Innovator CU10BT-CU5000BT Analog Transmitter
System Set Up Procedure
Instruction Manual, Rev. 0
64
Audio Input
The transmitter can accept either a 600 ohm balanced audio input, or a 75 ohm
unbalanced audio input. The balanced audio input connects to the terminal block
TB1 located on the rear panel of the tray. The unbalanced composite audio input
connects to the BNC Jack J4 located on the rear panel of the tray. Which audio input
is used is selected using the jumpers W1 and W5 on J1 and J6 on the analog
modulator board. When the jumpers are between pins 1 and 2 of J1 and J6, the
balanced audio input is selected. When the jumpers are between pins 2 and 3, the
unbalanced composite audio input is selected.
The input terminations of these inputs can be removed, converting each of them to a
high impedance input. Removing the jumper W3 from J4 removes the 600Ω
termination from the balanced audio input. Moving the jumper W6 from J8 pins 1
and 2 to 2 and 3 disables the 75Ω termination on the unbalanced audio input.
There is also a selectable pre-emphasis network that can be applied to the audio
input. The jumper W11 on J37 allows the selection of either 50 or 75 microseconds
for the pre-emphasis network. When the jumper W11 is connected between J37 pins
1 and 2 the pre-emphasis is set to 50 µsec. Connecting the jumper W11 to J37 pins
2 and 3 converts the pre-emphasis to 75 µsec. For System M/N, 75 usec should be
selected. Removing the jumper W2 from J2 disconnects the pre-emphasis network all
together.
The jumper W4 on J3 switches the audio gain between a setting of low and high. It
would normally be set to low gain, where it is connected between pins 2 and 3 of J3.
If the audio level into the tray is too low to attain the proper deviation level, the
jumper can be switched to between pins 1 and 2 of J3, but this should only be done
if the audio gain setting of R36 does not allow the transmitter to generate its full
audio depth of modulation. The aural modulation depth is set by R36 located on the
analog modulator board.
Visual/Aural Ratio
The ratio between the Visual and Aural Carriers is set by adjusting R103 located on
the modulator board. This ratio should be set after the frequency response of the
combined signal has been set using R99, R100, C85 and C86, as the frequency
response network can affect the ratio. Normally this ratio is set to 10 dB.
Frequency Response
The frequency response of the IF signal can bet set with R99, R100, C85 and C86 on
the modulator board. To set the frequency response of the IF signal, apply a Line
Rate sweep Video signal to the tray and monitor the IF output of the modulator
board at J16 with a Spectrum Analyzer. Adjust R99, R100, C85 and C86 as needed
for the best frequency response.
Non-Linear Precorrection
The IF Precorrector board has in phase and quadrature precorrection that can be
used to compensate for distortions in the output amplifier of the transmitter. The in
phase precorrection is intended to correct for Differential Gain and Luminance
Nonlinearity, and the quadrature correction is intended to fix the Differential Phase
and ICPM distortion. Both sets of precorrection circuitry will affect the in band and
Summary of Contents for Innovator CU10BT/CU0T-1
Page 72: ......
