1. CDM-Qx/QxL Satellite Modem with DoubleTalkTM Carrier-in-Carrier®
The Most Bandwidth Efficient Modem Ever !
March 2007

2. Agenda DoubleTalk Carrier-in-Carrier Overview
Business Case - Why use CDM-Qx/QxL with DoubleTalk Carrier-in-Carrier ?
CDM-Qx/QxL Overview
Architecture
Features
Configuration
DoubleTalk is a Trademark of Applied Signal Technology
Carrier-in-Carrier is a Registered Trademark of Comtech EF Data
All specifications are subject to change without notice.

3. SATCOM Optimization
Satellite Communication (SATCOM) users have always been confronted with power and bandwidth tradeoffs to achieve maximum efficiency
Now Comtech EF Data introduces a new product and a new technology that adds a new dimension to SATCOM optimization
CDM-Qx with DoubleTalk Carrier-in-Carrier is the most bandwidth and power efficient satellite modem available commercially

4. Optimize SATCOM
CDM-Qx/QxL with DoubleTalk Carrier-in-Carrier makes it possible to optimize satellite communications in multiple ways
Reduce OPEX
Reduce CAPEX
Increase throughput
Increase link availability
Reduce rack space

5. DoubleTalk Carrier-in-Carrier
Without DoubleTalk Carrier-in-Carrier
Based on Applied Signal Technology’s (APSG) DoubleTalk™ bandwidth compression system
Uses patented “Adaptive Cancellation”
Allows full duplex satellite links to transmit concurrently in the same segment of transponder bandwidth
Comtech EF Data licensed the technology from APSG, and after integrating it with CDM-Qx, is offering it as DoubleTalk Carrier-in-Carrier
Delivers unprecedented operating expense savings when combined with Comtech EF Data’s advanced Forward Error Correction and Modulation techniques
With DoubleTalk Carrier-in-Carrier

6. DoubleTalk Carrier-in-Carrier Theory of Operation

7. Theory of Operation (cont’d)
At start-up, the exact round-trip delay is calculated
The modulator provides a copy of the time delayed transmitted signal to the demodulator
The demodulator “cancels” the time delayed transmitted signal from the composite received signal
Nominal cancellation is 25 dB to 30 dB
The residual interfering signal appears as noise
i.e. the Noise Floor is raised, slightly degrading the Eb/No

8. Eb/No Degradation - QPSK
Very low degradation when using QPSK

9. Eb/No Degradation – 8-PSK
Low degradation except for TPC, Rate 17/18

10. Eb/No Degradation – 16-QAM
Low degradation for TPC, Rate 3/4

11. DoubleTalk Carrier-in-Carrier Operational Rules
Full-duplex links only
CDM-Qx must be configured as a “Modem”
“Loop-back” satellite (i.e. the transmitting station must be able to receive itself)
“Non-processing” satellite (i.e. does not demodulate/ remodulate the signal)
Symbol rate asymmetry of the 2 carriers should be within 3:1 for optimal performance
(Interfering carrier power – desired carrier power), in dB, < 10 dB (except for 16QAM, R=7/8)
Carrier offset within ±32 kHz
i.e., Center frequencies of the desired and the interfering carriers are within ±32 kHz

12. Bandwidth Limited vs. Power Limited Links
DoubleTalk Carrier-in-Carrier provides a mechanism to trade bandwidth and power
Contrary to intuition, DoubleTalk Carrier-in-Carrier can be used to achieve bandwidth and power savings in Bandwidth Limited as well as Power Limited scenarios
Recover power by using a lower order modulation & FEC
This increases the occupied bandwidth
Use DoubleTalk Carrier-in-Carrier to reduce occupied bandwidth

13. How To Use DoubleTalk Carrier-in-Carrier

14. CAPEX Reduction
Carrier spreading combined with DoubleTalk Carrier-in-Carrier allows CDM-Qx to achieve equivalent spectral efficiency (i.e. bps/Hz) using a lower order Modulation and/or FEC Code compared to any other modem
This translates into
Smaller BUC/HPA size
Smaller antenna size
This is in addition to monthly leased bandwidth savings

