ADTRAN TRACER 2xT1, Руководство пользователя

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TRACER 2xT1 User’s Manual
61280003L2-1B
Section 1 TRACER Description
3 Preliminary
spectrum systems to operate in the presence of one another with minimal interference if they are
operating with different sequences. The TRACER allows the selection of one of ten different 120-bit
long sequences.
CHANNEL SELECTION
The FCC has allocated 83.5 MHz of spectrum in the 2.4 GHz band and 125 MHz in the 5.8 GHz band in
which TRACER operates. A TRACER system fully uses the available bandwidth – transmitting in one
half and receiving in the other.
Figure 1-2 illustrates the bandwidth division.
The transmitter at one end (TxA) of a link will transmit in the lower half of the spectrum. Consequently
the receiver at the other end will receive in the lower half of the band and transmit in the upper half.
Thus, a system will operate in one of two frequency plans – transmit in the upper and receive in the
lower or vice versa. These two plans are called Plan A and Plan B. One end of a path will be on Plan A
and the other will be on Plan B. Shipment of a link will consist of an A and a B unless otherwise
specified.
FORWARD ERROR CORRECTION
With the addition of overhead data, error detection and correction capability can be added to a data
stream. Error correction can be accomplished by allowing the receiver to request the re-transmission of
an errored block once detected. The TRACER, on the other hand, implements forward error correction
(FEC) which adds enough overhead data for the receiver to detect and correct errors in the data stream.
This capability comes at the cost of bandwidth. The addition of FEC decreases the required signal-to-
noise (S/N) ratio by approximately 5.5 dB to achieve a given bit error rate (BER).
T1 Operation
Framing
The data in a T1 stream is delimited by framing bits. The pattern of the framing bits follows one of two
formats -- extended superframe ( ESF) or superframe (SF). The T1 interface must be prepared for the
format that will be used.
Figure 1-2. Bandwidth Division
2400 MHz 2441 MHz 2483.5 MHz
5725 MHz 5787 MHz
or
5850 MHz