Signal quality estimation and control system
View Patent ↗A signal quality estimation and control system for controlling a signal having noise. The system may include a signal strength determination system having an input configured to receive the signal and an output configured to output information indicative of the strength of the signal, a noise strength determination system having an input configured to receive the signal and an output configured to output information indicative of the strength of the noise in the signal, and a signal quality evaluation system. The signal quality evaluation system may have an input configured to receive the output of the signal strength determination system, an input configured to receive the output from the noise strength determination system, and an output configured to output information indicative of the quality of the signal based on the output from the signal strength determination system and the output from the noise strength determination system. A signal control system may be include that has an input configured to receive the output from the signal quality evaluation system and to control a switching function relating to the signal based on the output from the signal quality evaluation system.
1. An Second Audio Programming (SAP) signal quality estimation and control system for controlling an SAP signal having noise, the system comprising:
a signal quality estimation system having an input configured to receive the SAP signal and an output configured to output a quality signal indicative of the quality of the received signal, wherein the signal quality estimation system includes,
a signal strength determination system having an input configured to receive the SAP signal and an output configured to output a SAP strength signal indicative of the strength of the SAP signal, wherein the signal strength determination system includes (i) an envelope extraction system having an input configured to receive the SAP signal and an output configured to output a SAP magnitude signal indicative of the magnitude of the envelope of the SAP signal, and (ii) an averaging system having an input configured to receive the SAP magnitude signal from the envelope extraction system and an output configured to output an average SAP signal indicative of an average of the SAP magnitude signal;
a noise strength determination system having an input configured to receive the SAP signal and an output configured to output a SAP noise strength signal indicative of the strength of the noise in the SAP signal, the noise strength determination system including a subtracting system having an input configured to receive the SAP magnitude signal from the envelope extraction system, an input configured to receive the average SAP signal from the averaging system, and an output configured to output a difference signal indicative of the difference between the SAP magnitude signal and the average SAP signal from the averaging system, and wherein the noise strength determination system is configured to receive the difference signal from the output of the subtracting system;
a signal quality evaluation system having an input configured to receive the SAP strength signal from the output of the signal strength determination system, an input configured to receive the SAP noise strength signal from the noise strength determination system, and an output configured to output a SAP quality signal indicative of the quality of the SAP signal based on the SAP strength signal from the signal strength determination system and the SAP noise strength signal from the noise strength determination system; and
a signal control system having an input configured to receive the quality signal from the signal quality estimation system and to provide a switching function relating to the SAP signal.
2. The SAP signal quality estimation and control system of claim 1 wherein the signal control system is configured to control switching between an SAP channel and stereo channels.
3. The SAP signal quality estimation and control system of claim 1 wherein the signal control system is configured to control switching between an SAP channel and a monaural channel.
4. The SAP signal quality estimation and control system of claim 1 wherein the signal control system is configured to control switching between enabling and disabling selection of an SAP channel by a user.
5. The SAP signal quality estimation and control system of claim 1 wherein the signal control system is configured to control switching between playing and muting an SAP channel.
6. The SAP signal quality estimation and control system of claim 1 wherein the signal quality estimation system is implemented with a digital signal processing system.
7. A signal quality estimation and control system for controlling a signal having noise, the system comprising:
a signal strength determination system having an input configured to receive the signal and an output configured to output a signal strength signal indicative of the strength of the signal, wherein the signal strength determination system includes (i) an envelope extraction system having an input configured to receive an FM signal and an output configured to output a FM magnitude signal indicative of the magnitude of the envelope of the FM signal, and (ii) an averaging system having an input configured to receive the FM magnitude signal from the envelope extraction system and an output configured to output an average FM signal indicative of an average of the FM magnitude signal from the envelope extraction system;
a noise strength determination system having an input configured to receive the signal and an output configured to output noise strength signal indicative of the strength of the noise in the signal, wherein the noise strength determination system comprises a subtracting system having a first input configured to receive the FM magnitude signal, a second input configured to receive the average FM signal, and an output configured to output a difference signal indicative of the difference between the FM magnitude signal and the average FM signal, and wherein the noise strength determination system is configured to receive the difference signal from the output of the subtracting system;
a signal quality evaluation system having a first input configured to receive the signal strength signal from the output of the signal strength determination system, a second input configured to receive the noise strength signal from the noise strength determination system, and an output configured to output a quality signal indicative of the quality of the signal based on the signal strength signal and the noise strength signal; and
a signal control system having an input configured to receive the quality signal and to control a switching function relating to the signal based on the quality signal;
wherein the input to the signal strength determination system and the input to the noise strength determination system are configured to receive a SAP signal; and
wherein the signal control system is configured to control a switching function relating to the SAP signal.
8. The signal quality estimation and control system of claim 7 wherein the output of the signal quality evaluation system is configured to output information indicative of whether the signal quality is acceptable or not acceptable.
9. The signal quality estimation and control system of claim 8 wherein the output of the signal quality evaluation system is based on a comparison between the signal strength signal and a predetermined signal strength threshold.
10. The signal quality estimation and control system of claim 8 wherein the output of the signal quality evaluation system is based on a comparison between the noise strength signal and a predetermined noise strength maximum.
11. The signal quality estimation and control system of claim 8 wherein the output of the signal quality evaluation system is based on a comparison between the signal strength signal and the noise strength signal.
12. The signal quality estimation and control system of claim 11 wherein the comparison is between a ratio of the signal strength signal to the noise strength signal and a predetermined signal-to-noise ratio threshold.
13. The signal quality estimation and control system of claim 12 wherein the quality signal is also based on a comparison between the signal strength signal and a predetermined signal strength.
14. The signal quality estimation and control system of claim 7 wherein the averaging system includes an integrator.
15. The signal quality estimation and control system of claim 7 wherein the signal strength determination system and the noise strength determination system are each implemented with a digital signal processing system.