This is the summary notes of the important terms and concepts in Chapter 9 of the book "Electronic Communications System" by Wayne Tomasi. The notes are properly synchronized and concise for much better understanding of the book. Make sure to familiarize this review notes to increase the chance of passing the ECE Board Exam.
Is the transmission, reception, and processing of information
with the use of electronic circuits.
Is defined as knowledge or intelligence that is communicated
between two or more points.
Is the transmittal of digitally modulated analog signals
(carriers) between two or more points in a communication system.
System involving the transmission of digital pulses.
The information signal is digital and the amplitude (V) of the
carrier is varied proportional to the information signal.
Amplitude Shift Keying ( ASK )
The information signal is digital and the frequency (f) of the
carrier is varied proportional to the information signal.
Frequency Shift Keying ( FSK )
The information signal is digital and the phase (θ) of
the carrier is varied proportional to the information signal.
Phase Shift Keying ( PSK )
A modulation where both the amplitude and the phase are varied
proportional to the information signal.
Quadrature Amplitude Modulation ( QAM )
Performs level conversion and then codes the incoming data
into groups of bits that modulate an analog carrier.
Is a highly theoretical study of the efficient use of bandwidth
to propagate information through electronic communications systems.
Is a measure of how much information can be propagated through
a communications system and is a function of bandwidth and transmission time.
The most basic digital symbol used to represent information.
Binary Digit / Bit
In 1928, _________ of Bell Telephone Laboratories developed a
useful relationship among bandwidth, transmission time, and information
In 1948, mathematician _________ (also of Bell Telephone
Laboratories) published a paper in the Bell System Technical Journal relating
the information capacity of a communications channel to bandwidth and
Claude E. Shannon
Simply represents a digit that corresponds to the number of
conditions, levels, or combinations possible for a given number of binary
Refers to the rate of change of a digital information signal,
which is usually binary.
Refers to the rate of change of a signal on a transmission
medium after encoding and modulation have occurred.
Sometimes called a symbol and could be encoded as a change in
the amplitude, frequency, or phase.
The minimum theoretical bandwidth necessary to propagate a
According to ________, binary digital signals can be
propagated through an ideal noiseless transmission medium at a rate equal to
two time the bandwidth of the medium.
The carrier is either “on” or “off” which is why amplitude-
shift keying is sometimes referred to as ________.
A logic 1 frequency (fm) for FSK.
A logic 0 frequency (fs) for FSK.
The mark and space frequencies are separated from the mark and
space frequencies are separated from the carrier frequency by the _________
and from each of by 2 Δf.
Peak Frequency Deviation (Δf)
_______ is the peak frequency deviation of the carrier and is
equal to the difference between the carrier rest frequency and either the
mark or space frequency.
A type of FSK detection wherein there is no frequency involved
in the demodulation process that is synchronized either in phase, frequency,
or both with the incoming FSK signal.
A type of FSK detection wherein the incoming FSK signal is
multiplied by a recovered carrier signal that has exact same frequency and
phase as the transmitter reference.
Is binary FSK except the mark and space frequencies are
synchronized with the input binary bit rate.
Continuous-Phase FSK ( CP-FSK )
A signal state-space diagram, is similar to a phasor diagram
except that the entire phasor is not drawn. Only the relative positions of
the peaks of the phasors are shown.
Is a product modulator; the output signal is the product of
the two input signals.
Detect and regenerates a carrier signal that is both frequency
and phase coherent with the original transmit carrier.
Coherent Carrier Recovery Circuit
Also known as quadrature PSK that is another form of
angle-modulated, constant-amplitude digital modulation.
Quaternary PSK ( QPSK )
A group of two bits.
It modulates the carrier that is in phase with the reference
It modulates the carrier that is 90 out of phase or in
quadrature with reference carrier.
Is two BPSK modulators combined in parallel.
The highest fundamental frequency present at the data input to
the I or the Q balanced modulator is equal to _______ of the input data rate.
The fastest output rate of change (baud) is also equal to
________ of the input bit rate.
The outputs of the product detectors are fed to the ________,
here they are converted from parallel I and Q data channels to a single
binary output data stream.
Bit Combining Circuit
Is a modified for of QPSK where the bit waveforms on the I and
Q channels are offset or shifted in phase from each other by one-half of a
( OQPSK )
The advantage of OQPSK is the _________ that must be imparted
Limited Phase Shift
With ________, three bits are encoded, forming tribits and
producing eight different output phases.
Group of 3 bits.
Also known as maximum distance code used to reduce the number
of transmission errors.
Converts the I/C and Q/C bit pairs to serial, Q, and C output
Group of 4 bits.
16-PSK can undergo only a _______ phase shift during
transmission and still retain its integrity.
Is an M-ary encoding technique where M = 8. The output signal
from this modulator is not a constant-amplitude signal.
8 – QAM
The process of introducing transitions (pulses) into the
binary signal using a prescribed algorithm.
It uses the same algorithm for scrambling to remove the
Is an alternative form of digital modulation where the binary
input is contained in the difference between two successive signalling
elements rather than the absolute phase.
Differential Phase-Shift Keying ( DPSK )
Data transmission rates in excess of 56 kbps can be achieved,
over standard telephone circuits using an encoding technique called ________.
Trellis Code Modulation ( TCM )
__________ at IBM Zuerich Research Laboratory developed TCM,
which involves using convolutional (tree codes, which combines encoding and
modulation to reduce the probability of error, thus improving the bit error
Defines the manner in which signal-state transitions are
allowed to occur, and transitions that do not follow this pattern are
interpreted in the receiver as transmission errors.
The distance between symbols on the constellation of the TCM
coding scheme on standard QAM.
Is the ratio of the average carrier power (the combined power
of the carrier and its associated sidebands) to the thermal noise power.
Carrier-To-Noise Power Ratio
Is simply the energy of a single bit of information.
Energy Per Bit
The phase relationship between signalling elements for BPSK
(i.e., 180° out of phase) is the optimum signalling format, referred to as
Two types of FSK systems.
Noncoherent ( Asynchronous ) And Coherant (
The transmitter and receiver are not frequency or phase
Local receiver reference signals are in frequency and phase
lock with the transmitted signals.