Figure 2-4. Received Signal Strength Indicator Calibration Chart (Typical) - Microwave Data Systems MDS 4310 Installation, Operation & Field Maintenance

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.

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
diagnostics and control functions of the transceiver.
2-10
4
3.5
3
2.5
2
1.5
1
0.5
0
SIGNAL LEVEL (dBm)
command is required from the HHT or terminal to allow
OPEN
INSTALLATION MDS 05-2415A01, Rev. A