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.