8 NV1023 SDIF-2 Distribution Amplifier
3. OPERATION
Once configured for a particular application, the NV1023 SDIF-2
Distribution Amplifier needs no further attention. Refer to Section 5 -
Maintenance and Troubleshooting for recommendations on periodic
maintenance and performance checks.
4. FUNCTIONAL DESCRIPTION
Refer to the schematic diagram for the NV1023 active module
(Assembly EM0103) and the backplane drawing for Assembly
EM0104 during the following discussion.
The single-ended input to the NV1023 is a passive loop-through
connection, while the outputs are single-ended. While there are six
identical outputs on the active module, the BNC backplane assembly.
(EM0104) limits the number of available output connectors on the rear
panel to four.
4.1 INPUT CIRCUIT
Refer to page 1 of Schematic Diagram EM0103.
The signal enters the active module from the connector backplane
through interface connector J3 and is coupled to the input circuitry
through R4, a zero-ohm jumper in a resistor-like package. Jumper J1
provides a means for selecting the input termination resistance: 75 ohms
for terminating coaxial cables or high-impedance for loop-through
applications. Resistor R5 and voltage reference diode U5 bias the
inverting input of the RS-422 receiver integrated circuit (IC) U1 to +1.2
VDC. This provides a threshold for slicing the input signal and ensures
adequate noise rejection. Capacitor C5 provides a low-impedance
bypass for the reference diode at high frequencies.
4.2 OUTPUT CIRCUITS
See Schematic Diagram EM0103, page 2, and Schematic Diagram
EM0104.
The single-ended output of IC U1 is fed to six identical output circuits
comprising RS-422 driver ICs U2 and U3 and their associated circuitry.
One output circuit (Output #1) is described here; the others operate in
identical fashion.
SDIF-2 word clock data from pin 3 (output) of receiver IC U1 feeds pin
9 of quad RS-422 line driver IC U3. One side of the differential output
of U3C (non-inverting output, pin 10) is connected through zero-ohm
jumper/resistor R42 to input/output interface connector J3. From
interface connector J3, the single-ended signal enters SDIF-2 BNC
backplane EM0104, passes through zero-ohm resistor R4 and connects
Содержание NV1023
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