This manual provides installation and operation information for the Comtech EF Data
CRS-170 1:1 Redundancy Switch. This is a technical document intended for earth station
engineers, technicians, and operators responsible for the operation and maintenance of
the CRS-170 1:1 Redundancy Switch.
RELATED DOCUMENTS
Comtech EF Data CDM-600 Satellite Modem Installation and Operation Manual
Comtech EF Data SDM-300L3 Satellite Modem Installation and Operation Manual
CONVENTIONS AND REFERENCES
CAUTIONS AND WARNINGS
Indicates information critical for proper equipment function.
IMPORTANT
WARN ING
Indicates a potentially hazardous situation that, if not avoided, could result in
death or serious injury.
METRIC CONVERSION
Metric conversion information is located on the inside back cover of this manual. This
information is provided to assist the operator in cross-referencing non-metric to metric
conversions.
RECOMMENDED STANDARD DESIGNATIONS
Recommended Standard (RS) Designations are equivalent to the Electronic Industries
Association (EIA). Comtech EF Data will reference RS designator throughout the
manual.
TRADEMARKS
All product names mentioned in this manual may be trademarks or registered trademarks
of their respective companies and are hereby acknowledged.
REPORTING COMMENTS OR SUGGESTIONS CONCERNING THIS MANUAL
Comments and suggestions regarding the content and design of this manual will be
appreciated. To submit comments, please contact the Comtech EF Data Customer
Support Department.
EMC COMPLIANCE
This is a Class B product. In a domestic environment, it may cause radio interference that
requires the user to take adequate protection measures.
EN55022 COMPLIANCE
This equipment meets the radio disturbance characteristic specifications for information
technology equipment as defined in EN55022.
EN50082-1 COMPLIANCE
This equipment meets the electromagnetic compatibility/generic immunity standard as
defined in EN50082-1.
In order that the CRS-170 continues to comply with these standards, observe the
following instructions:
Connections to the transmit and receive IF ports (BNC female connectors) should be
made using a good quality coaxial cable; for example, RG58/U (50Ω) or RG59/U
(75Ω).
All 'D' type connectors attached to the unit must have back-shells that provide
continuous metallic shielding. Cable with a continuous outer shield (either foil or
braid, or both) must be used, and the shield must be bonded to the back-shell.
The equipment must be operated with its cover on at all times. If it becomes
necessary to remove the cover, the user should ensure that the cover is correctly
re-fitted before normal operation commences.
FEDERAL COMMUNICATIONS COMMISSION (FCC)
This equipment has been tested and found to comply with the limits for a Class B digital
device, pursuant to Part 15 of the FCC rules. These limits are designed to provide
reasonable protection against harmful interference when the equipment is operated in a
commercial environment.
This equipment generates, uses, and can radiate radio frequency energy. If not installed
and used in accordance with the instruction manual, it may cause harmful interference to
radio communications. Operation of this equipment in a residential area is likely to cause
harmful interference; in which case, users are required to correct the interference at their
own expense.
Note: To ensure compliance, properly shielded cables for DATA I/O shall be used. More
specifically, these cables shall be shielded from end to end, ensuring a continuous shield.
SAFETY COMPLIANCE
EN 60950
Applicable testing is routinely performed as a condition of manufacturing on all units to
ensure compliance with safety requirements of EN60950.
The equipment is rated for operation at +12 volts DC and -12 volts DC. It has a
maximum power consumption of 4.5 Watts, and draws a maximum of 250 mA at +12
volts DC and 120 mA at -12 volts DC. The power supply current is, in all circumstances,
supplied by either a single Comtech EF Data CDM-600 modem, or a pair of these
modems.
This equipment meets the Safety of Information Technology Equipment specification as
defined in EN60950.
EQUIPMENT CONNECTION
The CRS-170 is designed for operation ONLY with Comtech EF Data modems. These
modems supply DC operating current (electronically fused and protected) and control
signals for the correct functioning of this unit. Connection to other manufacturer’s
equipment could result in damage to the unit. The CRS-170 is not compatible with other
Comtech EF Data modems.
