VSATplus Product Website

Comtech EF Data CDM-760 Advanced High-Speed Trunking Modem


  • Symbol Rate: 0.1 to 150 Msps
  • Data Rate: 0.1 to 314 Mbps
  • DVB-S2 ETSI EN 302 307 compliant
  • DVB-S2-EB1 Efficiency Boost technology DoubleTalk Carrier-in-Carrier bandwidth compression
  • ACM and CCM
  • GSE – low overhead <1% encapsulation
  • Super Jumbo Frame 10,240 Byte Support
  • Modulation: QPSK, 8PSK, 16APSK, 32APSK
  • Dual IF: 70/140 MHz, L-Band and L-Band monitor (standard)
  • 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
    • 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)
  • Management: HTTP, SNMP, Telnet, RS 232/485
  • In-band (over satellite) M&C control
  • 1:1 and 1:N redundancy switching available


*Note: Contact our Sales Engineer for information on Configuration and Pre-Sale Pricing.

The CDM-760 offers an expansive range of symbol rates (1 ksps to 150 Msps) and data rates (100 kbps to 314 Mbps). Run in a duplex setting, this is a staggering 628 Mbps or 300 Msps. Coupling these speeds with the native Super Jumbo Frame Ethernet interfaces supporting Ethernet frames from 64 Bytes to >10,000 Bytes and the CDM-760 will process Ethernet frames at a blazing (> 1.2 Million packets / second).

TYPICAL USERSMobile OperatorsTelecom OperatorsISPsGovernment & MilitaryCOMMON APPLICATIONSIP TrunkingG.703 TrunkingHigh-Speed Content DeliveryDisaster Recovery & Emergency Communications

Expanding on the efficient DVB-S2 EN 302 307 standard, the CDM-760 again furthers spectral efficiency with its DVB-S2-EB1 (Efficiency Boost) waveforms. DVB-S2 is widely accepted as the most spectrally efficient standards-based waveforms. With our Efficiency Boost technology (DVB-S2-EB1), you can achieve a 10% – 35% increase in efficiency over the DVB-S2 standard without an increase in power or occupied bandwidth. The CDM-760 accomplishes this task by virtually doubling the number of available MODCODs, introducing three new ROF figures (5%, 10% and 15%) and minimizing implementation loss to near theoretical operation. The CDM-760 is software upgradeable to support future standards including DVB-S2 Efficiency Boost, DVB-S2 Extension and DVB-S3.

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 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.

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 and telco operator. When used in combination, however, the savings are astronomical. 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.


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.

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 efficiency, DoubleTalk Carrier-in-Carrier utilizing advanced signal processing techniques provides a new dimension in bandwidth and power efficiency.

DoubleTalk Carrier-in-Carrier allows satellite users to achieve spectral efficiencies (i.e. bps/Hz) that cannot be achieved with traditional links. E.g., DoubleTalk Carrier-in-Carrier when used with 16-QAM approaches the bandwidth efficiency of 256-QAM (8bps/Hz).

As DoubleTalk Carrier-in-Carrier allows equivalent spectral efficiency using a lower order Modulation and/or FEC Code, it can simultaneously reduce CAPEX by allowing a smaller BUC/HPA and/or antenna.

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.

Symbol Rate RangeDVB-S2: 100 Ksps to 150 Msps in 1 sps steps (modulation dependent)
DVB-S2-EB1: 100 Ksps to 150 Msps in 1 sps steps (modulation dependent)
Modulation TypeDVB-S2: ETSI EN 302 307 compliant
DVB-S2-EB1: DVB-S2 with Efficiency Boost technology
FEC FrameNormal (64,800 bits) or Short (16,200 bits)
PilotsOn or off
Alpha (Rolloff)DVB Compliant: 20%, 25% or 35%
Comtech Efficiency Boost DVB-S2-EB1: 5%, 10%, 15%, 20%, 25%, 35%
ManagementFront panel keypad / display RS-232 /485, or 10/100Base-T with SNMP, Telnet, HTTP
ReflashEthernet management port
Frequency StabilityInternal, 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 CModulator, demodulator and unit fault
Spectral SenseNormal and inverted
Configuration RetentionNon-volatile memory; Returns upon power up
FASTSymbol rate options
FAST & HardwareCarrier-in-Carrier options
FAST & HardwareK4 GZIP lossless compression
FASTACM point to point client / controller
FASTOptical Gigbit Ethernet enable
HardwarePIIC optional interface cards 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)
HardwareRack slides
Modulator (Dual IF)
70/140 MHz50 to 180 MHz in 100 Hz steps
Impedance / Connector75 Ω, BNC female. Return loss ≥ 18 dB
Output Power0 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 same frequency
L-Band950 to 2150 MHz in 100 Hz steps
Impedance / Connector50 Ω, Type N female. Return loss ≥ 15 dB
Output Power0 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 MonitorSame 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 OffTTL low signal
Quadrature Phase Error and Amplitude ImbalanceSideband 35 dB below unmodulated carrier
Demodulator (Dual IF)
70/140 MHz50 to 180 MHz in 100 Hz steps
Impedance / Connector75 Ω, BNC female. Return loss 15 dB min.
Input PowerDesired carrier: Min. = -118 + 10Log(SR in Msps) dBm.
Max. = -83 + 10Log(SR in Msps) dBm or +10 dBm whichever is less.
Max. Composite Power+20 dBm or = 14 + 10Log (180 / SRMSPS) dBc (whichever is less)
L-Band950 to 2150 in 100 Hz steps
Impedance / Connector50 Ω, Type N female. Return loss 10 dB min.
Input PowerDesired carrier: Min. = -130 + 10Log(SR in Msps) dBm.
Max. = -80 + 10Log(SR in Msps) 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 Range1 Msps to 63 Msps in 1sps steps
Delay Range0 to 400 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 RatioQPSK: 0.3 dB
8PSK: 0.3 dB
16APSK: 0.6 dB 32APSK: 1.0 dB
Symbol Rate RatioMax 3:1 TX/RX or RX/TX
Satellite ConfigurationTransmit 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 ManagementDB-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 ConnectorsBNC female (70/140 MHz)
Type-N female (L-Band)
L-Band MonitorSMA female
Ethernet Data Interfaces2 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
Test Functions
Data Test Pattern2^10-1, 2^15-1, 2^23-1 compatible with BERT on TX data on applicable interfaces
CWModulation disabled and CW signal is transmitted
SSB CarrierProvides suppressed carrier and suppressed sideband
LoopbackFull-duplex only
Environmental and Physical

0 to 50°C (32 to 122°F)
-40 to 70°C (-40 to 158°F)
Humidity95% maximum, non-condensing
Power Supply Input100 to 240 AC 50/60 Hz
Power Consumption
    120 VAC at 60 Hz
    230 VAC at 50 Hz

88 W, 93 VA typical
88 W, 133 VA typical
Dimensions (1RU) (height x width x depth)1.75” x 19” x 18.65” (48 x 47.4 x 4.4 cm)
Weight15 lbs (6.8 kg)
AC ReceptaclesIncludes restraint for standard IEC-320 inlet
Agency ComplianceCE Mark and FCC part 15
1:1 Modem RedundancyCRS-170A (L-Band), CRS-180 (70/140 MHz)
1:N Modem RedundancyCRS-500 70/140 MHz or L-Band (Only for use with 10/100/1000Base-T or G.703 T3/E3/STS-1 interfaces)

Comtech EF Data CDM-760 Advanced High-Speed Trunking Modem

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.