Process and device for the baseband transcoding of digital information
AssigneeSTMicroelectronics S.r.l.
InventorsThierry Fensch, Gérald Kohlenberger, Céline Cornu
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Abstract
The symbols of a first code are represented by sign and magnitude bits in a manner analogous to the sign and magnitude bits representing the symbols of a second code. A memory stores digital samples partially representing coding pulses, and each pair of sign and magnitude bits is used to control a common shaping filter. The shaping filter uses the samples stored in the memory to generate a sampled digital signal representative of the analog signal transmitted over the telephone line.
Claims22
A method for the baseband transcoding of a stream of digital information for transmission within an analog signal that is formed using pulses associated with coding symbols, said method comprising the steps of:
- storing first digital samples in a first memory, the first digital samples representing at least part of the pulses associated with symbols of a first type of coding;
- storing second digital samples in a second memory, the second digital samples representing at least part of the pulses associated with symbols of a second type of coding;
- selecting either the first type of coding or the second type of coding for the transmission;
- if the first type of coding is selected, performing a first coding process that includes the steps of:
- extracting pairs of bits from the stream of digital information;
- and
- delivering the pairs of bits at a first frequency, each delivered pair of bits corresponding to one of the symbols of the first type of coding;
- if the second type of coding is selected, performing a second coding process that includes the steps of:
- processing bits from the stream of digital information;
- and
- delivering corresponding symbols of the second type of coding at a second frequency, each symbol of the second type of coding being delivered as a pair of bits;
- reading the digital samples from the first or second memory at a third frequency based on the type of coding selected and the value of the delivered pair of bits;
- and
- generating a digital output signal from the read digital samples, the digital output signal being representative of the analog signal to be transmitted.
A device for the baseband transcoding of digital information for transmission within an analog signal that is formed by pulses associated with coding symbols, said device comprising:
- a first memory storing first digital samples representative of at least part of the pulses associated with the symbols of a first type of coding;
- a second memory storing second digital samples representative of at least part of the pulses associated with the symbols of a second type of coding;
- a preprocessing circuit;
- and
- a shaping filter that reads digital samples from either the first or the second memory at a first frequency on the basis of a selected type of coding and values of sign bits and magnitude bits, and that generates a digital output signal from the read digital samples, the digital output signal being representative of the analog signal to be transmitted,
- wherein when the first type of coding is selected, the preprocessing circuit extracts pairs of bits from the digital information and outputs the pairs of bits to the shaping filter at a second frequency, each output pair of bits representing one of the symbols of the first type of coding and being one sign bit and one magnitude bit, and
- when the second type of coding is selected, the preprocessing circuit processes the digital information and outputs symbols of the second type of coding at a third frequency, each symbol of the second type of coding being represented by a pair of bits that has one sign bit and one magnitude bit.
Dependencies are inferred from the claim text.