Wavetek 3HRV Operation Manual

WavetekWavetek

WavetekWavetek

Wavetek
CATV Division

5808 Churchman Bypass
Indianapolis, IN 46203-6109
[phone]
[phone]
Fax: [phone]
E-Mail: [e-mail]
Internet: http://www.wavetek.com

11/96 Rev. A
Manual Part No.
6510-00-0300

This document contains information proprietary to
Wavetek. The information in this document
is not to be used or duplicated in any manner without
the prior approval, in writing, of Wavetek.

OPERATION MANUAL

MODEL 3HRV

HEADEND REVERSE
SWEEP RECEIVER

WARRANTY

Wavetek warrants that all Products manufactured or procured by Wavetek conform to
Wavetek’s published specifications and are free from defects in materials and workmanship
for a period of one (1) year from the date of delivery to the original Buyer, when used under
normal operating conditions and within the service conditions for which they were designed.
This warranty is not transferrable and does not apply to used or demonstration products.

The obligation of Wavetek arising from a Warranty claim shall be limited to repairing, or at
its option, replacing without charge, any assembly or component (except batteries) which in
Wavetek’s sole opinion proves to be defective within the scope of the Warranty. In the event
Wavetek is not able to modify, repair or replace nonconforming defective parts or components
to a condition as warranted within a reasonable time after receipt thereof, Buyers shall receive
credit in the amount of the original invoiced price of the product.

Wavetek must be notified in writing of the defect or nonconformity within the Warranty
period and the affected Product returned to Wavetek’s factory, designated Service Provider,
or Authorized Service Center within thirty (30) days after discovery of such defect or
nonconformity. Buyer shall prepay shipping charges and insurance for Products returned to
Wavetek or its designated Service Provider for warranty service. Wavetek or its designated
Service Provider shall pay costs for return of Products to Buyer.

Wavetek shall have no responsibility for any defect or damage caused by improper storage,
improper installation, unauthorized modification, misuse, neglect, inadequate maintenance,
accident or for any Product which has been repaired or altered by anyone other than Wavetek
or its authorized representative or not in accordance with instructions furnished by Wavetek.

The Warranty described above is Buyer’s sole and exclusive remedy and no other warranty,
whether written or oral, expressed or implied by statute or course of dealing shall apply.
Wavetek specifically disclaims the implied warranties of merchantability and fitness for a
particular purpose. No statement, representation, agreement, or understanding, oral or
written, made by an agent, distributor, or employee of Wavetek, which is not contained in the
foregoing Warranty will be binding upon Wavetek, unless made in writing and executed by
an authorized representative of Wavetek. Under no circumstances shall Wavetek be liable for
any direct, indirect, special, incidental, or consequential damages, expenses, or losses,
including loss of profits, based on contract, tort, or any other legal theory.

Extended Warranty Programs

Extended warranties and service contracts are available for new and currently owned
equipment for an additional cost. Contact the Customer Service Department (800 851-

1198) for details pertaining to extended warranties and service contracts.

Return Authorization Procedure

The customer MUST obtain a RETURN AUTHORIZATION NUMBER from the
Customer Service Department (800 851-1198) prior to returning any equipment for
warranty or non-warranty repair. Wavetek accepts no liability for any instrument or
subassembly returned to the factory without this number. Any correspondence regarding

returned instruments or subassemblies should be referenced to that number.

