Looking for information on Manchester encoding and decoding?

manchester encoding?

hello
I need some info on manchester encode and decode.It is useful that someone describe the benefits of this method for transmitting data and its applications.
bye

**broken link removed**
XAPP339: Manchester Encoder-Decoder for Xilinx CPLDs v1.3 (10/02)

**broken link removed**
XAPP358: Wireless Transceiver for the CoolRunner CPLD Application Note v1.2 (12/02)

Hi 7rots51,

Benefits (+), drawbacks (-) and evens (=) of Manchester compared with NRZ (taken as a basic reference binary data format):

(=) It has the same theoretical performance (bit error probability vs. bit_energy / noise_spectral_density)

(-) Occuped bandwidth is double than NRZ (the main lobe of NRZ extends up to BR, and Manchester -also RZ- up to BR, BR being Bit Rate)

(+) Its power spectrum is null at DC, so it can be transmitted by non-lowpass channels. This allows the use of transformer coupling without problem. In the case or NRZ or RZ, the 'baseline' would be lost if you have a long string of data without transitions and the channel doesn't pass DC

(+) Synchronization is easy and more reliable because Manchester has al least one transition per bit. So less timing jitter.

Regards

Z

Encoding

/**********************************************************************
* Function Name: MancEnc *
* *
* Author: Christian *
* Description: Codificação Manchester *
* Argument(s): Data - Dado a ser Codificado *
* Return(s): DataEnc - Dado Codificado em Manchester *
**********************************************************************/
UINT16 MancEnc (UCHAR Data)
{
UCHAR Shift = 0x80;
UINT16 DataEnc = 0;

while(Shift > 0)
{
DataEnc <<= 2;
if(Data & Shift)
{
DataEnc |= 1;
}
else
{
DataEnc |= 2;
}
Shift >>= 1;
}
return(DataEnc);
}