15. Customer Example 1 C-band 13 m to 9.15 m
Original Link is Bandwidth Limited 

16. Customer Example 1 (cont’d)
With DoubleTalk Carrier-in-Carrier
Still Bandwidth Limited

17. Customer Example 2 Ku-band 5.6 m to 2.4 m
Original Link is Power Limited

18. Customer Example 2 (cont’d)
Lets add DoubleTalk Carrier-in-Carrier without making any other change
Leased Bandwidth increases to 8.48% from 7.22%
Transmit Flange also increases
This DID NOT HELP

19. Customer Example 2 (cont’d)
Now use spreading along with DoubleTalk Carrier-in-Carrier

20. Customer Example 3 – Cellular Backhaul
Network
26 x E1 full duplex links
99.95% availability
Hub
7.2 m antenna
26 Remote sites
3.7 m antenna
C-Band Satellite
EIRP: 37.5 dBW
SFD: -84 dBW/m2
G/T: -4 dB/K
$3,000 / MHz / month
Conventional Link
Hub to Remote
QPSK, TPC R=7/8
Remote to Hub
8PSK, TPC R=7/8
DoubleTalk Carrier-in-Carrier Links
Mix of QPSK, TPC R=3/4 & QPSK, TPC R=7/8

21. Customer Example 3 – Cellular Backhaul (cont’d)
Leased bandwidth (OPEX)
Conventional Link
66 MHz
$198K per month
CDM-Qx with DoubleTalk Carrier-in-Carrier
44 MHz
$132K per month
Monthly savings ~ $66K
CAPEX
Modem price
~ $4.5K additional per CDM-Qx
~ $234K total additional CAPEX
Remote BUC
~ $6K saving per remote site when using CDM-Qx
~ $156K total saving
Hub SSPA
1000W HPA at Hub in both cases
Total CAPEX difference
~ $78K additional CAPEX in a 27 node network with total CAPEX of over $1 million
Payback ~ 1.2 month
Over $790K Annual Savings Thereafter

22. Customer Example 4 – Cellular Backhaul
Hub-Spoke network with E1 links
7.2 m Antenna at Hub
3.7 m Antenna at Remote
C-Band satellite
EIRP: 36 dBW
SFD: -85 dBW/m2
G/T: -2 dB/K
BER: 1.0E-07

23. Customer Example 4 – Cellular Backhaul (cont’d)
Conventional Link
Hub to Remote: QPSK, TPC R=7/8
Allocated BW – 1521 kHz
Power Equivalent Bandwidth (PEB) – 900 kHz
Transmit Flange – 2 W
Remote to Hub: 16QAM, TPC R=7/8
Allocated BW – 761 kHz
Power Equivalent Bandwidth – 1396 kHz
Transmit Flange – 12 W
Requires 40W HPA/BUC
Total
Allocated BW – 2282 kHz
Power Equivalent BW – 2296 kHz
Leased Bandwidth – 2296 kHz
Link is Power Limited
With DoubleTalk Carrier-in-Carrier
Hub to Remote: QPSK, TPC R=7/8
Allocated BW – 1521 kHz
Power Equivalent Bandwidth (PEB) – 1027 kHz
Transmit Flange – 2.3 W
Remote to Hub: QPSK, TPC R=7/8
Power Equivalent Bandwidth – 325 kHz
Transmit Flange – 2.7 W
Requires Only 5W HPA/BUC
Total
Power Equivalent BW – 1352 kHz
Leased Bandwidth – 1521 kHz
Link is Bandwidth Limited

24. Customer Example 4 – Cellular Backhaul (cont’d)
Conclusions
Leased bandwidth savings of 775 kHz (34%)
The new link being BW limited, has enough additional transponder power
to provide additional link margin of 0.5 dB in each direction
or improve BER from 1.0E-07 to better than 1.0E-09
Remote HPA/BUC size reduction from 40W to 5W
Insignificant increase in Tx at Hub

