COMTECH CDM-760 Advanced High-Speed Trunking and Broadcast Modem

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The CDM-760 Advanced High-Speed Trunking and Broadcast Modem was designed to be the most efficient, highest throughput, point-to-point modem available. Accommodating the most demanding Internet Service Providers, Broadcasters, and telco backhaul links by offering users the most advanced combination of space segment saving capabilities while minimizing overhead.

The CDM-760 offers an expansive range of symbol rates (100 ksps to 150 Msps) and data rates (100 kbps to >720 Mbps) simplex. In a duplex setting, this is >1.4 Gbps or 300 Msps. The onboard Ethernet interfaces support Super Jumbo Frames from 64 Bytes to >10,000 Bytes and will process Ethernet frames at a blazing > 1.2 Million packets/second. With the optional Packet Processor card installed the CDM-760 can support > 350,000 packets per second while performing simultaneous Header Compression and QoS.

Comtech offers a variety of open or closed network specifications and MODCOD selections. The CDM-760 can be configured to run as DVB-S2 (EN 302 307), DVB-S2X (EN 302 307-2) open standard waveforms, or with Comtech’s DVB-S2-EB1& EB2 (Efficiency Boost) waveforms. All waveforms are interoperable with ACM and the CDM-760 DPD (Dynamic Pre-Distortion). DPD allows satellite amplifiers to push further into saturation, maximizing transponder efficiency. The pre-distortion function is constantly optimized by the modem and does not require any user intervention.

Implementing Adaptive Coding and Modulation (ACM) operation allows link margin to be converted to user capacity during non-faded conditions by taking advantage of the actual signal-to-noise ratio rather than calculated worst-case signal-to-noise.

By using the best encapsulation methods, the CDM-760 further increases throughput by using the minimal overhead. In G.703 synchronous mode, users can implement monitor and control over the satellite with no additional overhead. When using Ethernet bridge mode, less than 1% overhead is used for encapsulation.

An optional high-speed packet processor card has a powerful user-defined QoS engine for traffic shaping, performing header compression (greatly reducing WAN capacity with smaller packets >60%), and enabling static routing. The optional K4 GZIP lossless compression engine performs real-time compression of user payload. Performance testing shows a 52% to 59% compression rate when tested against an industry-standard Calgary Corpus profile.

DVB-CID ETSI TS 103 129 is the ETSI standard for combating satellite interference and is largely based on Comtech EF Data’s award-winning MetaCarrier® technology. MetaCarrier technology embeds and detects a small message and unique ID within a video or data satellite carrier. This embedded message and ID significantly reduce the time to identify and clear interference sources.

Additionally, the CDM-760 leverages our powerful DoubleTalk® Carrier-in-Carrier® “Adaptive Cancellation” technology. With the ability to overlay TX and RX carriers, Carrier-in-Carrier enables the operator to establish the perfect balance between bandwidth and power, enabling the best possible use of the satellite resource and reducing operating expenses (OPEX). These technologies alone offer enormous savings to the ISP, Broadcaster, and telco operator. When used in combination, however, the capacity savings cannot be matched. The innovative high-performance architecture of the CDM-760 allows efficient networking and transport over satellite links while supporting a wide range of applications and network topologies.

