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Hands-Free Free-Space Optical Communication

Team members

Li Jiang Yan (EPD), Ng Ruoqi (EPD), Cheryl Lui Run Ying (EPD), Poh Shi Hui (ISTD), Ong Xin Tong (ISTD)


Lu Zhuo Ming Kenny, Kwan Wei Lek

Writing Instructors:

Wong Yoke Chee Susan

Teaching Assistant:

Anirudh Maruvada


A hands-free system consisting of a transmitter and receiver that enables wireless speech-based instrument control via free-space optics (FSO) with infrared radiation, converting speech to Standard Commands for Programmable Instruments (SCPI) instructions and executes them.

The Problem

ps01 nobg

Current Situation

Engineers require both their hands during radiofrequency (RF) testing, for example, during interference hunting with one hand carrying a test instrument and the other holding an antenna. Hence, manually adjusting the settings is inconvenient and results in a loss of productivity. However, there are currently no non-RF wireless communication systems that can be used to control the test instrument without interfering with their testing. 


Project Objective

To develop a hands-free system for engineers to adjust the settings of the test instrument using voice commands over free space optical communication.



Our Solution



Key Product Features



  • 1. Headset with microphone
  • Voice: Captures voice at close distance to maximize audio clarity and accuracy even in noisy environments.
  • 2. Transmission of data with infrared radiation (IR) LEDs
  • Wireless: Prevents tripping hazard and allows for greater mobility
  • Designed for RF test instruments: IR prevents interference with RF test instrument measurements
  • Human-friendly: Safe for eyes as IR is not glaring to the eyes
  • Efficient system: High data transmission up to 2 meters even under indoor ambient light
  • 3. Powered by AI
  • Trigger word detection: Trigger word detection is used to start the system
  • Speech to Text: Converts speech to text
  • 4. Supports Standard Commands for Programmable Instruments (SCPI)
  • Text to SCPI: Converts text to SCPI commands
  • SCPI commands: Supports sending of SCPI commands to test instruments 



Optical Data Transmission System


• Transmission rate: 400 kbits/s

• Distance of transmission: up to 2 meters

• Angle coverage: ±60° horizontal, ±20° vertical

• Low power usage: 1.08 W max

• Zero to low transmission loss even at a distance of 2 meters

website setup

Transmitter iPerf results

Receiver iPerf results



Speech to SCPI System

Powered by AI

• Trigger word detection using model trained with CNN

• Speech to text using Julius speech recognition

• Text to SCPI command

Feature Extraction: MFCC

image 2021 08 06 01 50 12

Model: CNN

• NN Classifier
• Accuracy: 97.5%
• Loss: 0.11

_Noise _Unknown Hey_Photon
_Noise 99.0% 1.0% 0.0%
_Unknown 3.5% 94.8% 1.7%
Hey_Photon 0.7% 0.6% 98.6%
F1 Score 0.97 0.96 0.98
Video demonstation of converting speech to SCPI commands






About Rohde & Schwarz

website companylogo

Rohde & Schwarz (R&S) is an international electronics product development company that specializes in creating radiofrequency (RF) test and measurement instruments for broadcast and media, radiocommunications and network technology industries. With its tremendous success for over 85 years, the German company has expanded its business to over 70 countries, with 2 regional headquarters established in the United States, Columbia, Maryland and in Singapore. 


student Li Jiang Yan Engineering Product Development
student Ng Ruoqi Engineering Product Development
student Cheryl Lui Run Ying Engineering Product Development
student Poh Shi Hui Information Systems Technology and Design
student Ong Xin Tong Information Systems Technology and Design
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