CDM-625 Advanced Satellite Modem

CDM-625 Advanced Satellite Modem
Satellite Modems
Typical Users
The CDM-625 Advanced Satellite Modem builds on our legacy of providing
the most efficient satellite modems. It was our first modem to combine
advanced Forward Error Correction (FEC) such as VersaFEC and Low
Density Parity Check (LDPC) codes with the revolutionary DoubleTalk
Carrier-in-Carrier bandwidth compression, allowing for maximum savings
under all conditions. This combination of advanced technologies enables
multi-dimensional optimization, allowing satellite communications users to:
• Minimize operating expenses (OPEX)
• Maximize throughput without using additional transponder resources
• Maximize availability (margin) without using additional transponder
• Minimize capital expenses (CAPEX) by allowing a smaller BUC/HPA
and/or antenna
• Or, a combination to meet specific business needs
Mobile Network Operators
Telecom Operators
Satellite Service Providers
Government & Military
Common Applications
Mobile Backhaul
G.703 Trunking
IP Trunking
Offshore & Maritime Communications
Communications on-the-Move
Satellite News Gathering
DoubleTalk Carrier-in-Carrier bandwidth compression
Carrier-in-Carrier Automatic Power Control
Adaptive Coding and Modulation (ACM)
Packet Processor with header compression, payload
compression, advanced Quality of Service (QoS) and
Managed Switch Mode
4-port managed Ethernet switch with VLAN and QoS
Jumbo frame support
Dual Band Capability: 70/140 MHz and L-Band in same unit,
extended L-Band receive
Data Rate: 18 kbps to 25 Mbps
Symbol Rate: 18 ksps to 12.5 Msps
Modulation: BPSK, QPSK/OQPSK, 8PSK/8-QAM, 16-QAM
FEC: Viterbi, Sequential, Concatenated Reed Solomon, TCM,
Turbo Product Code (TPC) (IESS-315 Compliant), LDPC Code
and VersaFEC (low-latency LDPC)
Widest Range of data interfaces: EIA-422/530, V.35, G.703 T1,
G.703 E1, G.703 T2, G.703 E2, Quad G.703 E1, ASI, LVDS,
HSSI, 4-port 10/100Base-T Ethernet
IEEE 1588v2 Precision Time Protocol
• Sub Mux to multiplex IP/Ethernet traffic with serial or G.703
• Drop & insert for T1/E1
• Enhanced D&I++ for single T1/E1 & quad E1
• Management: 10/100Base-T Ethernet with SNMP, Distant
End SNMP Proxy, HTTP, Telnet and EIA-232/EIA-485
• Carrier ID using MetaCarrier Technology
• Embedded Distant-end Monitor and Control (EDMAC)
• Automatic Uplink Power Control (AUPC)
• Engineering Service Channel (ESC/ESC++)
• Standard high-stability internal reference
(± 6 x 10 )
• 5-tap Adaptive Equalizer
• L-Band TX: 10 MHz reference for BUC, FSK communications
and optional BUC power supply
• L-Band: Advanced FSK for LPOD M&C
• L-Band RX: 10 MHz reference and LNB power supply
• Open network modes
• 1:1 and 1:10 redundancy switches available
Doubletalk Carrier-In-Carrier
DoubleTalk Carrier-in-Carrier, based on patented “Adaptive Cancellation” technology, allows transmit and receive carriers of a duplex
link to share the same transponder space. DoubleTalk Carrier-in-Carrier is complementary to all advances in modem technology,
including advanced FEC and modulation techniques. As these technologies approach theoretical limits of power and bandwidth
efficiencies, DoubleTalk Carrier-in-Carrier utilizing advanced signal processing techniques provides a new dimension in bandwidth
Figure 1 shows the typical full-duplex satellite link, where the two carriers are adjacent to each other.
Figure 2 shows the typical DoubleTalk Carrier-in-Carrier operation, where the two carriers are overlapping, thus sharing the same
Figure 2
Figure 1
When observed on a spectrum analyzer, only the Composite is visible. Carrier 1 and Carrier 2 are shown in Figure 2 for reference only.
