GPS Signal Bands – Which of the following is a correct GPS L1 frequency? Select the option that correctly states the L1 carrier frequency used by GPS.
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AL1 with frequency 1520 MHz
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BL1 with frequency 1575.42 MHz
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CL1 with frequency 1227.6 MHz
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DL1 with frequency 1280.43 Hz
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EL1 with frequency 1625.00 MHz
Answer
Correct Answer: L1 with frequency 1575.42 MHz
Explanation
Introduction / Context:GPS transmits on multiple carrier frequencies, historically L1 and L2, with L5 added for safety-of-life and advanced civil use. Knowing the correct frequencies is essential for receiver design, interference analysis, and multi-frequency positioning techniques.
Given Data / Assumptions:
- Legacy GPS civil signal on L1 (C/A code) is widely used.
- L2 and L5 are additional carriers for dual/triple-frequency solutions.
- We seek the exact L1 frequency value.
Concept / Approach:
GPS L1 carrier is defined as 1575.42 MHz (which equals 154 * 10.23 MHz). L2 is 1227.60 MHz (120 * 10.23 MHz), and L5 is 1176.45 MHz (115 * 10.23 MHz). Any deviation from these precise values indicates a different band or a distractor.
Step-by-Step Solution:
Recall precise L1: 1575.42 MHz → matches option b.Check others: 1520 and 1625 MHz are not GPS L1; 1227.6 MHz is L2, not L1.1280.43 Hz is nonsensical (wrong unit and magnitude).Verification / Alternative check:
GNSS interface specifications list L1 = 1575.42 MHz; this value is standard across receiver documentation.
Why Other Options Are Wrong:
They either correspond to other bands, incorrect numbers, or incorrect units.
Common Pitfalls:
Mixing up L1 and L2, or not noticing frequency units (Hz vs MHz).
Final Answer:
L1 with frequency 1575.42 MHz