Contents

SECTION 1 - GENERAL INFORMATION

1.1 INTRODUCTION ................................................................ 1-1

1.2 SPECIFICATIONS ............................................................. 1-2

1.2.1 Frequency .................................................................... 1-2

1.2.2 Level Measurement ................................................... 1-2

1.2.3 Hum Measurement..................................................... 1-3

1.2.4 Carrier to Noise Measurement .................................. 1-3

1.2.5 Telemetry .................................................................... 1-4

1.2.6 Transmitter.................................................................. 1-4

1.2.7 Spectrum Mode........................................................... 1-4

1.2.8 Intermodulation Distortion ........................................ 1-5

1.2.9 Depth of Modulation .................................................. 1-5

1.2.10 Serial Interface .......................................................... 1-5

1.2.11 General....................................................................... 1-5

1.2.12 Powering .................................................................... 1-6

1.2.13 Standard Accessories................................................. 1-6

1.2.14 Options....................................................................... 1-6

1.2.15 Optional Accessories................................................. 1-6

SECTION 2 - INSTALLATION

2.1 INTRODUCTION ............................................................... 2-1

2.2 UNPACKING AND INSPECTION ................................... 2-1

2.3 INSTALLATION .................................................................. 2-1

2.4 WARRANTY INFORMATION .......................................... 2-2

2.5 POWER REQUIREMENTS ............................................... 2-3

2.6 CABLE SPECIFICATIONS ................................................ 2-3

2.7 TECHNICAL SUPPORT .................................................... 2-5

2.8 WORLDWIDE SALES OFFICES .....................................2-5

SECTION 3 - USER INTERFACE

3.1 INTRODUCTION .............................................................. 3-1

3.2 FRONT-PANEL DESCRIPTION ................................... 3-1

3.2.1 Soft Keys ...................................................................... 3-1

3.2.2 Measurement Mode Selection Keys ......................... 3-2

3.2.3 Support Mode Selection Keys ................................... 3-3

3.2.4 Arrow Keys .................................................................. 3-4

3.2.5 Alpha-Numeric Entry Keys ....................................... 3-5

3.2.6 Printing ........................................................................ 3-6

SECTION 4 - OPERATION - HOW TO USE THE 3HRV
HEADEND REVERSE SWEEP RECEIVER

4.1 INTRODUCTION .............................................................4-1

4.1.1 Wavetek Stealth Reverse Sweep Concept ..............4-1

4.1.2 Basic Reverse Sweep Procedure .............................. 4-1

4.1.3 Interfacing With Different Network Architectures 4-2

4.2 HOW TO SETUP YOUR 3HRV .....................................4-5

4.2.1 How to Setup for Reverse Sweeping .......................4-5

4.2.2 How to Setup for Measurement Modes .................. 4-12

4.3 SETUP.................................................................................. 4-13

4.3.1 General Setup.............................................................4-14

4.3.2 Measurement Setup...................................................4-18

4.3.3 How To Setup Your Channel Plan .......................... 4-19

4.3.4 How To Edit Channel Parameters .......................... 4-22

4.3.5 Reverse Sweep ........................................................... 4-28

4.3.6 Editing a Reverse Sweep Plan ................................. 4-34

4.4 HOW TO PERFORM LEVEL MEASUREMENTS.... 4-35

4.5 HOW TO MEASURE TILT-BALANCING AN

AMPLIFIER ........................................................................ 4-37

4.6 SCAN MODE ......................................................................4-39

4.7 HOW TO MEASURE C/N ................................................ 4-43

4.8 HOW TO MEASURE HUM ............................................. 4-45

4.9 MODULATION ................................................................. 4-46

4.10 SPECTRUM ANALYZER MODE ................................ 4-47

4.11 SWEEP MODE ................................................................. 4-52

4.12 FILE....................................................................................4-54

4.12.1 How to Store/View/Delete Measurement Files ...4-54

4.13 AUTO .................................................................................4-55

4.13.1 How to Create/Edit/Delete Test Locations ......... 4-55

4.13.2 How to Perform an Auto Test ................................4-59

4.13.3 Viewing/Printing Auto Test Files .......................... 4-67

4.14 STATUS ............................................................................. 4-73

APPENDIX A: STATUS INDICATORS ............................... A-1

APPENDIX B: USER MESSAGES ......................................... B-1

1-1

SECTION 1 GENERAL INFORMATION

1.1 INTRODUCTION

The 3HRV Reverse Sweep Receiver is a headend rack mounted unit
that handles the reverse sweep job for up to 10 different technicians
on the same cluster of nodes.