As DoubleTalk Carrier-in-Carrier allows equivalent spectral efficiency using a lower order modulation and/or code rate, it can
simultaneously reduce CAPEX by allowing a smaller BUC/HPA and/or antenna. Alternatively, DoubleTalk Carrier-in-Carrier can be
used to achieve very high spectral efficiencies E.g., DoubleTalk Carrier-in-Carrier when used with 16-QAM approaches the bandwidth
efficiency of 256-QAM (8 bps/Hz).
When combined with VersaFEC or LDPC/TPC, it can provide unprecedented savings in transponder bandwidth and power utilization.
This allows for its successful deployment in bandwidth-limited and power-limited scenarios, as well as reduction in earth station
BUC/HPA power requirements.
Carrier-in-Carrier® is a Registered Trademark of Comtech EF Data
DoubleTalk® is a Registered Trademark of Raytheon Applied Signal Technology
VersaFEC is a Registered Trademark of Comtech EF Data
Carrier-in-Carrier Automatic Power Control (CnC-APC)
The patent-pending Carrier-in-Carrier Automatic Power Control (CnC-APC) mechanism enables modems on both sides of a CnC link to
automatically measure and compensate for rain loss while maintaining the Total Composite Power. In addition to automatically
compensating for rain loss, CnC-APC also enables the modems to share link margin, i.e. a modem in clear sky conditions can
effectively transfer excess link margin to a distant end modem experiencing fade, thereby further enhancing overall availability.
VersaFEC Forward Error Correction
CDM-625 is the first modem to offer VersaFEC, a patent-pending system of high performance short-block low-latency LDPC codes
designed to support latency-sensitive applications, such as cellular backhaul over satellite. VersaFEC provides excellent coding gain
with lowest possible latency. VersaFEC’s Eb/No performance is similar to that of DVB-S2 (short block) or LDPC (16k block) with 7090% lower latency. Compared to TPC, VersaFEC can provide coding gain of 1.0 dB or more.
The new Ultra Low Latency (ULL) codes provide even lower latency compared to standard VersaFEC codes.
Adaptive Coding & Modulation (ACM)
Satellite users have traditionally relied on worst case link margin to overcome rain fade which leads to significant inefficiencies.
ACM converts the fade margin into increased throughput – gain of 100% or more is possible. ACM maximizes throughput under all
conditions – rain fade, inclined orbit satellite operation, antenna mis-pointing, noise, interference and other impairments.
ACM can also be used with DoubleTalk Carrier-in-Carrier.
Low Density Parity Check Codes (LDPC) & Turbo Product Codes (TPC)
CDM-625 offers an integrated LDPC and 2 Generation TPC codec. LDPC is an advanced Forward Error Correction technique
capable of providing performance much closer to Shannon limit. The current LDPC implementation can provide 0.7 to 1.2 dB additional
coding gain compared to an equivalent TPC code.
In order to take full advantage of the increased coding gain provided by LDPC, Comtech EF Data has developed a patented 8-QAM
modulation that allows for acquisition and tracking at much lower Eb/No compared to 8PSK.
Dual Band Capability
CDM-625 supports 70/140 MHz and L-Band capability in the same unit with independently selectable transmit and receive IF. This
simplifies sparing and stocking in networks requiring 70/140 MHz and L-Band units.
4-Port Managed Ethernet Switch with VLAN & QoS
CDM-625 base modem incorporates a 4-port 10/100Base-T managed Ethernet switch with VLAN capability and priority-based Quality
of Service. Access (Native) Mode and Trunk Mode are supported. Traffic can be prioritized using port-based priority or VLAN priority.
The maximum Ethernet frame size with Rev 2 HW is 2048 bytes.
Packet Processor
The Packet Processor enables efficient IP networking and transport over satellite by adding routing capability with very low overhead
encapsulation, header compression, payload compression and Quality of Service to the CDM-625. The advanced QoS combined with
header and payload compression ensures the highest quality of service with minimal jitter and latency for real-time traffic, priority
treatment of mission critical applications and maximum bandwidth efficiency.
