Band name |
Sub-voice band |
Voice band |
Medium band |
High-frequency |
Bandwidth |
f < 300 Hz |
f = 0,3 - 4 kHz |
f = 4 - 150 kHz |
f > 150 kHz |
Application |
MRC |
MRC |
RS, RO, RM Telephone and narrowband data services |
Telephone and broadband data services |
Exemplary frequencies |
0 Hz, 50 Hz 166 Hz, 217 Hz |
300 Hz – 2500Hz 300 Hz – 3400Hz 316 Hz, 425 Hz 1050 Hz |
3 – 95 kHz 9 – 95 kHz 95 – 148,5 kHz |
40 kHz – 750 kHz 1 MHz – 30 MHz |
There are common terms used for all these systems: Power Line Communication (PLC), Power Line Telecommunication (PLT) or Power Line (PL) – however, they include both broadband and narrowband telecommunication systems over power lines. More accurate term for broadband systems is Broadband Power Lines (BPL).
PLC systems are criticized by their opponents due to electromagnetic interference, which originates during operation. Data signal, which is injected into a power line, may thus appear for other communication systems as a source of interference. In the development of PLC systems, there were various problems with their interaction with other media. Electromagnetic compatibility (EMC) must be strictly monitored in PLC. Broadband BPL signal emitted to the surroundings of the power distribution lines, often exceeds the permissible limits specified in the international EMC standards. These, however, were formulated in a specific historical period, particularly with regard to the protection of radio reception from interference with spurious sources. In addition, different generations of PLC systems or systems by different companies can exhibit quite different properties in terms of emission of spurious signals.
From the principles of broadband signals transmission over copper lines, it can be concluded that each of them can somehow radiate a certain part of signal energy into space, and that certain radiation coming from the surrounding electromagnetic environment can get into it, as well. The amount of this radiation depends on construction of particular types of line and light coupling in the lines. Spurious emission of wideband signals transmitted over metallic lines is therefore a fact, and it refers to both electric power transmission and weak current installations, including relatively new telecommunications systems (e.g., ADSL and VDSL).