Error performance on satellite circuits A typical uncoded bit error rate (BER) figure for satellite links is often cited as approximately one bit error in how many transmitted bits?
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A10^7 bits
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B10^3 bits
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C10^2 bits
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D10^10 bits
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E10^5 bits
Answer
Correct Answer: 10^7 bits
Explanation
Introduction / Context:Bit error rate (BER) benchmarks help designers specify link budgets, coding, and modulation. Satellite links without heavy forward-error correction historically achieve BERs around 10^-5 to 10^-7, while modern coded systems may reach 10^-9 or better.
Given Data / Assumptions:
- “Typical” satellite circuit with reasonable carrier-to-noise and modest coding.
- Comparative options span poor to excellent BER values.
Concept / Approach:For legacy or minimally coded links, BER ≈ 10^-6 to 10^-7 is a common planning value. Therefore, “one error in 10^7 bits” is a representative figure frequently quoted in introductory texts and exams.
Step-by-Step Solution:Translate phrasing: “one error in N bits” → BER ≈ 1/N.Select N consistent with typical uncoded or lightly coded satellite links: N ≈ 10^7.
Verification / Alternative check:Link budget tools often target post-demodulation BER ≤ 10^-6 for voice/data acceptability before higher-layer error detection/correction.
Why Other Options Are Wrong:
- 10^3 or 10^2: unacceptably high BER for most services.
- 10^10: extremely stringent and usually requires strong coding and high C/N.
- 10^5: achievable but not the “typical” textbook figure requested here.
Common Pitfalls:
- Confusing pre-FEC and post-FEC BER targets.
- Assuming a single universal BER; practical values depend on service class.
Final Answer:10^7 bits