METHOD AND APPARATUS FOR SELECTING A RADIO CHANNEL FOR TRANSMITTING AN AUDIO SIGNAL TO A RADIO LOCAL RECEIVER

• US 20090149143A1
• Filed: 12/07/2007
• Published: 06/11/2009
• Est. Priority Date: 12/07/2007
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: VANYEK, DAVID A., WEIRICH, KEVIN L., KINDINGER, PETER A., CHRISTOPHER, GARY L., ROKUSEK, DANIEL S.
• Granted Patent: US 7,986,928 B2
• Time in Patent Office: Days
• US Class Current: 455/150.100
• CPC Class Codes: H04B 1/034 Portable transmitters
• CPC Class Codes: H04H 20/62 for transportation systems, e.g. in vehicles
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A transmitter device (100) receives an audio signal from an audio source device (112), and transmits the audio signal at a low power over a commercial broadcast channel to a local receiver (120). The transmitter device selects an initial channel by scanning the available spectrum, partitioned into sub-bands (210-206), and measuring the received signal strength in each channel. The channel having the lowest strength is used to set a threshold. The sub-band with most channels meeting the threshold is initially selected, and the channel in the initially selected sub-band with the lowest received signal strength is selected for initial use. A context-based weighting factor may be applied in selecting the initial channel or in selecting subsequent channels when the initial channel conditions degrade.

Claims

1. A method of selecting an FM radio channel for broadcasting a signal to an FM receiver by an FM transmitter, comprising:

initially scanning an FM band to determine signal strength in each of a plurality of FM channels, wherein the FM band is partitioned into a plurality of sub-bands;

identifying an FM channel having a lowest channel signal strength value;

selecting an initial sub-band from the plurality of sub-bands having a highest number of candidate FM channels, the candidate FM channels having a signal strength within a threshold offset of signal strength of the FM channel having the lowest channel signal strength;

selecting an initial FM channel in the initial sub-band having the lowest channel signal strength; and

transmitting an audio signal on the initial FM channel.

2. A method of selecting an FM radio channel as defined in claim 1, further comprising indicating the initial FM channel subsequent to selecting the initial FM channel.

3. A method of selecting an FM radio channel as defined in claim 2, wherein indicating the initial FM channel comprises providing a graphical display of the initial FM channel.

4. A method of selecting an FM radio channel as defined in claim 2, wherein indicating the initial FM channel comprises providing a synthesized voice announcement of the initial FM channel.

5. A method of selecting an FM radio channel as defined in claim 1, further comprising:

determining at least one usage parameter associated with the initial FM channel, wherein the at least one usage parameter includes at least one of a present location, a time of day, and a duration of use;

generating a weighting factor based at least in part on the at least one usage parameter; and

storing the weighting factor in association with the initial FM channel in a memory of the FM transmitter.

6. A method of selecting an FM radio channel as defined in claim 5, wherein generating the weighting factor is based at least in part on a previously determined weighting factor associated with the initial FM channel.

7. A method of selecting an FM radio channel as defined in claim 1, wherein the initial channel is a current channel and the initial sub-band is a current sub-band, further comprising:

receiving a user input at the FM transmitter indicating the current FM channel is no longer suitable;

selecting a new FM channel, comprising;

scanning stored favorite FM channels and FM channels of the current sub-band;

identifying new candidate FM channels from among the stored favorite FM channels and candidate FM channels in the current sub-band; and

selecting a new FM channel from among any new candidate FM channels.

8. A method of selecting an FM radio channel as defined in claim 7, wherein selecting a new FM channel from among any new candidate channels is based at least in part on a weighting factor associated with the new FM channel.

9. A method of selecting an FM radio channel as defined in claim 8, wherein if no new candidate FM channels are found among the favorite FM channels and channels in the current sub-band, the method further comprises scanning in an adjacent sub-band for new candidate FM channels.

10. A method of selecting an FM radio channel as defined in claim 1, further comprising, after selecting the initial FM channel in the initial sub-band, transmitting an initial FM channel identifier over an FM sub-channel to the FM receiver.

11. A method of selecting an FM radio channel for low power broadcasting from a transmitter device, comprising:

providing in the transmitter device a channel use history, stored in a memory of the transmitter device;

receiving an input to select an FM channel;

scanning an FM band to identify a plurality of candidate FM channels;

generating a weighting factor for each of the plurality of candidate FM channels to provide a plurality of weighted FM channels, wherein the weighting factor for each of the plurality of candidate channels is based at least in part of a present signal condition and a channel use history of the candidate FM channel;

selecting from among the plurality of weighted FM channels a present channel; and

transmitting an audio signal received from an audio source device over the present channel.

12. The method of claim 11, wherein the channel use history includes a use duration parameter.

13. The method of claim 11, wherein the channel use history includes a time of day parameter.

14. The method of claim 11, wherein the channel use history includes a location parameter, the method further comprises receiving location information at the transmitter device indicating a present geographic location of the transmitter device.

15. The method of claim 14, wherein receiving location information comprises receiving location information from an audio source device.

16. The method of claim 15 wherein the audio source device is a mobile communication device including a satellite positioning receiver.

17. The method of claim 16 wherein receiving location information comprises receiving the location information over a wireless link with the mobile communication device.

18. The method of claim 11, wherein scanning an FM band comprises scanning a sub-band of an available FM broadcast spectrum which includes a presently selected FM channel.

19. A transmitter device, comprising:

a controller,

an FM transmitter;

an FM receiver;

a memory including instruction code for configuring the controller to;

scan an FM band to identify a plurality of candidate FM channels using the FM receiver, wherein the FM band is partitioned into a plurality of sub-bands;

generate a weighting factor for each of the plurality of candidate FM channels to provide a plurality of weighted FM channels, wherein the weighting factor for each of the plurality of candidate channels is based at least in part of a present signal condition and a channel use history of the candidate FM channel;

select from among the plurality of sub-bands, a present sub-band having the most number of weighted FM channels meeting a preselected channel criteria

select a present channel in the present sub-band having the best channel criteria; and

transmit an audio signal over the present channel using the FM transmitter.

20. A transmitter device as claimed in claim 19, wherein the weighting factor includes at least a present geographic location of the transmitter device.