VSATplus Product Website

Comtech EF Data CDM-570A/L & CDM-570A/L-IP Satellite Modems


  • DoubleTalk Carrier-in-Carrier bandwidth compression
  • VersaFEC low latency LDPC (Constant Coding & Modulation Mode)
  • 5%, 10%, 15%, 20%, 25% and 35% Transmit Filter Rolloff
  • Data rate range from 2.4 kbps to 10.239 Mbps
  • CDM-570A: 50 to 90 or 100 to 180 MHz IF range CDM-570AL: 950 to 2250 MHz IF range
  • Modulation types: BPSK, QPSK, OQPSK, 8PSK, 8-QAM, 16-QAM
  • Forward Error Correction (FEC) choices include VersaFEC, Turbo Product Code (TPC), Viterbi, Reed-Solomon, and Trellis Coded Modulation (TCM)
  • Data Interfaces: EIA-422/530, V.35, G.703 T1/E1, sync EIA-232
  • Standards based management via SNMP, Web, or Telnet
  • G.703 clock extension
  • Automatic Uplink Power Control (AUPC)
  • Embedded Distant-end Monitor and Control (EDMAC/EDMAC2)
  • 1:1 and 1:N Redundancy options
  • CDM-570A: FSK communications to CSAT-5060 or KST-2000A
  • CDM-570AL: 10 MHz reference for BUC, FSK communications and optional BUC power supply
  • CDM-570AL: 10 MHz reference and power supply for LNB


The CDM-570A and the CDM-570AL are Comtech’s next generation satellite modems that provide industry-leading performance and flexibility in a 1 RU package at a very competitive price. With support for VersaFEC® low latency LDPC Forward Error Correction (FEC), the revolutionary DoubleTalk® Carrier-in-Carrier® bandwidth compression, and optimized transmit filter rolloffs, the CDM-570A and CDM-570AL provide significant 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 resources
  • Minimize capital expenses (CAPEX) by allowing a smaller BUC/amplifier and/or antenna
  • Or, a combination to meet specific business needs

The modems are available with 70/140 MHz or L-Band IF and EIA-530/-422, V.35, sync EIA-232 and G.703 T1/E1 data interfaces.


  • Enterprise
  • Internet Service Providers
  • Satellite Service Providers
  • Offshore & Maritime
  • Mobile Operators


  • Enterprise Networks
  • Offshore & Maritime Communications
  • obile Backhaul
  • Communications on-the-Move
  • Disaster Recovery & Emergency Communications
  • Satellite News Gathering


DoubleTalk Carrier-in-Carrier, based on patented “Adaptive Cancellation” technology, allows transmit and receive carriers of a duplex link to share the same transponder bandwidth. 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 efficiency. 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.

As DoubleTalk Carrier-in-Carrier allows equivalent spectral efficiency using a lower order modulation and/or code rate, it can reduce the power required to close the link thereby reducing CAPEX by allowing a smaller BUC/amplifier 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.

When combined with VersaFEC or TPC and optimized transmit filter rolloffs, DoubleTalk Carrier-in-Carrier provides 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/amplifier power requirements.


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 fade while maintaining the Total Composite Power. In addition to automatically compensating for rain fade, CnC-APC also enables the modems to share link margin, i.e. a modem can effectively transfer excess link margin to a distant end modem experiencing fade, thereby further enhancing overall availability.


VersaFEC is a patent-pending system of high-performance LDPC codes designed to provide maximum coding gain while minimizing latency. CDM-570A/L support Constant Coding & Modulation (CCM) mode of operation.

The Ultra Low Latency (ULL) codes provide even lower latency compared to standard VersaFEC codes.


CDM-570A/L support 5%, 10%, 15%, 20%, 25% and 35% transmit filter rolloff allowing users to further optimize the link. Carrier-in-Carrier

combined with VersaFEC and optimized transmit filter rolloffs can provide 50% or more BW savings compared to legacy modems.


