Editing Software-defined radio (section)

=== SpeakEasy phase II ===
The goal was to get a more quickly reconfigurable architecture, ''i.e.'', several conversations at once, in an ''open'' software architecture, with cross-channel connectivity (the radio can "bridge" different radio protocols). The secondary goals were to make it smaller, cheaper, and weigh less.{{fact|date=August 2022}}

The project produced a demonstration radio only fifteen months into a three-year research project. This demonstration was so successful that further development was halted, and the radio went into production with only a 4&nbsp;MHz to 400&nbsp;MHz range.{{fact|date=August 2022}}

The software architecture identified standard interfaces for different modules of the radio: "radio frequency control" to manage the analog parts of the radio, "modem control" managed resources for [[modulation]] and [[demodulation]] schemes (FM, AM, SSB, QAM, etc.), "waveform processing" modules actually performed the [[modem]] functions, "key processing" and "cryptographic processing" managed the cryptographic functions, a "multimedia" module did voice processing, a "human interface" provided local or remote controls, there was a "routing" module for network services, and a "control" module to keep it all straight.{{fact|date=August 2022}}

The modules are said to communicate without a central operating system. Instead, they send messages over the [[Peripheral Component Interconnect|PCI]] [[computer bus]] to each other with a layered protocol.{{fact|date=August 2022}}

As a military project, the radio strongly distinguished "red" (unsecured secret data) and "black" (cryptographically-secured data).{{fact|date=August 2022}}

The project was the first known to use [[FPGA]]s (field programmable gate arrays) for digital processing of radio data. The time to reprogram these was an issue limiting application of the radio. Today, the time to write a program for an FPGA is still significant, but the time to download a stored FPGA program is around 20 milliseconds. This means an SDR could change transmission protocols and frequencies in one fiftieth of a second, probably not an intolerable interruption for that task.{{fact|date=August 2022}}