Westell Inc. CSI-DSP85-U7C ユーザーズマニュアル
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If a CSI-DSP85 is installed in an area with very strong desired and/or undesired signals, it is important to ensure that the overall signal levels are
optimized to be within the best operating range of the repeater. Additionally, de-sensing of a nearby base station site must be avoided. These goals
can be accomplished by properly attenuating the antenna port(s) in the path of the donor antenna(s). In effect, one can imagine that the particular
repeater deployment is electrically moved farther from the base station using attenuators that are equivalent to increasing the path loss from the
donor antenna to the base station. The following potential outcomes result from the use of attenuators on the donor port(s) of the CSI-DSP85: Uplink
output power, as reported by the CSI-DSP85, is reduced by the value of the attenuation, protecting nearby base stations. Downlink signal to noise
ratio is high at the point of the attenuator, resulting in slight but negligible reduction in downlink performance. Other performance is essentially
unchanged.
optimized to be within the best operating range of the repeater. Additionally, de-sensing of a nearby base station site must be avoided. These goals
can be accomplished by properly attenuating the antenna port(s) in the path of the donor antenna(s). In effect, one can imagine that the particular
repeater deployment is electrically moved farther from the base station using attenuators that are equivalent to increasing the path loss from the
donor antenna to the base station. The following potential outcomes result from the use of attenuators on the donor port(s) of the CSI-DSP85: Uplink
output power, as reported by the CSI-DSP85, is reduced by the value of the attenuation, protecting nearby base stations. Downlink signal to noise
ratio is high at the point of the attenuator, resulting in slight but negligible reduction in downlink performance. Other performance is essentially
unchanged.
DONOR PORT
Server port attenuation may also be necessary, particularly where a powered DAS is present. The selection guidelines below apply to both server
and donor ports. In order to properly measure uplink signal strength, a signal generator should be used. If a signal generator is not available, placing
a test call while under the server antenna with the least path loss to the repeater should provide reasonable data.
The following potential outcomes result from the use of attenuators on the server port(s) of the CSI-DSP85: Downlink output power, as reported
by the CSI-DSP85, is reduced by the value of the attenuation. Uplink incoming power from the DAS is reduced, along with potentially strong and/
or harmful out-of-band signals (including noise) that are generated by the DAS.
and donor ports. In order to properly measure uplink signal strength, a signal generator should be used. If a signal generator is not available, placing
a test call while under the server antenna with the least path loss to the repeater should provide reasonable data.
The following potential outcomes result from the use of attenuators on the server port(s) of the CSI-DSP85: Downlink output power, as reported
by the CSI-DSP85, is reduced by the value of the attenuation. Uplink incoming power from the DAS is reduced, along with potentially strong and/
or harmful out-of-band signals (including noise) that are generated by the DAS.
SERVER PORT
Attenuator Selection Guidelines
Accurate attenuator values need to be chosen to ensure that the maximum total power (higher of Composite or In-Band Input) applied to the donor
and server port(s) does not exceed the following thresholds:
and server port(s) does not exceed the following thresholds:
Input Signal
Max Gain
Input Signal
Max Gain
<-45 dBm
85 dB
-32.2 dBm
69 dB
-44.3 dBm
84 dB
-31.4 dBm
68 dB
-43.6 dBm
83 dB
-30.6 dBm
67 dB
-42.9 dBm
82 dB
-29.8 dBm
66 dB
-42.2 dBm
81 dB
-29 dBm
65 dB
-41.5 dBm
80 dB
-28.2 dBm
64 dB
-40.6 dBm
79 dB
-27.4 dBm
63 dB
-39.7 dBm
78 dB
-26.6 dBm
62 dB
-38.8 dBm
77 dB
-25.8 dBm
61 dB
-37.9 dBm
76 dB
-25 dBm
60 dB
-37 dBm
75 dB
-24.4 dBm
59 dB*
-36.2 dBm
74 dB
-23.8 dBm
58 dB*
-35.4 dBm
73 dB
-23.2 dBm
57 dB*
-34.6 dBm
72 dB
-22.6 dBm
56 dB*
-33.8 dBm
71 dB
-22 dBm
< 55 dB*
-33 dBm
70 dB
*We recommend padding this level due to potential for fluctuating signal.
-25 dBm is the maximum input signal level that should be applied to the repeater, even if the gain is lower than 55 dB.
Input signals exceeding these thresholds will result in composite input attenuation, called “ADC Protect” (Analog to Digital Converter Protection).
Output power is reduced whenever the above thresholds are exceeded by reducing the gain by 1dB for each 1 dB that the threshold is exceeded.
ADC Protect should not be confused with AGC (Automatic Gain Control), which reduces gain to prevent In-Band (measured) output power from
exceeding the specified maximum output level. To determine the total power applied to the donor and server ports, please reference the “Composite
Input” values as reported in the Web (“System Status”) or Menu (“Link Status”) interfaces (depicted and explained later in this manual).
Input signals exceeding these thresholds will result in composite input attenuation, called “ADC Protect” (Analog to Digital Converter Protection).
Output power is reduced whenever the above thresholds are exceeded by reducing the gain by 1dB for each 1 dB that the threshold is exceeded.
ADC Protect should not be confused with AGC (Automatic Gain Control), which reduces gain to prevent In-Band (measured) output power from
exceeding the specified maximum output level. To determine the total power applied to the donor and server ports, please reference the “Composite
Input” values as reported in the Web (“System Status”) or Menu (“Link Status”) interfaces (depicted and explained later in this manual).
Large delta’s between in-band and composite input signals:
Care should be taken to isolate the best donor site to ensure the least possible delta between in-band and composite downlink signals. If the
(downlink) composite input exceeds the in-band input by more than 3 dB for the LTE band the maximum output power will be reduced. Example:
Band (LTE)
In-Band Input -45 dBm
Composite Input -38 dBm
Max Gain = 68 dB
Max Output = 23 dBm
Care should be taken to isolate the best donor site to ensure the least possible delta between in-band and composite downlink signals. If the
(downlink) composite input exceeds the in-band input by more than 3 dB for the LTE band the maximum output power will be reduced. Example:
Band (LTE)
In-Band Input -45 dBm
Composite Input -38 dBm
Max Gain = 68 dB
Max Output = 23 dBm