Teleste CXE851 - Optical Input Power Measurement

User Manual CXE85X
59300464 Rev.005
9.12.2013 10(44)
The status led blinks when the RF controls are under software control and
changing the rotary switch or jumpers has no effect. Hardware control can be
restored using the reset button.
RF output port
RF output port features an “open collector output” for purposes of alarming or
control signal output. The function is controlled by processor and can be used
for example to reset an external Ethernet switch installed next to CXE85x.
CXE85x measures the time elapsed since last received unicast packet to its IP
address. If CXE85x does not receive any unicast packets within user-specified
time, the control signal output is activated for user-specified time and the
unicast receive time calculation is restarted.
Although the open collector output allows a lot of wiring flexibility, care must be
taken not to destroy the circuit via over-voltage, transients or current overload.
Open collector output is specified for max. 100 mA switching current (30 VDC
max.). Inductive loads (relays or other solenoids) can generate very high
voltage spikes when the open collector switch is turned off. If such a load is
unavoidable, the use of transient suppression components parallel to the load is
required. This is critical, as a single transient pulse may destroy the output.
Note: If the control signal output functionality is not used the external control
jumper (Fig. 3 pos.10) must be set to OFF state
RF performance
Optical receivers are integrated within the CXE85x and will accept both 1310
and 1550 nm wavelength optical inputs. Each optical receiver have both a LED
indicator and DC voltage test point for measuring received optical power.
The output stage uses a GaAs MESFET output amplifier to improve RF
performance over the entire 47 to 1006 MHz passband.
Optical input power
Optical input power can be measured from the optical power DC voltage test
point (Figure 4 pos. 3, 4). The test point DC voltage is directly proportional to
optical input power in mW e.g. 1 V corresponds to 1.0 mW average optical
power in 1310 nm operation. In 1550 nm operation subtract 0.5 dBm.
Optical input power / dBm
Optical power testpoint / V
DC
1310 nm
1550 nm
+2
1.58
1.78
+1
1.26
1.41
0
1.00
1.12
-1
0.79
0.89
-2
0.63
0.71
-3
0.50
0.56
-4
0.40
0.45
-5
0.32
0.35
-6
0.25
0.28
-7
0.20
0.22
Table 2. Optical input power DC test point voltages
Do not connect any voltage to the test point or short circuit it to ground. Use a
voltage meter with an input resistance higher than 100 kΩ.