The addition of the 3HRV to the Wavetek Sweep System takes the
responsibility of the reverse sweep away from the 3ST. This serves to
speed up the reverse sweep rate. In addition, the 3HRV sends out
reverse ingress/noise information with every update of its forward
telemetry, so reverse telemetry need not be received in order to check
the reverse ingress condition.

Reverse Sweep Alignment

Reverse sweep alignment provides an optimum view of the frequency
response in unoccupied reverse spectrum, leaving nothing to the
imagination. A reverse sweep can uncover mismatch problems which
reveal themselves as standing waves, or diplex filter roll-offs that can
severely hamper the carriage of services in the reverse band.

Ingress Detection and Troubleshooting

The 3HRV provides feedback to the field as to the current condition
of noise and ingress in the headend. Even if the noise or ingress is
"swamping" the telemetry a "picture" of the headend noise/ingress is
sent out to the receiver via a special forward telemetry carrier for
display.

Easy To Read Noise/Ingress Display

The headend instrument provides a continuous display of the noise/
ingress performance of the connected nodes. This provides a quick,
easy way for the headend technician to verify performance. In addi­tion, the current reverse testing activity can be monitored.

The 3HRV also performs essential cable TV system preventive
maintenance tests with accuracy and ease. Signal levels, hum, C/N,
and frequency response can be quickly tested without subscriber
interference.

MODEL 3HRV

1-2

The 3HRV is a full-featured signal analysis meter, with a complete
spectrum display and an analog representation of single channel
measurement data. When tuned to a specific channel, a comprehen­sive set of information is provided: tuned channel, video frequency
and level, audio frequency and level, the difference between video
and audio carrier levels.

The 3HRV is a standard 19" rack mount unit, that weighs approxi­mately fifteen pounds. Its 320 X 240 dot matrix LCD shows measure­ment data in both graphical and numerical form.

The contents of this manual will describe the care and operation of
the Headend Reverse Sweep Receiver, including Reverse Sweep
operation.

1.2 SPECIFICATIONS

1.2.1 Frequency

Range: 5 to 1,000 MHz

Accuracy: + 10 ppm at 25°C; + 10 ppm drift over

temp.; + 3 ppm/year aging

Resolution Bandwidths: 30, 280 kHz (30 kHz for CSO)/CTB only)

Tuning Resolution: 10 kHz

Sweep Resolution: 250 kHz maximum

1.2.2 Level Measurement

Range: -40 to +60 dBmV

Resolution: 0.1 dB

Accuracy: + 1.0 dB from 0 to + 40°C (typical),

(relative to 25°C)

1-3

Digital Average Power
Option Accuracy: +1.8 dB at 25°C

1.2.3 Hum Measurement

(carrier > 0 dBmV) Non-scrambled channels only

Range: 0 to 10%

Resolution: <0.2%

Accuracy: +0.7%

1.2.4 Carrier to Noise Measurement

Non-scrambled channels only. No preselection required for 78
channels at +10 dBmV input level.

Carrier t o Noise Ratio

Depth of Measurement Char act eristics

Video Ca rrier Le vel (dBmV)

Carrier to Noise Range

0

10

20

30

40

50

60

-10 0 10 14 24

*Specified results with the measurement offset within 2 to 3 MHz
range above the video carrier.”

