摘要:
A device and a method for compressing signal information by removing (thinning out) the signal component of a signal in a specific frequency band. Firstly, an input time-series signal (e.g., a PCM signal) is converted by an analyzer (11) into a spectrum signal. Next, of the bands obtained by dividing the spectrum equally into bands, the band having a predetermined or higher correlation in the spectrum distribution with the lower frequency band is specified as a harmonic band by a frequency band masking unit (12). Then, a removal band from which the spectrum is to be removed is determined from the harmonic band, and the spectrum signal of this removal band, from which the spectrum component has been removed (namely the frequency component has been thinned out), is fed to a synthesizer (13).
摘要:
A method of optimizing the compression rate in Adaptive Differential Pulse Code Modulation (ADPCM) is disclosed. The modified pulse code modulation technique employs a prognostic code converter to generate variable length codes on top of the ADPCM coding, based on the probability of occurrence of data bits in a data sample. This variable-length coding is able to further reduce the compressed data size by increasing the compression rate of the conventional ADPCM coding.
摘要:
An apparatus for transforming digital data into encoded digital data describing analog signals representing the digital data. The apparatus comprises a CPU, memory, and control logic for the data translation. The control logic of the apparatus employs mathematical formulae to produce encoded digital data which describes the characteristics of analog signals representing digital data without converting the digital data into analog signals. The apparatus further performs the function of transforming encoded digital data describing analog signals representing digital data into digital data.
摘要:
A first transceiver transmits a set of test levels to a second transceiver as a signal through a communication channel as encoded samples and subjected to one or more of a plurality of line encoding algorithms. An information channel is superimposed in the signal transmitted through the communication channel. The second transceiver determines line encoding with, and conversion between, the companding laws present in the communication channel based on the received set of test signals. The set of test levels are signals having levels determined based on the difference between the normalized amplitude, vertex, or energy curves for the types of companding laws, with or without accounting for other sources of network distortion. Encoded samples representing the transmitted test levels are reconstructed by the second transceiver in accordance with the one or more detected line encoding algorithms, the encoded samples for each of the set of test levels packed into a corresponding sample cell. The encoded samples in a sample cell are compared with one another to form a tentative decision of the sample cell for the presence or absence of the superimposed information channel; and each tentative decision for different sample cells are compared to detect the presence or absence of the superimposed information channel.
摘要:
A device and a method for compressing signal information by removing (thinning out) the signal component of a signal in a specific frequency band. Firstly, an input time-series signal (e.g., a PCM signal) is converted by an analyzer (11) into a spectrum signal. Next, of the bands obtained by dividing the spectrum equally into bands, the band having a predetermined or higher correlation in the spectrum distribution with the lower frequency band is specified as a harmonic band by a frequency band masking unit (12). Then, a removal band from which the spectrum is to be removed is determined from the harmonic band, and the spectrum signal of this removal band, from which the spectrum component has been removed (namely the frequency component has been thinned out), is fed to a synthesizer (13). Lastly, the synthesizer (13) converts the spectrum signal having the thinned frequency component into a time-series signal. As a result, the compression of the information signal can be highly efficiently realized, and the high quality of an audio signal is retained in the case of a compression ration as high as that of the prior art.
摘要:
Method and signal processing apparatus for reducing the number of bits of a digital input signal (Mi) comprising the steps of adding a pseudo-random noise signal (Na) to the digital input signal (Mi) to obtain an intermediate signal (Di), the pseudo-random noise signal (Na) being defined by noise parameters (Np), and quantizing the intermediate signal (Di) having a word length of n bits to a reduced word length signal (Me) having a word length of m bits, n being larger than or equal to m. The method further comprises the step of quantizing the intermediate signal (Di) comprises a first transfer function which is non-linear, the first transfer function being defined by non-linear device parameters (NLDp). Also, the present invention relates to a method and signal decoding apparatus for recovering an output signal (Mo) from a reduced word length signal (Me) provided by the method according to the invention.
