(0)H04L:0/4:
IPC6
SECTION H - ELECTRICITY
TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
H04L
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<<   >>   H04L001/00 - H04L009/00  

H 04 L

 TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (typewriters B 41 J; order telegraphs, fire or police telegraphs G 08 B; visual telegraphy G 08 B, G 08 C; teleautographic systems G 08 C; ciphering or deciphering apparatus per se G 09 C; coding, decoding or code conversion, in general H 03 M; arrangements common to telegraphic and telephonic communication H 04 M; selecting H 04 Q) [4]
 

Note
 

This subclass covers transmission of signals having been supplied in digital form and includes data transmission, telegraphic communication, or methods or arrangements for monitoring.

 

 

 
 

 1
/ 00 Arrangements for detecting or preventing errors in the information received (correcting synchronisation H 04 L 7/00; arrangements in the transmission path H 04 B)

1
/ 02 • by diversity reception (in general H 04 B 7/02)  

1
/ 04 • • using frequency diversity  

1
/ 06 • • using space diversity  

1
/ 08 • by repeating transmission, e.g. Verdan system  

1
/ 12 • by using return channel  

1
/ 14 • • in which the signals are sent back to the transmitter to be checked  

1
/ 16 • • in which the return channel carries supervisory signals, e.g. repetition request signals  

1
/ 18 • • • Automatic repetition systems, e.g. van Duuren system  

1
/ 20 • using signal-quality detector [3]  

1
/ 22 • using redundant apparatus to increase reliability [3]  

1
/ 24 • Testing correct operation [3]  
 

 5
/ 00 Arrangements affording multiple use of the transmission path (multiplex communication in general H 04 J)

5
/ 02 • Channels characterised by the type of signal  

5
/ 04 • • the signals being represented by different amplitudes or polarities, e.g. quadriplex  

5
/ 06 • • the signals being represented by different frequencies (combined with time-division multiplexing H 04 L 5/26)  

5
/ 08 • • • each combination of signals in different channels being represented by a fixed frequency  

5
/ 10 • • • with dynamo-electric generation of carriers; with mechanical filters or demodulators  

5
/ 12 • • the signals being represented by different phase modulations of a single carrier  

5
/ 14 • Two-way operation using the same type of signal, i.e. duplex (conditioning for two-way transmission in general H 04 B 3/20)  

5
/ 16 • • Half-duplex systems; Simplex/duplex switching; Transmission of break signals  

5
/ 18 • • Automatic changing of the traffic direction  

5
/ 20 • using different combinations of lines, e.g. phantom working  

5
/ 22 • using time-division multiplexing  

5
/ 24 • • with start-stop synchronous converters  

5
/ 26 • • combined with the use of different frequencies  
 

 7
/ 00 Arrangements for synchronising receiver with transmitter

7
/ 02 • Speed or phase control by the received code signals, the signals containing no special synchronisation information  

7
/ 027 • • extracting the synchronising or clock signal from the received signal spectrum, e.g. by using a resonant or bandpass circuit [5]  

7
/ 033 • • using the transitions of the received signal to control the phase of the synchronising-signal- generating means, e.g. using a phase-locked loop [5]  

7
/ 04 • Speed or phase control by synchronisation signals  

7
/ 06 • • the synchronisation signals differing from the information signals in amplitude, polarity, or frequency  

7
/ 08 • • the synchronisation signals recurring cyclically  

7
/ 10 • • Arrangements for initial synchronisation  

Note
 

In group H 04 L 9/00 to H 04 L 9/32, in the absence of an indication to the contrary, classification is made in the last appropriate place. [5]
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