| Author |
WLAN QoD #3 (03/29/03)
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| meijin 2003-03-29, 12:27 pm |
| When discussing RF propagation or the length of an RF link, which items will effect it?
(Choose all that apply)
A. Transmission power
B. Time/season of year
C. Antenna Type
D. Environment
E. Channel being used
F. Frequency of the transmission
G. All of the above
H. None of the above | |
| Evilphil 2003-03-29, 5:49 pm |
| I'm gonna say A, B, C, and D...
This is one of those vague questions like the ones on the test. Does environment refer to weather? | |
| ccieToBe 2003-03-29, 6:52 pm |
| G. | |
| Evilphil 2003-03-29, 8:25 pm |
| quote:
Originally posted by ccieToBe
G.
According to page 260 of the Official study guide, "three things will affect the range of an RF link: transmission power, antenna type and location, and environment."
They go on to explain the three on the following page. I also remember somewhere in the book where it mentions seasonal pattern changes is RF propagation. | |
| meijin 2003-03-29, 9:06 pm |
| Keep reading in the study guide EvilPhil...they mention the main ones and then at the end they add another...see what I mean? | |
| Evilphil 2003-03-29, 9:10 pm |
| I've read it once, and re-skimmed it 3 times for compartmental information... Where does it mention the other one? | |
| meijin 2003-03-29, 9:16 pm |
| I don't have the book right in front of me, but I remember it and have it down in my handwritten notes. At then end they talk about frequency and how that can be an effect as well. 900 MHz is more "stable" than 2.4 GHz and how 2.4 GHz is more "stable" than 5 GHz, etc.
Find it? I can post the exact reference on Monday when I get back to the office. I am studying off my hand written notes now...probably because I have taken the test so many damn times!  | |
| wirelessboy 2003-03-29, 9:20 pm |
| my answer would be G
i dont see much difference between E and F, please explain later
regards | |
| Evilphil 2003-03-29, 9:33 pm |
| quote:
Originally posted by meijin
900 MHz is more "stable" than 2.4 GHz and how 2.4 GHz is more "stable" than 5 GHz, etc.
Understanding that the period of each wave is larger in the lower frequencies, I can see why one would be inclined to lean toward that (the wave loses amplitude with higher frequencies at the same distance)... However, when do you determine when they are asking you info from the book, or info from actual real world application. Microsoft does this also... | |
| rkp11 2003-03-29, 10:59 pm |
| I agree with your and meijin's concern fully. No doubt, the offical study guide is very good and informative, but as a study aid, it is like an oceanic unsolved jigsaw puzzle. Things pop in and out, in very suttle sentences, that need to be put back co-hesively.
BTW, in the site surveying chapter, they leave an open ended question on whether the plane engine noise effect the performance of the LAN ?
any thoughts ! feedback ! | |
| ccieToBe 2003-04-01, 8:03 pm |
| I've not done any studying for the CWNP exam, so I'm not sure what the book answer is. I do run a wireless ISP though, and have seen every one of these issues affect performance:
A - this should be obvious
B - think about how the water content and vegetation on trees varries.
C - a parabolic's going to give you a lot more range then a rubber ducky
D - humidity and rain are factors
E - I tune each access point that I install the the channel with the least amount of interference. Cordless phones spew a ton of noise at 900MHz and 2.4GHz.
F - frequency - definately a factor. I established a link at 900MHz a couple weeks ago that was impossible to establish at 2.4GHz. The level of noise also varries according to frequency | |
| Evilphil 2003-04-01, 8:38 pm |
| I'm going to revise my previous answer.
A, B, C, D, and F. Within each frequency band, it is understandable that the wavelength is smaller the higher you get. However, I think what they're looking for is theory rather than incremental real world knowledge.
With all things equal, what you're experiencing has more to do with interference than RF propagation. | |
| meijin 2003-04-01, 9:40 pm |
| CCIEToBe:
I'm not arguing the point...but with all of the Cisco certs that you have you should know that there is a right answer and there is a Cisco answer. On the test Cisco rules. Same way with Planet3....they indicate the answers that I outlined and that is what they want to see on the test...the real world be damned...so to speak. |
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