The CRS-170 must not be operated in an environment where the unit is exposed to
extremes of temperature outside the ambient range 0 to 500C (32 to 1220F), precipitation,
condensation, or humid atmospheres above 95% RH, altitudes (un-pressurized) greater
than 2000 meters, excessive dust or vibration, flammable gases, corrosive or explosive
atmospheres.
Operation in vehicles or other transportable installations that are equipped to provide a
stable environment is permitted. If such vehicles do not provide a stable environment,
safety of the equipment to EN60950 may not be guaranteed
TELECOMMUNICATIONS TERMINAL EQUIPMENT DIRECTIVE
In accordance with the Telecommunications Terminal Equipment Directive 91/263/EEC,
this equipment should not be directly connected to the Public Telecommunications
Network.
LOW VOLTAGE DIRECTIVE (LVD)
The following information is applicable for the European Low Voltage Directive
(EN60950):
<HAR> Type of power cord required for use in the European Community.
CAUTION: Double-pole/Neutral Fusing.
!
International Symbols:
Symbol Definition Symbol Definition
Alternating Current.
ACHTUNG: Zweipolige bzw. Neutralleiter-Sicherung.
Fuse.
Protective Earth.
Chassis Ground.
Note: For additional symbols, refer to “Cautions” listed earlier in this preface.
This Comtech EF Data product is warranted against defects in material and workmanship
for a period of two years from the date of shipment. During the warranty period, Comtech
EF Data will, at its option, repair or replace products that prove to be defective.
For equipment under warranty, the customer is responsible for freight to Comtech EF
Data and all related custom, taxes, tariffs, insurance, etc. Comtech EF Data is responsible
for the freight charges only for return of the equipment from the factory to the customer.
Comtech EF Data will return the equipment by the same method (i.e., Air, Express,
Surface) as the equipment was sent to Comtech EF Data.
LIMITATIONS OF WARRANTY
The foregoing warranty shall not apply to defects resulting from improper installation or
maintenance, abuse, unauthorized modification, or operation outside of environmental
specifications for the product, or, for damages that occur due to improper repackaging of
equipment for return to Comtech EF Data.
No other warranty is expressed or implied. Comtech EF Data specifically disclaims the
implied warranties of merchantability and fitness for particular purpose.
EXCLUSIVE REMEDIES
The remedies provided herein are the buyer's sole and exclusive remedies. Comtech EF
Data shall not be liable for any direct, indirect, special, incidental, or consequential
damages, whether based on contract, tort, or any other legal theory.
DISCLAIMER
Comtech EF Data has reviewed this manual thoroughly in order to provide an easy-to-use
guide to the equipment. All statements, technical information, and recommendations in
this manual and in any guides or related documents are believed reliable, but the accuracy
and completeness thereof are not guaranteed or warranted, and they are not intended to
be, nor should they be understood to be, representations or warranties concerning the
products described. Further, Comtech EF Data reserves the right to make changes in the
specifications of the products described in this manual at any time without notice and
without obligation to notify any person of such changes.
If you have any questions regarding the equipment or the information in this manual,
please contact the Comtech EF Data Customer Support Department.
The CRS-170 L-Band 1:1 Switch Module is an L-Band Tx-Rx signal switch designed for
use with L-Band satellite modems in a 1:1 configuration. The Tx side switches four
modem output signals that are multiplexed onto the transmit coaxial cable:
• 950-1950 MHz L-band transmit RF
• 10 MHz BUC frequency reference
• 600 KHz BUC FSK control and status communication
• BUC DC power supply
The receive side of the switch uses both power dividers and relays to provide the
redundant modem interface for three signals multiplexed onto the LNB coaxial cable:
• 950-1950 MHz L-Band RX RF from LNB
• 10 MHz frequency reference to LNB
• DC power supply to LNB
The CRS-170 is designed to support 1:1 redundancy for Comtech EF Data CDM-600L,
SDM-300L3, SNM-1001L, and SNM-1010L modems. Table 1 summarizes the
applications including requirements for supporting data switching hardware and software.
