# Question 2.5: For the QPSK modulator shown in Figure 17, construct the tru......

For the QPSK modulator shown in Figure 17, construct the truth table, phasor diagram, and constellation diagram.

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For a binary data input of Q = 0 and I = 0, the two inputs to the I balanced modulator are -1 and sin $ω_{c}t$, and the two inputs to the Q balanced modulator are -1 and cos $ω_{c}t$. Consequently, the outputs are

I balanced modulator = (-1)(sin $ω_{c}t$) = -1 sin $ω_{c}t$
Q balanced modulator = (-1)(cos $ω_{c}t$) = -1 cos $ω_{c}t$

and the output of the linear summer is

-1 cos $ω_{c}t$ – 1 sin $ω_{c}t$ = 1.414 sin($ω_{c}t$ – 135°)

For the remaining dibit codes (01, 10, and 11), the procedure is the same. The results are shown in Figure 18a.

Question: 2.15

## For a QPSK system and the given parameters, determine a. Carrier power in dBm. b. Noise power in dBm. c. Noise power density in dBm. d. Energy per bit in dBJ. e. Carrier-to-noise power ratio in dB. f. Eb/N0 ratio. C = 10^-12 W fb = 60 kbps N = 1.2 × 10^-14 W B = 120 kHz ...

a.  The carrier power in dBm is determined by subs...
Question: 2.13

## For an 8-PSK system, operating with an information bit rate of 24 kbps, determine (a) baud, (b) minimum bandwidth, and (c) bandwidth efficiency. ...

a.  Baud is determined by substituting into Equati...
Question: 2.11

## For a 16-QAM modulator with an input data rate (fb) equal to 10 Mbps and a carrier frequency of 70 MHz, determine the minimum double-sided Nyquist frequency (fN) and the baud. Also, compare the results with those achieved with the BPSK, QPSK, and 8-PSK modulators in Examples 4, 6, and 8. Use the 16 ...

The bit rate in the I, I′ , Q, and Q′ channels is ...
Question: 2.10

## For a quadbit input of I = 0, I′ = 0, Q = 0, and Q′ = 0 (0000), determine the output amplitude and phase for the 16-QAM modulator shown in Figure 33. ...

The inputs to the I channel 2-to-4-level converter...
Question: 2.9

## For a tribit input of Q = 0, I = 0, and C = 0 (000), determine the output amplitude and phase for the 8-QAM transmitter shown in Figure 30a. ...

The inputs to the I channel 2-to-4-level converter...
Question: 2.8

## For an 8-PSK modulator with an input data rate (fb) equal to 10 Mbps and a carrier frequency of 70 MHz, determine the minimum double-sided Nyquist bandwidth (fN) and the baud. Also, compare the results with those achieved with the BPSK and QPSK modulators in Examples 4 and 6. Use the 8-PSK block ...

The bit rate in the I, Q, and C channels is equal ...
Question: 2.7

## For a tribit input of Q = 0, I = 0, and C = 0 (000), determine the output phase for the 8-PSK modulator shown in Figure 23. ...

The inputs to the I channel 2-to-4-level converter...
Question: 2.6

## For a QPSK modulator with an input data rate (fb) equal to 10 Mbps and a carrier frequency of 70 MHz, determine the minimum double-sided Nyquist bandwidth (fN) and the baud. Also, compare the results with those achieved with the BPSK modulator in Example 4. Use the QPSK block diagram shown in ...

The bit rate in both the I and Q channels is equal...
Question: 2.17

## Which system requires the highest Eb/N0 ratio for a probability of error of 10^-6, a four-level QAM system or an 8-PSK system? ...

From Figure 49, the minimum E_{b}/N_{0}[/la...
From Figure 48, the minimum E_{b}/N_{0}[/la...