Header Compression
The Packet Processor incorporates industry-leading header compression for IP traffic. Header compression can reduce the 40 byte
IP/UDP/RTP header to as little as 1 byte. For TCP/IP, the 40 byte header is reduced to as little as 3 bytes. For applications such as
VoIP, header compression can provide bandwidth savings exceeding 60%. E.g. the 8 kbps G.729 voice codec requires 24 kbps of IP
bandwidth once encapsulated into an IP/UDP/RTP datagram. With header compression, the same voice call needs about 8.5 kbps – a
saving of almost 65%. And, bandwidth requirements for typical Web/HTTP traffic can be reduced by 10% or more with TCP/IP header
Payload Compression
The Packet Processor incorporates industry-leading payload compression for IP traffic. Implemented in the hardware for maximum
throughput and efficiency, payload compression can reduce the required satellite bandwidth by as much as 40-50%.
Streamline Encapsulation (SLE)
The Packet Processor incorporates Comtech EF Data’s patent-pending very low overhead Streamline Encapsulation (SLE). SLE can
reduce the encapsulation overhead by as much as 65% compared to industry standard HDLC.
Advanced Quality of Service (QoS)
The Packet Processor incorporates multi-level QoS to ensure the highest quality service with minimal jitter and latency for real-time
traffic, priority treatment of mission critical applications and maximum bandwidth efficiency.
Supported modes are:
• DiffServ – Industry-standard method of providing QoS enabling seamless co-existence in networks that implement DiffServ
• Max/Priority – Provides multi-level traffic prioritization with the ability to limit maximum traffic per priority class
• Min/Max – Provides a Committed Information Rate (CIR) to each user defined class of traffic with the ability to allow a higher
burstable rate depending on availability
Managed Switch Mode
Managed switch modem enables layer 2 operation with the Packet Processor. This provides significant bandwidth savings for layer 2
operation with very low overhead Streamline Encapsulation, header compression and payload compression.
Quad E1 Interface (QDI) with Enhanced D&I++
The CDM-625 supports a Quad E1 interface that can aggregate up to four full or fractional E1s into a single carrier, with very low
overhead. This provides significant CAPEX savings by reducing the number of modems and could possibly reduce the BUC/HPA size
by eliminating the multi-carrier backoff. A proprietary, closed network drop & insert (D&I++) allows for dropping or inserting any
combination of 1 to 31 time slots on each E1. D&I++ is supported for E1-CCS only.
IP Sub Multiplexer
The IP sub mux allows multiplexing IP/Ethernet traffic with serial or G.703 traffic into a single carrier. This is particularly useful for
cellular backhaul when both E1 and IP backhaul is required. This reduces the number of modems and could possibly reduce the
BUC/HPA size by eliminating the multi-carrier backoff. The IP sub mux ratio ranges from 9:1 (IP data rate is 9 times that of the serial or
G.703 data rate) to as low as 1:59.
The CDM-625 supports EDMAC, EDMAC-2, EDMAC-3 and AUPC. EDMAC/EDMAC-2/EDMAC-3 can be used to monitor and control
the distant end of a satellite link using a proprietary overhead channel. EDMAC-3 is also used for SNMP management of the distant
end modem. AUPC enables automatic uplink power control for a duplex link.
Management & SNMP Proxy
The modem can be managed via the front panel, the remote M&C port (EIA-232/EIA-485), or the 10/100Base-T Ethernet port. With
support for SNMP, HTTP and Telnet, the modem can be easily integrated into an IP-based management system.
The CDM-625 can also act as SNMP proxy for the distant end modem. This allows distant end modem management using SNMP
without requiring an end-to-end IP link.
IEEE 1588v2 Precision Time Protocol (PTP)
PTP has emerged as the key technology for frequency, time and phase synchronization over a packet network. The CDM-625 is the
first satellite modem to incorporate hardware support for PTP, thereby significantly improving synchronization accuracy for satellite
backhaul. PTP requires Revision 2 modem hardware.
Advanced FSK for LPOD Monitoring & Control
The Advanced FSK allows for monitoring and control of LPOD through modem front panel menus, serial remote control and Telnet.
Feature Enhancements
Enhancing the capability of the CDM-625 in the field is easy. Features that do not require additional hardware can be added on site,
using FAST access codes purchased from Comtech EF Data.