The CDM-570A/L-IP has the ability to monitor and control the distant end of a point-to-point satellite link using EDMAC or EDMAC2. User data is framed and bits are added to pass control, status, and AUPC information. This is transparent to the user.


The modems support SNMP, web-based and command line interfaces for management. The modems can also be configured and monitored from the front panel, or through the remote M&C port. Ten complete RF configurations may be stored in the modem. An event log stores alarm and status information in non-volatile RAM, while the link statistics log stores link performance (Eb/No and AUPC performance) for monitoring and reporting purposes.


The FAST codes make it easy to upgrade the modem capability in the field. New features can be added on site, using FAST access codes purchased from Comtech EF Data that can be entered via the front panel.

Comtech EF Data CDM-570A Satellite Modem
Data Rate Range2.4 kbps to 10.239 (depending on modulation, FEC and framing), 1 bps step with fully independent TX and RX rates
Symbol Rate4.8 ksps to 3.0 Msps
Frequency RangeCDM-570A: 50 to 90 or 100 to 180 MHz, 100 Hz resolution
CDM-570AL: 950 to 2250 MHz, 100 Hz resolution
Data InterfacesEIA-422/-530 DCE, V.35 DCE, Sync EIA-232, G.703 T1 balanced, G.703 E1 balanced or unbalanced, 10 / 100BaseT Ethernet (option)
Modulation & FEC OptionsData Rate Range
VersaFEC-2 (Long Block)
BPSK 0.48818.115 kbps to 1.468 Mbps (Minimum 37 ksps)
QPSK 0.489, 0.537, 0.586, 0.611,
0.635, 0.660, 0.684, 0.733
36.230 kbps to 4.397 Mbps(Minimum 37 ksps)
8-ARY 0.521, 0.537, 0.562, 0.586,
0.611, 0.635, 0.660, 0.684, 0.708, 0.733
125.081 kbps to 6.596 Mbps(Minimum 80 ksps)
16-ARY 0.586, 0.611, 0.635, 0.660,
0.684, 0.708, 0.733, 0.757, 0.782
234.527 kbps to 9.381 Mbps(Minimum 100 ksps)
32-ARY 0.660, 0.684, 0.708, 0.733,
0.757, 0.782, 0.801, 0.831, 0.855, 0.879
824.511 kbps to 10.239 Mbps(Minimum 250 ksps)
VersaFEC-2 (Short Block)
BPSK 0.48918.115kbps to 0.489Mbps(Minimum 37 ksps)
QPSK 0.489, 0.537, 0.586, 0.611,
0.635, 0.660, 0.684, 0.733
36.230 kbps to 1.465Mbps(Minimum 37 ksps)
8-ARY 0.521, 0.537, 0.562, 0.586,
0.611, 0.635, 0.660, 0.684, 0.708, 0.733
125.081 kbps to 2 Mbps(Minimum 80 ksps)
16-ARY 0.586, 0.611, 0.635, 0.660,
0.684, 0.708, 0.733, 0.757, 0.782
