MEASURING THE TEMPERATURE AT
A DISTANCE USING TELEPHONY
SYSTEM
Automation
seminar(telecommunication
engineering)
t94772(Siddhartha Lama)
Introduction
• Telephone has become mainstay in modern communication. People
can easily communicate with others around the world or in the
office down the block without ever having to leave their desk.
• They make information flow more efficient and timely as a result.
We use the telephone for end to end communication.
• The enhancement in end to end communication our purpose is a
combination of the RF and the telephone.
• To facilitate the communication effectiveness, here, we use RF
module and the telephone line with DTMF to measure physical
parameters like temperature (pressure, wind, ice, etc, time
permitting) of remote area with the help of respective sensors.
Objective
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The main objectives of this project are
Expand the capabilities of the existing communication.
Allow users to know the weather conditions of remote
area and hardly accessible area.
To encourage the service providers to provide this
facility in their communication services.
To enhance the communication services by allowing
transmission of remote data
Tourism can be enhanced by knowing the remote area
weather condition like Everest base camp etc
System Requirements
HARDWARE:
* LM 35 temperature sensor
• 89c52 microcontroller
• RF modules(FS 1000s)
• DTMF encoder-um91215A
• DTMF decoder-MT8870
• Crystal oscillators
• NE 741(op-amp)
• LCD(16 pin)
Software:
c programming, VHDL
Block diagram
Methodology
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The total hardware of the system can be broadly
classified into nine units:
1. input units.
2. ADC units.
3. Microcontroller units.
4. RF units.
5. DTMF encoder unit.
6. Injection unit.
7. Recover unit.
8 . DTMF decoder unit.
9. Output/display unit.
Methodology
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Signal conditioning of signal(data) from temperature sensor (LM 35) is performed with the help of zener diode and
op-amp.
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This signal is fed to the control mode ADC which gives 8 bit digital output by performing three functions namely
sampling, quantization and encoding which is given to the input of microcontroller.
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After serialization, these data are passed to the RF transmitter module through transmitting pin 3.1 of
microcontroller.
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RF transmitter module transmit data which is received by RF receiver module located at intermediate distance
and passed to the microcontroller through the receiving pin 3.0 of
microcontroller and finally to a port.
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These data are loaded onto the DTMF encoder which gives corresponding tone.
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Now, DTMF encoder output is injected onto the telephone line with the help of injection circuit.
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The injected signal is recovered at the final destination end with the help of recover circuit.
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The recovered signal is passed to the DTMF decoder circuitry which decodes DTMF tones into
corresponding 4 bit digital data which is fed to the microcontroller.
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Finally, after converting binary data into ASCII, the data are displayed on the LCD
Expected Output
• Our project is mainly aimed at the places which may
not be connected to direct PSTN lines but the main
PSTN office may be a little distance away from the
area of concern.
• We install sensors at that area and transmit the
information conveyed by them to nearest telephone
stations by the use of RF transmitter and receiver.
• We then encode the information to sent via telephone
lines and receive the output at the desired destination.
• After decoding the data we could display the desired
result in the users LCD.
Conclusion
• For the enhancement in end to end
communication ,our purpose is a combination
of the RF module and the telephone. To
facilitate the communication effectiveness,
here, we use RF module and the telephone
line with DTMF to measure physical
parameters like temperature (pressure, wind,
ice, etc, time permitting) of remote area with
the help of respective sensors.
References
• http://talkingelectronics.com/projects/circuits
onweb/circuitsonweb.html
• http://www.8051projects.net/downloads
167.html
• http://www.planet-sourcecode.com/vb/defult.asp?lngWid=3#categories