Resolution: 0.5 dB

Range 52 dB maximum

*

+3.0 dB Accuracy

+2.0 dB Accuracy

Out of Measurement Range

1-4

1.2.5 Telemetry

Frequency: User defined, 5 to 1,000 MHz

Modulation: FSK, 100 kHz deviation

Spectrum Required: »1 MHz recommended

1.2.6 Transmitter

Frequency Range: 5 to 1,000 MHz

Level Range: +20 to +50 dBmV; settable in 2 dB

increments

Spectral Purity: Hars -30 dBc; Spurs -35 dBc

1.2.7 Spectrum Mode

Spans: 3, 5, 10, 20, and 50 MHz (0.3, 0.5, 1, 2, and

5 MHz/div)

Sweep Rates: 2 seconds (50 & 5 MHz)

Display Scaling
and Range: 0.5, 1, 2, 5, and 10 dB/division; 6 vertical

divisions

Spurious Free
Dynamic Range: 60 dB (typical specifications)

1-5

1.2.8 Intermodulation Distortion

CSO / CT B Ch a racteristics

Video S ign al Level (dBmV)

Depth of Measurement (dB)

(without preamplification / with

preselection)

0

10

20

30

40

50

60

-20 -10 0 10 20 30

*Typical Specifications

Range: 60 dB maximum

Resolution: 1 dB

1.2.9 Depth of Modulation

Assumes presence of white reference on any VITS line. Non­scrambled channels only.

Range: 80 to 100%

Resolution: <0.5% at 85%

1.2.10 Serial Interface

Serial, RS232; Epson, IBM Printers

1.2.11 General

Log Linearity: +0.5 dB (typical)

Flatness: +0.5 dB @ 25 °C, @ 20 dBmV

*

Out of Measurement Range

+3.0 dB Accuracy

+2.5 dB Accuracy

1-6

Dimensions: 3HRV: 48.3 cm (W) x

13.3 cm (H) x 35.6 cm (D), 19" (W) x 5.25"
(H) x 14" (D)

Weight: 3HRV: 6.8 kg (15 lbs.)

Operating
Temperature Range: 0 to +50°C; 32 to 122°F

1.2.12 Powering

Frequency 47 to 63 Hz ~ 100 VA

Input Current: 1.2A @ 100 VAC.

0.5A @ 265 VAC.

Fuse 1.25 A, 250V 5X20mm SLO-BLO (2

required)

1.2.13 Standard Accessories

Line Cord
Channel Plan Transfer Cable
Operations Manual

1.2.14 Options

16/64 QAM Digital Carrier Power Measurement - Enables Stealth to
perform accurate level measurements on digital carriers.

1.2.15 Optional Accessories

1010-00-0342 Citizen PN60 (thermal fusion) Printer
1019-00-0457 Optional Battery for PN60 Printer
3010-59-0009 Citizen PN60 Printer Ribbons (2) (included with

printer)
1217-50-0159 Citizen PN60 Printer Cable (included with printer)
4010-00-0105 Charger/Adapter 120VAC to 18VDC
1019-00-0437 Charger/Adapter 220VAC to 18 VDC

1-7

SBC-1 Charger for one spare Stealth Battery Cartridge
SBC-6 Charger for up to six spare Stealth Battery

Cartridges
1217-50-0151 Stealth Serial Printer Cable
PP-75 Precision Preselector for Carrier-To-Noise and

Intermodulation Distortion Testing (55 to 440 MHz)
PP-55-110 Tunable Precision Preselector (55 to 110 MHz)
PP-110-220 Tunable Precision Preselector (110 to 220 MHz)
PP-220-440 Tunable Precision Preselector (220 to 440 MHz)
PP-440-880 Tunable Precision Preselector (440 to 880 MHz)
7201 Tunable Precision Preselector (31 to 62 MHz)
7202 Tunable Precision Preselector (62 to 125 MHz)
7203 Tunable Precision Preselector (125 to 250 MHz)
7204 Tunable Precision Preselector (250 to 500 MHz)

2-1

SECTION 2 INSTALLATION

2.1 INTRODUCTION

This section provides information on how to install the 3HRV
Headend Reverse Sweep Receiver.

2.2 UNPACKING AND INSPECTION

The instrument was inspected, and given final operational and quality
control tests prior to being carefully packaged for shipment. The unit
should operate in accordance with the specifications listed in this
manual.