234.527 kbps to 2 Mbps(Minimum 100 ksps)
32-ARY 0.660, 0.684, 0.708, 0.733,
0.757, 0.782, 0.801, 0.831
824.511 kbps to 2 Mbps(Minimum 250 ksps)
BPSK 0.4882.4 kbps to 1.462 Mbps
QPSK 0.5335.2 kbps to 3.200 Mbps
QPSK 0.6316.1 kbps to 3.785 Mbps
QPSK 0.7066.8 kbps to 4.233 Mbps
QPSK 0.8037.8 kbps to 4.818 Mbps
8-QAM 0.576 (ECCM)8.3 kbps to 5.179 Mbps
8-QAM 0.6429.3 kbps to 5.782 Mbps
8-QAM 0.71110.3 kbps to 6.401 Mbps
8-QAM 0.78011.3 kbps to 7.021 Mbps
16-QAM 0.644 (ECCM)12.4 kbps to 7.726 Mbps
16-QAM 0.73114.1 kbps to 8.776 Mbps
16-QAM 0.78015 .0 kbps 9.361 Mbps
16-QAM 0.82916.0 kbps to 9.946 Mbps
16-QAM 0.85316.4 kbps to 10.239 Mbps
VersaFEC Ultra Low Latency (ULL) Codes
BPSK 0.493 (ULL)2.4 kbps to 1.479 Mbps
QPSK 0.493 (ULL)4.8 kbps to 2.959 Mbps
QPSK 0.654 (ULL)6.3 kbps to 3.923 Mbps
QPSK 0.734 (ULL)7.0 kbps to 4.405 Mbps
BPSK 5/162.4 kbps to 0.937 Mbps
BPSK 21/442.4 kbps to 1.430 Mbps
QPSK/OQPSK 21/444.8 kbps to 2.860 Mbps
QPSK/OQPSK 3/47.2 kbps to 4.500 Mbps
QPSK/OQPSK 7/88.4 kbps to 5.250 Mbps
QPSK/OQPSK 0.959.1 kbps to 5.666 Mbps
8PSK/8-QAM 3/410.8 kbps to 6.750 Mbps
8PSK/8-QAM 7/813.6 kbps to 7.875 Mbps
8PSK/8-QAM 0.9515.3 kbps to 8.500 Mbps
16-QAM 3/414.4 kbps to 9.000 Mbps
16-QAM 7/816.8 kbps to 9.980 Mbps
BPSK 1/22.4 kbps to 1.500 Mbps
QPSK/OQPSK 1/24.8 kbps to 3.000 Mbps
QPSK/OQPSK 3/47.2 kbps to 4.500 Mbps
QPSK/OQPSK 7/88.4 kbps to 5.250 Mbps
Viterbi + Reed Solomon
BPSK 1/22.4 kbps to 1.363 Mbps
QPSK/OQPSK 1/24.3 kbps to 2.727 Mbps
QPSK/OQPSK 3/46.5 kbps to 4.090 Mbps
QPSK/OQPSK 7/87.5 kbps to 4.666 Mbps
16-QAM 3/413.0 kbps to 4.000 Mbps
16-QAM 7/816.8 kbps to 4.666 Mbps
TCM + Reed Solomon
2/3 8PSK TCM (Closed network)8.7 kbps to 4.400 Mbps
Uncoded BPSK4.8 kbps to 3.000 Mbps
Uncoded QPSK/OQPSK9.6 kbps to 5.000 Mbps
ScramblingMode dependent – ITU V.35, or proprietary externally synchronized
M&C InterfaceEthernet 10/100Base-T, EIA-232, EIA-485
Input/Output ImpedanceCDM-570A: matched for 50/75 Ω, 17 dB minimum return loss, BNC connector 
CDM-570AL: transmit and receive 50 Ω, > 17 dB (950 MHz to 2250 MHz) and >19 dB (1000 MHz to 1900 MHz) minimum return loss, female Type N connector
External Reference Input1, 2, 5, or 10 MHz, BNC connector
Form C RelaysTX, RX traffic alarms and unit faults
Frequency Stability (With Internal Reference)

