Last Friday is the beginning of the project, and a lot of activities has been conducted. Firstly, we decided to design a AM transmitter and a AM receiver, because AM circuits are easier to be design when compared with FM circuits.
For better research, we surfed on the internet and find a large quantity of information of the AM transmitters and receivers.
The short range wireless AM transmitter and receiver can work at the frequency range from 540kHz to 1.6 MHz.
Transmitter modifies the input signals in order to cope with the limitations imposed by the channel. For lower-power transmitter, it is often used in communication systems and radio systems. A simple AM transmitter achieves amplitude modulation.
Receiver processes the received signal by reversing the signal modifications made at the transmitter. When the AM receiver receives the signal, after modulation passing through the audio amplifier, then spread to the earphone or speaker. Therefore, we can hear the sound or program.
Therefore, the transmitter and receiver as a pair are specifically designed to combat the deleterious effects of the channel to achieve more efficient information transmission.
The link below contains a number of designs of the AM circuits, which can be referred and is helpful for us to design the circuit.
Instructables: http://www.instructables.com
After working out the circuit design, we ordered the components.
For transmitter circuit,
555 timer chip
An NPN transistor
10nF capacitors ×2
1nF capacitor
1 kΩ resistors ×2
10 kΩ resistor
5 kΩ potentiometer
3.5mm female audio jack
male audio jack to jack connector
antenna
breadboard
For receiver circuit,
LM 386 op amp IC chip
1000μF capacitors ×2
100μF capacitor
9V battery
3.5mm female audio jack
earphones
The software Multisim and PSpice are also be used to build the circuits and analysis the characteristics of the circuits.
All the goals were achieved in Week 1. Next week, The real circuit should be made, especially, the receiver. Hope we can success next week :-D
没有评论:
发表评论