Serial interface and method for transferring digital data over a serial interface

A digital transmitting device for transmitting a serial sequence of data bits and a number of associated synchronization signals over a wired connection, comprising:

• primary transmitter means for converting a serial sequence of data bits into successive data signal levels in an output line, said data signal levels being selected from a first group of levels,
• secondary transmitter means for converting synchronization signals into synchronization signal levels on said output line, said synchronization signal levels being selected from a second group of revels which consists of different levels than said first group of levels,
• means for disabling the output of data signal levels into said output line for the time of outputting synchronization signal levels into said output line, and wherein
• said primary transmitter means comprise a first transmitter having a data input, an output and an enable or select input,
• said secondary transmitter means comprise a second transmitter having a data input, an output and an enable or select input,
• the digital transmitting device comprises a selection signal line, and
• said selection signal line is coupled to the enable or select input of said first transmitter with direct polarity and to the enable or select input of said second transmitter with reverse polarity.

A digital transmitting device for transmitting a serial sequence of data bits and a number of associated synchronization signals over a wired, comprising:

• primary transmitter means for converting a serial sequence of data bits into successive data signal levels in an output line said data signal levels being selected from a first group of levels,
• secondary transmitter means for converting synchronization signals into synchronization signal levels on said output line, said synchronization signal levels being selected from a second group of levels which consists of different levels than said first group of levels, and wherein
• said output line is a differential wired connection consisting of a first signal line and a second signal line, and
• said primary transmitter means is a low-voltage level differential transmitter.

A digital receiving device for receiving a serial sequence of data bits and a number of associated synchronization signals over a wired connection, comprising:

• primary receiver means, responsive to a first group of signal levels, for converting a sequence of successive data signal levels in an input line into a serial sequence of data bits,
• secondary receiver means, responsive to a second group of signal levels which consists of different levels than said first group of signal levels, for converting synchronization signal levels in said input line into synchronization signals, and wherein
• said primary receiver means is a low-voltage level differential receiver responsive to voltage signals at a certain first distance from zero, and
• said secondary receiver means comprises two parallel differential amplifiers coupled as level indicators to said input line with opposite polarities and responsive to voltage signals at a certain second distance from zero, which is larger than said first distance.

A portable terminal of a telecommunications system comprising a first circuit element and a second circuit element for processing digital image data consisting of data sequences and synchronization signal, comprising:

• within the first circuit element a digital transmitting device for transmitting a-serial sequence of data bits and a number of associated synchronization signals over a wired connection, said digital transmitting device comprising:
• primary transmitter means for converting a serial sequence of data bits into successive data signal levels in an output line, said data signal levels being selected from a first group of levels, and
• secondary transmitter means for converting synchronization signals into synchronization signal levels on said output line, said synchronization signal levels being selected from a second group of levels which consists of different levels than said first group of levels;
• and
• within the second circuit element a digital receiving device for receiving a serial sequence of data bits and a number of associated synchronization signals over a wired connection, said digital receiving device comprising:
• primary receiver means, responsive to a first group of signal levels, for converting a sequence of successive data signal levels in an input line into a serial sequence of data bits, and
• secondary receiver means, responsive to a second group of signal levels which consists of different levels than said first group of signal levels, for converting synchronization signal levels in said input line into synchronization signals, and
• wherein said output line from said primary transmitter means leads to said input line of said primary receiver means.

A digital transmitting device for transmitting a serial sequence of data bits and a number of associated synchronization signals over a wired connection, comprising;

• primary transmitter means for converting a serial sequence of data bits into successive data signal levels in an output line, said data signal levels being selected from a first group of levels;
• secondary transmitter means for converting synchronization signals into synchronization signal levels on said output line, said synchronization signal levels being selected from a second group of levels which consists of different levels than said first group of levels;
• and
• selection means connected to enable terminals of said primary and said secondary transmitters for enabling said primary and said secondary transmitters alternately with one of said transmitters being enabled while the other of said transmitters is disabled.

An interface between first and second components of a telecommunications system wherein the first component is a digital transmitting device that comprises a primary transmitter means and a secondary transmitter means, and the second component is a digital receiving device, the interface comprising:

• primary transmitter means for converting a serial sequence of data bits into successive data signal levels in an output line connecting with said digital receiving device, said data signal levels being selected from a first group of levels;
• and
• secondary transmitter means for converting synchronization signals into synchronization signal levels on maid output line, said synchronization signal levels being selected from a second group of levels which consists of different levels than said first group of levels to attain reduction of signal power and reduction of electromagnetic interference, and
• wherein said first arid said second components are located within a portable terminal of the telecommunications system, and said output line from said primary transmitter means leads to said digital receiving device.