Pulse or digital communications – Systems using alternating or pulsating current
Reexamination Certificate
1996-11-21
2001-08-07
Vo, Don N (Department: 2631)
Pulse or digital communications
Systems using alternating or pulsating current
C704S205000
Reexamination Certificate
active
06272182
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a digital transmission system having a transmitter and a receiver for transmitting and receiving a digital audio signal, the digital audio signal being in the form of digital samples having a specific wordlength and occurring at a specific sampling rate. The invention further relates to a transmitter for use in the transmission system, a receiver for use in the transmission system, to a record carrier obtained with the transmitter and to a transmission signal.
2. Description of the Related Art
A transmission system as defined in the opening paragraph is known from U.S. Pat. No. 5,323,396.
The transmitter therein includes a subband encoder which splits a wideband digital audio signal into a plurality of subband signals, carries out a quantization on the subband signals based on a psychoacoustic masking model so as to obtain a data reduction of the amount of audio information to be transmitted. Subsequently, the quantized subband signals are combined into a composite transmission signal so as to enable transmission. Together with the data reduced audio information, an information word relating to the sampling frequency of the wideband digital audio signal is also transmitted in order to regenerate the wideband digital audio signal with the same sampling frequency upon reception.
SUMMARY OF THE INVENTION
The invention aims at providing a transmission system as per the opening paragraph which is capable of processing and transmitting audio signals having a wide range of sampling frequencies and wordlengths of the samples of the wideband digital audio signal.
It is a further object of the invention to enable the reception of the transmitted audio signals, with the possibility to convert the sampling frequencies of such audio signals to a desired sampling frequency in a receiver.
The transmission system in accordance with the invention has a transmitter and a receiver for transmitting and receiving a digital audio signal, the digital audio signal being in the form of digital samples having a specific wordlength and occurring at a specific sampling rate, the transmitter comprising
input means for receiving the digital audio signal and for also receiving a first information word having a relationship with the specific wordlength and a second information word having a relationship with the specific sampling rate,
formatting means for combining the digital audio signal and the first and second information words into a serial datastream suitable for transmission via a transmission medium, the wordlength of the samples in the digital audio signal, expressed in number of bits, being equal to n, where n is an integer larger than zero, and the sampling rate being equal to 2
p
.F
s
, where p is an integer larger than zero and F
s
is equal to a frequency value taken from a group of at least two frequency values, said group of frequency values including 44.1 kHz and 48 kHz.
It is a further object of the invention to carry out a data compression step on the digital audio signal which is not based on a subband coder data compression step. Preferably, the data compression step is a lossless data compression step, such as a variable length coding, a Huffman coding, an arithmetic encoding or a Lempel-Ziv encoding. Such data compression steps are much simpler to realize, compared to the subband coding algorithm known from the prior art.
REFERENCES:
patent: 5225787 (1993-07-01), Therssen
patent: 5323396 (1994-06-01), Lokhoff
patent: 5627536 (1997-05-01), Ramirez
patent: 5719571 (1998-02-01), Akune et al.
patent: 0402973 (1990-12-01), None
W.H. Fletcher and S.C. Wegerif, “A Single Chip Solution For Interfacing Digital Audio in Broadcast Applicationts”, International Broadcasting Convention, pp. 217-222, 1990.*
R.W. Stewart, “An Overview of Sigma Delta ADCs and DAC Devices”, IEE Colloquim on Oversampling and Sigma-Delta Strategies for DSP, pp. 1-9, 1995.
Belk Michael E.
U.S. Philips Corporation
Vo Don N
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