GLOSSARY 149
POTS Plain Old Telephone Service. Basic dial telephone connections to the
public switched network, without any added features or functions.
Rx Short for Receive Data. A line used to carry received serial data from
one device to another, such as from a modem to a computer.
rx Short for Receive Data.
SNR signal to noise ratio
Symbol Rate The analog modem baud rate.
Tx Short for Transmit data. A line used to carry transmitted data from one
device to another, as from a computer to a modem.
tx Short for Transmit data.
US Up stream. The direction in VDSL away from the user workstation.
Vac Volts Alternating Current. The measure of the peak-to-peak voltage
swing of an electrical signal.
VCN Visitor and Community Network. The system that deploys the VCN
Access Concentrator and the VCN Access point(s).
VCN AC VCN Access Concentrator, formerly called NCU.
VCN AP VCN Access Point, formerly called NAU.
Vdc Voltage of direct current.
VDSL Very high bit rate Digital Subscriber Line. The data line which connects
the VCN AC to the VCN AP unit. Operates at a rate of 1-10 Mbps.