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So what are they calling modulation?
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| meijin 2003-03-29, 11:12 pm |
| I don't have the study guide with me, so maybe someone else can look this up.
One of the questions I remember is asking about what modulation 802.11b uses at 11 Mbps. I always answer DQPSK (Differential Quaternary Phase Shift Keying). However, I was looking at the demo on cert21 and they say it is CCK or Complementary Code Keying. I was under the impression the breakdown was as follows:
1 Mpbs - DBPSK/Barker
2 Mbps - DQPSK/Barker
5.5 Mbps - DQPSK/CCK
11 Mpbs - DQPSK/CCK
To my understanding the DBPSK and DQPSK are the modulation technique. I cannot remember what they are calling CCK and Barker. Can someone look that up? And which is right?
Thanks! | |
| meijin 2003-03-29, 11:19 pm |
| I may have found the answer in my hand written notes. Under the section for FHSS, I have modulation and spreading written...and for that I have:
1 Mbps - 2GFSK/Barker
2 Mbps - 4GFSK/Barker
My understanding is the 2GFSK/4GFSK is the modulation and Barker is the spreading. Is this what the study guide has? Damn...I wonder if they have been looking for Barker or CCK as the modulation and this is one of the questions I have been missing? | |
| Evilphil 2003-03-29, 11:23 pm |
| quote:
Originally posted by meijin
I may have found the answer in my hand written notes. Under the section for FHSS, I have modulation and spreading written...and for that I have:
1 Mbps - 2GFSK/Barker
2 Mbps - 4GFSK/Barker
My understanding is the 2GFSK/4GFSK is the modulation and Barker is the spreading. Is this what the study guide has? Damn...I wonder if they have been looking for Barker or CCK as the modulation and this is one of the questions I have been missing?
I think your first answer was correct in your first post...
I want you to take the cert21 exam practice test to verify what I'm seeing. Email me at Evilphil69@aol.com and I'll give you my account info. | |
| rkp11 2003-03-29, 11:24 pm |
| According to CWNA Study Guide, Second Edition, page 313, table 8.10 :
2.4 GHz, DSSS, 802.11b at 11Mbps uses DQPSK modulation Technology and CCK Spreading code. | |
| meijin 2003-03-29, 11:27 pm |
| Thanks rkp11 and EvilPhil...that is what I thought...by the way...the question about the FHSS modulation is something you should remember...HINT HINT
Phil...I emailed you. |
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