Pulse or digital communications – Repeaters – Testing
Patent
1992-06-08
1994-06-28
Kuntz, Curtis
Pulse or digital communications
Repeaters
Testing
375 76, 375 94, 371 51, H04B 346, H04B 1700
Patent
active
053253973
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention described herein relates to a digital communication channel or link parameter monitor which can be used as a Bit Error Rate Monitor.
A communication channel or link parameter monitor can be used to assess a digital communication link or channel. By such assessment, information can be determined as to the nature of the Bit Error Rate associated with transmission of digital signals across the communication channel or link, as well as other channel or link parameters such as signal to noise ratio, fading and the type of noise affecting the link.
The present invention can be applied to any channel and terminal equipment through which digital signals are transmitted which constitute a digital communication channel or link and may be applied to any digital service including voice, data and video.
The present invention is not limited to the radio, telephony and like communication systems but can find application in any system where communication occurs and where continuous signals are used to communicate information, and such signals are interpreted into one of a plurality of symbols. Such systems include for example, optical disk reading, digital magnetic tape reading, compact disk audio disks and magnetic hard disks.
It will be appreciated that whilst the present invention is described herein in relation to communication between binary digital systems, it can be applied to communication between digital systems characterised by another number system base; for example ternary.
The present invention was conceived whilst conducting research into methods of determining a bit error rate associated with digital communication links. It has been realised that the present invention is applicable to a number of channel or link state parameters besides bit error rate. More will be said below in regard to the application of the present invention to other link state parameters.
2. Description of the Related Art
A link or channel state parameter is any parameter which characterises a communication link or channel. Examples of link state parameters are signal to noise ratio, eye pattern, interference type and bit error rate.
A communication channel is normally defined as the medium connecting a transmitter and a receiver. In the case of a radio link, the channel is often the atmosphere between the transmitting antenna and the receiving antenna; for an optical link, the channel would be the optical fibre.
A communication link is normally considered to include the following physical stages of a communication system: encoder, modulator, transmitter, channel, receiver, demodulator and decoder. The term link herein, unless contrary to the context, means the stages of a communication link listed above except for the decoder. This is because the received signal is tested prior to decoding. It will be appreciated that the majority of disturbances occur prior to this last stage.
In the situation of reading magnetic tape which has information digitally stored upon it, the channel mentioned above is the magnetic medium and a decision variable is the continuous valued signal which the detector interprets as digital information.
A demodulator within a receiver of a digital communication system uses a decision variable to interpret what symbol was sent. Whilst not limiting the meaning of decision variable, a decision variable is the parameter of the received signal which the demodulator interprets as a symbol. As examples, in the case of binary phase modulation, a decision variable is the phase component of the received signal; for an amplitude modulated signal the decision variable is the amplitude of the received signal after matched filtering; and for quadrature amplitude modulation there are two decision variables associated with phase and amplitude of the received signal respectively. In baseband systems, decision variable recovery is achieved by a line decoder which may be considered as an equivalent, in this regard, to a demodulator.
A decision variable is a continu
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Cook Stephen C.
Giles Timothy C.
Scholz Jason B.
Kuntz Curtis
The Commonwealth of Australia
Webster Bryan
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