Microwave Data Systems MDS 4310, Установка, эксплуатация и техническое обслуживание на месте

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2-10 INSTALLATION MDS 05-2415A01, Rev. A
PIN 19: +8 Vdc Regulated Source
This pin provides a convenient source of regulated 8 Vdc at 10 mA for powering
external equipment.
PIN 20: No Connection
PIN 21: RSSI (Received Signal Strength Indicator)
A received signal strength indicator (RSSI) output is provided on this pin to aid in
steering antennas and monitoring changes in relative signal strength of received
signals.
Figure 2-4 is a graph plotting the typical RSSI voltage versus signal input. When
measured with a DVM, the accuracy of the RSSI is approximately
±
10 dBm. The
RSSI will be within 3 dBm when displayed on the HHT.
0
0.5
1
1.5
2
2.5
3
3.5
4
–140 –120
–100
–80
–60
–40
DC VOLTS
SIGNAL LEVEL (dBm)
Figure 2-4. Received Signal Strength Indicator Calibration Chart (Typical)
PIN 22: Loopback Test—Receive Audio Input
A direct input to the loopback and diagnostics module’s DTMF decoder. Can be
used with external DTMF encoder to simulate a polling request from a master
station. Nominal input signal level required: –10 dBm.
PIN 23: Open Diagnostics
A low on this input opens the diagnostics channel. If the terminal cable provides a
ground for this pin the diagnostics channel automatically opens. If this pin is not
grounded, the
OPEN
command is required from the HHT or terminal to allow
diagnostics and control functions of the transceiver.