What is the advantage of manchester coding in encoding audio data?

[shashi_reddy21]

what is the advantage of manchester coding in encoding audio data .?i want the coding format for a data .

 

[10kangstroms]

Re: manchester coding

what is the advantage of manchester coding in encoding audio data .?i want the coding format for a data .

See **broken link removed**. Manchester coding includes frequent transitions at the clock boundaries, making clock extraction with a phaselocked loop relatively simple.

 

[abhigopal]

manchester coding

refer behrouz fourouzan - data communication networks
Best for coding

 

[electron_boy]

Re: manchester coding

main advantages of manchester coding are 0 D.C. value of the signal. and synchronization.refer "digital communication"-simon haykin

 

[pixel]

Re: manchester coding

1 is coded as a +1 at the first, and -1 at the 2nd half of the bit interval.
0 is coded as a -1 at the first, and +1 at the 2nd half of the bit interval.
->dc=0

 

[as_518]

Re: manchester coding

the best advantage of manchester coding is that the clok is embaded in th signal hence the synchronization made easier.

 

[Bukitoo]

Re: manchester coding

Adventages:

1- Embended Clock: You can recovery the transmisor clock easy (evn if the bit train is the same)
2 - You dont have DC (less transmition power)

Disadventages:

1- the double bandwidth (compared with NRZ or other coding schemes)

 

[teteamigo]

Failure in Clock recovery of manchester coding like NRZ

I have a doubt:

NRZ-----------| 1 | 0 | 1 | 0 | 1 | 0 |
Manchester-|1 0|0 1|1 0 |0 1|1 0|0 1 |


This sequence generate a failure in clock recovery.

In this case the manchester signal have period=3/2*T.


The 0|0 adjacency don't have transitions, then impulse is impossible.


This don't matter if the carrier recovery system ( PLL) have hold time, but this isn't eternal.

Ex: 10Mbps-->T=1/2*(1/10M)=0.05us

if i have a word of 8 bits like the previous with Time duration=0,4us


The PLL should ensure that lock time is greater than 0,4us.

But today in applications that input clock varies, we need lock time small than the time that clock is constant.

 

[sbhalerao]

Re: manchester coding

There is a transition in every bit duration .. The transition density is high which makes the clock extraction using PLL easier. In other baseband encoding methods (eg- RZ unipolar) there is a DC value - this poses sgnificant problems in RF communication systems (like, transformer coupled repeaters cannot be used )
Manchester encoding has zero DC component...

 

[teteamigo]

Re: manchester coding

I want that people reads and understand my problem. It's very important that we don't give pocket answers.

 

[tkbits]

Re: Failure in Clock recovery of manchester coding like NRZ

The 0|0 adjacency don't have transitions, then impulse is impossible.

That isn't how clock recovery works. The PLL is the receiver reference clock. The transitions in the bit stream keep the PLL synchronized to the bit stream.

You start data transmission by sending sync bits. That locks the clock frequency. Then you send a sync pattern that tells the receiver where the clock bits and data bits are located.

If all intervals between transitions are small enough, the PLL will not drift too far from its locked frequency. "Small enough" may be several bit times, as in SDLC or USB.

PLL recovery relies on stable clocking. If you want variable clocking, you use a second clock signal line, as in IIC, SPI, and other similar protocols.

 

[teteamigo]

Re: Failure in Clock recovery of manchester coding like NRZ

The 0|0 adjacency don't have transitions, then impulse is impossible.

That isn't how clock recovery works. The PLL is the receiver reference clock. The transitions in the bit stream keep the PLL synchronized to the bit stream.

NRZ-10101010101010101010 translated to Manchester code give us waveform with a clock different from original.

Like


NRZ 11111111111111 or 000000000000000 don't have the regular frequency clock.

I made this comparison. And I explained why!!!

The transitions fault.


By other way I know that is a particular situation. But NRZ situation is wellknown and Manchester no.

 

[jjohn]

manchester coding

In telecommunication, Manchester code (also known as Phase Encoding, or PE) is a form of data communications line code in which each bit of data is signified by at least one voltage level transition. Manchester encoding is therefore considered to be self-clocking, which means that accurate synchronisation of a data stream is possible. Each bit is transmitted over a predefined time period.

Manchester coding provides a simple way to encode arbitrary binary sequences without ever having long periods without level transitions, thus preventing the loss of clock synchronisation, or bit errors from low-frequency drift on poorly-equalized analog links (see ones-density). If transmitted as an AC signal it ensures that the DC component of the encoded signal is zero, again preventing baseline drift of the repeated signal, making it easy to regenerate and preventing waste of energy. However, there are today many more sophisticated codes (8B/10B encoding) which accomplish the same aims with less bandwidth overhead, and less synchronisation ambiguity in pathological cases. Regardless of these losses, Manchester coding has been adopted into many efficient and widely used telecommunications standards, such as Ethernet.

To accomplish this, Manchester codes always have a transition at the middle of each bit period, and depending on the state of the signal, may have a transition at the beginning of the period as well. The direction of the mid-bit transition is what carries the data, with a low-to-high transition indicating one binary value, and a high-to-low transition indicating the other. Transitions that don't occur mid-bit don't carry useful information, and exist only to place the signal in a state where the necessary mid-bit transition can take place. Though this allows the signal to be self-clocking, it carries significant overhead as there is a need for essentially twice the bandwidth of a simple NRZ or NRZI encoding.

 

[teteamigo]

Re: manchester coding

To accomplish this, Manchester codes always have a transition at the middle of each bit period, and depending on the state of the signal, may have a transition at the beginning of the period as well. The direction of the mid-bit transition is what carries the data, with a low-to-high transition indicating one binary value, and a high-to-low transition indicating the other. Transitions that don't occur mid-bit don't carry useful information, and exist only to place the signal in a state where the necessary mid-bit transition can take place. Though this allows the signal to be self-clocking, it carries significant overhead as there is a need for essentially twice the bandwidth of a simple NRZ or NRZI encoding.

Good explaination. So I have an evidence of all time periodic event - mid-bit-transition.

Simple thing that i couldn´t remember because i only search the init-bit transition.

Thanks jjohn