Key Features

• Symbol Rate: 0.1 to 150 Msps
• Data Rate: 0.1 to >720 Mbps (Simplex), >1.4 Gbps (Duplex)
• DVB-S2 ETSI EN 302 307 & DVB-S2X EN 302 307-2 compliant
• DVB-S2-EB1&EB2 Efficiency Boost technology
• DoubleTalk Carrier-in-Carrier bandwidth compression
• ACM and CCM
• Embedded MetaCarrier DVB-CID ETSI TS 103 129
• GSE – low overhead <1% encapsulation
• K4 GZIP lossless compression
• Automatic Uplink Power Control (AUPC)
• Dynamic Pre-Distortion (DPD)
• Super Jumbo Frame 64 - 10,240 Byte Support (In Non-Packet Processor Mode)
• Packet Processor with > 190,000 PPS simplex and > 350,000 PPS duplex
• 9,000 Byte Jumbo Frame (In Packet Processor Mode)
• Layer 3 Routed Mode operation with up to 256 static routes (>105,000 PPS simplex, >150,000 PPS duplex)
• Modulation: QPSK, 8PSK, 16APSK, 32APSK, 64APSK, 128APSK, 256APSK
• Dual IF: 70/140 MHz, L-Band and L-Band monitor (standard)
• LNB power and 10MHz reference, BUC 10MHz reference
• Data Interfaces
▪ 2 Gigabit 10/100/1000Base-T interfaces (standard)
▪ 1 Optical Gigabit interface (optional)
▪ Processes > 600,000 pps simplex, 1.2M pps duplex
▪ PIIC optional interface cards
▪ ASI (DVB Asynchronous Serial Interface)
▪ G.703 E3/T3/STS-1 (34.368, 44.736, 51.84 Mbps)
▪ STM-1 Copper SDH (155.52 Mbps)
▪ OC-3 SONET single mode or multi-mode 1300 nm (155.52 Mbps)
• Multistream capable (Multi-Interface mux)
• Supports FSS, HTS, GEO, MEO, and LEO mode operation
• Management: HTTP, SNMP, Telnet, RS-232/485 with In-band (over satellite) M&C control
• 1:1 and 1:N redundancy switching available

Typical Users

• Mobile Operators / Telecom
• Broadcasters
• ISPs
• Government & Military

Common Applications

• IP & Telco Trunking
• DVB-S2 & S2X Video Delivery
• HTS, GEO, and MEO Trunking
• Disaster Recovery & Emergency Communications

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.

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 spectrum.

When observed on a spectrum analyzer, only the Composite is visible. Carrier 1 and Carrier 2 are shown in Figure 2 for reference only. Carrier-in-Carrier® is a Registered Trademark of Comtech EF Data DoubleTalk® is a Registered Trademark of Raytheon Applied Signal Technology

Packet Processor

The optional High-Speed Packet Processor enables efficient IP networking and transport over satellite with a processing engine capable of handling >190,000 PPS simplex and >350,000 PPS duplex. The packet processor performs header compression and Quality of Service (QoS) ensuring the highest quality of service with minimal jitter and latency for real-time traffic, priority treatment of mission critical applications and maximum bandwidth efficiency.

The Packet processor functions in Managed Switch Mode of operating as a layer 2 switch with VLAN and MPLS support.

Header Compression

The Packet Processor incorporates industry-leading header compression for Ethernet and IP traffic. In managed switch mode, header compression can reduce the 54 byte Ethernet/IP/UDP/RTP header to as little as 1 byte. For applications such as VoIP, header compression can provide bandwidth savings exceeding 65%. E.g. the 8 kbps G.729 voice codec requires 31.2 kbps once encapsulated into an Ethernet frame with IP/UDP/RTP. With header compression, the same voice call needs about 9 kbps – a saving of almost 70%. And, bandwidth requirements for typical Web/HTTP traffic can be reduced by 10% or more with TCP/IP header compression.

Supported Layer 2, 2+ Headers	Supported Layer 3 Headers
Ethernet	IP
Ethernet + VLAN	TCP
Ethernet + VLAN + VLAN	UDP
Ethernet + MPLS	RTP (Codec Independent)
Ethernet + MPLS + MPLS
Ethernet + VLAN + MPLS
Ethernet + VLAN + MPLS + MPLS
Ethernet + VLAN + VLAN + MPLS
Ethernet + VLAN + VLAN + MPLS + MPLS

Traffic Shaping Functionality (QoS)

Traffic Shaping Functionality (QoS) – The high-speed packet processor functions in a layer 2 mode of operation while performing the three processes that comprise traffic shaping: Classification, Prioritization, and Drain.

• Classification of traffic is the basic mechanism by which a packet or frame can be sorted and associated with a particular group or priority. The more flexible a classification engine is, the more likely the high-value services can be protected.

• Prioritization of traffic is a method of assigning various value levels to a particular packet or frame. Prioritization ensures that the packets/frames are “ordered” in such a manner that the highest level of protection is provided to the most valuable traffic.

• Drain – Once the packets or frames are classified and prioritized, it needs to be determined how to drain the traffic. Does your network require you to pass all high-level traffic in a strict priority manner such that lower priority traffic could be “starved” in times of congestion? Or, can determinations be made about the maximum and minimum levels of service you can accept on a per classification basis? The CDM-760 packet processor gives the operator or service provider many options to choose from.

