Olson Technology OTR-3550-DC User Manual

OTR-3550-DC

FREQUENCY AGILE - TELEVISION PROCESSOR

FOR

CHINA PAL D STANDARD

INSTRUCTION MANUAL

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E-Mail: [e-mail]

025-000187 REV B 11-20-02

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1) INTRODUCTION

The Olson T echnology OTR-3550-DC is a frequency agile television processor which consists of an agile
demodulator internally connected to an agile modulator . This unit will select any broadcast VHF/UHF or cable
input channel from 49.75 MHz to 855.25 MHz, and will provide a high level (+60dBmV typical) output on any
channel from 49.75 MHz (channel DS-1) through 543.25 MHz (channel SD-22). All input and output chan­nels are selectable in .25 MHz increments by front panel DIP switches.

The OTR-3550-DC uses dual SA W filtering for 60dB adjacent channel rejection and has high level spurious
free output. This unit also offers the unique Olson Technology feature of >80dB out-of-band carrier to noise
ratio, which will allow virtually unlimited numbers of the OTR-3550-DC to be combined without the need for
external band pass filters.

The OTR-3550-DC has low power consumption (17 watts @ 220 VAC) for economical and reliable long
term operation.

OTR-3550-DC

FREQUENCY AGILE - F .C.C. COMP ATIBLE

TELEVISION PROCESSOR

2) INPUT CHANNEL SELECTION - DEMODULA TOR

Remove the front panel plate marked “Input Channel Select” to expose the channel select and band select
DIP switches as shown in Figure 1.

FIGURE 1 - INPUT CHANNEL SELECT DIP SWITCHES

A) CHANNEL SELECTION - Channel selection is accomplished by properly setting the 12-position

DIP switch to the correct code for the desired channel. Switch codes can be selected from T able 4 at
the rear of this manual. Set the DIP switches from left to right as shown in the table. For example, if
channel DS-1 is selected, its corresponding switch code is:

CAUTION: The switch codes for input and output channel selection are completely different. Be sure to refer to
the correct table and set the switches carefully .

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B) BAND SELECTION - Band selection is accomplished by setting the 6-position DIP switch to select

the correct band for the desired channel. The second, third and fourth switch positions of the 6­position DIP switch are used for band selection. Switch settings for the band select switch are included
with the channel codes in T able 4 at the rear of this manual.

For example, the correct band switch setting for channel DS-1 is:

C) AFC SELECTION - The OTR-3550-DC has an AFC circuit which may be switched-on if
the channel being received has a tendency to drift around in frequency . Although this feature may not
normally be needed, it may be activated by moving position 5 of the 6-position DIP switch down.
The AFC is shown as selected of f in T able 4.

For example, the correct setting for channel SD-22 with the AFC on would be:

D) INPUT CONNECTION - After the input selection DIP switches have been properly set (Steps A

through C), connect an antenna or cable source to the RF Input fitting. Any VHF, UHF or cable
source can be connected to the RF input. For optimum video quality , the input signal level should be
+10dBmV . This unit has an internal squelch circuit that will cut off signals below -30dBmV .

3) DEMODULA TOR AGC ADJUSTMENT

The demodulator delayed AGC adjustment is factory set for a +5 to +10dBmV threshold. This setting provides
the best signal-to-noise ratio for low level off-air signals.

When operating the OTR-3550-DC with cable channels at the input, where high-level adjacent channel signals
may be present, adjacent channel performance may be improved by lowering the AGC threshold level.

T o adjust the delayed AGC threshold level for cable signal inputs:

A. Connect a cable source carrying three adjacent channels at a level of +20dBmV maximum to

the RF input connector. Connect a television receiver , through approximately 50dB of attenuation
so as not to overload it, to the OTR-3550-DC output.

B. Set the input channel select DIP switches to the channel located in the center of the three

channels. Set the television receiver to the output channel of the OTR-3550-DC.

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C. Remove the OTR-3550-DC top cover and locate the delayed AGC control potentiometer

R54. R54 is located near the center of the circuit board towards the front of the unit. Adjust
the demodulator delayed AGC control (R54) slightly for the least amount of adjacent channel
interference as seen on the television receiver .

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4) OUTPUT CHANNEL SELECTION - MODULATOR SECTION

Remove the front panel plate marked “Output Channel Select” to expose the channel select and offset select DIP
switches as shown in Figure #2.

Figure #2 - OUTPUT CHANNEL SELECT DIP SWITCHES

The OTR-3550-DC has a rear-panel toggle switch which is also used in setting output frequency .

A) CHANNEL SELECTION - Channel selection is accomplished by properly setting the 12-position

DIP switch to the correct code. Switch codes can be selected from T able 5 at the rear of this
manual. Set the DIP switches from left to right as shown in the table. For example, if channel DS-1
is selected, its corresponding switch code is:

B) OFFSET SELECTION - Although it may not be required in P AL D China applications, the

OTR-3550-DC has a feature which allows output channels to be offset from their nominal frequency .
Fixed offsets of +12.5 KHz and +25 KHz are available in addition to operation on the nominal channel
frequency (+0 KHz offset).

If offset output frequencies are desired, the 4 position DIP switch must be set properly . The +0 KHz,
+12.5 KHz, or +25 KHz position of the 4-position switch must be moved to the down position - all
other positions must be in the up position. These positions are identified in Figure 2.

For example, if 0 KHz offset (normal operation) is desired, the proper switch settings would be:

The fourth position of this switch is not used. Settings for this switch are not shown in T able 5.

C) OUTPUT CONNECTION - The output signal is present at the RF output connector . This unit has an

output test point which is useful when recording operating levels, trouble-shooting, etc. The RF test
output is approximately 20 dB below the main output. Reference readings may be taken at the RF test
output after the output level is properly set for the system.

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