Circuits > Security and other sensors and detectors > 4 channel Telemetry System
4 channel Telemetry System
Basic Description
Basic Idea for the the project is to transmit the data from one point to
another, this transmission may be wireless or with wire, well wireless is more
enhance technology than with-wire transmission so we adopted wireless
transmitting and receiving data. This project transmits 4 types of data by
different types of sensors. They include Temperature sensor, Fuel level Sensor,
Pressure sensor and rpm sensor. These all sensors have analog output in the form
of voltages so we have to convert it into digital data then we will able to
transmit.
Why convert analog into digital data?
Well we converted analog data into digital data. Why? Because four different
types of data are being transmitted trough one channel so multiplexing is
required. Due to this we used a digital switch which multiplexed the four data
and convert it into digital form one by one. Note: Transmitter range 12-15 feet
Data transmission
Block Diagram shows the data Transmission of the message signal by some
modulation process.
Data Receiving
After receiving Data from receiver, it will be demodulate after the process
of demodulation we will get the real data which we required and we want to
transmit and we can easily display it. Note: Transmitter Works on 98 MHz
Function Block Diagramm
Circuit Diagram
Circuit Description
| This is the circuit for the project Section A of the
circuit is receiving signals from the four sensors, here we use an IC M4066
this is just an analog as well as digital switch which have three four input/outputs
having a controlling signal pin which controls the data flow in the circuit.
This controlling is made by the pins of microcontroller with ports 2.1-2.4.
As these all signals are analog signals, so we have to convert it into
digital data by converter called Analog to Digital Converter ADC. For this
purpose we used an IC ADC0804. this will convert the analog signal in to
digital equivalent. The main thing is that Why we analog to digital
converter??
Due to the fact that we have three sensors and we have to transmit these
signals so multiplexing is required and this multiplexing is done in the
digital signals that’s the basic reason of using this analog into digital
converter. The output of the digital 8 bit signal will go into the
controller’s port 1.0-1.7.
After entering data into microcontroller it will transmit by transmitter. |
 |
 |
Well this is the end of section A of the circuit. Here another section
of the circuit which is the transmission sections. Let explore this part
of the circuit. To transmit some signal we have to modulate this signal to
transmit it for far distance. Well the modulation circuit is built in the
transmitter circuit. Here we use Frequency Modulation, the main aspect is
that frequency modulation is easier to use can be transmit through a
distance which we required, this is near about 2 Km. so in Radio
Frequencies FM is widely use for the data transmission. This transmitter
transmits the signal on 102 MHz.
The Output wave form is just like square wave not exactly. Well we can say
that the wave form is just a square wave form. Here we cant describe the
exactly wave form because oscilloscope is required for the purpose.
|
Data Flow Diagram
Data Sheet
Source code:
4066.asm
4066.hex
4066.obj
Calculations for downlink
1. Free space path loss at distance 2km is 78.285dB
2. Frequency 98 MHz
3. Effective Isotropic radiated Power is 9dB
4. Antenna gain is 10
5. radiated power is 0.8W
6. Carrier to noise ratio C/N = 159.35dB can’t calculate satellite gain and
additional atmospheric losses because we haven’t much knowledge about it.
What Next??
1.
increase the range up to 2Km
2.
output voltage at receiving side be 5V
3.
What type of antenna can be used for transmission and
receiving data?
4.
What type of amplifier will use for transmitting and
receiving power?
5.
If less effective antenna will use on transmission side and
high effective antenna is used for receiving side then what will it effects?
Title: 4 channel Telemetry System
Source: www.electronics-lab.com
Published on: 2005-02-10
Reads: 1130
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