25. Is DoubleTalk Carrier-in-Carrier Always The Best Solution ?
Greenfield installations
Generally with savings from BUC/HPA size reduction, and possible Antenna Size reduction, CDM-Qx with DoubleTalk Carrier-in-Carrier can pay for itself in as little as 0 – 3 months
Existing links that reuse BUC/HPA and Antenna
At T1/E1 rates and above, the payback period for modem replacement is generally within 6 months
Even at lower data rates, the payback period is generally within 6 – 12 months
Continues to provide significant OPEX savings after that

26. Typical Applications Cellular backhaul High speed trunking
Offshore communications
Limited rack space installations

27. CDM-Qx Overview Modular multi-channel satellite modem in 1 RU chassis
DoubleTalk Carrier-in-Carrier bandwidth compression
Data rates up to 20 Mbps
Viterbi, Concatenated Reed Solomon and 2nd generation Turbo Product Codes (TPC)
70/140 MHz or L-Band IF
EIA-422, Sync EIA-232, V.35, HSSI, G.703 (T1/E1) and Quad-E1 data interface
D&I++ for G.703 E1 & Quad-E1
Legacy and Standards based monitoring & control
External & Limited Internal redundancy options

28. Architecture A CDM-Qx consists of:
A chassis
1 RU size
4-slots per chassis, each capable of holding a modulator or a demodulator card
Power supply
M&C board with EIA-232/485 and 10/100BaseT Ethernet port
Tx IF, Rx IF and Ref
Combination of Modulator and/or Demodulator cards
Data interface
Optional TPC encoder/decoder
Power Supply
Digital & IF
Backplanes
M&C
4 Slots
Modulator
IF Interface
Note: Quad-E1 requires 2 chassis slots

29. CDM-Qx Chassis Valid Configurations (per Chassis) are
1 to 4 Modulators
1 to 4 Demodulators
1 Modem
2 Modems in 1:1 configuration (i.e. only 1 modem is online at a time)
DoubleTalk Carrier-in-Carrier license (option)
CDM-Qx: 50 to 90, 100 to 180 MHz
75 ohm, BNC
50 ohm, BNC (option)
CDM-QxL: 950 to 1950 MHz
50 ohm, Type-N Female
Primary power supply
VAC or –48 VDC
BUC Power Supply option (CDM-QxL)
Internal redundancy options for modulator and/or demodulator card

30. DoubleTalk Carrier-in-Carrier Licensing
Must be configured as a Modem
Requires 1 license per Modem
Available tiers
Up to 512 kbps
Up to 1 Mbps
Up to 2.5 Mbps
Up to 5 Mbps
Up to 10 Mbps
Up to 20 Mbps
Note: Minimum is 128 ksps for all tiers

31. Special Licensing Rules - 1:1 Internal Redundancy
Even when a chassis is configured for 1:1 internal modem redundancy, 2 licenses are required
Max Data Rate Required (kbps)
Online Modem License
Backup Modem License
512 kbps
1 Mbps
2.5 Mbps
5 Mbps
10 Mbps
20 Mbps

32. Demo Mode
The CDM-Qx supports a Demo Mode which allows users to test the DoubleTalk Carrier-in-Carrier capability
In the Demo Mode, DoubleTalk Carrier-in-Carrier can be used for up to 45 days
The 45 day countdown timer can be turned ON and OFF as many times as needed
Up to 10 Mbps operation on 1st Modem
Up to 2.5 Mbps operation on the 2nd Modem
Up to 10 Mbps operation if used in a 1:1 Internally Redundant configuration

33. Modulator/Demodulator
Separate card for Modulator and Demodulator
L-band or 70/140 MHz
Cannot mix-and-match in a chassis
Transmit/Receive data rate
Up to 5 Mbps (standard)
Up to 10 Mbps (FAST option)
Up to 20 Mbps (FAST option)
Independently selectable for each Modulator/Demodulator
Modulation/Demodulation
BPSK, QPSK (standard)
8-PSK (FAST option)
16-QAM (FAST option)

