Method for selection of a receiver tuning frequency
View Patent ↗Method for tuning the reception of radio broadcast signals to an FM RDS transmitter using program related data and transmitter related data and receiver executing the method, providing a band scanning search for detecting FM RDS transmitters exceeding a predetermined reception quality level. To enhance efficiency in data processing and use of storage capacity, transmitter related data including tuning data is stored separately from program related RDS data. Per each detected transmitter a permanency factor indicating the permanency in reception quality thereof is being allocated to each detected RDS transmitter and stored in a first memory bank, along with the relevant tuning data. Per each program identification code carried in the RDS data of the so detected transmitters program related FM RDS data are being stored in a second memorybank, a linkage code defining the storage address within the second memory bank containing the program data carried by the relevant FM RDS transmitter being allocated to the transmitter data of each FM RDS transmitter and stored in the first memory bank.
1. A method for selecting a tuning frequency for receiving an RF transmitter within an RF frequency band, the method comprising:
periodically performing a band scanning search to detect transmitters exceeding a predetermined reception quality level;
storing the tuning data for the detected transmitters;
allocating a permanency factor indicating the permanency in reception quality for the transmitters exceeding the predetermined reception quality level and based on the number of times the transmitter exceeds the predetermined reception quality in the band scanning searches; and
selecting a tuning frequency on the basis of the permanency factor.
2. A method according to claim 1 wherein the band scanning search is repeated in subsequent scan cycles, and each detected transmitter increasing or decreasing respectively in permanency factor depending on the detection or the absence of detection respectively in subsequent scan cycles.
3. A method according to claim 2 further comprising erasing the tuning data of transmitters having a permanency factor decreasing below a predetermined permanency threshold level.
4. A method according to claim 1 further comprising selecting an RF transmitter from the detected transmitters carrying audio programs belonging to a predetermined PTY category.
5. A method according to claim 1 further comprising selecting an RF transmitter from the detected FM transmitters carrying traffic messages on the basis of field strength.
6. An FM receiver comprising:
a first tuner circuit for receiving a first FM transmitter;
a second tuner circuits for periodically detecting FM transmitter signals received with a reception quality exceeding a predetermined quality threshold level in an FM band;
storage means for storing the tuning data of the detected FM transmitters, wherein the first tuner circuit switches over from an actually received first FM transmitter to a second FM transmitter selected from the detected FM transmitters when the reception quality of the first FM transmitter decreases below a predetermined level;
a processing unit which allocates a permanency factor indicating the permanency in reception quality to each detected FM transmitter, the permanency factor based on the number of times when the detected FM transmitter exceeds the predetermined level after the initial detection and wherein the selection of the second FM transmitter is based on the permanency factor.
7. An FM receiver according to claim 6 , further comprising a tuning control means for varying the tuning of the second tuner circuit to repeat the band scanning search in subsequent scan cycles and wherein the processing unit increases stepwise the permanency factor of the transmitter at each detection or decreases the permanency factor stepwise in the absence of detection of the transmitter in a subsequent scan cycle.
8. An FM receiver according to claim 7 , wherein the storage locations of the tuning data relating to transmitters decreasing in permanency factor below a predetermined permanency threshold level are released for storage of other transmitter data in the storage means.
9. An FM receiver according to claim 6 wherein the FM receiver is capable of receiving RDS signals and wherein when selecting the second FM transmitter, the processing unit continuously monitors the permanency factor of the FM transmitters carrying an audio program in the same PTY category as the audio program of the first FM transmitter.
10. An FM receiver according to claim 6 wherein the FM receiver is capable of receiving RDS signals, and wherein the processing unit operates to monitor the permanency factor of FM transmitters carrying traffic message information as well as the field strength thereof, the second FM transmitter being selected from the detected FM transmitters upon receiving a traffic announcement signal on the basis of field strength.