Motorola SG4-DRT-2X User Manual

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SG4-DRT-2X Installation Sheet 509978-001

The Motorola® Digital Return Transmitter (SG4-DRT-2X) implements Time Division Multiplexing (TDM) to convert two, independent 5 to 65 MHz analog RF return-path signals, into one digital optical signal within SG4000 optical nodes. This digital optical signal with 10-bit resolution and 3.125 Gbps rate is suitable for optical transmission on the International Telecommunications Union (ITU) grid to the GX2-DRR-2X Digital Return Receiver (DRR) where the original analog return-path signals are recreated.

The transmitter is configured with an 8 dBm digital Distributed Feedback (DFBT) laser that is thermally stabilized to minimize wavelength drift. Multiple ITU wavelengths are available depending on specific link requirements. The specific ITU channel and frequency are stamped on the label on each transmitter and are identified in the subsection SG4-DRT-2X Models at the end of this document.

The SG4-DRT-2X transmitter features high-speed digital technology to achieve reliable return path communications at greater distances. The system is completely scalable and can be expanded from a single transmitter/receiver to groups of 4, 8, 16, 32, or 40 wavelengths over a single fiber with the use of muxing and demuxing equipment. The system is compatible with Motorola low-noise optical amplifiers (EDFAs), enabling network designs that cover large geographical areas. Without amplification, the SG4-DRT-2X Dense Wave Division Multiplexing (DWDM) digital return system is capable of achieving a link loss budget of 26 dB.

The system achieves superior noise power ratio (NPR) and dynamic range (DR) performance in return path communications. The SG4-DRT-2X system is HMS compliant and features an enable/fault LED to report local status information. The SG4-DRT-2X comes standard with SC/APC optical connectors; E2000 adapters are optional.

To facilitate easy upgrades, the double-wide SG4-DRT-2X module has the same set-up levels as the analog return transmitters and can accomplish any two-transmitter configuration using only a single fiber.

Figure 1 illustrates a block diagram of the SG4-DRT-2X:

Figure 1 SG4-DRT-2X block diagram

Return

Channel

Input B

5-65 MHz

Te st

Input B

-20 dB

Return

Channel

Input B

5-65 MHz

Te st

Input B

-20 d

JXP Coupler EQ Fiber A/D

JXP

Coupler

FiberEQ

TXF

A/D

Transmit

Signal

Processing

Mux

Laser

Te st Po in t

Laser driver

Laser

TEC

Optical Output

-3 Gbps

SG4-DRT-2X Installation Sheet

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Figure 2 illustrates the SG4-DRT-2X with the cover on (left) and cover off (right):

Figure 2 SG4-DRT-2X transmitter

CH BCH A

-5 dBmV

NOMINAL

TOTAL POWER

INVISIBL E LASER RADIATION. AVOID

EXPOSURE TO BEAM.

CLASS 3B LASER

PRODUCT.

ENABLE/FAULT

J X P

0.5 V/mW

J X P

-5 dBmV

NOMINAL

TOTAL POWER

A / DA / D

2X DIGITAL TRANSMITTER

Figure 3 illustrates the user-interface features of the SG4-DRT-2X:

Figure 3 User features

CH BCH A

J X P

-5 dBmV

NOMINAL

TOTAL POWER

-5 dBmV

NOMINAL

TOTAL POWER

/ DA / D

INVISIBLE LASER RADIAT ION. AV OI D

EXPOSURE TO BEAM.

CLASS 3B LASER

PRODUCT.

ENABLE/FAULT

2X DIGITAL TR ANSMITT ER

SG4-DRT-2X Installation Sheet

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Table 1 identifies and provides information on the user-interface features of the SG4-DRT-2X:

Key Feature Description

0.5 V/mW

ENABLE/FAULT

This test point enables monitoring of the optical output level of the module. The nominal scale factor is 0.5 V/mW. Note that the optical power test point does not track changes in optical power due to the laser tracking error.

A red LED ( limits. Because the laser output requires a short period of time to stabilize, it is normal for the LED not to illuminate for approximately 10 seconds. Note

FAULT) indicates that the laser output power is below normal

that the module must be enabled for the fault indicator to function.