34. Modulator/Demodulator (cont’d)
FEC Encoding/Decoding
Viterbi (standard)
Concatenated Reed-Solomon (standard)
Comtech (220, 200)
EF Data Closed (225, 205)
IESS-310 8PSK/TCM (219, 201)
2nd Gen TPC Encoder/Decoder card (hardware option)
Up to 5 Mbps (included with hardware)
Up to 10 Mbps (FAST option)
Up to 20 Mbps (FAST option)
Each Modulator or Demodulator requires a separate 2nd Gen TPC Encoder/Decoder card
Independently selectable for each Modulator/Demodulator

35. Modulator/Demodulator (cont’d)
Data interface (hardware selection)
EIA-422/232/V.35 (D25)
EIA-422 up to 12 Mbps
V.35 up to 12 Mbps
HSSI
Up to 20 Mbps
G.703 T1/E1 Balanced (D15)
G.703 T1/E1 Unbalanced (BNC)
Select one per Modem (i.e. Modulator and Demodulator card combination) OR one per Modulator card and Demodulator card if using independently
In case of “Modem”, only the Demodulator card requires an interface

36. Enhanced D&I++ Available with G.703 E1 data interface
Supported for E1-CCS only
Any combination of 1 to 31 time slots can be selected
Simultaneous use of EDMAC and AUPC
Low overhead
2.2% including EDMAC and AUPC
Interoperable with CDM-600/CDM-600L
For up to 24 slots
Viterbi and TPC FEC only

37. Quad E1 Interface (QDI)
Quad-E1 interface aggregates up to 4 full and/or fractional E1’s into a single satellite carrier
Eliminates multi-carrier backoff for HPA/BUC
Generally 50% or more reduction in HPA/BUC size
Reduction in number of modems required
Reduction in rack space
Quad-E1 Module
RJ-45 connector for each E1 (balanced)
Requires 2 slots in the chassis
The other 2 slots must be occupied by a “modem”

38. Quad-E1 Interface (QDI) (cont’d)
Independent D&I++ For Each E1
Allows for Dropping or Inserting any combination of 1 to 31 Time Slots on each E1
Aggregate, 1 to 128 Time Slots
E1-CCS only
Very Low Overhead – 0.4%
EDMAC/AUPC overhead is additional (if used)
Extremely efficient compared to 6.67% required by IBS
Clocking/Synchronization
All 4 E1 must have same clock source
QDI only interoperates with another QDI at the other end

39. FEC, Modulation & Data Rate Summary (Unframed Operation)

40. EDMAC and AUPC Embedded Distant End Monitoring & Control
Supports EDMAC and EDMAC-2 framing
EDMAC
Interoperable with CDM-600/CDM-600L and CDM-570/CDM-570L
EDMAC-2
Interoperable with CDM-570/CDM-570L
Automatic Uplink Power Control
Interoperable with CDM-600/CDM-600L (EDMAC framing)
Interoperable with CDM-570/CDM-570L (EDMAC or EDMAC-2 framing)

41. Internal Redundancy For Modulator/Demodulator Card(s)
CDM-Qx can provide redundancy for modulator and/or demodulator card(s) within the chassis without requiring an external switch
1:1 Redundancy for Modulator & Demodulator card when configured as a Modem
1:1, 1:2 or 1:3 Redundancy when using Modulators Only or Demodulators Only
It ONLY protects against a failure in the modulator and/or demodulator card
No protection against failures in Data Interface, M&C module or other common sub-systems in the chassis
For critical links, use of external redundancy is strongly recommended

42. Management CDM-Qx can be managed through Modem front panel
Menu driven, easy to operate, user interface via keypad and display
Nested menus provide access to all M&C functions
Remote M&C port
EIA-232 or EIA-485 operation
Remote commands provide access to all M&C functions
10/100BaseT Ethernet port
Configuration and management using TCP/IP based protocols
SNMP
Web browser (http)
telnet
Access to all M&C functions

