Adjacent channel suppression based on adjacent channel properties in FM radio broadcast receivers
Exemplary aspects are directed to FM-radio circuitries and systems in which, at the receiving end of an FM broadcast transmission, circuitry is used to set the bandwidth for receiving the desired channel of the FM broadcast signal based on measured signal properties of immediately-adjacent channel(s) and based on an inverse relationship between an indication of FM modulation level of the other channel(s) and the amount for which the bandwidth is to be set. FM-signal processing circuitry such as logic/CPU circuitry, then receives the desired channel, including information carried by the FM broadcast signal, in response to setting the bandwidth based on the measured signal properties.
1. A method comprising:
setting a bandwidth for receiving a desired channel of a frequency modulated (FM) broadcast signal based on measured signal properties of another channel that is immediately adjacent to the desired channel and based on an inverse relationship between an indication of FM modulation level of the other channel and an amount for the setting of the bandwidth; and
receiving the desired channel, including information carried by the FM broadcast signal, in response to setting the bandwidth based on the measured signal properties;
wherein setting the bandwidth includes accounting for the signal properties as a function of a selected maximum bandwidth minus an amplitude-level difference between a measured amplitude of the desired channel and a measured amplitude of the other channel, as multiplied by an indication of FM modulation level of the other channel.
2. The method of claim 1 , further including signal-processing circuitry measuring the signal properties including the indication of FM modulation level of the other channel.
3. The method of claim 1 , wherein the signal properties include an indication of amplitude-level difference between a measured amplitude of the desired channel and a measured amplitude of the other channel.
4. The method of claim 1 , wherein the inverse relationship between an indication of FM modulation level of the other channel and the amount is characterized in that: based on a relatively large indication of FM modulation level of the other channel, the step of setting a bandwidth for receiving a desired channel includes setting a relatively narrow bandwidth; and
whereas based on a relatively small indication of FM modulation level of the other channel, the step of setting a bandwidth for receiving a desired channel includes setting a relatively wide bandwidth.
5. The method of claim 1 , wherein setting a bandwidth includes accounting for the signal properties as a function of a selected maximum bandwidth minus: an indication or function of amplitude-level difference between a measured amplitude of the desired channel and a measured amplitude of the other channel, as multiplied by an indication of FM modulation level of the other channel.
6. The method of claim 1 , wherein setting a bandwidth includes accounting for the signal properties as a function of a selected maximum bandwidth minus a function of both: amplitude-level difference between a measured amplitude of the desired channel and a measured amplitude of the other channel, and an indication of FM modulation level of the other channel.
7. The method of claim 1 , further including signal-processing circuitry measuring the signal properties as including one or more of the following: an indication of a measured amplitude of the other channel impacts spectrum corresponding to bandwidth control provided for the desired channel; an indication of amplitude-level difference between a measured amplitude of the desired channel; and a measured amplitude of the other channel.
8. The method of claim 1 , wherein the step of setting the bandwidth is performed by a FM radio receiver having circuitry which measures or estimates modulation of channels on each side of the desired channel.
9. The method of claim 1 , wherein the step of setting the bandwidth is performed by a FM radio receiver having circuitry which uses an amplitude of a possible-interfering channel regularly or continuously so as to provide an adaptive spectrum estimation.
10. The method of claim 1 , wherein the signal properties include an indication of amplitude-level difference between a measured amplitude of the desired channel and a measured amplitude of the other channel, and wherein the step of setting the bandwidth is based on a limited range of the level difference, and thereby setting a maximum allowed bandwidth dependent on the range.
11. The method of claim 10 , wherein the step of setting the bandwidth is based on minimum upper bandwidth parameter and a minimum lower bandwidth parameter.
12. The method of claim 1 , wherein the FM broadcast signal is used in a European region.
13. The method of claim 1 , wherein the FM broadcast signal is used in a North American region.
14. The method of claim 1 , wherein the FM broadcast signal is used in a region of Asia.
15. An apparatus comprising:
circuitry to set a bandwidth for receiving a desired channel of a frequency modulated (FM) broadcast signal based on measured signal properties of another channel that is immediately adjacent to the desired channel and based on an inverse relationship between an indication of FM modulation level of the other channel and an amount the bandwidth is to be set; and
FM-signal processing circuitry to receive the desired channel, including information carried by the FM broadcast signal, in response to setting the bandwidth based on the measured signal properties;
wherein the circuitry to set the bandwidth accounts for the signal properties as a function of a selected maximum bandwidth minus an amplitude-level difference between a measured amplitude of the desired channel and a measured amplitude of the other channel, as multiplied by an indication of FM modulation level of the other channel.
16. The apparatus of claim 15 , wherein the inverse relationship between an indication of FM modulation level of the other channel and the amount is characterized in that: based on a relatively large indication of FM modulation level of the other channel, the step of setting a bandwidth for receiving a desired channel includes setting a relatively narrow bandwidth; and whereas based on a relatively small indication of FM modulation level of the other channel, the step of setting a bandwidth for receiving a desired channel includes setting a relatively wide bandwidth.
17. The apparatus of claim 15 , further including circuitry to measure and generate the measured signal properties of one channel or a pair of channels that is immediately adjacent to the desired channel.
18. The apparatus of claim 15 , further including circuitry to measure the signal properties including an indication of a measured amplitude of the other channel impacting spectrum corresponding to bandwidth control provided for the desired channel; and wherein the circuitry to set a bandwidth accounts for measured signal properties of yet another channel that is immediately adjacent to and on another side of the desired channel.
19. The apparatus of claim 15 , further including circuitry to measure the signal properties including at least two of the following: an indication of a measured amplitude of the other channel impacting spectrum corresponding to bandwidth control provided for the desired channel; an indication of amplitude-level difference between a measured amplitude of the desired channel; and a measured amplitude of the other channel.
20. A method comprising:
setting a bandwidth for receiving a desired channel of a frequency modulated (FM) broadcast signal based on measured signal properties of another channel that is immediately adjacent to the desired channel and based on an inverse relationship between an indication of FM modulation level of the other channel and an amount for the setting of the bandwidth; and
receiving the desired channel, including information carried by the FM broadcast signal, in response to setting the bandwidth based on the measured signal properties;
wherein setting a bandwidth includes accounting for the signal properties as a function of a selected maximum bandwidth minus an indication or function of amplitude-level difference between a measured amplitude of the desired channel and a measured amplitude of the other channel, as multiplied by an indication of FM modulation level of the other channel.