A green LED (

ENABLE) provides visual indication of the transmitter’s enable

status.

CH A RF input test point (−5 dBmV nominal total power)

CH A JXP attenuator location. Used to adjust −5 dBmV nominal total power

reading at

CH A test point.

This MCX connector provides the SG4-DRT-2X with

CH A RF input through a

cable connection from the configuration board in an SG4000.

Optical bulkhead with SC/APC type connector that provides output from the SG4-DRT-2X

This MCX connector provides the SG4-DRT-2X with

CH B RF input through a

cable connection from the configuration board in an SG4000.

CH B JXP attenuator location. Used to adjust −5 dBmV nominal total power

reading at

CH B test point.

CH B RF input test point (−5 dBmV nominal total power)

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Installing the SG4-DRT-2X in the SG4000 Node

The SG4000 carries each RF return path individually to the lid configuration boards and typically no adjustments to the RF modules in the housing base are necessary.

Before you install the SG4-DRT-2X in the SG4000, ensure that you have the return configuration boards for the specific application. Simply stated, the SG4-DRT behaves as two analog transmitters. A single SG4-DRT-2X transmitter supports the split return configuration. (Note: A single SG-DRT-2X also accommodates combined and combined redundant configurations, but these applications are not covered in this Installation Sheet). You may place a single transmitter in optics slots 3 and 4 or 5 and 6 in the SG4000 lid. Dual SG4-DRT-2X transmitters support split return redundant and segmented configurations. The dual transmitters occupy slots 3 and 4 and 5 and 6 in the SG4000 lid.

The SG4-DRT-2X transmitter design enables you to install it while the node is in service. The module’s flat bottom provides an excellent thermal transfer surface and has locating holes that align with guide pins in the lid of the node.

To install the SG4-DRT-2X:

1 If present, remove any analog transmitter that occupies lid optics slots 3 and 4, and/or 5 and

6 in the SG4000 lid as illustrated in Figure 3, and then install the double-wide SG4-DRT-2X:

Figure 4 SG4000 lid with two analog transmitters

2 Position the SG2-DRT-2X module in the appropriate slot and press gently on the casting

until it is fully seated.

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Tighten the three 1/4 inch mounting bolts to 8 – 12 in/lbs to secure the module in the

SG4000 lid.

4 Repeat as required for a second SG4-DRT-2X.

Figure 5 illustrates a properly installed and cabled SG4-DRT-2X:

Figure 5 SG4-DRT-2X installed in SG4000

-5 dBmV NOMINAL

TOTAL POWER

INVISIBLE LASER RADIATION. AVOID

EXPOSURE TO BEAM.

CLASS 3B LASER

PRODUCT.

ENABLE/FAULT

CH BCH A

-5 dBmV

NOMINAL

TOTAL POWER

A / DA / D

-5 V/mW

2X DIGITAL TRANSMITTER

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Split Return

In the split return configuration, each pair of RF returns is applied to a separate 2X redundant return configuration board. In a typical installation, the RF modules in Ports 1 and 3 are connected to the 2X redundant return board in return configuration location 2. The RF modules in Ports 4 and 6 are connected to the 2X redundant return configuration board in configuration location 3. The 2X redundant return configuration board, in location 2, directs RF to CH B of the SG4-DRT-2X. The 2X redundant return configuration board, in location 3, directs RF to CH A of the SG4-DRT-2X. The same configuration board is used in the split redundant return configuration explained in the next subsection.

Figure 6 illustrates the split return configuration:

Figure 6 Split return configuration

Port 3 Port 4

Port 1 Port 6

CH BCH A

-5 dBmV NOMINAL

TOTAL POWER

-5 dBmV

NOMINAL

TOTAL POWER

A / DA / D

INVISIBLE LASER RADIATION. AVOID

EXPOSURE TO BEAM.

CLASS 3B LASER

PRODUCT.

ENABLE/FAULT

-5 V/mW

2X DIGITAL TRANSMITTER

Split Return

Configuration board

location #3

CH A CH B

Split Return

Configuration board

location #

SG4-DRT-2X Installation Sheet

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