Apparatus for modulation and demodulating digital data
AssigneeNortel Networks Limited
InventorMilan Vlajnic
Life of this patent
Estimating the term…
Abstract
A modem comprising entirely digital components and circuitry for receiving a digital signal of a first format from a first device, converting the digital signal to a digital signal of a second format and transmitting the digital signal of a second format to a second device. In one embodiment, a digital signal processor replaces at least a portion of the digital components and circuitry for receiving a digital signal of a first format and converting the digital signal to a digital signal of a second format and transmitting the digital signal of a second format to a second device.
Claims25
A digital modem, comprising:
- means for receiving a digital signal at a first sampling rate from a first device;
- means for buffering said digital signal from the first device;
- digital means for expanding the buffered digital signal;
- means for interpolating the expanded digital signal from a first sampling rate to a digital signal at a second sampling rate;
- means for subtracting far end echo from the interpolated digital signal;
- means for resampling the interpolated digital signal from which the far end echo has been subtracted;
- and
- means for transmitting the resampled interpolated digital signal to a second device.
A method for modulating a data signal transmitted between a first device and a second device communicatively coupled to transmit said data signal therebetween, comprising the steps of:
- receiving a digital signal at a first sampling rate from a first device;
- buffering said digital signal from the first device;
- digitally expanding the buffered digital signal;
- interpolating the expanded digital signal from a first sampling rate to a digital signal at a second sampling rate;
- subtracting far end echo from the interpolated digital signal;
- resampling the interpolated digital signal from which the far end echo has been subtracted;
- and
- transmitting the resampled digital signal to a second device.
A digital modem, comprising:
- a receiver to receive a digital signal at a first sampling rate from a first device;
- a buffer communicatively coupled to the receiver for buffering said digital signal;
- an inverse compander circuit communicatively coupled to the buffer for expanding the buffered digital signal;
- a decoder circuit communicatively coupled to said inverse compander circuit for interpolating the expanded digital signal from a first sampling rate to a digital signal at a second sampling rate;
- a subtractor circuit communicatively coupled to the decoder circuit for subtracting far end echo from the interpolated digital signal;
- a resampler circuit communicatively coupled to the subtractor circuit for resampling the interpolated digital signal from which the far end echo has been subtracted;
- and
- a transmitter for transmitting said digital signal of a different format to a second device.
Dependencies are inferred from the claim text.