Abstract
Atmospheric measurement techniques often require synchronous data capturing throughout the day, at the exact moment, more than capturing it at preset points in time. The system utilizes time stamps sent from the atomic clocks on navigation satellites. Time stamps received from the satellites by the GNSS receiver are turned into a triggering impulse. Impulses are needed for triggering the repurposed low-noise scientific cameras. The cameras must be mobile in an outdoor setup with a synchronized triggering system. However, the system is not limited to low-noise scientific cameras; it can be fitted to suit other applications requiring synchronous impulse, with a timestamping option. Systems comprise a microcontroller paired with a GNSS receiver which has access to the constant, one pulse per second, stream of GNSS satellite emitted time impulses. The GNSS receiver is connected to the camera and the microcontroller unit (MCU). 1PPS pin on the GNSS module is connected to a camera acting as its external trigger. The microcontroller is connected to the GNSS module accepting the NMEA sentences. Further, MCU communicates via USB with a data storage device, providing formatted time tagging data. The satellite impulse is directly converted to the camera trigger signal, allowing an indefinite number of devices to be triggered within a 30 nanosecond gap, with the possibility of triggering multiple low-noise cameras and other trigger-needing sensors distributed hundreds of meters or kilometers apart. The microprocessor generates the time tag without influencing the moment of the time of the trigger. GNSS module independently gives synchronous triggers while parallelly sending the data to the MCU to process it before the next satellite signal, which comes every second. We evaluate the solution on three commonly available prototyping boards in search of the least time difference between their trigger pulses.