▪ DiffServ – Industry-standard method of providing QoS enabling seamless co-existence in networks that implement DiffServ
▪ Max/Priority – Provides traffic prioritization with the ability to limit maximum traffic per priority class
▪ Min/Max – Provides a Committed Information Rate (CIR) to each class of traffic with the ability to allow a higher burstable rate depending on availability

▪ Max/Priority with Weighting Mode
o Weights have applied all queues that have not reached their max BW limit
o Once the max BW is reached, the scheduler will not drain any more data irrespective of its weights

▪ Min/MAX with Weighting Mode
o First serves the minimum BW
o Once the minimum BW is met, the weights are applied until the Max BW is met
o Once the max BW is met, the scheduler will not drain any more data

Classification	Prioritization	Drain
DiffServ	Up to 8 different levels of prioritization	DiffServ
MPLS	Weighting can be enabled per level	Max / Priority
VLAN		Min / Max
Protocol		Max / Priority with Weighting
Source IP Address		Min / Max with Weighting
Destination IP Address
Source Port
Destination Port

Layer 3 Routed Mode

In some cases, it may be desirable to function in a layer 3 routed mode of operation. The packet processor can be configured to run as a layer 3 device with static routing. The packet processor can have up to 256 static routes based on the destination IP address mask. The packet processor in layer 3 routed mode can support >105,000 PPS simplex or >150,000 PPS duplex.

Symbol Rate Range	100 Ksps to 150 Msps (Simplex) in 1 sps steps (modulation dependent over 64APSK)
Modulation Type	DVB-S2/S2X: ETSI EN 302 307 / 302 307-2 compliant DVB-S2-EB1&EB2: DVB-S2 with Efficiency Boost technology
FECFrame	Normal (64,800 bits) or Short (16,200 bits)
Pilots	On or off
Alpha (Rolloff)	DVB-S2 and EB1: 20%, 25%, or 35% DVB-S2X and EB2: 5%, 10%, 15%, 20%, 25%, 35%
Management	Front panel keypad/display RS-232 /485, or 10/100Base-T with SNMP, Telnet, HTTP
Reflash	Ethernet management port
Frequency Stability	Internal, stability ± 0.06 ppm
External Reference Input / Output (BNC Female)	Internal, 1, 2, 5, or 10 MHz for IF and data, internally phase locked. Output: off or internal 10 MHz
Form C	Modulator, demodulator, and unit fault
Spectral Sense	Normal and inverted
Configuration Retention	Non-volatile memory; Returns upon power up

Options

Type	Option
FAST	DVB-S2X with DVB-S2-EB1 & EB2
FAST	Symbol rate options
FAST & Hardware	Carrier-in-Carrier options
FAST & Hardware	Packet Processor (Can not be installed with any PIIC data interface cards)
FAST & Hardware	K4 GZIP lossless compression
FAST	ACM point-to-point client / controller
FAST	DPD (Dynamic Pre-Distortion) 20 Msps – 63 Msps
FAST	Optical Gigbit Ethernet enable
FAST	PIIC optional interface cards: ASI (DVB Asynchronous Serial Interface) G.703 E3/T3/STS-1 (34.368, 44.736, 51.84 Mbps) STM-1 Copper SDH (155.52 Mbps) OC-3 SONET single mode or multi-mode 1300 nm (155.52 Mbps)
Hardware	Rack slides

Modulator (Dual IF)

70/140 MHz	50 to 180 MHz in 100 Hz steps
Impedance / Connector	75 Ω, BNC female. Return loss ≥ 18 dB
Output Power	0 to -25 dBm, 0.1 dB steps (70/140 MHz)
Power Accuracy	± 0.5 dB of nominal at 25C; Within ± 0.5 dB from 25C value at the same frequency
L-Band	950 to 2150 MHz in 100 Hz steps
Impedance / Connector	50 Ω, Type N female. Return loss ≥ 15 dB
Output Power	0 to -40 dBm, 0.1 dB steps
Power Accuracy	± 0.5 dB of nominal at 25C ± 0.5 dB from 25C value at same frequency
L-Band Monitor	Same as L-Band or 900 + 70/140 MHz IF at -27 dBm ± 3 dB
Harmonics and Spurs	< 60 dBc/4kHz, modulated carrier; Excludes spectral mask area
External TX Carrier Off	TTL low signal
Quadrature Phase Error and Amplitude Imbalance	Sideband 35 dB below unmodulated carrier

