| 摘要 |
An error detecting arrangement for a digital transmission line, wherein signals are transmitted in the form nBIP, and which also provides the possibility of signal validation and a signalling channel. The output of a toggle (4) has a line spectrum at fo/2(n+1) or fo/(n+1), where fo is the line digit frequency, depending on whether the parity is odd mark or even mark. The toggle output is bandpass filtered (at 5) as appropriate and applied to envelope detector (6). Errors can be counted (at 10). The envelope detector output is low pass filtered (at 7), the output of which is an analogue measure of the error rate. The latter is compared (at 9) with a threshold BER and the result can be used for validation or providing a signalling channel (FIG. 2).
|