When unpacking the instrument, inspect the shipping container and
instrument for shipping damage. If the container is damaged, phone
Wavetek immediately. Save the shipping carton and packing materials
for possible future use.

FOR CUSTOMER SERVICE call: WAVETEK: [phone],
International Customers, contact your local Wavetek Representative.

2.3 INSTALLATION

Proper installation of the 3HRV is essential to correct operation of the
system. The 3HRV is typically installed in a headend rack. There are
two different recommendations for setting up the system. One entails
receiving the reverse sweep signal at a standard reverse node com­biner, and inserting the telemetry with a directional coupler (test
point) at the input of the foward combining network.

Alternately, to prevent from having to tap into the system an addi­tional time, you may also insert the telemetry by connecting to the
output of the 3ST. The telemetry insertion directional coupler (DC
b) tap loss must be taken into account when setting the insertion level
of the telemetry signal.

2-2

The transmitter output level is variable from +20 to +50 dBmV in 2
dB increments. The output level will be attenuated by the tap value
of the directional coupler. For example, if a telemetry signal level of
+16 dBmV is desired on the system and the output of the 3HRV is
set to +36 dBmV, a directional coupler value of 20 dB may be used,
or the combination of a lower value directional coupler and an
attenuator pad.

An alternate method would be to insert the 3ST Transmitter output
at one of the combining network inputs, and connect the (transmit­ter) reference input to the headend amplifier input test point. This
method eliminates the need to add directional couplers at the
combiner output.

Note: A diplex filter must be used to couple the foward path to the

input of the 3HRV for all measurement mode operations other
than reverse sweeping.

For detailed setup information, see "Stealth Sweep Start-up Proce­dure", page 4-1.

2.4 WARRANTY INFORMATION

The 3HRV is covered by a one year parts and labor warranty (for
details, see "Warranty", opposite Table of Contents).

2-3

2.5 POWER REQUIREMENTS

The 3HRV operates on 90-265 VAC, 57-63 Hz single phase input
power source.

2.6 CABLE SPECIFICATIONS

There are two cables associated with the operation of the 3HRV;
Stealth to Stealth, and a Serial Printer cable. The following informa­tion describes each of the associated cables.

Stealth to Stealth

The Stealth to Stealth cable, (1217-50-0149) provided with each
3HRV, is used for communications between Stealth units.

Rx

Tx

DTR

GND

DSR
RTS
CTS

RI

Tx
Rx
DTR
GND
DSR
CTS
RTS
RI

2-4

Serial Printer Cable

The Serial Printer Cable, (1217-50-0151) can be used to print data
directly from the 3HRV.

Tx
Rx

GND

DTR

Rx
Tx
DTR
GND
DSR
CTS

2-5

2.7 TECHNICAL SUPPORT

We've worked hard to make the 3HRV as easy-to-use as possible.
However, if you have a problem using your unit you can contact
Wavetek's Technical Support for help. You can reach Wavetek's
Technical Support, Monday through Friday between 8 am and 5 PM
at [phone]. Wavetek also maintains a support forum on the
Internet. You can leave messages and a Support Specialist will get
back to you at Internet address: [e-mail].

If you received your Stealth unit and found it to be damaged or
incomplete in any way, phone Wavetek immediately. Save the
shipping carton and packing material in the event that you have to
return it.

FOR CUSTOMER SERVICE call: WAVETEK [phone],
International Customers, contact your local Wavetek Representative.

The above numbers can also be accessed on your unit by pressing the
FCN key followed by the help key.

2.8 Worldwide Sales Offices

Austria (Vienna) Hong Kong
Tel: [phone] Tel: [phone]
Fax: [phone] Fax: [phone]

China (Beijing) Japan (Tokyo)
Tel: [phone] Tel: [phone]
Fax: [phone] Fax: [phone]

France (Paris) Singapore
Tel: [phone] Tel: [phone]
Fax: [phone] Fax: [phone]

Germany (Munich) United Kingdom (Norwich)
Tel: [phone] Tel: [phone]
Fax: [phone] Fax: [phone]

3-1

SECTION 3 USER INTERFACE

3.1 INTRODUCTION

This section will help you become familiar with the front-panel
controls of the Model 3HRV. Included are descriptions of the front­panel and notes on the use of features.

