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11.
64-QAM modulation alters which two of the following aspects of an RF signal?
- A.Frequency
- B.Amplitude
- C.Phase
- D.Quadrature
- Answer & Explanation
- Report
Answer : [B and C]
Explanation :
Explanation :
| Both 16-QAM and 64-QAM alter the amplitude and phase of a signal. |
12.
OFDM offers data rates up to 54 Mbps, but DSSS supports much lower limits.
Compared with DSSS, which one of the following does OFDM leverage to achieve
its superior data rates?
- A.Higher-frequency band
- B.Wider 20-MHz channel width
- C.48 subcarriers in a channel
- D.Faster chipping rates
- E.Greater number of channels in a band
- Answer & Explanation
- Report
Answer : [C]
Explanation :
Explanation :
| OFDM uses 48 subcarriers in a single 20-MHz-wide channel, allowing it to transmit data bits in parallel. DSSS uses a single 22-MHz channel with only one main carrier signal. |
13.
Which regulatory body allocated the 2.4–2.5-GHz band for industrial, scientific, and
medical use?
- A.IEEE
- B.ETSI
- C.ITU-R
- D.FCC
- Answer & Explanation
- Report
Answer : [C]
Explanation :
Explanation :
| The ITU-R allocated the ISM bands for global use. |
14.
The U-NII-1 band is used for which one of the following purposes?
- A.2.4-GHz wireless LANs
- B.5-GHz wireless LANs
- C.Medical applications
- D.Point-to-point links
- Answer & Explanation
- Report
Answer : [B]
Explanation :
Explanation :
| The U-NII-1 band is the first of four 5-GHz bands set aside for wireless LAN use |
15.
In the 2.4-GHz band, the FCC limits the EIRP of a point-to-multipoint link to which
one of the following maximum values?
- A.100 mW
- B.20 dBm
- C.50 mW
- D.36 dBm
- Answer & Explanation
- Report
Answer : [D]
Explanation :
Explanation :
| The EIRP is always limited to +36 dBm in the 2.4-GHz band, except in the case of point-to-point links. |
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