RS232 wireless computer link

This is an idea of designing a RS232 wireless unidirectional computer link. This system includes two separate devices which allow a transmitter connected to a RS232 port of the first computer to communicate with the receiver connected to a RS232 port of the second computer. Each device will act as a self-contained independent system. The data will be sent over RF waves on a chosen carrier frequency which could be 315 MHz, 418 MHz or 433 MHz. The modulation technique used is Frequency Shift Keying (FSK) which converts the logic level data from RS232 serial port to radio frequency. Amplitude Shift Keying (ASK) also can be used to modulate this data as its alternative modulation method. There are several objectives to be archived in this project, firstly it is to choose the allowable carrier frequency as mentioned earlier and also a suitable modulation scheme is required for the design. The second objective of this project is to construct an RS232 wireless unidirectional computer link between PCs. The method for doing this can either be RF carrier, acoustic or optical link. It is only one transmitter and one receiver for demonstration purposes. The design can send data from one computer to the other computer via RS232 port wirelessly. Finally is to ensure that the design is a system that could be used for further development of bi-directional communication between a PC.

The design uses the AM Hybrid Transmitter and AM RF Receiver modules at 433MHz. The interface circuits used was the level converter and buffer. As usual the level converter is used to convert the RS232 level to TTL/CMOS level. In order to match the modules with the level converter, a buffer circuit is required. Buffer in the transmitter part is the same as in the receiver, but it performs different functions.

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