摘要:
A pulse amplitude modulated (PAM) mapper includes a constellation matrix memory which stores indications of a plurality of different constellations, wherein at least one of the different stored constellations is of different dimension than another of the stored constellations. The constellations are used individually or together to support a plurality of different modem data rates. In a preferred embodiment, the mapper also includes a logic block, a constellation controller, a PAM code generation block, and an output register. The logic block receives incoming bits and groups the bits as a function of the desired or agreed upon bit rate as indicated by the constellation controller, and provides a plurality of each group of bits to the PAM code generation block, and one or more sign bits to the output register. The PAM code generation block uses the provided bits to choose at least one point from one of the constellations, and uses each chosen constellation point to generate a PAM code (typically .mu.-law or A-law code level) word. Each PAM code word is provided to the output register, and together with associated sign bits generates output bytes. Algorithms are provided for choosing multiple points from the 2D and higher dimensional constellations from provided groups of bits, and for limiting power by substituting combinations of high-power constellation points with otherwise unused lower-power combinations.
摘要:
A compensation system is configured to improve the accuracy of digital signals that are communicated through a digital network by reducing loss from digital attenuation quantization (DAQ; digital pad quantization) and rob bit signaling (RBS). The combined DAQ/RBS compensation system can be employed within a transmitting modem connected to the digital network and is constructed as follows. In a first embodiment, a first adjustment mechanism combines a DAQ compensation quantity with each segment of the digital data, prior to transmission, in order to enhance accuracy of the received digital data. The value of the DAQ compensation quantity depends on feedback that is provided to the compensation system during a series of test transmissions. Next, the word is communicated to a linear-mu-linear converter, which is configured to simulate a digital transmission by mu-law encoding each digital data word into a code word and then subsequently mu-law decoding each code word back into a linear digital data word, while taking into account the compensation quantity during the encoding/decoding process. In addition, the linear-mu-linear converter includes an RBS compensation system that causes an RBS compensation quantity to be mathematically combined with each segment to be tainted by RBS in order to enhance accuracy of the RBS segments, which typically occur periodically. A second adjustment mechanism is connected to the linear-mu-linear converter. The second adjustment mechanism combines the reciprocal of the DAQ compensation quantity with the linear data from the linear-mu-linear converter. Finally, the linear digital data word is passed from the linear-mu-linear converter to a linear-mu converter for conversion into a mu-law code word and transmission to the network. In a second embodiment of the combined DAQ/RBS system, the RBS compensation system is not implemented within, but after, the linear-mu-linear converter.
摘要:
Disclosed is a circuit for adding loss to a signal in a loop carrier transmission system. As data is being transmitted, the circuit determines the digital output needed for an appropriate amount of loss for each channel unit at the end user interface.
摘要:
A method and apparatus for generating low level noise signals are provided. Two random numbers X.sub.1 and Y.sub.1 are first generated and bits 0-4 of the first random number X.sub.1 are extracted to produce a number X.sub.2. A number X.sub.3 is further computed by the formula: X.sub.3 =2.sup.-N (X.sub.2 .multidot.I), where N is a predetermined number and 1.ltoreq.I.gtoreq.2.sup.N -1. Bit 7 of the second random number Y.sub.1 is then extracted and combined as a sign bit with the computed number X.sub.3 to produce a sign-magnitude eight bit number W representing a sample of low level noise encoded in accordance with .mu.-law.
摘要翻译:提供了一种用于产生低电平噪声信号的方法和装置。 首先生成两个随机数X1和Y1,并且提取第一随机数X1的位0-4产生数X2。 通过以下公式进一步计算X3:X3 = 2-N(X2×I),其中N是预定数,1 / N = 2N-1。 然后提取第二随机数Y1的位7并将其组合为具有计算出的数量X3的符号位,以产生表示根据μ-lo编码的低电平噪声样本的符号幅度八位数W。