Baseband
Baseband refers to the original frequency range of a
transmission signal before it is converted, or modulated, to a different
frequency range. For example, an audio signal may have a baseband range from 20
to 20,000 hertz.
When it is transmitted on a radio frequency (RF), it is modulated to a much
higher, inaudible, frequency range.
Signal modulation is used for radio broadcasts, as well as
several types of telecommunications,
including cell phone conversations and satellite transmissions. Therefore, most
telecommunication protocols
require original baseband signals to be modulated to a higher frequency before
they are transmitted. These signals are then demodulated at the destination, so
the recipient receives the original baseband signal. Dial-up modems are a good
example of this process, since they modulate and demodulate signals when they
are transmitted and received. In fact, the word "modem" is short for
modulator/demodulator.
While most protocols require the modulation of baseband
signals, some can transmit in baseband without any signal conversion. A common
example is the Ethernet
protocol, which transfers data using the original baseband signal. In fact, the
word "BASE" in "10BASE-T," "100BASE-T," and
"1000BASE-T" Ethernet refers to baseband transmission. These Ethernet
protocols do not require signal modulation. However, unlike broadband networks,
baseband Ethernet networks are limited to single transmission channel.
No comments:
Post a Comment