PXI is a modular instrumentation technology providing tight synchronization between modules along with high-speed data transfers between individual modules.
Precision modular instruments are typically placed in a mainframe (or chassis) which provides power, synchronization, and data transfer between the modules. The PXIbus, for example, provides common clock signals which are accurate to better than 1 ns when distributed to different modules within a chassis. Multiple chassis can also be synchronized by careful distribution of clock signals between the PXI mainframes.
Now imagine a modular data acquisition system where we only have the modules, but no “box” or chassis to put them in. This is possible if we used stand-alone “nano-synchronized” sensors, where each self-contained sensor derives its precision clock from an external wireless signal (such as GPS).
Although the GPS synchronization is not as accurate (better than 100 ns) as hardware synchronization, it is available globally. This creates a “virtual” PXI chassis, by ensuring the synchronization without any wired connections. This means that the number of modules that can be synchronized is essentially unlimited, meaning that the system architecture has “unlimited scalability” (“geek speak” for how big a system it is possible to build). Such a box-less architecture has a broad range of applications where synchronous acquisition or control is required, but where high-speed data transfers between nodes are not necessary.
We’d like to challenge you, the readers of this blog, to contribute with application ideas. Just to get you imagination warmed up, think about sensors the size of golf balls that can be placed anywhere, dropped from the air, floated down rivers, through sewers, transported by animals, people, drones, balloons, or cars. Imagine the freedom when the sensor is no longer physically locked to a single location, but the sensor with its entire data acquisition system is free to move around. (Yes, we already have a lot of that with mobile phones logging location based data).
This is why we sometimes refer to this concept as “nanoPXI”. “nano”, because it is small and wireless. “nano”, because it is nano-synchronized. nanoPXI, because it is a subset of the PXI capabilities.
And only half joking, perhaps it is a “Giga”-big concept, because it has no inherent upper limit in terms of the number of nodes/sensors in the system, and it has no restrictions on the distance between synchronous nodes (as long as it is on or near our Earth 😉