The first technique used to ensure a minimum density of marks was zero code suppression a form of bit stuffing, which set the least significant bit of each 8-bit byte transmitted to a 1. (This bit was already unavailable due to robbed-bit signaling.) This avoided the need to modify the AMI code in any way, but limited available data rates to 56,000 bits per second per DS0 voice channel. Also, the low minimum density of ones (12.5%) sometimes led to increased clock slippage on the span.
Increased demand for bandwidth, and compatibility with the G.703 and ISDN PRI standards which called for 64,000 bits per second, led to this system being superseded by B8ZS.
Read more about this topic: Modified AMI Code
Famous quotes containing the words code and/or suppression:
“Wise Draco comes, deep in the midnight roll
Of black artillery; he comes, though late;
In code corroborating Calvin’s creed
And cynic tyrannies of honest kings;
He comes, nor parlies; and the Town, redeemed,
Gives thanks devout; nor, being thankful, heeds
The grimy slur on the Republic’s faith implied,
Which holds that Man is naturally good,
And—more—is Nature’s Roman, never to be
scourged.”
—Herman Melville (1819–1891)
“Fashion required the suppression of all naturalness—’to walk upright, with unbending joints; to shake hands after the pump- handle formula; to look inexpressibly indifferent towards everybody and everything; and speak only in a mincing voice was to be a decorous member of society.’”
—For the State of Rhode Island, U.S. public relief program (1935-1943)