ppt and documentation of fpga manchester encoder and deccoder

Encoder and decoder applications

The radio frequency spectrum is full of noise and other signals, especially those frequencies where the operation of the unlicensed transmitter is allowed under the rules of part 15 of the FCC. When using a wireless remote control system it is desirable to have a way of filtering or ignoring those unwanted signals to prevent false data from being received. A simple way to accomplish this is to use an IC encoder in the transmitter and an IC decoder in the receiver. The encoder generates serial codes that are automatically sent three times and must be received at least twice before the data is accepted as valid by the decoder circuit. In the early days of "radio control", before these coding ICs were available, radio controlled garage doors were sometimes opened when they received transmissions from an overhead plane or from a bidirectional radio operating in area. Encoding and decoding is now used in most wireless control systems to avoid this type of interference. A GL-104 IC in an 18-pin DIP packet available in Glolab can be used as an encoder or decoder simply by changing the connection to a pin. These devices also offer more flexibility than standard encoder and decoder encoders. You need a GL-104 configured as an encoder for each transmitter and one that is configured as a decoder for each receiver. You will also need a 4 MHz ceramic resonator (CR) and a voltage detector (VDR) to use with each GL-104. The GL-104 will be used in the following application examples. These devices have four data channels.