Wireless Baby Monitor Farida Siddiqi Nelson Rosario Senior Project Presentation Advisors: Professor Ekram Hassib Professor Emad A. Andarawis

Presentation Outline Wireless Baby Monitor Present Baby Monitors Wireless Baby Monitor FAN05 The Design of FAN05 Trigger Circuit Results Future Work References Questions

What is a Wireless Baby Monitor? A wireless baby monitor is a device that allows the constant surveillance of a child’s safety without the need of the parent to be in the same environment. The basic design consists of a video, audio, or combination of both components connected to a transmitter which allows the transfer of data to receiver. Data exchange containing real-time video/sound of the child’s action in surroundings.

Basic Design of a Wireless Baby Monitor Audio/Video Component – the use of a microphone and/or camera to capture sound and/or video to monitor child Transmitter- receives audio/video signal and converts it to modulated radio frequency signal and transmits to receiver Receiver-picks up modulated radio frequency, converts it to original audio/video signal Monitor- device which allows parent to see child

Present Baby Monitors Monitor with two receivers Allows one way interaction, receivers can be placed in two areas of the home Listen and talk monitor Allows two way audio communication Vibrations monitor with remote control Device delivers sounds and vibrations to the crib from a wireless monitor Movement sensor with sound monitor Sensor mat placed under mattress detects motion accompanied by a second device that detects sound Video/Audio Monitor System allows parent to view and hear their child, some monitors contain infrared LED for low light settings.

Wireless Baby Monitoring and FAN05 Present wireless baby monitors offer: - Sensing of motion and/or audio - Infrared sensors for monitoring in low light environment - Two way audio communication between child and parent Why design a new wireless baby monitor? - A design which will combine the features offered by individual wireless baby monitors into one system and incorporates video, audio and an alert signal transmission upon the detection of an infant cry.

Design of FAN05 Microphone/Camera- captures analog audio/video signal and sends to transmitter Transmitter- receives audio/video signal converts to modulated radio frequency signal and transmits to receiver Receiver- picks up modulated radio frequency, converts it to original audio/video signal Trigger Circuit – Receives the amplified audio signal, has an output of a square wave which is added to the video and audio signals to be transmitted. This square wave is used to generate an alarm signal at the receiver. Monitor- device which allows parent to see child

Design Process of FAN05 Researched individual baby monitors with similar functions as our design. We reverse engineered the “Summer Infant Baby Monitor” which contained audio/video transmission with incorporated infrared LED for low light surroundings and a carrier wave of 900 MHz, transmitting audio and video up to a distance of 200 feet.

Video Camera

Transmitter

Analog Video Signal The horizontal sync (HSYNC): signals the beginning of each new video line. Back porch: used as a reference level to remove any DC components from the floating (AC-coupled) video signal. Active pixel region: Area where there is signal content and video data Front Porch: The end of a video signal frame Reference Value of the line frequency: kHz The signal consists of a horizontal sync signal, back porch, active pixel region, and front porch. National Instruments

Results of Video for FAN05 Video signal with no objects around lens National Instruments

Results of Video for FAN05 video signal when nelson's hand is approximately 7.5 inches from the lens video signal when nelson's hand is standing approximately 21 inches from the camera lens

Audio for FAN05 Audio signal detected by microphone, and analyzed by oscilloscope. Microphone signal: relatively no sound in the environment

Analog Audio Signal Results Microphone signal : music is playing on the computer volume 61, approximately 15 inches from computer speaker Microphone signal: music is playing on the computer volume 100,15 inches from computer speaker

Fundamental Frequency The fundamental frequency is the vibration frequency produced in the vocal cords. The fundamental frequency determines the pitch of the voice There are fluctuations in the fundamental frequency in infants which reflect different states of emotion.

Infant Cry Modes Infants have three modes of vocal mechanisms: -Phonation: the vocal cords are fully vibrating periodically at a frequency between 250 Hz and 650 Hz. -Dysphonation: turbulence noise is generated at the vocal cords and is modulated by vocal fold vibrations. Frequency between 650 Hz-850 Hz -Hyperphonation: when the frequency of the vocal cords shifts to 900 Hz Hz. For our purposes we are interested in this frequency range.

Diagram of Vocal Folds Phonation is the process of converting the air pressure from the lungs into audible vibrations. When the air passes through the elastic vocal folds and causes them to vibrate, the type of phonation is called voicing.

Characteristics of Infant Cries In the phonation mode the cry harmonics are distinct and clear. During dysphonation the harmonics become obscured by noise and occasionally disappear. ( Two month old infant)

Characteristics of Infant Cries

Filter Design Analog Filtering: Filtering accomplished by the use of a bandpass filter. Triggering that results from a cry reaching a certain threshold frequency. Due to frequency analysis, we saw infant cry frequencies ranged from 900 Hz Hz Pros: In Analog filtering, once it is simulated in MATLAB, it could be easily constructed into circuitry. Concerns: Do analog filters provide a filtering method that will trigger on the precise frequency range negating any other factors in the environment? Digital Signal Filtering: If a digital signal filtering algorithm is used then the microphone signal properties are compared with those of an infant crying. Upon detection the processor would send a control signal to the transmitter. Pros: Method involves digital filtering, thus modifications of algorithm could be accomplished on the computer. Detection algorithm could easily be modified in the need for better detection accuracy. Concerns: Developing detection algorithm could be complex thus time consuming.

Selected Design We have chosen Analog filtering: Reasoning: The detection of infant cry can be accomplished through the use of analog filters. We know that infant cries have a range of 900Hz-1200Hz, by designing a bandpass filter we could be able to trigger on a specified frequency range. The circuit could use a variable resistor to set the sensitivity to the desired frequency range.

The Trigger Circuit The trigger circuit starts with a child's cry that will be picked up by the microphone. Then the signal will be amplified and sent through a band pass filter. If the frequency of the voice is between 900 Hz and 1200 Hz then the signal will be rectified by the diode then the signal will pass through a low pass filter to eliminate the high frequency components.

The Trigger Circuit (cont.) The resulting DC signal will trigger one of the comparator inputs. Then a reference voltage of 0.5V will be connected to the second input of the comparator. When the rectified signal is lower than 0.5V then we have a low output. When the rectified signal is higher than 0.5V then we have a high output. When the output of the comparator is high this will trigger the reset pin at the TLC555 timing circuit generating a square wave output. The square wave is added to the video and audio signals to be transmitted. This square wave is used to generate an alarm signal at the receiver.

Pspice-Filter Circuit Design

Output of TLC555 Timing Circuit

Results of Pspice

Results of Constructed Circuit

Filtering Bandpass Properties 800 Hz900 Hz 1000 Hz1100 Hz

Results of Real Circuit Not triggering at 800Hz Triggering at 1100Hz Triggering at 1200Hz

Future Work The use of thermal sensors to detect changes in infant temperature.

References National Instruments 30?OpenDocument#2 Inline Inc. Microphones Acoustic Analysis of the Infant Cry Classical and New Methods: G. Várallyay Jr., Z. Benyó, A. Illényi, Z. Farkas, L. Kovács Automatic classification of infants cry- Dror Lederman Perceptual differences in infant revealed by modifications of acoustic features - Athanassios Protopapasa and Peter D. Eimas

Acknowledgements Professor Ekram Hassib Professor Emad A. Andarawis Gene Davison

Questions