Developing a motherboard with an RF transmitter, 16-bit ADCs, and extremely low power consumption for a Single-Board RIO device.
To meet the timing accuracy requirement, we used a GNSS receiver with an RTC that can be calibrated. Due to the low power consumption requirement, the GNSS receiver cannot be used continuously. We use it once daily to calibrate the RTC and fix the timing error. Then we use the RTC timing throughout the day. This helps us achieve an accuracy of 100–200 ms, which is well within the required 400 ms range.
This is a data logger system with 24 analog inputs with 16-bit resolution, eight digital inputs, and two SDI-12 inputs. It consumes 50 mAh. First, we log the data for 30 minutes, then we do the preprocessing and, at predefined time intervals, we transmit the results to the satellite (INSAT and INSAT C3). We use GNSS-synchronized RTC for implementation of TDMA. This allows installation of 1,800 systems using the same carrier.