User Manual
Product information and planning
9500 MPR Rel. 3.1
3DB18809AAAA Issue 1164/980
2.8.11 Radio Transmission Features with ODU300
2.8.11.1 Frequency Agility
The Frequency Agility feature gives the Operator the possibility to set via ECT the frequency of a single
Transceiver within a chosen sub–band to select the RF working channel. This implies benefits for spare
parts, order processing and frequency co–ordination.
2.8.11.2 Automatic Transmit Power Control (ATPC)
The Automatic Transmit Power Control (ATPC) function automatically increases or decreases the trans-
mit output power upon request from the opposite terminal. The opposite terminal constantly monitors
Receive Signal Level (RSL), receive signal quality, and aggregate Bit Error Rate (BER) of the receive sig
-
nal.
When ATPC Enabled is checked on the Modem Card Settings screen, the transmit output will remain at
it's lowest level until a fade occurs (or a receive circuit alarm is detected). When the change in RSL is
detected at the receive end, a command is sent to the transmit end to increase power in 1 dB steps to
it's highest level. After the fade is over, the receive end commands the transmit power to decreases in 1
dB steps to the lowest level.
The ATPC range (high and low limits) is variable, determined by link distance, link location, and link fre-
quency. When ATPC Enabled is checked, the range values are shown in parenthesis (minimum - maxi-
mum) following ATPC Range.
When ATPC Enabled is not checked on the Modem Card Settings screen, the transmit output will always
operate at it's highest level.
2.8.11.3 Transmitted power control: RTPC function
The capability to adjust the transmitted power in a static and fixed way (RTPC = Remote Transmit Power
Control) has been introduced for those countries where, due to internal rules, the ATPC function is not
accepted or for those hops in which due to the short length and interface problems, a fixed reduced
transmitted power is preferred. The range of the possible attenuation depends on the frequency band
involved. The setting of the transmitted power can be performed locally through ECT.
Output power is band and modulation dependent.
2.8.11.4 Power Monitoring
The ODU300 incorporates a detector for Tx power measurement. It is used to provide measurement of
forward power as a performance parameter, and to provide a calibration input for transmitter operation
over temperature and output range.
Viewed Tx power ranges always match the capabilities of the ODU300 for a given modulation. When
modulation is changed, the WebEML automatically adjusts/restricts Tx Power to be within valid range.
2.8.11.5 Adaptive Equalization
Adaptive equalization (AE) is employed to improve reliability of operation under dispersive fade
conditions, typically encountered over long and difficult paths.
This is achieved through a multi-tap equalizer consisting of two registers, one with feed-forward taps, the
other with feed-back taps. Each of these registers multiply successive delayed samples of the received
signal by weighting-coefficients to remove propagation induced inter-symbol interference.
To Next Page
Loading...
