Kaval BDA1300, Руководство по эксплуатации оборудования

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BDA1300 Equipment Manual
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Kaval Telecom Inc Page 4-14 of 51
4.3 Power De-Rating Requirements
BDA’s will amplify all signals that fall within their Pass-Band range. The output power will be “shared”
between all channels being amplified. Another multiple channel effect is Intermodulation signals
produced from non-linear effects between the intended channel signals. These intermodulation may
cause interference to receiving equipment.
In order to minimize Intermodulation signals, Power de-rating must be applied. In the USA there are
FCC Intermodulation Specifications published in the EIA Standard PN2009. The tables 2.2 shows the
maximum per channel
Output Levels allowed as a function of the number of channel.
Note that depending on the actual amplifier input levels, the gain of the BDA may need to be reduced to
comply with the above regulations.
4.4 Automatic Gain Control (AGC)
Both Downlink and Uplink paths are equipped with AGC. The Amplifier based AGC has a dynamic
attenuation range that ensures that a field set (adjustable) nominal composite output power is not
exceeded. The AGC gain varies dynamically to maintain this composite power level by limiting strong
signal levels which could cause excessive intermodulation.
For example, if the AGC limit is set for +25 dBm and the gain of the unit is set for 40dB , then the AGC
circuit will begin to attenuate composite incoming signals at +25dBm – 40dBm = -15dB (composite
power input). The AGC circuit will maintain this composite power limit even if the input signals
increased. This composite level would be maintained by reducing the gain from 40 dB. For every 1dB
increase in input signal there would be a 1dB decrease in the gain.
The BDA Controller is used to set the AGC composite power threshold level. The AGC setting is a
value ranging from 0 to 255.
4.5 AGC Threshold level Setting
BDA’s may be shipped with an AGC setting chart specific to that unit.
This includes a 5 dB insertion loss for the internal Duplexers. Consult the Factory for more information.
The AGC Threshold level (in dBm) for the number of channels to be amplified is shown on the next
page. This AGC threshold should be set to ensure intermodulation products do not exceed –13dBm.
This table also shows the de-rated power per channel for the number of channels to be amplified.
BDA Controller
AGC Setting # Composite Power Level
Setting
(+/- 1 dB)
240 +30 dBm
160 +25 dBm
118 +20 dBm
94 +15 dBm
77 +10 dBm