Midterms_COM8

Higher than

The bit rate is ______ the baud rate if multiple level encoding is used.

300 bps

FSK is used primarily in low-speed modems capable of transmitting data up to a speed of

QAM, FSK, and PSK

Digital modulation technique used in modems.

Binary

M-ary is a term derived from the word

Phase referencing

The process of extracting a phase-coherent reference carrier from a received signal

Gaussian

It refers to the shape of a filter that is used before the modulator to reduce the transmitted bandwidth of the signal

Recovered from the BPSK signal

The carrier used with a BPSK demodulator is

Biphase modulation

With _____, two output phases are possible for a single carrier frequency

PAM

It is used as an intermediate form of modulation with PSK, QAM, and PCM

Trellis coding

In QAM modems, _____ adds extra bits to improve performance on a noisy line.

16

How many points will be on the constellation diagram of a QAM system using 8 phase angles and 2 amplitude levels?

OQPSK

CDMA system commonly uses

Pi/4 DPSK

IT is a system commonly uses for TDMA and PCS systems.

Signal-state space diagram

In a _____, only the relative positions of the peaks of the phasors are shown

Baud rate

The number of amplitude, frequency, or phase changes that take place per second is known as the

23 dBk

For an equivalent noise bandwidth of 10 MHz and a total noise power of 0.0276 pW, determine the equivalent noise temprature.

45 degrees

IN 8-PSK, the angular separation between two adjacent phasor is

FSK

The oldest and simplest form of modulation used in modem is

1000 Hz

Find the bandwidth for a QPSK signal transmitting at 2000 bps

Binary FSK

It is used for low performance, low cost, asynchronous modems.

Information Density, Spectral Efficiency, and Bandwidth Efficiency.

It refers to how well a specific modulation technique produces a maximum data rate in a minimal bandwidth.

Lower

Coherent OOK needs a ______ signal-to-noise ratio than incoherent OOK for a given BER

FSK

It is used for transmitting burst of data over systems that are mainly analog

FSK

It is used for low-data rate applications such as pagers

PSK and QAM

Modems capable of transmitting at standard higher rates of 1200, 2400, 4800, and 9600 bps use

Gray code

It is used to reduce the number of transmission errors

DPSK

A carrier recovery circuit is not needed with

AFSK

It is a variant of FSK that uses an audio tone of two or more different frequencies to modulate a conventional analog transmitter for data transmission

Bandwidth Efficiency

It is a ratio of data rate to transmission bandwidth.

1928

What year was the Hartley's law developed?

Squaring loop

A common method of achieving carrier recovery for BPSK is the ________.

Information density

It used to compare the performance of one digital technique to another.

QAM

A 9600 baud rate signal can pass over the voice-grade telephone line if which kind of modulation is used?

1948

When was the Shannon-limit for information capacity developed?

4000

Calculate the bits per second capacity of a system sending 1000 symbols per second with 16 possible states per symbol.

Balanced modulators

The basic modulator and demodulator circuits in PSK are

QAM

It is the most popular system to achieve high data rates in limited bandwidth channels.

19.77 dB

Determine the minimum C/N ratio for an 8-PSK system when the transmission rate is 60 Mbps, the minimum energy of bit-to-noise density ratio is 15 dB, and the receiver bandwidth is equal to the minimum Nyquist bandwidth.

FSK

Slow speed modems use

40.5 dB

Determine the energy of bit-to-noise density ratio when the receiver input carrier is -85 dBW, the receiver input noise temperature is 400 K, and a 50-Mbps transmission rate is used

-200.8 dBW

Determine the noise density for a receiver with an input bandwidth of 20 MHz and an equivalent noise temperature of 600 K.

FSK

The most common modulation system used for telegraphy is

2.641 V, 1.082 V

In 8-PSK, the C bits determine the magnitude of the output analog signal which have the values of logic 1 = ___ and logic 0 = _____

19 dB

Determine the minimum C/N ratio for a QSK system when the transmission rate is 80 Mbps, the minimum energy of bit-to-noise density ratio is 16dB, and the receiver bandwidth is equal to the minimum Nyquist bandwidth

26.18 dB

Determine the energy per bit-to-noise density ratio when the receiver input carrier is -100 dBW, the receiver input noise temperature is 290 K, and a 60-Mbps transmission rate is used.

OOK

Data transmission by varying the amplitude of the transmitted signal.

Twice

The channel capacity is _____ the channel bandwidth when no noise is present

GMSK

Global system for Mobile Communication commonly uses

Deviation ratio

It is the modulation index that yields the widest output bandwidth

Balanced modulator

The circuit used to demodulate BPSK is a