Comtech EF Data is recognized as a technology leader and innovator. As the leader in satellite bandwidth efficiency and link optimization, our advanced technologies reduce OPEX/CAPEX and increase throughput for fixed and mobile/transportable satellite-based applications.
Below is a sampling of our advanced technologies developed through new product design and incremental improvements to existing products.
Our revolutionary and award-winning technology allows full duplex satellite links to transmit concurrently in the same segment of transponder bandwidth. When combined with the advanced forward error correction and modulation techniques in our modems, DoubleTalk Carrier-in-Carrier delivers improved satellite transponder utilization and unprecedented operating expense savings.
Our patent-pending Automatic Carrier-in-Carrier Power Control (ACPC) mechanism solves the power control optimization problem in a very general way for CnC links. It provides a unique opportunity for modems on both sides of a CnC link to automatically measure and compensate for rain loss while maintaining a fixed PEB on the satellite during all conditions. In addition to automatically compensating for rain loss, ACPC also enables CnC modems to share link margin between modems (i.e. a modem experiencing clear sky conditions can effectively give excess link margin to a distant end modem experiencing rain conditions, thereby further enhancing overall availability). This feature is implemented using values measured by the modems and general rain model knowledge (i.e. a system level implementation is not required). The net effect of ACPC technology is a significant increase in effective link margin and availability for CnC links while ensuring no increase in the PEB at the satellite.
Forward Error Correction is a powerful technique for improving the performance of error-prone channels found in communication systems. The performance of FECs can be evaluated based on their distance from Shannon limit. We offer traditional and advanced methods of forward error correction to improve performance of error-prone channels. Examples of our modems' advanced FECs are:
- Low-Density Parity-Check Codes (LDPCs)
- DVB-S, DVB-DSNG and DVB-S2
- 2nd Generation Turbo Product Codes (TPC)
Satellite interference has a significant financial impact on both satellite operators and end users. We developed the MetaCarrier technology to address this severe, industry-wide challenge. The 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. The MetaCarrier is embedded using spread spectrum techniques within the carrier itself without adding appreciable noise or power to the host carrier. The robust spread spectrum signal enables the host carrier to be identified even when the host carrier is well below another carrier or near the noise floor itself.
Our products utilize ASIC and FPGA modulator and demodulator designs, and support BPSK, QPSK, OQPSK, 8-PSK, 8-QAM, 16-QAM, 64-QAM, DVB-S2, 16-APSK and 32-APSK. Depending on the modem, demodulation is accomplished by either frequency conversion down to an intermediate frequency or directly down to base band with over sampling employed. Filtering is accomplished either by switched analog filters or digitally with polyphase FIR filters in the conversion FPGA. Due to the all-digital implementation with polyphase filters, designs are readily transferred to other data rates. Our modulation and demodulation technologies operate as low as 2.4 kbps to over 238 Mbps.
Adaptive Coding and Modulation is a statistical, non-static advantage that enables dynamic changes in user throughput. Benefits and value vary over time and are not guaranteed, but are predictable. ACM technology converts link margin to an increase in the data throughput of satellite links. When utilizing ACM operation in our modems and Advanced VSAT Solutions, link margin can be converted into increased throughput of satellite links.
We added a new approach to continuously optimize satellite communication efficiency – Dynamic Predistortion (DPD) on the CDM-760. Working in tandem with DPD, a new crest factor reduction (CFR) technique is dynamically applied as well to further enhance performance. These innovative technologies, collectively labeled and referred to as DPD, create high signal integrity while operating the satellite transponder in the higher efficiency nonlinear region. They provide a significant increase in link margin, by as much as 2 dB, and/or in spectral efficiency, by as much as 6%.
RAN Optimization can significantly reduce the satellite bandwidth required for cellular backhaul. It provides the user complete control over the desired level of optimization and link quality. The pre-emptive bandwidth management maintains superior voice and service quality even under WAN congestion. Depending on the traffic profile, typical bandwidth reduction of 30-35% can be achieved with little or no impact to the voice quality. RAN optimization is available in select modems, Memotec products and the Advanced VSAT Solutions.
