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公开(公告)号：US3634773A
公开(公告)日：1972-01-11
申请号：US3634773D
申请日：1969-12-15
Applicant: IBM
Inventor： KOBAYASHI HISASHI
CPC classification number: H04L7/0054 , H04L7/007
Abstract: Iterative and sequential techniques for carrier phase and sample time recovery are employed in the demodulator of PAM single sideband data transmission systems. The summation of the respective products of samples taken from an inphase and quadrature channel provide recursive estimates of the carrier phase for automatically converging the demodulator phase upon carrier phase. Likewise, the summation of the respective products of samples taken from the inphase and a differentiated inphase channel provide recursive estimates of sample time for automatically converging the demodulator sample time upon an optimum sample time.
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公开(公告)号：US3648265A
公开(公告)日：1972-03-07
申请号：US3648265D
申请日：1969-12-30
Applicant: IBM
Inventor： KOBAYASHI HISASHI , TANG DONALD T
CPC classification number: G11B20/10009
Abstract: A digital magnetic recording system which uses conventional NRZI coding and a readback channel of conventional design operates, in effect, as a precoding and correlative level coding process that is characterized by a transfer function of 1-D (where ''''D'''' is a delay operator). Under these conditions, the minimum spacing that can be permitted between adjacent digit symbols in the magnetic recording medium without incurring excessive intersymbol interference during readback is rather large and severely limits the recording density. The present invention uses interleaved NRZI coding and a special filter in the readback channel to provide a precoding and correlative level coding scheme characterized by a transfer function 1-D2. This mode of operation permits much denser packing of the data in the recording medium without causing excessive intersymbol interference during readback.
Abstract translation: 使用常规NRZI编码的数字磁记录系统和传统设计的回读通道实际上作为预处理和相关电平编码处理，其特征在于1-D的传递函数（其中“D”是延迟算子 ）。 在这些条件下，在磁记录介质中相邻数字符号之间可以允许的最小间距，而不会在回读期间引起过多的符号间干扰，这是相当大的，严重限制了记录密度。 本发明在回读通道中使用交错NRZI编码和特殊滤波器来提供以传递函数1-D2为特征的预编码和相关级编码方案。 这种操作模式允许数据在记录介质中更加密集地打包，而不会在回读期间引起过多的码间干扰。
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公开(公告)号：GB1277159A
公开(公告)日：1972-06-07
申请号：GB5991470
申请日：1970-12-17
Applicant: IBM
Inventor： KOBAYASHI HISASHI , TANG DONALD TAO-NAN
Abstract: 1277159 Data storage INTERNATIONAL BUSINESS MACHINES CORP 17 Dec 1970 [30 Dec 1969] 59914/70 Addition to 1277158 Heading G4C Binary sequences are converted into interleaved NRZI form, recorded, read and then encoded by a correlative level coding process having delay by more than one digit in its encoding function. The input sequence (kth bit being ak) is converted to interleaved NRZI form in which the kth bit b k is given by this being equivalent to dividing by 1 - D 2 then reducing mod 2. The interleaved NRZI form is recorded on magnetic tape, disc or drum, each 1 reversing the magnetization. On read-out, a conventional (differentiating) read head followed by a corrective filter with a cosine frequency characteristic performs the correlative encoding to produce bits c k according to this being equivalent to multiplying by 1 - D 2 . The result is then divided by 1 - D 2 in a first decoder which feeds a second decoder which multiplies by 1 - D 2 and takes the result mod 2, thus reproducing the original input sequence. If any digit at the output of the first decoder is other than 0 or 1, an error signal is produced by a level detector to give a warning to the operator or cause re-reading of the recorded data.
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公开(公告)号：CA951425A
公开(公告)日：1974-07-16
申请号：CA100733
申请日：1970-12-16
Applicant: IBM
Inventor： KOBAYASHI HISASHI , TANG DONALD T
Abstract: A digital magnetic recording system which uses conventional NRZI coding and a readback channel of conventional design operates, in effect, as a precoding and correlative level coding process that is characterized by a transfer function of 1-D (where "D" is a delay operator). Under these conditions, the minimum spacing that can be permitted between adjacent digit symbols in the magnetic recording medium without incurring excessive intersymbol interference during readback is rather large and severely limits the recording density. The present invention uses interleaved NRZI coding and a special filter in the readback channel to provide a precoding and correlative level coding scheme characterized by a transfer function 1-D2. This mode of operation permits much denser packing of the data in the recording medium without causing excessive intersymbol interference during readback.
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公开(公告)号：CA982265A
公开(公告)日：1976-01-20
申请号：CA173798
申请日：1973-06-12
Applicant: IBM
Inventor： BAHL LALIT R , GROSSMAN DAVID D , BARNEA DANIEL I , KOBAYASHI HISASHI
Abstract: A system for compacting digital data by means of prediction error coding. Prediction for each unknown bit is a function of previous detected levels in the data stream. A plurality of n-bit up-down counters, each associated with one of the possible states of prediction for an unknown bit, is utilized to arrive at a prediction of the level of the unknown bit. If the value found in the up-down counter is above a pre-specified level, a prediction will be made that the unknown bit is a one, otherwise, the prediction is zero.
