3
45 MB/S TO 2.7 GB/S OPTICAL 2R RECEIVER MODULE
WITH FSK TONE DETECTION OPTION
Optical Incoming Signal and the Envelope Signal
Characteristics of Envelope Detector
Parameter
Symbol
Minimum
Typical
Maximum
Output AC voltage signal (note1)
Venv
5 mVp-p
-
632 mVp-p
-42 dBm
-
0 dBm
Low cut-off frequency (-1 dB)
-
50 KHz
Low cut-off frequency (-20 dB)
15 KHz
-
High cut-off frequency (-1 dB) (note1)
500 KHz
-
High cut-off frequency (-20 dB) (note1,2)
-
4000 KHz
Clipping and distortion (note3)
-
10 %
S/N in a 40 KHz bandwidth (note4)
14 dB
-
Spurious level (note5)
-
6 dB above noise floor
1. Incoming optical signal with power in the range of -32 dBm to -7 dBm and modulation depth of 5% to 10% (dBm values assume a single tone, not random data with two
tones for FSK channel).
2. The gain at frequencies below the Low cut-off frequency (-20 dB) and above the High cut-off frequency (-20 dB) must be smaller than -20 dB.
3. The envelope-detected signal should not be clipped to the extent the FSK signal-to-noise ratio goes below 14 dB in a 40 KHz bandwidth with an optical input of -7 dBm
and modulation index of 10%.
4. The measurement is conducted at two frequencies: one centered at 80 KHz and the other at 180 KHz. In addition, the measurements are performed at:
a. Carrier data rate of 622 MHz and PRBS 223-1 data pattern with total power into the receiver of -32 dBm and 10% modulation index
b. Carrier data rate of 2488 MHz and PRBS 223-1 data pattern with total power into the receiver of -32 dBm and 5% modulation index
5. Spurs measured with OC 48, PRBS 223-1 signal input and measured between:
a. 55 KHz and 105 KHz
b. 155 KHz and 205 KHz
at a resolution bandwidth of 3 KHz.
Optical
Input
Power
Envelope
Output
Voltage
Eye pattern of SONET,
GE, etc.
t
f1
f2
f1
Note: The envelope signal is a FSK signal. It is a sine wave that contains two frequencies [f1 and f2, where f2 - f1 = 14.3 KHz (max.), and 50 KHz < f1, f2 <500 KHz].