The CDM-600L and SDM-300L3 modems do not have built in switching capability for
the terrestrial data side of the link. One-for-one redundancy for the CDM-600L requires
both a CRS-150 switch to act as controller and terrestrial data switch, and a CRS-170 to
perform the RF side switching.
The CRS-170 is required because the CRS-150 RF switching is limited to the 70/140
MHz band, and will not handle the high current BUC power supply multiplexed onto the
transmit coaxial cable. Similarly, the SDM-300L3 requires an SMS-301 switch together
with the CRS-170.
In both cases, the CRS-170 is controlled by the supporting data switch, and places the
“A” or “B” modem RF on-line to match the data switch state. The CDM-600L modems
supply redundant power to the CRS-170 through the CRS-150. The SMS-301 itself has
redundant power supplies, and feeds power to the CRS-170 through the control cable.
Online-standby modem configuration matching is provided by the CRS-150 controller
communication with the CDM-600L modem. The SMS-301 does not automatically
configure the standby modem.
The CRS-150 is an accessory product designed specifically for the Comtech EF
Data CDM-600 and CDM-600L modems, and must not be used with any other
WARN ING
equipment.
The SMS-301 is configured differently for use with the SDM-300L3 than for
use with the SDM-300A. The configuration must be done at the factory and
IMPORTANT
must be specified at the time of order.
For correct operation of the CRS-170, the CDM-600L modems must have
installed:
Firmware Version 1.1.4 (or higher)
Hardware Revision 3
If the modem does not meet this requirement, please contact the factory.
Flash firmware upgrades are free, and may be downloaded from the CEFD
web page. Hardware revision upgrades must be performed at the factory.
For correct operation of the CRS-170 with CDM-600L, the CDM-600L
modems must have installed:
IMPORTANT
2.1 UNPACKING
If the modems do not meet this requirement, contact the factory for further
instructions.
Firmware Version 1.1.4 (or higher)
Hardware Revision 3 (or higher)
Inspect shipping containers for damage. If shipping containers are damaged, they
should be kept until the contents of the shipment have been carefully inspected
and checked for normal operation.
Remove the packing list from the outside of the shipping carton. Open the carton
and remove the contents, checking the contents against the packing list. Verify
completeness of the shipment and that the unit functions correctly. If damage is
evident, contact the carrier and Comtech EF Data immediately and submit a
damage report. Be sure to keep all shipping materials for the carrier's inspection.
If the unit needs to be returned to Comtech EF Data, use the original shipping
container.
The CRS-170 is designed to be mounted in the rear of a rack containing the
modems. Because of the module’s small size and weight, one installation option is
to let the module hang freely supported by the interfacing cables. Alternatively, a
rack mounting kit (KT/10254) is available that allows the module to be mounted
to the rack horizontally or vertically as shown in Figure 1. In applications with the
CDM-600L and the CRS-150, the CRS-170 is best mounted horizontally above or
below the CRS-150.
Figure 2 shows how to connect a pair of CDM-600L Modems together with the
CRS-150 and CRS-170 switches.
User
Data
Interface
DATA A
-301
SMS
DATA B
CRS-150
Data
Data
Notes:
1.
Carries Tx L
2.
Carries Rx L
Modem A
CDM-600L
SDM-300L3
P3B
170 Control & Power
P3B
CDM-600L
SDM-300L3
Modem B
-
Band, BUC DC, 10 MHz and FSK
-
Band, LNB DC, 10 MHz
J2
J1
J2
J1
Tx
(Note 1)
Rx
(Note 2)
Tx
(Note 1)
Rx
(Note 2)
J5
Tx A
J1
Rx A
J3 (Top)
J4 (Bottom)
CRS-170
CRS-170
J6
Tx B
J2
Rx B
J8
J7
Figure 2. Connection Diagram, CDM-600L and CRS-150
Tx
L - Band
BUC DC
10 MHz
FSK
Rx
L - Band
LNB DC
10 MHz
The following table lists cable assemblies that may be supplied with the CRS-170 when
used with the CDM-600L and CRS-150. Other cables between the CRS-150 and the
CDM-600L modems are supplied with the CRS-150.