Data Rate
Symbol Rate
Major Operating
(See User Manual
For Details)
FEC Options
Viterbi: k=7, per
Viterbi with Reed
Reed Solomon
TCM (Per IESS310)
Integrated LDPC
and TPC (2nd Gen)
Codec (Optional
Plug-in Module)
VersaFEC Codec
(Optional Plug-in
Form C Relays
External Reference
(Input OR Output)
18 kbps to 25 Mbps, in 1 bps steps
(modulation, FEC & data interface dependant)
18 ksps to 12.5 Msps
50 – 180 MHz (standard) and
950 – 2000 MHz (TX) & 950 – 2150 MHz (RX) (Option),
(Note: extended L-Band receive supported on modems
shipped since January 2013)
100 Hz resolution, independent TX and RX operation
Open network, per IESS-308 / 309 / 310 / 314
transparent, closed network per IESS-315
LDPC / TPC Codec (optional plug-in module)
VersaFEC Codec (optional plug-in module) with ACM or
Constant Coding & Modulation (CCM)
EDMAC Framed with/without AUPC
RS Outer Codec
High rate ESC / Enhanced ESC (ESC++)
Drop & insert (D&I) /Enhanced D&I++
Quad E1 drop & insert (QDI)
DoubleTalk Carrier-in-Carrier (optional plug-in module)
Rate 3/4 16-QAM
Rate 7/8 16-QAM
See CDM-625 user manual for details
Open network and closed network modes
8PSK/TCM Rate 2/3
LDPC Code Rates
TPC Code Rates
Rate 5/16 BPSK
BPSK Rate 0.488
QPSK Rate 0.533, 0.631, 0.706, 0.803
8-QAM Rate 0.576 (ECCM), 0.642, 0.711, 0.780
16-QAM Rate 0.644 (ECCM), 0.731, 0.780, 0.829, 0.853
BPSK 0.493 (ULL)
QPSK 0.493, 0.654, 0.734 (ULL)
IDR Mode, no RS, - per ITU V.35 (Intelsat variant)
IBS mode, no RS - per IESS-309, externally frame
Transparent Closed Network mode, no RS or Turbo coding per ITU V.35 (Intelsat variant)
EDMAC mode, no RS coding - externally frame
synchronized - proprietary
Turbo Product Code/LDPC/VersaFEC modes - externally
frame synchronized - proprietary
All RS modes - externally frame synchronized per IESS308/309/310
10/100Base-T Ethernet with SNMP, HTTP and Telnet
support, EIA-232, EIA-485 (2- or 4-wire)
Hardware fault, RX and TX traffic alarms, open network
backward alarms
BNC connector
Input: 1, 2, 5, or 10 MHz, -6 dBm to
+10 dBm, 50 Ω/75 Ω (nominal)
Output: 10 MHz, 2.7 V peak-to-peak
± 0.4 V, low impedance output
Data Interfaces
EIA-422/-530 DCE , Up to 14 Mbps
V.35 DCE , Up to 14 Mbps
LVDS Serial , Up to 25 Mbps
HSSI Serial , Up to 25 Mbps
G.703 T1, 1.544 Mbps
(Balanced 100 Ω)
G.703 T2, 6.312 Mbps
(Unbalanced 75 Ω or balanced
110 Ω)
G.703 E1, 2.048 Mbps
(Unbalanced 75 Ω or balanced
120 Ω)
G.703 E2, 8.448 Mbps (Unbalanced 75 Ω)
ASI , Up to 25 Mbps
Additional 2.048 Mbps E1 Ports for QuadE1 (Balanced 120 Ω)
Overhead Data
Modem Alarms
4-port 10/100Base-T Managed Ethernet
(Optional Packet Processor Available)
Frequency Stability
Transmit Filtering
Transmit Filter Rolloff
Harmonics and Spurious
Transmit On/Off Ratio
Output Phase Noise
Output Power
Power Accuracy
Output Impedance &
Return Loss
Clocking Options
External TX Carrier Off
BUC Reference
(10 MHz)
BUC Power Supply
(HW Option)
25-pin D-sub (female)