3.2 FRONT-PANEL DESCRIPTION

The hardware portion of the user interface consists of a 320x240 dot
matrix LCD and a 40-key keypad. The keypad includes:

• eight Soft keys

• eight Measurement Mode selection keys

• four Support Mode selection keys

• four Arrow keys

• sixteen Numeric Entry keys

3.2.1 Soft Keys

There are a total of eight vertically oriented soft keys, four on either
side of the display. The function of each soft key changes depending
on the particular operation being performed. The function is indi­cated on the display next to the associated soft key. Soft keys are not
always active. When a soft key is inactive, it’s indicator is either
dimmed (grayed) or does not appear at all.

3-2

3.2.2 Measurement Mode Selection Keys

Measurement modes are chosen by pressing the appropriate Mea­surement Mode Selection key. There is a key for each of the eight
major measurement functions. These keys are located directly below
the display.

LEVEL: Signal level measurements on individual channels are made

by entering a specific channel number and pressing the
channel key. Measurements can also be made by selecting
the carrier with a marker in the Scan mode and pressing the
Level key.

TILT: The Tilt mode simplifies the balancing of pilot levels by

displaying a bar graph with a representation of up to nine
different user selected video carrier levels.

3-3

SCAN: Use the Scan mode to get a good look at absolute carrier

levels. In this mode a bar graph showing all carrier levels is
displayed.

SWEEP:

This mode monitors the signals injected into vacant

spectrum areas by the 3SRVs. Also, through telemetry
transmits to the field current condition of noise and ingress
to any 3SRV Receivers that are connected to the system.

NOTE: Telemetry occurs only while the unit is in Sweep mode.

Selecting another mode will result in a loss of telemetry to
any Receivers connected to the system.

C/N: Measures the C/N (carrier to noise) ratio of the tuned

channel or frequency will be displayed.

HUM: Measures the hum modulation of the tuned channel, will

display in either % or dB as selected by the operator.

MOD: Allows the user to listen to the modulation of the tuned

channel of frequency and measure Depth of Modulation of a
video carrier.

SPECT: Provides a Spectrum Analyzer display, and CSO/CTB

measurements.

3.2.3 Support Mode Selection Keys

Support modes are accessed using the Support Mode Selection keys.
There is a key for each of the four support functions. These keys are
located to the right of the display.

3-4

File: Allows the user to access measurement files.

Auto: This function provides automated FCC 24 hour testing

capabilities.

Setup: The setup functions are used to set or adjust the operating

parameters of the unit.

Print: Allows the user to print the current measurement screen.

3.2.4 Arrow Keys

The four Arrow keys are used for various purposes. There functions
are described in the individual sections for each operating mode.
These keys are located to the right of the Support Mode Selection
keys.

3-5

3.2.5 Alpha-Numeric Entry Keys

The Alpha-Numeric keys are used to enter data as needed during the
operation of the unit. There are three indicators associated with
keypad entry. These indicators appear in the title bar to the left of
the time. The three are as follows:

A

B

C

- alpha entry mode

1

23 - numeric entry mode

- multiple choice mode

Alpha Entry Mode

Most numeric keys have alphabetic characters printed on them.
These characters can be accessed when the alpha entry indicator
appears in the title bar. In the alpha entry mode, a cursor appears
below the active position. Repeated pressing of an alphanumeric key
sequences through the values printed on the key. Once the desired
character is selected, the cursor is moved to the next position using
the LEFT or RIGHT arrow keys. Special characters are available
using the UP and DOWN arrow keys.

Alpha entry must be terminated by pressing the ENTER key.

