Interfacing PIC with PC via USART via wireless

Anyway, the data to be transmitted is a byte which represents the status of the PIC's port.

Additional Q: I attached an LED to between the output of RF receiver and Gnd. I noticed the LED was constantly blinking although the transmitter is OFF.

Zacky

Often this type of receiver hunts for any signal it can find.
With the transmitter off it will amplify noise.
You may only get a useful result with the transmitter on.
If switching the transmitter on makes no difference, the transmitter may be the
problem.
Have you got good antennas on both modules ?

Also the blinking rate varied with different values of caps which is connected between the supply rail (i.e: +5V and GND). Does the caps plays a major role is this problem?

Zacky

Presumably the receiver is picking up noise from the power supply.
A good power supply filter needs small high frequency caps as well as large power caps.
Try some ferrite beads as well.

Could you use another power supply ?

I used wires at the length described on the datasheet. The technician told me, its ok to use wires. I tried switching power supply, still the same. I did some research on several other websites. One of them stated that the input to the RF modules are usually AC coupled and the connection directly to the USART/serial port for data transmission will not produce the desired output. He suggested to use Manchester Encoding scheme. So, was my circuit wrong?

that the input to the RF modules are usually AC coupled and the connection directly to the USART/serial port for data transmission will not produce the desired output. He suggested to use Manchester Encoding scheme. So, was my circuit wrong?

Zacky

Could be
It's easy enough to put a small capacitor between the PIC and the transmitter.

I'd concentrate on getting your test led to flash in response to the transmitted signal
for now,and not worry so much about sending real data.

Try a range of baud rates, some may transmit better that others.

Out of curious, I connected the RF module to 2 PICs instead of PC-PIC, the receiving PIC managed to pick up some signals but missed some signals. I programmed the transmitter PIC to transmit characters from A-Z, only capital letters, and the receiver did not capture all the signals. Some data was missed. The interval between the transmission was 1sec, so that I can observe the data on LCD before it changes. So my Q: can RF modules be connected directly to serial port of PC. If the RF transmission between PIC is fine, I'm going to connect in such: PC-PIC-RX/TX....RX/TX-PIC. As long as I can get a bidirectional communication between the PIC and PC via wireless.

The baud rate used for my PIC-PIC communication was 1200. Tried several baud rates (600/1200/2400/9600). But all gave the same result.

first dont keep modules too close, that may cause noise sometimes. keep baud low as its recommended.

you cannot connect modules directly to serial port you need Max232 in between.