±1 ppm, 0º to 50ºC (32º to 122ºF)
±0.06 ppm, 0º to 50ºC (32º to 122ºF)
Output Power

0 to –25 dBm, 0.1 dB steps 
0 to –40 dBm, 0.1 dB steps

± 0.5 dB over frequency and temperature 
± 1.0 dB over frequency and temperature
Phase Noise 

< 0.75 degrees RMS double-sided, 100 Hz to 1 MHz
< 1.2 degrees RMS double-sided, 100 Hz to 1 MHz
Output Spectrum/ FilteringMeets IESS-308/-309 power spectral mask
Alpha (Rolloff)5%, 10%, 15%, 20%, 25% and 35%
Harmonics and Spurious-60 dBC/4 kHz from 600 to 2600 MHz (L-Band), from 1 to 400 MHz (IF)
Transmit On/Off Ratio55 dB minimum
External TX Carrier OffBy TTL LOW signal, or RTS
TX Clock OptionsInternal (SCT), external (TT), loop timing with symmetric or asymmetric operation (data interface dependent)
Input Power Range

-30 to -60 dBm
-130 + 10 log symbol rate, dBm (minimum)
-90 + 10 log symbol rate, dBm (maximum)
Max Composite Level 

+35 dBc, up to -5 dBm absolute max.
+40 dBc, up to -10 dBm absolute max.
Acquisition Range

± 1 to ± 32 kHz,1 kHz step 
± 1 to ± 32 kHz, 1 kHz step, symbol rate <= 625 ksps
± 1 to ± 200 kHz,1 kHz step, symbol rate > 625 ksps
Acquisition TimeHighly dependent on data rate, FEC rate, and demodulator acquisition range. Example: 120 ms average at 64 kbps, Rate 1/2 QPSK, ± 10 kHz acquisition sweep range, 6dB Eb/No
Plesiochronous/ Doppler Buffer±128, 256, 512, 1024, 2048, 4096, 8192, 16384 or 32768 bits
Receive Clock OptionsBuffer disabled (RX satellite), buffer enabled (symmetric or asymmetric operation) (data interface dependent)
Clock Tracking± 100 ppm minimum
Monitor FunctionsEb/No, frequency offset, BER, buffer fill status, RX signal level
DoubleTalk Carrier-in-Carrier
Delay Range0 to 330 ms
Power Spectral Density Ratio
(Interferer to Desired)
-7 dB to +7 dB
Maximum Symbol Rate Ratio3:1 (TX:RX or RX:TX)
Eb/No Degradation0 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 RestrictionsSatellite in “loop-back” mode (i.e., the transmit station can receive itself) “Non-processing” satellite (i.e., does not demodulate or remodulate the signal)
Low-Noise Block Converter(LNB) Support
LNB Voltage13 and18 VDC
LNB Reference10 MHz via RX center conductor
Block Up Converter (BUC) Support
BUC Voltage24 VDC, 90 W @ 50°C, 100 W @ 30°C 
(internally fitted option) 
48 VDC, 150 W @ 50°C, 180 W @ 30°C 
(internally fitted option, not available with -24 VDC input)
BUC Reference10 MHz via TX center conductor
FSK SupportVia TX center conductor with FSK BUCs
Environmental & Physical

0 to 50°C (32 to 122°F)
-25 to 85°C (-13 to 185°F)
Power Supply100 to 240 VAC, 50/60 Hz 
-24 VDC (HW option) 
-48 VDC (HW option)
Power ConsumptionCDM-570A: 29 W typical (32 W max.) 
CDM-570AL: 29 W typical (32 W max.) w/o BUC
(height x width x depth)
CDM-570A: 1.75” x 19” x 13” (4.4 x 48.3 x 330 cm) 
CDM-570AL: 1.75” x 19” x 16” (4.4 x 48.3 x 40.6 cm)
WeightCDM-570A: 5 lbs (2.3 kg) 
CDM-570AL: 7 lbs (3.2 kg) (without BUC P/S) 
CDM-570AL: 16 lbs (7.2 kg) including 150 W BUC power supply
Operations & Maintenance
Configuration and ManagementFront panel 
Remote port – EIA-232 or EIA-485 (2- or 4-wire) 
SNMP with MIB II and private, modem-specific MIB 
Web browser (HTTP)
Software/firmware upgrade via FTP
Faults and alarms
Configuration backup and restoral
Password protection for web, ftp and telnet
Access list
CE MarkEN 301 489-1 (ERM) 
EN55022 (Emissions) 
EN55024 (Immunity) 
EN 61000‐3‐2 
EN 61000‐3‐3 
EN60950 (Safety)
FCCFCC Part 15, Subpart B

Comtech EF Data CDM-570A/L Satellite Modem

Comtech EF Data CDM-570A/L-IPEN Satellite 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 )

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.