3-6

Numeric Entry Mode

In the numeric entry mode, only the numerals 0 through 9 and the
decimal point can be entered. When negative values are allowed, the
FCN, +/- key sequence toggles between positive and negative entry.
The numeric value may also be incremented and decremented using
the UP and DOWN arrow keys.

Numeric entry must be terminated by pressing the ENTER key.

Multiple Choice Mode

This mode allows you to sequence through a series of choices which
appear in the edit box.

3.2.6 Printing

Any measurement mode screen can be printed directly. Press the
Print key to print the current measurement screen. To print a
measurement file, simply view the file and print it as you would a
current measurement screen.

4-1

SECTION 4 OPERATION - HOW TO USE THE 3HRV HEADEND
REVERSE SWEEP RECEIVER

4.1 INTRODUCTION

This section provides detailed operation of the 3HRV. Included are
detailed descriptions of the various displays of the selected modes of
operation.

4.1.1 Wavetek Stealth Reverse Sweep Concept

With the reverse sweep option, a transmitter is built into the hand­held sweep receiver. The headend reverse sweep receiver (3HRV) is
set up to receive the reverse sweep sent from the field. When a
reverse sweep is activated from a field test point, the 3HRV receives
the telemetry signal that indicates which receiver is sending the
sweep. The headend receiver measures the sweep, and sends the
results, along with the serial number of the sending receiver via its
telemetry signal to the field. The field receiver with the tagged serial
number then displays the sweep response as measured in the headend
on its LCD. Up to 10 receivers at a time can perform reverse sweep­ing. If additional receivers attempt to sweep a message is displayed.

4.1.2 Basic Reverse Sweep Procedure

Sweeping the reverse path is a little different from sweeping the
forward path. Because the system is designed with appropriate spacing
for the forward high frequency range, the reverse path may not require
amplification at each station. The lower frequencies aren't attenuated
in cable as much as the higher frequencies. In sweeping the forward
path the amplifier is aligned such that its output is within certain
limits (the amplifier compensates for the cable behind it). However in
sweeping the reverse path the amplifier is aligned such that the
response at the headend is within certain limits from this amplifier
alignment point. So, in the reverse path the amplifier compensates for
loss characteristics in the cable in front of it.

4-2

This is why it is best to transmit the sweep from the amplifier test
point and measure it in the headend. This ensures that the system is
properly aligned to carry signals in the reverse path.

4.1.3 Interfacing With Different Network Architectures

Single Cable - Split Band Network

The Model 3HRV is connected in the headend as shown in figure 1.
The connections are similar to those made for forward sweep, with
the monitor output connected to the combining network. This allows
the 3SRV to receive telemetry signal from the 3HRV.

Figure 1. Single Cable — Split Band Network Reverse Sweep

Configuration With Bi-Directional Test Points.

In the field, systems with bidirectional test points, (forward and
reverse signals both present on the same test point) a summing
network (provided with each reverse sweep option) is used to enable
reception of forward telemetry and sweep, as well as inject reverse
telemetry and sweep. This summing network simplifies the
connection of the field receiver to the test point.

Systems with directional test points are set up as shown in figure 2.
In this configuration two directional couplers are used to provide a
sample of the reverse sweep output to the input of the 3SRV re­ceiver.

4-3

The directional coupler on the input side should be designed for at
least the frequency range of the forward bandwidth of the network
under test. (This coupler network should never be connected to the
system without the 3SRV attached, or the resulting lack of isolation
may cause signals from the forward path to bleed over to the reverse
path.)

Figure 2. Single Cable - Split Band Network Reverse Sweep

Configuration With Directional Test Points.

Another common architecture, which is only slightly different from
those described above, prescribes the use of fiber optics to "nodes".
In these architectures the installation of the 3HRV in the headend is
as shown in figure 3. The connection at the node may be as shown in
figure 4. Notice that in this configuration the forward and reverse test
points are separated, and two directional couplers must be used. In
all of these connection scenarios, either a summing network or two
directional couplers are used to interface with the system test points.
Care should be taken to use the same interface at each test point to
ensure that the normalization process is cancelling out any response
variation caused by the interface.