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Patent Agency Ranking
公开(公告)号：CA926012A
公开(公告)日：1973-05-08
申请号：CA100734
申请日：1970-12-16
Applicant: IBM
Inventor： TANG D , KOBAYASHI HISASHI
IPC: H04L1/00 , H04L25/48 , H04L25/497
Abstract: 1277158 Data transmission INTERNATIONAL BUSINESS MACHINES CORP 13 Nov 1970 [30 Dec 1969] 54015/70 Heading H4P A data transmission system uses correlation encoding with resulting increase in the number of signal value levels. In Fig. 2, an input signal train A(D)= a 0 + a 1 + D + a 2 D 2 + ... (where D is a time delay operator) where each signal can have any of m levels, is preceded at 10 (to prevent propagation of a chain of errors from a single error in the received transmission) by dividing by G(D)= g 0 + g 1 D + g 2 D 5 + ... and taking the resulting levels mod m, to give a train B(D)=b 0 + b 1 D + b 2 D 2 + .... This is correlatively encoded, 12, by multiplying by G(D) to give C(D)=c 0 + c 1 D + c 2 D 2 + ... in which each level can have any of M (greater than m) levels. C(D) is transmitted over a channel 14 and the received signal C 1 (D) decoded, 18, by dividing by G(D) to give B 1 (D) which in the absence of error equals B(D) and so has only m levels. If there are more than m levels, a level detector 22 (two thresholders feeding an OR gate) produces an error signal to give a warning or cause retransmission and inhibition of a decoder 20 which otherwise multiplies B 1 (D) by G(D) and takes the resulting levels mod m to give A 1 (D), which is equal to A(D) in the absence of errors. A modified system combines 10 and 12 into a unitary encoder, combines 18, 20, 22 into a unitary decoder and precedes the latter with a level splitter which standardizes the received levels to their nominal values after detecting them with thresholders. Fig. 4 shows the unitary encoder, assuming G(D)=g 0 + g 1 D + g 2 D 2 + ... 5 + g N D N , and is self-explanatory, the notation being as before. The unitary decoder is like Fig. 4 except that the mod m detector 34 follows the adder 46, the result from multiplier 36 is not taken mod m, and the output from this multiplier is also fed to a level detector to produce the error signal. If G(D) is 1 - D 2 , then b k =a k + b k-2 , mod m, and c k = b k - b k-2 . A(D) may have m = 3 and result from a preliminary 2-to-3 level transformation (no details).
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公开(公告)号：DE2058450A1
公开(公告)日：1971-11-25
申请号：DE2058450
申请日：1970-11-27
Applicant: IBM
Inventor： KOBAYASHI HISASHI
Abstract: 1323446 Automatic phase control INTERNATIONAL BUSINESS MACHINES CORP 26 Nov 1970 [15 Dec 1969] 56356/70 Heading H3A A data communication system including signal sampling means is characterized in that the sampling time is controlled by a circuit which includes means for differentiating an input to the sampling means and means for combining the differentiated signal with the output from the sampling means to produce the sample time control signal. Amplitude modulated data signals from input 21 are fed to demodulators 25, 49 together with in-phase and quadrature carrier signals from local carrier source 47. The two demodulated signals are sampled and the resulting sampled signals are fed to a comparator 53 to produce an error signal for controlling the phase of the carrier source 47. The signal from demodulator 25 is also fed to a second comparator 55, the other input of which is derived from the differentiated and sampled output from the demodulator 25. The resulting output from the comparator 55 provides a control signal for correcting the sampling time. This signal is fed to a further comparator (85, Fig. 3, not shown) where it is compared with a ramp signal to produce a sampling pulse whenever the amplitudes of the ramp and error signal are equal.
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公开(公告)号：CA996275A
公开(公告)日：1976-08-31
申请号：CA173792
申请日：1973-06-12
Applicant: IBM
Inventor： BAHL LALIT R , KOBAYASHI HISASHI , BARNEA DANIEL I
Abstract: A data compaction system wherein segmented binary data that has redundancy between segments is compacted by means of differential run-length encoding. For compaction of document digitized data, the segments represent lines on the document. Black image points on the document which are represented by a "1" are coded relative to the position of a 1 appearing in the line above the one being coded. The differential distance between binary 1 bit positions on successive lines are coded in accordance with a compaction code. Codewords having a small number of bits are used for small differentials.
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公开(公告)号：DE2257929A1
公开(公告)日：1973-07-12
申请号：DE2257929
申请日：1972-11-25
Applicant: IBM
Inventor： KOBAYASHI HISASHI , TANG DONALD TAO-NAN
IPC: H03H15/00 , H04L25/03 , H04L25/497 , H04L25/04
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公开(公告)号：DE2425776A1
公开(公告)日：1975-01-02
申请号：DE2425776
申请日：1974-05-28
Applicant: IBM
Inventor： BAHL LALIT RAI , BARNEA DANIEL IZHAK , KOBAYASHI HISASHI
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