43. M&C Screens (Web Based)
Modem configuration

44. M&C Screens (Web Based)
Modulator & Demodulator configuration

45. Spectrum Analyzer Function
One of the demodulators can be used to view the spectrum or the constellation map
While in this mode, the demodulator is not available for user data
Available through a stand alone MS Windows application or a web browser
Windows application can be downloaded from Comtech EF Data’s web site

46. Spectrum Analyzer (Windows App)

47. Spectrum Analyzer (Web Based)

48. Additional Features Rolloff (a) External Redundancy Options
20% and 35%
20% rolloff can reduce carrier spacing to 1.1 x Symbol Rate, however it is more susceptible to link impairments compared to 35% Rolloff
External Redundancy Options
1:10 redundancy switch
CRS-300-Qx
1:1 redundancy switch (April ‘07)
CRS-311-Qx

49. Configuration Example 1
CDM-Qx with DoubleTalk Carrier-in-Carrier to support 1 T1
Chassis – 1
DoubleTalk Carrier-in-Carrier license – 128 ksps to 2.5 Mbps
Modulator – 1
8-PSK Modulation (if needed)
2nd Gen TPC encoder up to 5 Mbps
Demodulator – 1
8-PSK Demodulation (if needed)
2nd Gen TPC decoder up to 5 Mbps
G.703 T1 Interface – 1

50. Configuration Example 2
CDM-Qx with DoubleTalk Carrier-in-Carrier to support 4 E1
Chassis – 1
DoubleTalk Carrier-in-Carrier license – 128 ksps to 10 Mbps
Modulator – 1
8-PSK Modulation (if needed)
2nd Gen TPC encoder up to 10 Mbps
Demodulator – 1
8-PSK Demodulation (if needed)
2nd Gen TPC decoder up to 10 Mbps
Quad E1 Data Interface – 1

51. Configuration Example 3
CDM-Qx with DoubleTalk Carrier-in-Carrier to support 20 Mbps full-duplex, 1:1 internally redundant
Chassis – 1
DoubleTalk Carrier-in-Carrier license – 128 ksps to 20 Mbps (online)
DoubleTalk Carrier-in-Carrier license – 128 ksps to 2.5 Mbps (backup)
1:1 redundancy
Modulator – 2, each with
8-PSK/16QAM Modulation (if needed)
2nd Gen TPC encoder up to 20 Mbps
Data rate up to 20 Mbps
Demodulator – 2, each with
8-PSK/16QAM Demodulation (if needed)
2nd Gen TPC decoder up to 20 Mbps
HSSI interface – 1

52. Conclusions CDM-Qx with DoubleTalk Carrier-in-Carrier can
Reduce OPEX
Reduce CAPEX
Increase link availability (i.e. margin)
Increase throughput
Typical payback period of 0 to 3 months
Significant OPEX savings there after

53. Modem Accessories
Variety of accessories to enhance the functionality of our satellite modems
1:1 and 1:N Redundancy Switches – Provides fully automatic or manual protection of circuits
Performance Enhancement Proxies – Accelerates the TCP traffic over impaired satellite links
Comtech Monitor & Control System – Provides management of Comtech EF Data equipment (modems, transceivers, converters and redundancy switches)
And, more

54. Comtech EF Data Delivers global services and support
Specializes in solutions that optimize satellite communications
Has technologically advanced infrastructure products installed in more than 160 countries
Provides “around the clock” customer support
Has authorized service centers around the world
Is prepared to help you:
Optimize satellite communications
Minimize operating expenses
Maximize transponder utilization
Lower the total cost of ownership

55. Contact Us: 2114 West 7th Street Tempe, AZ 85281 USA Tel 1. 480. 333
Contact Us: 2114 West 7th Street Tempe, AZ USA Tel FAX