MultiDyne DVM-2200 - Manual (Page 7)

Instruction Manual, DVM-2200 FEATURES and OPERATION 7
*** Confidential *** Multidyne Video & Fiber Optic Systems
When installing a 1310 or 1550 nm Singlemode Laser system the launched optical power
can vary from -8 dBm to +3 dBm depending on the model purchased. The receiver will
compensate for variations in optical attenuation. The receiver unit will operate with an optical
signal from –32 to +3 dBm with out over-load.
The DVM-2200-FRX Fiber Optic Receiver for Singlemode applications all has an optical
window from the wavelength of 1100 to 1600 nm. If a Singlemode system is to be Wave Division
Multiplexed with other optical wavelengths in the 1100 to 1600 nm range, the appropriate optical
filters and wave division multiplexers should be used. The user may contact MULTIDYNE to
purchase such devices.
POWER REQUIREMENTS
The UTIL-200-DVM-AC operates from 85 to 265 VAC with two dual redundant power
supplies each with a separate line cord. The UTIL-200-DVM is available with a 48 VDC Telco
Power supply. The PWR 1 and PWR2 LEDs glow green when the unit is powered up and
operating properly. If the unit is plugged into an active outlet and the POWER LED does not
glow, check the internal fuse.
NOTE
Use only a 2 Amp replacement fuse for the PS-200-DVM-AC and PS-200-DVM-48VDC power
supplies
for the UTIL-200-DVM Series of Trays
CIRCUIT DESCRIPTION
The Multidyne DVM2200 is a highly linear low noise, low distortion fiber optic link.
The circuitry in the transmitter processes and digitizes seven analogue and 3 digital signals and,
through high speed time division multiplexing, serializes them into a single, self clocking bit
stream that modulates the output of an LED or a laser. At the receiving end a high speed
demultiplexer extracts the imbedded clock and then the data in a parallel format to be presented
to seven digital to analogue converter that reconstruct the 7 analogue signals.
DVM-2200-FTX TRANSMITTER DESCRIPTION
U22 is an AD8052 dual wide band operational amplifier. The first half is the input video
buffer. It interfaces video to the anti-aliasing low pass filter after some processing. Diodes D10 to
D13 suppress transients that could be harmful to the buffer. R60 adjusts the common mode
rejection of the buffer. Capacitors C89 to C92 together with resistors R65 to R68 form a 4-pole
variable cable equalizer that restores the phase and amplitudes of certain video frequency
components. LPF1 is an elliptical 11-pole low pass filter. It attenuates out of band signals that
would produce aliasing products at the output of U23, the video analogue to digital converter. The
second half of U22 is the video post amplifier that overcomes the filter losses and, through the
adjustment of C68 trims the high frequency response of the input video channel. R48 is adjusted
to 1VPP terminated in 75
collector. Q2 is a “box car” pulse former that generates a positive going pulse beginning with the