Quantity Part # Description
2 CA/WR10456-4 Data/Control Y Cable, DB25 Male to Male 4 ft, DB9 Male 1 ft
4 CA/6357-2 IF Coax Cable, 50Ω, length = 2 feet
When connecting the Control cable between the CRS-170 and the modems,
ensure that screw locks on the ‘D’ type connectors are securely fastened.
IMPORTANT
This will prevent the accidental un-mating of the cable, particularly when a
standby unit is being removed or replaced.
Figure 3 shows how to connect a pair of SDM-300L3 Modems together with the
SMS-301 and CRS-170 switches. The same configuration applies to SNM-1001L
and SNM-1010L.
The following table lists cable assemblies that may be supplied with the CRS-170
when used with the SDM-300L3 and SMS-301. The other cables between the
SMS-301 and the SDM-300L3 are the same cables supplied with the SMS-301 in
an SDM-300A application.
Quantity Part # Description
1 CA/WR10163-1 SMS-301 to CRS-170 Control, DB15 Male to DB9 Male 4 ft
4 CA/6357-2 IF Coax Cable, 50Ω, length = 2 feet
J2 A
Data
User
Data
Interface
J1
SMS - 301
-301
SMS
J3 B
Data
Modem A
CP1
J8
SDM-300L3
SDM-300L3
CP3
1:1 Control
CP1
J8
SDM-300L3
SDM-300L3
CP3
Modem B
Tx
(Note 1)
Rx
(Note 2)
Tx
(Note 1)
Rx
(Note 2)
J5
Tx A
J1
Rx A
J3 (Top)J14
CRS-170
CRS-170
J6
Tx B
J2
Rx B
J8
Tx
L - Band
BUC DC
10 MHz
FSK
Rx
L - Band
LNB DC
10 MHz
J7
Notes:
Includes Tx L -Band, BUC DC, 10 MHz and FSK
Figure 3. Connection Diagram, SDM-300L3 and SMS-301
1.
Includes Rx L -Band, LNB DC, 10 MHz
2.
When connecting the Control cable between the CRS-170 and the SMS-301,
ensure that screw locks on the ‘D’ type connectors are securely fastened.
IMPORTANT
This will prevent the accidental un-mating of the cable, particularly when a
standby unit is being removed or replaced.
The CRS-170 L Band 1:1 Switch module performs the transmit and receive coaxial
switching required for redundant modem operation with an outdoor BUC and LNB. It
switches all of the BUC and LNB interface signals that are multiplexed onto the transmit
and receive coaxial cables:
• Tx and Rx L-Band signals
• 10 MHz reference to BUC and LNB
• DC Power to BUC and LNB
• FSK signaling to the BUC
Operation with two CDM-600L modems requires an additional CRS-150 1:1 switch for
terrestrial data switching and 1:1 control, while operation with two SDM-300L3 modems
requires an additional SMS-301 1:1 switch to handle terrestrial data and control. Thus,
there are three functional configurations for the CRS-170.
The CRS-150 connects to two modems, an online unit, and a standby unit, monitors the
fault status of these two units, and controls the routing of data to and from the two units.
IF signals, 10MHz reference signals, DC power for the BUC and LNB, and FSK
signaling to the BUC are switched in the CRS-170 under control of the CRS-150. In the
case of an equipment failure, switching automatically takes place to protect the traffic
circuit. At the heart of the CRS-150 is a Controller State Machine, which is responsible
for fault monitoring and control of switching functions. It is implemented in a CPLD.
The CRS-150 redundancy switch derives its operating power from the two modems,
online and standby, via extra power carrying wires in the data cable from each modem.
