Transmit-only ground sensor systems are inherently less complex, costly, and power-hungry than their two-way counterparts. For many applications, such as asset tracking, perimeter or border vibro-acoustic sensing, and environmental monitoring, the end-user is only interested in receiving data; there is no need to communicate with the emplaced device. In fact, many of these applications are resource-prohibitive (in cost, size, or power) unless a transmit-only solution is available. By shifting signal processing complexity away from the many distributed transmitters and into a single receiver, the system as a whole is optimized to reduce the cost for the user to monitor widespread information-gathering devices. AeroAstro's Sensor Enabled Notification System (SENS) is a satellite-based communications network that accomplishes this goal of reducing data exfiltration cost and complexity by using transmit-only remote units. Using Code Phase Division Multiple Access (CPDMA) spread-spectrum algorithms, the remote transmitters need not be synchronized or otherwise prevented from transmitting simultaneously; the central receiver can, within reasonable bounds, distinguish many transmissions "in the air" at the same time and receive all of their data. Sensors whose data can be captured into relatively infrequent burst packet transmissions, like most unattended remote sensors, are candidates for using this technology.
The long lead and cycle times currently associated with development and launch of satellite systems have established a prohibitive environment for responsive deployment of tactical capability to orbit. With the advent of the RASCAL program - poised to offer launch capability to Low Earth Orbit (LEO) within 24 hours - there is a clear motivation for a comparable, multi-mission, rapidly configurable microsatellite. The SCOUT program is developing the key enabling technologies that will enable this capability while also addressing the production and logistic challenges essential to its implementation. Intrinsic to the design will be a "Plug-and-Sense" capability, which will enable a vehicle to detect the presence and orientation of integrated subsystem modules, as well as ascertain their function, and communicate key performance parameters. The system will utilize a heuristic, self-interrogation approach to provide a robust means of performing configuration and diagnostics activities that transcend nominal housekeeping routines to include an enhanced degree of system autonomy. A minimally structured design, emphasizing a lightweight, interchangeable framework will enable quick integration and deployment, while preserving high on-orbit payload mass fraction. Similarly, the system will also feature a novel approach to assembly, integration, and test activities that spans ground through on-orbit operations.