Data Logger With Satellite Transmitter for INSAT C3

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"Using NI Single-Board RIO, LabVIEW FPGA, and other innovative technologies in the process of designing MSS Datalogger System, we have significantly increased performance and lowered the cost."

- Orbel Sevoyan, OLYMP Engineering LLC

The Challenge:
Developing a motherboard with an RF transmitter, 16-bit ADCs, and extremely low power consumption for a Single-Board RIO device.

The Solution:
Using an external ARM processor for the control and timing of a Single-Board RIO device, and using LabVIEW software and LabVIEW FPGA programming to develop a competitive product with supreme performance.

Author(s):
Orbel Sevoyan - OLYMP Engineering LLC

About the Company

OLYMP Engineering LLC, an NI Alliance Partner, specializes in RF and wireless systems. We develop various communication protocols, algorithms, and RF hardware for different applications. The systems we build have already been deployed in Russia, India, and Singapore. The range of services provided by our company is constantly expanding because of modern technologies and highly qualified personnel.

India needs accurate weather forecasts to improve agriculture. The government installed automatic weather stations, with different sensors attached, throughout the country. In many of these areas no electric power is available and the system should be powered from a solar panel with backup battery. Therefore, power consumption should be limited (maximum average level 500 mAh). Another challenge is that more than 1,500 systems will be installed all over India and they will mostly use the same frequency. This constraint required us to use TDMA with a very accurate timing source.

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.

The customer had an issue with the crystal oscillator (XO) used in real-time clock (RTC) in the previous system. After one year of operation the aging of XO resulted in more than one second RTC drift in a day. To avoid this problem, we used an RTC with XO calibration capability. We selected an sbRIO-9606 device to satisfy our needs without compromising system performance. We have experience developing high-performance, highly optimized FPGA-based algorithms and customized hardware. By choosing us, the customer benefited from our experience and domain knowledge, which guaranteed that the project was delivered on time and with the highest quality.

Problem Background and Solution

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. The sbRIO-9606 handles all processing including:

• Modulation
• Coding
• Package forming
• Preprocessing data
• Acquiring GNSS data
• Programming and calibrating RTC
• Operating display and keypad
• Configuring ADCs

By using sbRIO-9606, we passed the certification test in just five hours.

System Specifications

MSS data logger
• Frequency range: 2,670 MHz to 2,700 MHz
• Power consumption: 50 mAh
• Tx output power: 1–4 W, configurable from software
• ADC inputs:24
• ADC resolution: 16 bits
• Counter inputs: 8
• Maximum count frequency: 2,000 Hz
• Method of operation: 16-button keypad
• Display: 30 x 6 characters
• Power supply voltage: 12 V

DRT data logger

• Frequency range: 400 MHz to 410 MHz
• Power consumption: 50 mAh
• Tx output power: 1–10 W, configurable from software
• ADC inputs:24
• ADC resolution: 16 bits
• Counter inputs: 8
• Maximum count frequency: 2,000 Hz
• Method of operation: 16-button keypad
• Display: 30 x 6 characters
• Power supply voltage: 12 V

Benefits of Using NI Hardware and Software

NI technology helped us deliver a fully software controlled and defined data logger. We used
LabVIEW for ease of programming and so we could spend more time working on the data logger itself and solving challenges, than on actual programming. The key tools that we used in our development were LabVIEW, the LabVIEW Real-Time Module, and the LabVIEW FPGA Module, which is one of the most powerful FPGA programming tools available.

Our solution achieved low power consumption, software-defined functionality, ease of use, and a higher functionality per cost ratio than our competitors.

Conclusion

Our customer’s objective was to build a system capable of logging data from 24 AI channels and 8 DIO channels for 30 minutes and then transmit to satellite with TDMA. We used the NI platform to fulfill all the requirements and even go further.

Author Information:
Orbel Sevoyan
OLYMP Engineering LLC
Hovsep Emin 123
Yerevan
Armenia
Tel: +374(55)688597
info@olympmail.am

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