It is also important to remember not to make absolute level measure­ments through the summing network due to the insertion loss and
frequency response characteristics of the interface.

4-4

Figure 3. Transmitter Connections In Headend For Hybrid Fiber/Coax

Networks

Figure 4. Fiber Node Test Point Connections

Dual Cable Network

Another possible, though rare, network configuration is the "Dual
Cable Network", in which a full bandwidth is used for both forward
and reverse - essentially two cable systems overlaying each other with
signals carried in opposite directions. These networks are impossible
to sweep simultaneously in both directions with one man.

4-5

The problem is that the two systems use the same spectrum,
making it impossible to distinguish between the two with one
instrument.

The recommended method for these systems is to first sweep the
forward portion of the network, then move the transmitter out to the
furthest extremity and sweep the reverse portion.

4.2 HOW TO SETUP YOUR 3HRV

4.2.1 HOW TO SETUP FOR REVERSE SWEEPING

To setup the Reverse Sweep on the 3HRV, press the SETUP key
and select the “Reverse” option from the Setup menu. The Reverse
Sweep setup screen will appear.

Important: To prevent the 3HRV reverse sweep from contending

with the 3ST, disable the 3ST's reverse sweep. This will
speed up the 3ST's forward sweep. Multi-user contention
can also be eliminated by offsetting reverse channel
plans, and by using different telemetry frequencies.

4-6

Forward Telemetry Frequency

Use the UP and DOWN arrow keys or the numeric keypad to enter
the telemetry frequency.

NOTE: For successful Stealth mode operation, the Rx Foward

Telemetry frequency (3HRV) must match the Tx telemetry
frequency setting of the Model 3SRV.

Caution: Do not place the telemetry signal too close to the diplex

filter cut-off frequency in that roll-off may attenuate the
telemetry signal to the degree that communication fails.
This same caution applies to placing the signal in the high
end roll-off region.

Forward Telemetry Level

This is the level of the carrier that the 3HRV uses to transmit
telemetry data. Use the edit box to set the Telemetry Level to an
appropriate value. When adjusting the Telemetry Level, take into
consideration the following losses; system, summing network, test
point, and amplifier desired input.

Use the UP and DOWN arrow keys or the numeric keypad to enter
the telemetry level (20-50 dBmV).

Reverse Telemetry Frequency

This is the frequency at which 3SRV units with the Reverse Sweep
option will transmit telemetry data. Optimally this will be in a
portion of the reverse frequency band with at least 1 MHz free, and
at best case, in the high end of the return band to avoid potential
interference from ingress.

IMPORTANT: The frequency of the reverse telemetry carrier

should be carefully selected such that it will not
interfere with any existing carriers on the reverse
plant.

4-7

Reverse Sweep Plans

Reverse Sweep Plans are used to define the frequencies at which
sweep points will be inserted by 3SRV units with the Reverse Sweep
option. To access Reverse Sweep Plans, select the “Reverse Sweep
Plans” option and then press the ENTER key.

Selecting a Reverse Sweep Plan

The Reverse Sweep Plan screen presents a list of all Reverse Sweep
Plans stored in memory. The current active Reverse Sweep Plan is
displayed beneath the list of plans. Use the up or down arrow to
select the plan you want, then press the Load soft key to load the
selected plan into memory for use. Press the Exit soft key to return
to the previous screen or the SWEEP key to begin sweeping.

Creating a New Reverse Sweep Plan

Press the New soft key to create a new Reverse Sweep Plan. You will
be asked to enter a name for the plan that you are creating. Use the
alphanumeric keys followed by the ENTER key. Then press the OK
soft key to continue.

NOTE: A warning message will appear if a Reverse Sweep Plan

currently exists with the same name as the plan you are
creating.