World’s Smallest Software-Defined Radio for Troposcatter Communications

Comtech Systems Inc, a subsidiary of Comtech Telecommunications, has introduced the world’s first software-defined adaptive troposcatter combination radio/modem, packaged in a compact sealed module. The CS67PLUS uses a unique, patented adaptive architecture that is capable of supporting line-of-sight (LOS) and troposcatter beyond-line-of-sight (BLOS) communications with a capacity of up to 210 Mbps of full duplex data throughput. Offering a wide selection of modulation techniques from BPSK to 64APSK, coupled with the most powerful Error Correction in the industry, Low Density Parity Check (LDPC), the CS67PLUS Tropo Radio is a solid foundation for any troposcatter communication system.

Operating in the 70 MHz to 6 GHz frequency range, the compact size of the CS67PLUS is possible due to its Zero-IF design, providing the lowest cost, lowest power, and the smallest footprint solution of any modern troposcatter radio/modem technology to date. The radio module is mounted in a single rack unit connectorized interface chassis. It contains two transmit channels and four receive channels and is user-configurable for Single, Dual or Quad Diversity system configurations, essential to modular tactical troposcatter terminals.

In another industry first, the CS67PLUS can operate in dual-stream mode, intelligently shifting data between diversity channels in order to double throughput in favorable conditions. It utilizes Phase Shift Keying (PSK) modulation schemes, critical in troposcatter applications for its low peak-to-average power ratio (PAPR). A modulation with low PAPR is essential when using high power amplifiers such as Solid-State Power Amplifiers (SSPAs). Operating with a smaller back-off than other forms of modulation, such as Quadrature Amplitude Modulation (QAM), PSK modulation increases the range of the troposcatter system.

To maximize link availability and data throughput, the CS67PLUS features a patented deep learning Adaptive Coding Modulation (ACM). ACM continuously selects the best modulation and error correction coding scheme on a frame-by-frame basis, based upon troposcatter link conditions, to continuously provide maximum throughput and link availability. For applications where network equipment requires a fixed throughput, the CS67PLUS can be operated in Fixed Data Rate mode. As standard on previous Comtech Systems troposcatter modems, it features Automatic Link Power Control (ALPC), which adjusts the transmit power level based upon link conditions to maintain the customer-selected level of service desired. This also reduces the probability of interference at distant stations and reduces the probability of signal intercept.

For critical mission links, a redundant CS67PLUS system can be supplied equipped with two (2) modules mounted in the 1RU chassis. Modules are easily removable and are hot-swappable. The features and capabilities described above, coupled with Comtech’s field proven performance, have led to the U.S. Marine Corps selection of the CS67PLUS for their NGT (Next Generation Tropo) program.

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