Browse Prior Art Database

Companding Code

IP.com Disclosure Number: IPCOM000082299D
Original Publication Date: 1974-Nov-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 24K

Publishing Venue

IBM

Related People

Blanc, A: AUTHOR

Abstract

In order to transmit a low-speed digital signal over a high-speed transmission channel, a method consists in sampling the signal to be transmitted at a sufficiently high rate n to avoid excessive distortion.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 100% of the total text.

Page 1 of 2

Companding Code

In order to transmit a low-speed digital signal over a high-speed transmission channel, a method consists in sampling the signal to be transmitted at a sufficiently high rate n to avoid excessive distortion.

The proposed scheme consists in grouping the sample bits in groups of m = 2/p/ bits. m is chosen so that the maximum distortion encountered in the bits to be sampled is lower than 1 - m/n. Thus, the bit value, 1 or 0, will change only once in a group at most.

The first bit of the group is recorded. Then, the number of sample bits preceding the first bit the value of which changes are counted. A number between 1 and 2/p/- 1 is obtained. This number is codified in the form of a p-bit code. Thus, with the first bit of the group, a p + 1 bit code has been obtained to replace the m bits of the group.

In the example illustrated the sampling rate is n = 13. With p = 3, each group includes 2/3/ = 8 sample bits. The first bit of group 1 being 0 and as the bit change takes place after two bits, the corresponding code is 0010. Likewise, the code corresponding to group 2 is 1110.

1

Page 2 of 2

2

[This page contains 2 pictures or other non-text objects]