Chapter 1 Data Communications and Networks Overview
... —must be enough to be detected —must be sufficiently higher than noise to be received without error ...
... —must be enough to be detected —must be sufficiently higher than noise to be received without error ...
CMPE 150 – Spring 06
... • If octet of all zeros and last voltage pulse preceding was positive encode as 000+-0-+ • If octet of all zeros and last voltage pulse preceding was negative encode as 000-+0+• Causes two violations of AMI code • Unlikely to occur as a result of noise • Receiver detects and interprets as octet of a ...
... • If octet of all zeros and last voltage pulse preceding was positive encode as 000+-0-+ • If octet of all zeros and last voltage pulse preceding was negative encode as 000-+0+• Causes two violations of AMI code • Unlikely to occur as a result of noise • Receiver detects and interprets as octet of a ...
Cable Testing and Cabling LANs and WANs
... • dB measures the loss or gain of the power of a wave. • Decibels are usually negative numbers representing a loss in power as the wave travels, but can also be positive values representing a gain in power if the signal is amplified • log10 implies that the number in parenthesis will be transformed ...
... • dB measures the loss or gain of the power of a wave. • Decibels are usually negative numbers representing a loss in power as the wave travels, but can also be positive values representing a gain in power if the signal is amplified • log10 implies that the number in parenthesis will be transformed ...
What is the convergence in the field of information and
... all the PSKs since it takes the highest level of noise or distortion to make the demodulator reach an incorrect decision. It is, however, only able to modulate at 1 bit/symbol and so is unsuitable for high data-rate applications. QPSK: Quadrature Phase-Shift Keying. QPSK uses four points on the con ...
... all the PSKs since it takes the highest level of noise or distortion to make the demodulator reach an incorrect decision. It is, however, only able to modulate at 1 bit/symbol and so is unsuitable for high data-rate applications. QPSK: Quadrature Phase-Shift Keying. QPSK uses four points on the con ...
IS- 162 Final Exam Winter 2011
... Look at the table. T1 is the basis. All the T carriers are derived therefrom. 8. [ D ] (ABCD) Some common modulation modes used in RF communications are: A FM -- Frequency Modulation B AM – Amplitude Modulation C FSK – Frequency Shift Keying (for data) D All of the above We talked about AM and FM s ...
... Look at the table. T1 is the basis. All the T carriers are derived therefrom. 8. [ D ] (ABCD) Some common modulation modes used in RF communications are: A FM -- Frequency Modulation B AM – Amplitude Modulation C FSK – Frequency Shift Keying (for data) D All of the above We talked about AM and FM s ...
Background And Preview
... 0.8 Analog and Digital Types of Communications a. Guidelines of designing the transmitter and the receiver - Encode/modulate the signal,transmit it over the channel and produce an ’’estimate” of the original signal at the receiver output that satisfies the requirements - Do all of this at an afford ...
... 0.8 Analog and Digital Types of Communications a. Guidelines of designing the transmitter and the receiver - Encode/modulate the signal,transmit it over the channel and produce an ’’estimate” of the original signal at the receiver output that satisfies the requirements - Do all of this at an afford ...
Basic Communications Theory
... transmitted over a transmissions medium without distorting the signals. ...
... transmitted over a transmissions medium without distorting the signals. ...
CSC 335 Data Communications and Networking I
... of bits sent per cycle can be increased if the encoding scheme permits multiple bits to be encoded in a single cycle of the carrier. • ASK and FSK work well but require at least one cycle of a carrier wave to send a single bit. • PSK changes the timing of the carrier wave abruptly to encode data. Su ...
... of bits sent per cycle can be increased if the encoding scheme permits multiple bits to be encoded in a single cycle of the carrier. • ASK and FSK work well but require at least one cycle of a carrier wave to send a single bit. • PSK changes the timing of the carrier wave abruptly to encode data. Su ...
Quadrature amplitude modulation
Quadrature amplitude modulation (QAM) is both an analog and a digital modulation scheme. It conveys two analog message signals, or two digital bit streams, by changing (modulating) the amplitudes of two carrier waves, using the amplitude-shift keying (ASK) digital modulation scheme or amplitude modulation (AM) analog modulation scheme. The two carrier waves, usually sinusoids, are out of phase with each other by 90° and are thus called quadrature carriers or quadrature components — hence the name of the scheme. The modulated waves are summed, and the final waveform is a combination of both phase-shift keying (PSK) and amplitude-shift keying (ASK), or (in the analog case) of phase modulation (PM) and amplitude modulation. In the digital QAM case, a finite number of at least two phases and at least two amplitudes are used. PSK modulators are often designed using the QAM principle, but are not considered as QAM since the amplitude of the modulated carrier signal is constant. QAM is used extensively as a modulation scheme for digital telecommunication systems. Arbitrarily high spectral efficiencies can be achieved with QAM by setting a suitable constellation size, limited only by the noise level and linearity of the communications channel.QAM is being used in optical fiber systems as bit rates increase; QAM16 and QAM64 can be optically emulated with a 3-path interferometer.