Carrier‑in‑Carrier® is based on Applied Signal Technology’s DoubleTalk® bandwidth compression technology. DoubleTalk uses “Adaptive Cancellation,” a patented technology that allows the transmit and receive carriers of a full‑duplex satellite link to be transmitted in the same transponder space.

When combined with advanced forward error correction and modulation techniques, DoubleTalk Carrier‑in‑Carrier can deliver unprecedented operating expense savings.

In addition to operating expense (OPEX) savings, DoubleTalk Carrier‑in‑Carrier can also provide capital expenditure (CAPEX) savings by allowing a smaller BUC/HPA and/or antenna.

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.

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.

DoubleTalk Carrier-in-Carrier allows satellite users to achieve spectral efficiencies (i.e. bps/Hz) that cannot be achieved with traditional links. For example, 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.

DoubleTalk Carrier-in-Carrier can be used to save transponder bandwidth and/or transponder power thereby allowing successful deployment in bandwidth-limited as well as power-limited scenarios. The following example illustrates the typical process for implementing DoubleTalk Carrier-in-Carrier in a power-limited scenario:
The conventional link is using 8-PSK, TPC 3/4:

Spread the signal by switching to a lower order modulation and/or FEC code – say QPSK, TPC 7/8. This increases the total transponder bandwidth, while reducing the total transponder power:

Now using DoubleTalk Carrier-in-Carrier, the second QPSK, TPC 7/8 carrier can be moved over the first carrier – thereby reducing the total transponder bandwidth and total transponder power when compared to the original side-by-side 8PSK, TPC 3/4 carriers:

DoubleTalk Carrier-in-Carrier is currently available in three form factors:

• As an option for the CDM-625 Advanced Satellite Modem
• As an option for the CDM-Qx and CDM-QxL Multi-Channel Satellite Modems
• CLO-10 Link Optimizer (modem agnostic)

Does DoubleTalk Carrier-in-Carrier make sense for your satellite links? An easy way to analyze the possible benefits is to download our new Excel-based Link Optimization Tool. We created this tool to highlight the multi-dimensional optimization that can be achieved with our advanced technologies. Explore the value today and download this free tool.

Notice: Comtech EF Data reserves the right to change specifications of products described in these documents at any time without notice and without obligation to notify any person of such changes.  Information in these documents may differ from information published in other Comtech EF Data documents.