Similarly, the CRS-170 derives its +12V power from both modems through Y-cable
connection to the same cables. The required online and offline control signals are also
included in these cables. A diode sharing arrangement with a current sharing circuit
ensures that power is taken equally from the two modems in normal operation. In the
event that one of the two units is removed, however, the remaining modem can supply
all of the current requirement. The modems supply +12 volts DC (at a combined total of
400 mA max) and -12 volts DC (at a combined total of 120 mA max). Maximum power
consumption occurs in a serial LVDS mode at maximum data rate (20 Mbps). Power
consumption in EIA-232 modes is approximately 40% of the maximum values. The
modem employs electronic fuses which prevent excessive current from being drawn by
the CRS-150 should an anomalous condition occur.
Transmit Clock and Data signals entering the CRS-150 via the Data Interface are
buffered and fed to both modems simultaneously. This parallel feed ensures that the
standby unit sees the same traffic conditions as the online unit. Receive Data and Clock
signals coming from the online modem are routed through signal relays to the Data
Interface. In the event that a switchover occurs, these relays switch so the standby unit
then supplies the Data and Clock signals.
As only one modem in the pair (the online unit) is permitted to transmit its IF carrier
signal at any one instant, the standby unit is forced to disable its TX carrier by asserting
the TX Carrier Off signal at the Data Interface. In addition, the CRS-170 provides further
isolation (and security) by using an RF relay within the unit.
The Rx IF signal is fed to both modems simultaneously through the power divider in the
CRS-170. This divider does introduce a loss of approximately 3.5 dB, but given the wide
dynamic range of the demodulator in the CDM-600L, this is not considered to be a
problem. The advantage of this scheme is that the demodulators in both online and
standby units are locked, and therefore, if a switchover does occur, there will be no delay
while waiting for the demodulator to acquire lock.
Fault status information is fed from each of the two modems via the Data Interface
connector. The Controller State Machine in the CRS-150 decides, based on the fault
status, whether the ‘A’ or ‘B’ unit is to be the online unit. It will assert a control signal to
the standby unit, which mutes its Tx IF carrier, and simultaneously indicates to the
microcontroller within the standby unit that the unit is no longer ‘online’. Consequently,
the ‘online’ LED on the front panel of the standby modem is extinguished, and the
standby status is also reported over the remote control bus so an external M&C system
can determine the state of the redundancy system. At the same time, a green LED will
illuminate on the front of the CRS-150 to indicate whether the ‘A’ or ‘B’ unit is online,
and a green LED on the antenna side of the CRS-170 will indicate the same status.
3.2 OPERATION WITH SDM-300L3 AND SMS-301
The SMS-301 is modified from the standard version that operates with 70/140 MHz IF
SDM-300A modems. The BNC IF connectors are removed since the connectors and
internal switching are not suitable for L-Band operation. Signals on the Status/Faults
connector (J14) are modified to provide +12VDC power output and A/B switch control
outputs to the CRS-170. The SMS-301 has its own redundant power supplies, so the
CRS-170 receives redundant power.
Operation here is similar to operation with two CDM-600L modems and a CRS-150
switch. The SMS-301 operates as the principal switch and controller with the CRS-170
providing the required switching for L-Band signals, references, and power supplies that
the SMS-301 cannot handle. The SMS-301 connects to two modems, an online unit, and
a standby unit, monitors the fault status of these two units, and controls the routing of
data to and from the two units. IF signals, 10MHz reference signals, DC power for the
BUC and LNB, and FSK signaling to the BUC are switched in the CRS-170 under
control of the SMS-301. In the case of an equipment failure, switching automatically
takes place to protect the traffic circuit. Consult the SMS-301 manual for detailed
information on operation of the SMS-301. All operation as a 70/140 MHz modem switch
applies except that the RF switching is done in the CRS-170.
For operation with the SNM-1001L or SNM-1010L, refer to sections pertaining to the
SDM-300L3.
The modem side connectors provide all necessary external connections between
the CRS-170 L-Band Switch Module and the CDM-600L/CRS-150, or SDM300L3/SMS-301.
Name Ref Des Connector Type Function
RX A J1 Type N RF Input to Modem A
RX B J2 Type N RF Input to Modem B
TX A J5 Type N RF Output from Modem A
TX B J6 Type N RF Output from Modem B
Control A J3 9-pin D (female) Control Interface with Modem A
Control B J4 9-pin D (female) Control Interface with Modem B
To maintain compliance with the European EMC Directive (EN55022,
IMPORTANT
EN50082-1) properly shielded cables are required for data I/O.