WAN Optimization consists of two components, acceleration and optimization.
- Optimization – Reduces the amount of data that traverses the link by using compression and caching techniques. Provides traffic shaping on the link to allow different users and applications to get appropriate access.
- Acceleration – Gets the data to the user faster by reducing and overcoming the limitations of the underlying protocols. There is a natural synergy between acceleration and optimization. When the amount of data is reduced, it will also get there faster.
Our advanced functionality allows for efficient IP networking and transport over satellite, and is available for select modems and the Advanced VSAT Series. Available options include header compression, payload compression, ultra low overhead streamline encapsulation and quality of service. When utilizing the advanced IP functionality, real-time traffic and other low priority traffic can seamlessly co-exist on the same link without impacting the voice quality or delivery of mission critical data. The functions provide high bandwidth efficiency, information security and simplified network design/configuration.
There are some applications where it becomes necessary, at the distant end of a satellite link, to provide a high-stability G.703 timing reference for timing equipment connected to the modem. For example, in cellular backhaul applications, the BTS equipment may require such a reference even though the satellite link itself may be operating at a data rate other than 1.544 Mbps or 2.048 Mbps. This is sometimes accomplished by adding a specialized GPS receiver at the distant end, which then provides the G.703 synchronizing signal. However, with the G.703 clock extension mode this may become unnecessary, as our modems with this feature – operating at either end of the link, where the local modem has access to a high-stability G.703 signal – can provide an almost perfect copy of this signal at the distant end. The presence of Doppler shift on the link is the only factor affecting the overall accuracy. If Doppler shift were not present, the copy of the clock would be perfect.
Our EDMAC capability permits the users to access the M&C features of distant-end modems in a satellite link. This is accomplished by adding extra information to the user data in a manner that is completely transparent to the users.
AUPC is a feature whereby a local modem is permitted to adjust its own output power level in order to attempt to maintain the Eb/No at the remote modem. AUPC relies upon EDMAC for its operation. The remote modem constantly sends back information about the demodulator Eb/No using reserved bytes in the overhead structure. The local modem then compares this value of Eb/No with a pre-defined target value. If the Remote Eb/No is below the target, the local modem increases its output power, creating a closed-loop feedback system over the satellite link. A particularly attractive benefit of this feature is that whenever framed operation is selected, the remote demodulator's Eb/No can be viewed from the front panel display of the local modem.
Our modems are extremely flexible and powerful, and incorporate a large number of optional features that can be purchased at the initial order or while in the field. The FAST technology facilitates on-location upgrade of the operating feature set without removing a modem from the setup. With FAST technology, users have maximum flexibility for enabling functions as they are required. FAST allows a user to order a modem precisely tailored for the initial application. When service requirements change, the operator can upgrade the topology of the modem to meet those requirements within minutes. FAST permits the purchase and installation of options through special authorization codes loaded into the unit either via the front panel keypad or entered remotely via the remote port located on the modem rear panel. This accelerated upgrade can be accomplished because of FAST's extensive use of the programmable logic devices incorporated into our products.
AutoEQ supports amplitude and group delay equalization over the satellite system. When installed, it offers the ability to compensate the overall system group delay and amplitude flatness by pre-correcting the uplink carrier. This eliminates the need for external group delay/amplitude equalizers and makes possible equalization at L-Band.
Our Vipersat Management System (VMS) automates bandwidth utilization while optimizing space segment efficiency. The software allows intelligent management of satellite networks through system configuration and alarm management of the network. VMS is the engine that provides dynamic SCPC (dSCPC) bandwidth management of space segment.
Our frequency converters utilize the patented "Daisy Chain" integrated switching technology. The Daisy Chain design removes the relays associated with a centralized protection switch tray and distributes them across the individual converters. We were awarded patent 5,666,646 on this distributed protection switch topology.
DoubleTalk® is a Registered Trademark of Raytheon Applied Signal Technology
VersaFEC® is a Registered Trademark of Comtech EF Data
MetaCarrier® is a Registered Trademark of Comtech EF Data