Astrapi Corporation

Space and Missile Systems Center, Los Angeles Air Force Base, has identified fighting SATCOM as a number one priority with a goal date of 2023. In the face of future electronics warfare, Space Force has indicated that multiple software-defined radio (SDR) solutions are necessary to provide for a resilient communications network that will overcome and persist through battle. The proposed project will enhance the spectral efficiency of established satellite technology. Based on the deployed and market-proven platform of a strong teaming partner, Astrapi’s Spiral Modulation technology will directly address the dual-use need to improve communication performance by increasing data throughput and reducing signal power requirements. Backed by private investment and over $1M in National Science Foundation funding, Astrapi has external validation for the capability to reduce signal power requirements by 2-4 dB (approximately a factor of two) for matched data throughput and occupied bandwidth. Astrapi accomplishes this through Spiral Modulation, which for the first time fully exploits the capabilities of a continuously non-stationary spectrum. Spiral Modulation bypasses an implicit assumption in classical channel capacity theory that the spectrum is at least approximately stationary (constant power in each frequency). Spiral Modulation therefore opens the door to much higher spectral efficiency.

Stronger RF links extend eVTOL/UAM capabilities, providing higher data throughput and reduced SWaP. At the physical layer, existing radio communications methods are approaching their theoretical spectral efficiency limit. Astrapi’s Spiral Modulation makes use of symbol waveform alphabets designed using polynomials. Polynomials allow for a very large symbol waveform design space, which can be used to create symbol waveform alphabets with greater inter-symbol distinguishability, and therefore greater noise resistance, than traditional signal modulation technology. Significant spectral efficiency improvement is possible with Spiral Modulation because it fully exploits the capabilities of a continuously non-stationary spectrum. Unlike classical channel capacity theory which contains an implicit assumption that the spectrum is at least approximately stationary, Spiral Modulation introduces polynomials with continuously varying amplitude. A recent Beyond-Line-of-Sight (BLOS) troposcopic scatter telecommunications project resulted in third-party validation for a 2-4 dB signal power advantage compared to traditional signal modulation. Astrapi is now transitioning its TRL 4 software defined radio (SDR) technology to our second-generation state-of-the-art Xilinx Zynq ZCU111. Our ZCU111-based SDR implementation will provide a prototype capable of specialization into many implementations, including to support eVTOL, UAM and many other missions, initially designed for Near Earth Networks (NEN) ground stations and then in-orbit SDRs.

Astrapi has introduced a new patent-pending form of physical-layer signal security called “Symbol Waveform Hopping” (SWH) that provides an advanced cyber communication capability. Based on new mathematics and new symbol waveform design capabilities, SWH forces an adversary to distinguish between many more possible symbol waveforms than the intended receiver. The signal-to-noise power ratio (SNR) makes it impossible for an adversary to determine the time-amplitude values transmitted, blocking any further attempt at decryption. SWH is similar to Frequency Hopping (FH) in that both change an aspect of the signal at the physical layer according to a pseudo-random sequence known only to the sender and intended receiver. But whereas FH operates in the frequency domain, SWH operates in the time domain. Symbol Waveform Hopping (SWH) extends the capability gap needed to address near peer competition in the environment of "Great Power Competition", especially in space. SWH is in principle unbeatable if the pseudo-random sequence is not known. SWH and Frequency Hopping can be combined. SWH is based on Astrapi’s Spiral Modulation technology, which greatly increases the bandlimited symbol waveform design space, from which signals are generated. As with traditional signal modulation, each symbol alphabet (set of component bit sequences) is paired with an equivalent alphabet of symbol waveforms for transmitting those bits. SWH generates many symbol waveform alphabets, and switches between them based on a pseudo-random sequence known only to the transmitter and receiver. The proposed technology was vetted and accepted as part of the prestigious USAF AFRL/RV sponsored Catalyst Cyber Space program hosted virtually at their campus in Colorado Springs, CO. Astrapi was one of eight companies accepted to this cohort. Many believe our satellite is most at risk from cyber attacks. Of course, commercial networks are as well. So the need to protect these critical infrastructure networks is acute. The capability is dual-use and extends into other RF-enabled modems, radios, smart devices, and sensors. And it may be aggregated with other encryption and frequency hopping approaches.