25-pin D-sub (female)
9-pin D-sub (female)
BNC (female)
BNC (female)
9-pin D-sub (female)
44-pin High-density D-sub (male)
15-pin D-sub (male)
4 x RJ-45
± 0.06 ppm (± 6 x 10-8), 0° to 50°C (32° to
122°F) with internal reference
Per IESS-308
25%, 35%
Better than -60 dBc/4 kHz
(typically <-65 dBc/4kHz)
Measured from 1 to 500 MHz
(50-180 MHz band)
Measured F0 ± 500 MHz
(950-2000 MHz band)
-60 dBc minimum
< 0.480° rms double sided, 100 Hz to 1 MHz
(Minimum 16 dB better overall than the Intelsat IESS308/309 requirements)
Frequency Offset
100 Hz
1 kHz
10 kHz
100 kHz
Fundamental AC line spurious is -42 dBc or lower
The sum of all other single sideband spurious, from 0
to 0.75 x symbol rate, is -48 dBc or lower
50-180 MHz:
0 to -25 dBm, 0.1 dB steps
950-2000 MHz:
0 to -40 dBm, 0.1 dB steps
50-180 MHz:
± 0.5 dB over frequency, data rate, modulation type
and temperature range of 15 to 35° C
± 0.8 dB over frequency, data rate, modulation type
and temperature range of 0 to 50° C
950-2000 MHz:
± 0.7 dB over frequency, data rate, modulation type
and temperature range of 15 to 35° C
± 1.0 dB over frequency, data rate, modulation type
and temperature range of 0 to 50° C
50-180 MHz: 50 Ω/75 Ω, 16 dB minimum return loss
(18 dB typical), BNC connector
950-2000 MHz: 50 Ω, 19 dB minimum return loss (21
dB typical), Type-N connector
Internal, ± 0.06 ppm (SCT)
External, locking over a ± 100 ppm range (TT)
Loop timing (RX satellite clock) – supports
asymmetric operation
External clock
By TTL ‘low’ signal or external contact closure
Via TX IF center conductor, 10.0 MHz
± 0.06 ppm (with internal reference), selectable
on/off, 0.0 dBm ± 3 dB
24 VDC, 4.17 Amps max., 90 W @ 50° C
48 VDC, 3.125 Amps max., 150 W @ 50° C (180 W
@ 30° C)
Supplied through TX IF center conductor and
selectable on/off via M&C control
Input Power Range, Desired
Max Composite Operating
Absolute Maximum
Adaptive Equalizer
Acquisition Range
Below 64 ksymbols/sec
Between 64 and
389 ksymbols/sec
Above 389 ksymbols/sec
Acquisition Time
Doppler Buffer
Receive Clock
Clock Tracking
LNB Reference (10 MHz)
LNB Voltage
Monitor Functions
50-180 MHz: -105 + 10 log (symbol rate) to
-70 + 10 log (symbol rate) dBm
950-2150 MHz: -130 + 10 log (symbol rate) to -80 +
10 log (symbol rate) dBm
50-180 MHz:
94 – 10 log (symbol rate, desired carrier) dBc, +10
dBm max., with the additional requirement that
within ± 10 MHz of the desired carrier the
composite power is
≤ +30 dBc
950-2150 MHz:
102 – 10 log (symbol rate, desired carrier) dBc, +10
dBm max., with the additional requirement that
within ± 10 MHz of the desired carrier the
composite power is
≤ +30 dBc
+20 dBm
5-tap design, selectable on/off
Programmable in 1kHz increments
± 1 kHz to ± (Rs/2) kHz, where Rs = symbol rate in
± 1 kHz to ± 32 kHz
± 1 kHz to ± (0.1 * Rs) kHz, up to a maximum of ±
200 kHz
Highly dependent on data rate, FEC rate, and
demodulator acquisition range.
