Automatic bandwidth control with high-deviation detection
A signal processing system and methods for controlling a bandwidth of the signal processing system are disclosed. One method includes the steps of detecting a presence of an adjacent signal on at one adjacent channel relative to a desired channel, detecting a modulation characteristic of the desired channel, measuring a signal strength on the at least one adjacent channel, measuring a signal strength on the desired channel, and adjusting a bandwidth filter applied to the desired channel in response to the measurements and detection steps.
1. A method for controlling a bandwidth of a signal processing system, the method comprising the steps of:
tuning the signal processing system to at least one adjacent channel relative to a desired channel;
detecting a presence of an adjacent signal on the at least one adjacent channel relative to the desired channel;
detecting a modulation characteristic of the desired channel while tuned to the at least one adjacent channel;
measuring a signal strength on the at least one adjacent channel;
measuring a signal strength on the desired channel; and
adjusting a bandwidth filter applied to the desired channel in response to the measurements and detection steps.
2. The method according to claim 1 , wherein the steps of the method are performed by the signal processing system including a processor and at least one tuner circuit.
3. The method according to claim 1 , wherein the presence of an adjacent signal is detected based on at least one of detecting a pilot waveform, measuring intermediate frequency quality, comparing sideband symmetry, and performing demodulation and measuring ultra-sonic noise.
4. The method according to claim 1 , wherein the modulation characteristics include at least one of a modulation level, a level of frequency deviation of the carrier signal, and bandwidth on the frequency content of a modulating signal.
5. The method according to claim 1 , wherein the modulation characteristics of the desired channel are detected based on at least one of a level of ultrasonic noise, a modulation level, an audio level, an intermediate frequency measurement, and a frequency content.
6. The method according to claim 1 , wherein the bandwidth filter is adjusted in response to characteristics of the adjacent signal on the at least one adjacent channel and the modulation characteristic of the desired channel.
7. The method according to claim 1 , wherein the bandwidth filter is adjusted to minimize distortion from adjacent interference, while maximizing bandwidth to limit distortion on the desired channel.
8. A method for controlling a filter bandwidth of a signal processing system, the method comprising the steps of:
tuning to a first adjacent channel having a higher broadcast frequency relative to a desired channel;
detecting a presence of an adjacent signal on the first adjacent channel;
detecting a modulation characteristic of the desired channel while tuned to the first adjacent channel;
measuring a signal strength on the first adjacent channel;
tuning to a second adjacent channel having a lower broadcast frequency relative to a desired channel;
detecting a presence of an adjacent signal on a second adjacent channel;
measuring a signal strength on the second adjacent channel;
detecting a modulation characteristic of the desired channel while tuned to the second adjacent channel;
tuning to the desired channel;
measuring a signal strength on the desired channel; and
adjusting a bandwidth filter applied to the desired channel in response to the measurements and detection steps.
9. The method according to claim 8 , wherein the steps of the method are performed by the signal processing system including a processor and at least one tuner circuit.
10. The method according to claim 8 , wherein the presence of an adjacent signal is detected based on at least one of detecting a pilot waveform, measuring intermediate frequency quality, comparing sideband symmetry, and performing demodulation and measuring high-frequency noise.
11. The method according to claim 8 , wherein the modulation characteristics include at least one of modulation level, a level of frequency deviation of the carrier signal, and bandwidth on the frequency content of a modulating signal.
12. The method according to claim 8 , wherein the modulation characteristics of the desired channel are detected based on at least one of a level of ultrasonic noise, a modulation level, an audio level, an intermediate frequency measurement, and a frequency content.
13. The method according to claim 8 , wherein the bandwidth filter is adjusted in response to characteristics of the adjacent signal on the at least one adjacent channel and the modulation characteristic of the desired channel.
14. The method according to claim 8 , wherein the bandwidth filter is adjusted to minimize distortion from adjacent interference, while maximizing bandwidth to limit distortion on the desired channel.
15. A signal processing system with automatic bandwidth control comprising:
an antenna for receiving a plurality of broadcast signals;
a tuner circuit for tuning to a pre-determined range of frequencies from a total spectrum of broadcast signals, wherein the tuner circuit tunes to receive at least one broadcast signal on at least one desired channel and tunes to receive at least one adjacent channel relative to the at least one desired channel;
a channel filter in communication with the tuner circuit and adapted to receive the at least one broadcast signal on the at least one desired channel, wherein the channel filter substantially blocks broadcast signals outside a pre-determined frequency band, while providing transmission of the at least one broadcast signal having a frequency within the pre-determined frequency band; and
a processor in communication with the tuner circuit and the channel filter, wherein the processor analyzes the at least one broadcast signal, analyzes at least one content characteristic of the at least one desired channel while tuned to the at least one desired channel and the at least one adjacent channel, analyzes at least one content characteristic of the at least one adjacent channel, and controls a bandwidth of the channel filter in response to the analysis of the at least one broadcast signal, the analysis of the at least one desired channel, and the analysis of the at least one adjacent channel.
16. The signal processing system according to claim 15 , further comprising:
an analog-to-digital converter in communication with the tuner circuit, the analog-to-digital converter adapted to receive the at least one broadcast signal and convert the at least one broadcast signal into a discrete digital representation;
a digital down converter in communication with the analog-to-digital converter, the digital down converter adapted to receive the discrete digital representation and center the discrete digital representation at a substantially zero frequency.
17. The signal processing system according to claim 15 , wherein the analysis of the at least one broadcast signal includes measuring at least one of: a modulation level; an audio level; an intermediate frequency level; a level of frequency deviation of a carrier signal; and a bandwidth on the frequency content of a modulating signal.
18. The signal processing system according to claim 15 , wherein the analysis of the at least one desired channel includes at least one of: detecting a presence of an actual signal; detecting modulation characteristics; detecting a pilot waveform, measuring intermediate frequency quality, comparing sideband symmetry, and performing demodulation and measuring ultra-sonic noise.
19. The signal processing system according to claim 15 , the channel filter is adjusted to minimize distortion from adjacent interference, while maximizing bandwidth to limit distortion on the desired channel.