--- title: "Data logging system for optical, satellite, Bluetooth" subject: "Instrumentation II" chapter: 5 key: "semester_5/instrumentation_ii:data-logging-three-schemes" source: https://www.bctengineer.com/q/semester_5/instrumentation_ii/data-logging-three-schemes site: BCT Engineering --- # Data logging system for optical, satellite, Bluetooth Instrumentation II · Chapter 5: Data Acquisition And Transmission - Asked in: 2078 Kartik, 4 marks - Answer checked by Claude Sonnet 5.5 on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_5/instrumentation_ii/data-logging-three-schemes - Whole chapter: https://www.bctengineer.com/md/semester_5/instrumentation_ii/chapter-5 ## Question Design a data logging and storage system that is capable of receiving and storing signals from optical fibers, satellites and Bluetooth devices. Provide the block diagram of the overall system, which should show how messages get transmitted over the three transmission schemes and how the logger receives them. ## Short answer Optical receiver uses photodiode and amplifier; satellite receiver uses dish, LNB, down-converter, and demodulator; Bluetooth uses 2.4 GHz GFSK receiver. All three digital streams are interfaced to a microcontroller that time-stamps, error-checks, and stores data in flash memory, accessible via PC link. ## Answer The logger needs three receiving front ends (optical fibre, satellite, Bluetooth) feeding a common processing and storage unit. ```text OPTICAL FIBRE Sensor/Data -> E/O (LED/laser) ==fibre==> O/E (photodiode+amp) --+ SATELLITE | Data -> Modulator -> Up-converter -> HPA -> Dish ~~> Satellite | Satellite ~~> Dish+LNB -> Down-converter -> Demodulator ---------+ BLUETOOTH | Device -> BT radio ~~~ 2.4 GHz ~~~> BT receiver (antenna, GFSK demod) -+ v +---------------------------------------------------+ | Interface / multiplexer -> Microcontroller (decode, | | time-stamp, error check) -> Memory (flash/disk) | +-------------------------+-------------------------+ Display, PC / network link, power supply ``` - **Optical fibre:** an LED or laser converts the electrical data into light pulses; the logger receives with a photodiode and a transimpedance amplifier and regenerates the bits. - **Satellite:** the earth station modulates, up-converts and transmits to the satellite; the logger has a dish, LNB, down-converter and demodulator that recover the data. - **Bluetooth:** short-range 2.4 GHz radio; the logger's Bluetooth receiver recovers packets. - Each front end gives digital data to the controller via a serial interface (UART/SPI); the controller identifies the source, checks errors (CRC), time-stamps and stores to non-volatile memory, and gives data to the PC. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. How does the logger receive data sent over optical fibre? A. A Bluetooth radio B. A dish and LNB C. An LED on the receive side D. A photodiode with a transimpedance amplifier converts light to electrical data Answer: D. O/E conversion regenerates the bits. (Key point: Fibre front end) 2. Which parts are in the satellite receive chain? A. Dish, LNB, down-converter and demodulator B. Photodiode and TIA C. GFSK demodulator only D. LED and laser Answer: A. The dish and LNB collect the weak signal which is then down-converted and demodulated. (Key point: Satellite front end) 3. Which front end receives Bluetooth data? A. A photodiode B. A 2.4 GHz receiver with antenna and GFSK demodulator C. An LNB D. An up-converter and HPA Answer: B. Bluetooth is short range 2.4 GHz radio. (Key point: Bluetooth front end) 4. What does the controller do with data from the three front ends? A. Only displays it B. Converts it all to analog C. Identifies the source, checks errors (CRC), time-stamps and stores in non-volatile memory D. Discards error packets silently without checking Answer: C. Each front end sends digital data via a serial interface to the controller. (Key point: Common unit) ## Related in Instrumentation II - [Data logger with Bluetooth scatternet](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Abt-datalogger-scatternet) — Instrumentation II, chapter 5 - [Data logger block diagram and operation](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Adl-block) — Instrumentation II, chapter 5, asked 6× - [Compact data logger characteristics and block diagram](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Acompact-dl-block) — Instrumentation II, chapter 5 - [Case study: proposed system design](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Acs-proposed-system-design) — Instrumentation II, chapter 10 - [Advantages of optical fiber over copper](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Aoptical-fiber-advantages) — Instrumentation II, chapter 5, asked 3× - [Double handshake data transfer with 8255-PPI](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Adouble-handshake-8255) — Instrumentation II, chapter 2 ## Related in other subjects - [Analog communication block diagram; FDM of three signals](https://www.bctengineer.com/question.md?key=semester_6%2Fcommunication_systems%3Aanalog-block-fdm-three-signals) — Communication Systems, chapter 5 - [Digital data acquisition system block diagram](https://www.bctengineer.com/question.md?key=semester_4%2Finstrumentation_i%3Adigital-data-acquisition-system) — Instrumentation I, chapter 6 - [Optical fiber vs satellite transmission](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Aoptical-fiber-vs-satellite) — Data Communication, chapter 4 - [Data acquisition block diagram and DCS advantages](https://www.bctengineer.com/question.md?key=semester_6%2Fdigital_control_system%3Adata-acquisition-advantages) — Digital Control System, chapter 1