Virtual Labs

Pass band implementation of Amplitude shift keying, Frequency Shift Keying, Binary Phase Shift Keying: Generation and Detection

In a passband ASK system operating over an AWGN channel, which factor most significantly degrades its performance at low SNR?

a: Phase distortion Explanation

Explanation

b: Amplitude sensitivity to noise Explanation

Explanation

c: Bandwidth inefficiency Explanation

Explanation

d: Non-coherent demodulation Explanation

Explanation

In coherent passband FSK systems, how is intersymbol interference (ISI) minimized?

a: By increasing the frequency deviation Explanation

Explanation

b: By using orthogonal frequencies Explanation

Explanation

c: By applying raised cosine filtering Explanation

Explanation

d: By differential encoding Explanation

Explanation

Compared to passband PSK, passband FSK is generally more robust in which type of communication channel?

a: AWGN channels Explanation

Explanation

b: Frequency-selective fading channels Explanation

Explanation

c: Additive impulsive noise channels Explanation

Explanation

d: Flat-fading channels with strong phase jitter Explanation

Explanation

Why is coherent detection preferred over non-coherent detection in passband PSK systems?

a: It allows simpler hardware implementation. Explanation

Explanation

b: It improves BER performance by recovering phase information. Explanation

Explanation

c: It reduces bandwidth consumption. Explanation

Explanation

d: It makes the system more robust to frequency offset. Explanation

Explanation

What limits the minimum frequency separation in passband binary FSK for orthogonality?

a: Carrier phase offset Explanation

Explanation

b: Modulation index Explanation

Explanation

c: Symbol duration Explanation

Explanation

d: Signal power Explanation

Explanation

In passband ASK systems, what is the main reason it is rarely used in power-constrained wireless applications?

a: It requires excessive bandwidth. Explanation

Explanation

b: It suffers from poor spectral efficiency. Explanation

Explanation

c: It has high peak-to-average power ratio (PAPR). Explanation

Explanation

d: It is highly susceptible to amplitude variations from fading. Explanation

Explanation

For Binary PSK in a passband system, what is the theoretical BER expression over an AWGN channel with coherent detection?

a: Q(√(2Eb/N0)) Explanation

Explanation

b: Q(√(Eb/N0)) Explanation

Explanation

c: 1/2 × erfc(√(Eb/N0)) Explanation

Explanation

d: exp(−Eb/N0) Explanation

Explanation

What is the impact of Doppler spread on passband PSK systems in mobile channels?

a: Causes symbol timing offset Explanation

Explanation

b: Induces amplitude fading only Explanation

Explanation

c: Destroys carrier phase coherence Explanation

Explanation

d: Improves diversity performance Explanation

Explanation

For coherent M-PSK, why does increasing M require higher SNR to maintain the same bit error rate?

a: Because the angular separation between adjacent constellation points decreases Explanation

Explanation

b: Because symbol duration decreases Explanation

Explanation

c: Because bandwidth decreases Explanation

Explanation

d: Because carrier frequency shifts Explanation

Explanation

In a passband PSK system over a fading channel, which factor primarily causes errors even if SNR is high?

a: Additive white Gaussian noise Explanation

Explanation

b: Rapid phase variations due to Doppler spread Explanation

Explanation

c: Symbol rate being too low Explanation

Explanation

d: Carrier frequency being too high Explanation

Explanation