In synchronous data communication, what is the name of the receiver-side equalizer that continually adjusts itself to compensate for changing line conditions?

Introduction / Context:Synchronous modems and modern digital receivers must undo channel distortion introduced by bandwidth limits, echoes, and frequency-dependent attenuation. Equalizers compensate these effects to restore symbol integrity at the detector.

Given Data / Assumptions:

• Channel characteristics may vary with temperature, load, or loop length.
• Receiver needs to maintain low error rates over time.

Concept / Approach:An adaptive equalizer updates its filter coefficients dynamically based on error signals (e.g., from training sequences or decision-directed feedback). This allows continuous compensation as conditions change, unlike fixed “compromise” settings that only suit an average case.

Step-by-Step Solution:

Verification / Alternative check:Constellation diagrams show tighter clusters after equalization; bit error rate (BER) improves compared to an uncompensated channel or a fixed compromise equalizer.

Why Other Options Are Wrong:

• Impairment equalizer/statistical equalizer: nonstandard terms in this context.
• Compromise equalizer: fixed setting chosen for typical loops; less effective as conditions vary.
• None: incorrect because adaptive equalizers are the standard solution.

Common Pitfalls:Confusing echo cancellers with equalizers; assuming a one-time calibration suffices on all lines; neglecting training duration impacts on startup latency.

Final Answer:Adaptive equalizer