Method and apparatus for selecting a radio channel for transmitting an audio signal to a radio local receiver
View Patent ↗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.
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.