Patent ID: 9496850
Filing Date: 2016-11-15
CPC Classification: G10L,H03H,H04S

Claim Text:
1. A method of processing a first digital signal and a second digital signal, the method comprising: splitting the first digital signal into a first and a second frequency subbands to generate a first and a second subband signal, the first frequency subband corresponding to a high-frequency subband, the second frequency subband corresponding to a low-frequency subband; splitting the second digital signal into the first and second frequency subbands to generate a third and a fourth subband signal, the third frequency subband corresponding to the high-frequency subband, the fourth frequency subband corresponding to the low-frequency subband; generating first and second downsampled subband signals by downsampling or decimating the first and second subband signals; generating third and fourth downsampled subband signals by downsampling or decimating the third and fourth subband signals; determining a transition frequency band between the first and second frequency subbands; generating first and second processed subband signals by applying a low-complexity subband processing filter to the first downsampled subband signal and a high-complexity subband processing filter to the second downsampled subband signal; generating third and fourth processed subband signals by applying at least one subband processing filter to at least one of the third and fourth downsampled subband signals; combining the first and second processed subband signals to reconstruct a first output signal; and combining the third and fourth processed subband signals to reconstruct a second output signal, wherein the subband processing filters are substantially matched in amplitude and phase in order to reduce the generation of aliased components in corresponding output signals, wherein the design of the high-complexity subband processing filter applied to the low-frequency subband signal is selected such that the matching of phase and amplitude in the high-frequency subband signal can be accomplished in conjunction with the low-complexity subband processing filter applied to the high-frequency subband signal, thereby optimizing both phase and amplitude matching while ensuring that the matching in the transition band is sufficient to keep the magnitude of aliased components below a predetermined threshold; and wherein the subband processing filters are applied to a combination of the first and third downsampled subband signals.