E.g.: 120 ms average at 64 kbps, R1/2 QPSK, ± 10
kHz acquisition sweep range,
6 dB Eb/No
Selectable from 64 to 262,144 bits, in 16-bit steps
(Additional limitations for G.704 frame boundaries)
RX satellite, TX terrestrial, external reference
± 100 ppm minimum
Via RX IF center conductor, 10.0 MHz
± 0.06 ppm (with internal reference), selectable
on/off, -3.0 dBm ± 3 dB
Selectable on/off, 13 VDC, 18 VDC per DiSEq 4.2
and 24 VDC at 500 mA maximum
Eb/N0 estimate, corrected BER, frequency offset,
buffer fill state, receive signal level
or 48 VDC primary power supply
Integrated TPC (2 generation) and LDPC Codec module
DoubleTalk Carrier-in-Carrier module
VersaFEC Codec module
Packet Processor
L-Band IF (in addition to 70/140 MHz)
Modem data rate – 10 Mbps, 15 Mbps, 20 Mbps or 25 Mbps
8PSK and 8-QAM modulation (8-QAM requires TPC/LDPC or
VersaFEC Codec)
16-QAM modulation
TPC/LDPC Codec data rate – 10 Mbps, 15 Mbps, 20 Mbps or 25
DoubleTalk Carrier-in-Carrier (full) – 512 kbps, 1.1 Mbps, 2.5
Mbps, 5 Mbps, 10 Mbps, 15 Mbps, 20 Mbps or 25 Mbps
DoubleTalk Carrier-in-Carrier (fractional) – 2.5 Mbps, 5 Mbps, 10
Mbps, 15 Mbps, 20 Mbps or 25 Mbps
VersaFEC Codec data rate (CCM) – 2.5 Mbps, 5 Mbps or
16 Mbps
VersaFEC Codec symbol rate (ACM) – 300 ksps, 1.2 Msps or 4.1
Open network – IBS with high rate IBS ESC, IDR and audio
D&I / D&I++ for single Port T1/E1
D&I++ For Quad E1 Port 2, 3 and 4
Quality of Service (requires Packet Processor)
Header Compression (requires Packet Processor)
Payload Compression (requires Packet processor)
Advanced Network Timing (IEEE 1588v2 PTP)
Environmental and Physical
DoubleTalk Carrier-in-Carrier
Delay Range
Power Spectral Density
(Interferer to Desired)
Maximum Symbol Rate
Eb/No Degradation
Satellite Restrictions
0 to 330 ms
BSPK/QPSK/8PSK/8-QAM: –7 dB to
+11 dB
16-QAM: -7 dB to +7 dB
3:1 (TX:RX or RX:TX)
0 dB Power Spectral Density Ratio
8-QAM: 0.4 dB
8PSK: 0.5 dB
16-QAM: 0.6 dB
+10 dB power spectral density ratio
Additional 0.3 dB
Satellite in “loop-back” mode (i.e., the transmit
station can receive itself)
“Non-processing” satellite (i.e., does not
demodulate or remodulate the signal)
Power Supply
Power Consumption
Dimensions (1RU)
(height x width x
CE Mark
Available Options
100 – 240 VAC, 175 W AC primary power supply
-48 VDC, 125 W primary power supply
-24 VDC, 120 W primary power supply
24 VDC, 90 W @ 50°C BUC power supply, AC, 24 VDC or 48
VDC primary power supply
48 VDC, 150 W @ 50°C (180 W @ 30°C) BUC power supply, AC
1:1 Modem Redundancy Switch (L-Band)
1:1 Modem Redundancy Switch (70/140 MHz)
1:10 Modem Redundancy Switch
(Not available with Packet Processor)
1:10 IF Redundancy Switch (70/140 MHz)
1:10 IF Redundancy Switch (L-Band)
1:N Modem Redundancy System
(For use with Packet Processor Only)
1:10 IF Redundancy Switch
(For use with CRS-500)
Operating: 0 to 50°C (32 to 122°F)
Storage: -25 to 85°C (-13 to 185°F)
100 – 240 VAC, +6%/-10%, 50/60 Hz, auto sensing
-24 VDC (HW option)
-48 VDC (HW option)
48 W (typical with TPC/LDPC Codec and Carrier-inCarrier module installed), 55 W (max.)
60 W (typical with TPC/LDPC Codec, Packet Processor
and Carrier-in-Carrier module installed), 67 W max.
280 W (typical with TPC/LDPC Codec, Carrier-in-Carrier
module and 48 VDC BUC power supply installed), 300 W
1.75” x 19.0” x 17.65”
(4.4 x 48 x 44.8 cm) approximate
10.8 lbs (4.9 kg) maximum, with all option modules and
48 VDC BUC power supply installed
EN 301 489-1 (ERM)
EN55022 (Emissions)
EN55024 (Immunity)
EN 61000‐3‐2
EN 61000‐3‐3
EN60950 (Safety)
FCC Part 15, Subpart B
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