China
Africa
Explore chapters and articles related to this topic
From the Top Down: Channel Multiplex to Interleaver–Layer 2 and Part of Layer 1
Published in David P. Maxson, The IBOC Handbook, 2007
There are two adders in the scrambler—one to generate the scrambling sequence and one to apply that sequence to the information bits. A modulo-2 adder sums the values of the bits input to the adder, divides by two and reports the remainder. In the IBOC scrambler, the second and eleventh bits in the shift register are added, modulo-2. If both input bits are ones, their sum is binary 10. Dividing by two (which is binary 10) there is no remainder and the output is 0. Similarly, if both values are zero, the sum is zero and the remainder is zero. If one value is a one and the other is a zero, the adder outputs a remainder of 1.
Data Link Layer
Published in Mário Marques da Silva, Cable and Wireless Networks, 2018
An interleaver is somewhat similar to the scrambler described in Chapter 6. Nevertheless, while the interleaver simply changes the sequential position of the bits, splitting a sequence of corrupted bits into several frames, the scrambler performs a mathematical operation using shift registers, at the transmitting side. The de-interleaver, located at the receiver side, performs the opposite operation, repositioning the bits into the original sequence. This way, the number of corrupted bits that appear in each frame becomes possible to be corrected by an error correction code.
Digital Hierarchy
Published in Jerry D. Gibson, The Communications Handbook, 2018
B. P. Lathi, Maynard A. Wright
The two DS1s which are to be multiplexed are bit interleaved together to form the DS1C payload. Prior to bit interleaving, DS1 number 2 is logically inverted. Prior to inserting the interleaved payload into the DS1C overhead structure, the payload is scrambled in a single-stage scrambler. The output of the scrambler is the modulo-2 sum of the current input bit and the previous output bit.
An Overview of Digital Audio Steganography
Published in IETE Technical Review, 2020
Hrishikesh Dutta, Rohan Kumar Das, Sukumar Nandi, S. R. Mahadeva Prasanna
In an early work in the field of steganography, data are hidden in audio streams using sub-band coding, LSB coding, and a shift register-based data scrambler [48]. Sub-band coding breaks a signal into a number of bands of different frequencies and encodes each band independently. A scrambler inverts or transforms signals or otherwise employs an encoding technique such that the retrieval of the message becomes difficult for a receiver which is unaware of the encoding technique. The broadband input signal is first separated into 32 equally spanned sub-bands. Then the data to be concealed is embedded into the LSBs of the certain sub-bands which are synthesized into a broadband signal again.