The Modem A Control connector is a 9-pin D female interface located on the
modem side of the L-Band Switch Module. Refer to Table 2 for pin assignments.
Pins 2, 3, and 4 carry signals looped through the switch module from Modem B to
Modem A, while pins 6, 7, and 8 loop the same signals from Modem A through to
Modem B. The 12VDC input, which is diode OR’ed with the corresponding
12VDC input from modem B, powers the switch module.
Table 2. J3A - Modem A Control Connector Pin Assignments
Pin #Signal Function Signal Name Direction
1 Signal Ground Ground 2 Modem B 232 Tx AUX_SER_TX_B Out
3 Modem B Online Indication ONLINE_OUT_B Out
4 Modem B Fault Indication /FAIL_OUT_B Out
5 Signal Ground Ground 6 Modem A 232 Tx AUX_SER_TX_A In
7 Modem A Online Indication ONLINE_OUT_A In
8 Modem A Fault Indication /FAIL_OUT_A In
9 +12 VDC +12VDC In
The Modem B Control connector is a 9-pin D female interface located on the
modem side of the L-Band Switch Module. Refer to Table 3 for pin assignments.
Pins 2, 3, and 4 carry signals looped through the switch module from Modem A to
Modem B, while pins 6, 7, and 8 loop the same signals from Modem B through to
Modem A. The 12VDC input, which is diode OR’ed with the corresponding
12VDC input from modem A, powers the switch module.
Table 3. J3B - Modem B Control Connector Pin Assignments
Pin # Signal Function Signal Name Direction
1 Signal Ground Ground 2 Modem A 232 Tx AUX_SER_TX_A Out
3 Modem A Online Indication ONLINE_OUT_A Out
4 Modem A Fault Indication /FAIL_OUT_A Out
5 Signal Ground Ground 6 Modem B 232 Tx AUX_SER_TX_B In
7 Modem B Online Indication ONLINE_OUT_B In
8 Modem B Fault Indication /FAIL_OUT_B In
9 +12 VDC +12VDC In
Two 50Ω female Type N connectors on the antenna side of the CRS-170 L-Band
Switch Module provide the coaxial cable connections to the outdoor transmit and
receive equipment (BUC and LNB). Refer to Figure 5.
BUC 10 MHz
Reference
Switching
BUC FSK Comm
Switching
LNB Power
Switching
LNB 10 MHz
Reference
Switching
Tx-Rx Isolation
IF Impedance
IF Connectors
IF Frequency
range
L-Band 1:1 Redundancy Switch
Comtech EF Data, Tempe, Arizona
Comtech EF Data CDM-600L with CRS-150 1:1 Data Switch
Comtech EF Data SDM-300L3 with SMS-301 1:1 Data Switch
Fully Automatic under control of supporting 1:1 switch.
Manual under control of supporting 1:1 switch.
Full bridging architecture when supported by CRS-150, or SMS-301 data
switching and control, with configuration synchronization.
Tx redundancy supports all BUC interface signals (RF, 10 MHz reference, FSK
communications, and power supply)
Rx IF signal fed to both Online and Standby units. Rx switching supports all LNB
interface signals (RF, 10 MHz reference, and power supply.)
Tx/Rx switching follows state of supporting data switching via control input from
data switch.
Tx IF: Switched by RF relay (1 dB max loss, 40 dB min ON/OFF isolation)
Rx IF: Passive power splitting (7 dB max loss)
Switched by power relay (60VDC max, 4A max)
Switched by relay (1 dB max loss, 70dB min ON/OFF isolation)
Switched by relay (70dB min ON/OFF isolation)
Switched by power relay (28 VDC max, )
Switched by relay (1 dB max loss, 70dB min ON/OFF isolation)
90dB min, 950-1950 MHz
Optimized for 50Ω (> 10 dB return loss on external IF ports)