Apparatus and method for determination of signal format
View Patent ↗The determination of the signal modulation format for a channel is an important aspect of the operation of a signal receiver. A method ( 700 ) is described including the steps of receiving ( 710 ) a signal, comparing ( 720 ) a sample of the received signal to a first threshold value and a second threshold value, creating ( 720 ) a signal profile based on the comparison, and selecting ( 750 ) a modulation format for the received signal based on the signal profile. An apparatus ( 500 ) is also described including a ring counter ( 510 ) that receives a sample of an input signal, compares the sample to a first threshold value and a second threshold value, and creates a signal profile for the input signal, a signal profiler ( 550 ) that compares the signal profile for the input signal to at least two reference profiles, and a detector ( 560 ) that determines a modulation format for the input signal based on the comparison in the signal profiler ( 550 ).
1. A method comprising the steps of:
receiving a signal;
comparing a sample of the received signal to a first threshold value and a second threshold value;
creating a signal profile based on the comparison, the step of creating a signal profile further including creating a histogram using at least two comparisons from the comparison step; and
selecting a modulation format for the received signal based on the signal profile, wherein the step of selecting includes offsetting a set of values in the histogram based on a weighted average of a set of values for at least two reference histograms.
2. The method of claim 1 , wherein the modulation format is at least one of a sixteen level quadrature amplitude modulation (16QAM), thirty two level quadrature amplitude modulation (32QAM), sixty four level quadrature amplitude modulation (64QAM), one hundred twenty eight level quadrature amplitude modulation (128QAM), and two hundred fifty six level quadrature amplitude modulation (256QAM).
3. The method of claim 1 , wherein the step of comparing includes comparing a signal level of the sample of the received signal.
4. The method of claim 3 , wherein the signal level is a magnitude of the signal level.
5. The method of claim 1 , further comprising the step of demodulating the received signal using the selected modulation format.
6. The method of claim 1 , wherein the weighted average is an equally weighted average of the set of values for the at least two reference histograms.
7. The method of claim 1 , wherein the weighted average is an unequally weighted average of the set of values for the at least two reference histograms.
8. An apparatus comprising:
means for receiving a signal containing digital samples;
means for comparing a sample value of the received signal to a first threshold value and a second threshold value;
means for creating a signal profile based on the comparison, the means for creating a signal profile further including means for creating a histogram using at least two comparisons;
means for correlating the signal profile against at least two reference profiles; and
means for selecting a modulation format for the received signal based on the correlation, wherein the means for selecting includes means for offsetting a set of values in the histogram using a weighted average of a set of values for at least two reference profiles.
9. The apparatus of claim 8 , wherein the modulation format is at least one of a sixteen level quadrature amplitude modulation (16QAM), thirty two level quadrature amplitude modulation (32QAM), sixty four level quadrature amplitude modulation (64QAM), one hundred twenty eight level quadrature amplitude modulation (128QAM), and two hundred fifty six level quadrature amplitude modulation (256QAM).
10. The apparatus of claim 8 , wherein the sample value is a magnitude value of a signal level.
11. The apparatus of claim 8 , further comprising means for demodulating the received signal using the selected modulation format.
12. The apparatus of claim 8 , wherein the weighted average is an equally weighted average of the set of values for at least two reference profiles.
13. The apparatus of claim 8 , wherein the weighted average is an unequally weighted average of the set of values for at least two reference profiles.
14. An apparatus comprising:
a ring counter that receives a sample of an input signal, compares the sample of the input signal to a first threshold value and a second threshold value, and creates a signal profile for the input signal;
a signal profiler, coupled to the ring counter, that compares the signal profile for the input signal to at least two reference profiles; and
a detector, coupled to the signal profiler, that determines a modulation format for the input signal based on the comparison in the signal profiler.
15. The apparatus of claim 14 , wherein the modulation format is at least one of a sixteen level quadrature amplitude modulation (16QAM), thirty two level quadrature amplitude modulation (32QAM), sixty four level quadrature amplitude modulation (64QAM), one hundred twenty eight level quadrature amplitude modulation (128QAM), and two hundred fifty six level quadrature amplitude modulation (256QAM).
16. The apparatus of claim 14 , further comprising an equalizer coupled to the ring counter, the equalizer adjusting the amplitude and phase of the input signal to compensate for distortion introduced during signal transmission.
17. The apparatus of claim 14 , further comprising a demodulator coupled to the detector, the demodulator demodulating the input signal using the modulation format.
18. The apparatus of claim 14 , wherein the signal profiler) includes an offset circuit that adjusts the signal profile for the input signal based on a weighted average of at the least two reference profiles.