Digital FM radio system

• US 7,088,740 B1
• Filed: 12/21/2001
• Issued: 08/08/2006
• Est. Priority Date: 12/21/2000
• Status: Expired

• Current Assignee: OL Security LLC (Intellectual Ventures LLC)
• Original Assignee: BAE Systems Information and Electronic Systems Integration Incorporated (BAE Systems Plc)
• Inventors: Schmidt, Michael
• Primary Examiner(s): NGUYEN, BRIAN D
• Application Number:
  US10/032,235
• Time in Patent Office: 1,691 Days
• Field of Search: 370/480, 370/485, 370/486, 370/487
• US Class Current: 370/490
• CPC Class Codes: H04H 20/22 Arrangements for broadcast of identical information via plural broadcast systems
• CPC Class Codes: H04H 20/48 for FM stereophonic broadcast systems

Abstract

The present invention is for a high quality digital FM radio system that utilizes the subcarrier band to generate digital audio signals. The hybrid FM radio system utilizes the subcarrier band to transmit the digital FM signals that are synchronized to the analog FM signals. The receiver processes both the analog and digital signals and a high quality FM signal results. The receiver may switch between the traditional analog signal and the higher quality digital signal automatically to present the best possible audio to the user.

Claims

1. A hybrid FM radio system providing an audio output, comprising:

a transmitter section transmitting an audio transmission as a standard analog FM signal and a digital FM signal, wherein said digital FM signal is packetized and transmitted on a subcarrier band, and said analog FM signal transmitted on a main carrier band;

a receiver section for receiving said analog FM signal and said digital FM signal, wherein said digital FM signal is decoded and converted to a digital decoded analog FM output and said analog FM signal is processed to provide a standard analog FM output, and wherein said standard analog FM output and said digital decoded analog FM output are synchronized; and

a means for automatically determining said audio output from said digital decoded analog FM output and said standard analog FM output.

2. The hybrid FM radio system according to claim 1, wherein said digital FM signal is directly derived from a digital source.

3. The hybrid FM radio system according to claim 1, wherein said digital FM signal is derived from said analog FM signal.

4. The hybrid FM radio system according to claim 3, further comprising an analog delay in said analog FM signal, wherein said analog delay is substantially equivalent to a cumulative time delay of processing said digital FM signal in said transmitter section and processing said digital FM signal in said receiver section.

5. The hybrid FM radio system according to claim 1, wherein said means for determining is a multiplexer that switches between said standard analog FM output and said digital decoded analog FM output.

6. The hybrid FM radio system according to claim 1, wherein said digital FM signal is packetized in an MP3 format.

7. A hybrid FM radio system producing a quality audio output at a receiver, comprising:

a transmitter section transmitting an analog FM signal and a digital FM signal, wherein said digital FM signal is packetized and transmitted on a subcarrier band;

a receiver section for receiving said analog FM signal and said digital FM signal, wherein said digital FM signal is decoded and converted to an analog output;

a multiplexer connected to said analog FM signal and said digital FM signal, wherein said multiplexer switches in response to parameters selected from the group consisting of;

a user input, a determination that said digital FM signal is a copy of said analog FM signal, a status determination that said digital FM signals is decoded without errors, and a synchronization determination that said digital FM signal is synchronized with said analog FM signal; and

wherein a multiplexer output generates said audio output.

8. The hybrid FM radio system according to claim 7, wherein said multiplexer automatically switches between said digital FM signal and said analog FM signal.

9. The hybrid FM radio system according to claim 7, further comprising an analog delay in said analog FM signal, wherein said analog delay is substantially equivalent to a cumulative time delay of processing said digital FM signal in said transmitter section and processing said digital FM signal in said receiver section.

10. The hybrid FM radio system according to claim 7, wherein said digital FM signal is packetized in an MP3 format.

11. A hybrid FM receiver capable of receiving an analog FM signal and a digital FM signal and producing an audio output, comprising:

an antenna for receiving said analog FM signal and said digital FM signal with a front end processing section and a FM demodulator;

an analog FM receiver section connected to said FM demodulator with a means for analog processing;

a digital FM receiver section connected to said FM demodulator with a receiver processor and a music processor, wherein said receiver processor performs receiver digital signal processing and wherein said music processor performs music digital signal processing; and

a multiplexer connected to said analog FM signal and said digital FM signal, wherein a multiplexer output generates said audio output.

12. The hybrid FM receiver according to claim 11, wherein said receiver processor includes a memory means for storing a receiver digital signal processing software.

13. The hybrid FM receiver according to claim 11, wherein said receiver processor is programmable and has an external interface for downloading a receiver digital signal processing software.

14. The hybrid FM receiver according to claim 13, wherein said receiver digital signal processing software is downloaded using a radio data system (RDS) format.

15. The hybrid FM receiver according to claim 11, wherein said music processor includes a memory means for storing a music compressor/decompressor (CODEC).

16. The hybrid FM receiver according to claim 15, wherein said music processor is programmable and has an external interface for downloading said music CODEC.

17. The hybrid FM receiver according to claim 11, further comprising an output switch for switching between said analog FM signal and said digital FM signal.

18. The hybrid FM receiver according to claim 11, further comprising a mixer for mixing said analog FM signal and said digital FM signal to produce said audio output.

19. The hybrid FM receiver according to claim 11, wherein said digital FM signal is packetized in an MP3 format.