Demodulator (Dual IF)

70/140 MHz	50 to 180 MHz in 100 Hz steps
Impedance / Connector	75 , BNC female. Return loss 15 dB min.
Input Power	Desired carrier: Min. = -58 + 10Log (SRMSPS) dBm Max. = -23 + 10Log (SRMSPS) dBm or +10 dBm whichever is less.
Max. Composite Power	+20 dBm or = 14 + 10Log (180 / SRMSPS) dBc (whichever is less)
L-Band	950 to 2150 in 100 Hz steps
Impedance / Connector	50 Ω, Type N female. Return loss 10 dB min.
Input Power	Desired carrier: Min. = -70 + 10Log (SRMSPS)dBm Max. = -20 + 10Log (SRMSPS) dBm or +20 dBm whichever is less.
Maximum Composite	+20 dBm or = 43 – 10Log (SRMSPS) dBc (whichever is less)

Doubletalk Carrier-In-Carrier

Symbol Rate Range	1 Msps to 63 Msps in 1sps steps
Delay Range	0 to 300 ms (factory default 230 – 290 ms)
CnC Ratio	+7 dB to -7 dB interferer to desired
Es/No degradation (dB) measured at 0.0 dB CnC Ratio	QPSK: 0.3 dB 8PSK: 0.3 dB 16APSK: 0.4 dB 32APSK: 0.5 dB 64APSK: 0.6 dB 128APSK: 0.7 dB 256APSK: 0.8 dB
Symbol Rate Ratio	Max 3:1 TX/RX or RX/TX
Satellite Configuration	Transmit station sees own carrier. Non- processing satellite.

Base Unit Connectors

Alarm Connector (DB-15 Male)	Form C: TX, RX and unit faults External TX carrier off IQ test point
Unit Management	DB-9 male with RS-232 and RS-485 2- wire / 4-wire RJ-45 Ethernet (maximum Ethernet packet size 1536 bytes including Ethernet header & CRC)
TX & RX IF Connectors	BNC female (70/140 MHz) Type-N female (L-Band)
L-Band Monitor	SMA female
Ethernet Data Interfaces on main modem (Non-Packet Processor)	2 x RJ-45 10/100/1000Base-T Ethernet 1 x Optical Gibabit Ethernet (optional) Note: All Data GigE interfaces support super jumbo frames with a maximum Ethernet frame size of 10,240 bytes including Ethernet header & CRC
Packet Processor Interface	4 x RJ-45 10/100/1000Base-T Ethernet interface (User Traffic), 1 x RJ11 (CLI serial), 1 x 10/100/1000Base-T Ethernet interface (Management) Note: Cannot use any PIIC interfaces cards if Packet Processor is installed. Packet processor card will support super jumbo frames with a maximum Ethernet frame size of 9,000 bytes including Ethernet header & CRC

Test Functions

Data Test Pattern	2^10-1, 2^15-1, 2^23-1 compatible with BERT on TX data on applicable interfaces
CW	Modulation disabled and CW signal is transmitted
SSB Carrier	Provides suppressed carrier and suppressed sideband
Loopback	Full-duplex only

Environmental & Physical

Temperature Operating Storage	0 to 50C (32 to 122F) -40 to 70C (-40 to 158F)
Humidity	95% maximum, non-condensing
Power Supply input	100-240 VAC 50/60 Hz 43-60 VDC (48 VDC option)
Power Consumption 120 VAC at 60 Hz 230 VAC at 50 Hz 48 VDC	88 W, 93 VA typical 88 W, 133 VA typical 85 W typical
Dimensions (1RU) (height x width x depth)	1.75” x 19” x 18.65” (48 x 47.4 x 4.4 cm)
Weight	15 lbs (6.8 kg)
AC Receptacles	Includes restraint for standard IEC-320 inlet
Agency Compliance	CE Mark and FCC part 15

Accessories

Type	Option
1:1 Modem Redundancy	CRS-170A (L-Band), CRS-180 (70/140 MHz)
1:N Modem Redundancy	CRS-500 70/140 MHz or L-Band (Only for use with 10/100/1000Base-T or G.703 T3/E3/STS-1 interfaces)