a high magnetic permeability element to form a high-Q inductor;
means coupled to said transmitter for controlling the frequency of a transmitted carrier signal;
a modulator coupled to said transmitter for modulating the carrier signal in response to an applied electrical signal representing audio information;
means for accepting an audio signal and converting it to a corresponding electrical signal;
an A to D converter coupled to said accepting means for converting the electrical signal into digital form;
a memory for storing the digital form of the electrical signal;
a D to A converter coupled to said memory and to said modulator for converting the digital form to a second electrical signal and applying it to said modulator; and
control means coupled to said memory and to said D to A converter for repeatedly reading the digital form of the electrical signal from said memory.
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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.
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Citations
5 Claims
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1. A low power AM band broadcast station, comprising:
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an antenna; a transmitter; a tuning circuit coupled to said antenna and to said transmitter, wherein said tuning circuit has an inductor and a capacitor in parallel, wherein said tuning circuit matches the impedance of the transmitter with that of the antenna, and wherein the inductor is formed on a high magnetic permeability element to form a high-Q inductor; means coupled to said transmitter for controlling the frequency of a transmitted carrier signal; a modulator coupled to said transmitter for modulating the carrier signal in response to an applied electrical signal representing audio information; means for accepting an audio signal and converting it to a corresponding electrical signal; an A to D converter coupled to said accepting means for converting the electrical signal into digital form; a memory for storing the digital form of the electrical signal; a D to A converter coupled to said memory and to said modulator for converting the digital form to a second electrical signal and applying it to said modulator; and control means coupled to said memory and to said D to A converter for repeatedly reading the digital form of the electrical signal from said memory. - View Dependent Claims (2, 3, 4, 5)
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Specification