# Using Spectrum Anaylsis

Can anyone give me an idea what i should be seeing with the spectrum anaylsis? I have all green indicators on all freq’s. i assume that if i had interference that the color would be something else?

Refresh the screen a few times and montior it as long as you possibly can to try to see any frequency hopping devices. Then look at the current and max values. Strong signals would be indicated by the green bars moving more to the right. You will want to use a frequency that has the lowest power value. Example a 1" green bar is better than a 5" green bar.

here are the two pictures from the new users manual…based off what you said Canopy_Support I’m a little confused.

 Strong signals would be indicated by the green bars moving more to the right. You will want to use a frequency that has the lowest power value.

that tells me that i would want to use anywhere from 913.0 to 919.0 or down at the bottom 927.0 to 930.0 with 930.0 being the best

however based off of this quote
 Example a 1" green bar is better than a 5" green bar.

a shorter bar to me means a higher power level like 900.00 having a -61 but it’s green bar is shorter than the rest

i’m guessing on the 2.4 tabular graph the ideal frequency to select would be 24475 with a power level of -72dBm

am i correct in saying that the ideal 900Mhz frequency would be 930.0 as well

i’m asking because i don’t understand how a 1’’ green bar is better than a 5’’ green bar…when the shorter the bar the higher the number and i thought you want low numbers for that

wav11 wrote:

i'm asking because i don't understand how a 1'' green bar is better than a 5'' green bar...when the shorter the bar the higher the number and i thought you want low numbers for that

What you are looking for is the quietest frequencied to use. The fewer signals present at a given frequency, the shorter the bar. For the purpose of setting up your gear you should use th frequencies that have the least amount of interference.

While the number is larger also not that it is a negative number. In our numbering system the number -61 is larger than -91 although in absolute terms 91 is higher than 61.

On the number scale:

-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10

Consider 0 as the center of the scale if you got to the right of zero each succeding number is LARGER. If you go to the left of 0 each succeding number is SMALER

Since what you are using the spectrum analyer for is to minimumize interference, you want to chose the frequency with the least interference. since you are dealing with negative numbers, this means going further to the left on the above scale, Thus -91 is a better reading than -61 for celcting a useable frequency. Since the bottom scale on the analyzer has the lowest numbers on the left, then -9 draws a shoter line than -61 thus the shorter bars are what you want for picking a frequency to use.

If you are looking for the strongest signal to associate an SM with then everything above is reversed :lol:

Hope it helps

Panzer

this whole time i was unknowingly selecting the frequency with the most noise in it then because i was selecting the one with the lowest like -64dBm for my AP frequency instead of like -94dBm…hopefully this will help with some of my speed issues and SMs dropping connection

thanks again

man, I have never seen so much signal all across the 900 band. where is this, on a busy downtown rooftop? I’ll be suprised if anything works with that kind of noise floor. I’m used to finding something around -90 dbm. remember that the canopy uses a wide bandwidth and only has 3 non overlapping channels. finding one quiet slot on the spectrum analyzer doesn’t mean you can fit into it.

I think it was out of the manual so it may have been taken by a bunch of test radios. I asked the documentation team that a better looking spectrum analysis be put in the online manual so that people can clearly see the difference.

wav11 wrote:
this whole time i was unknowingly selecting the frequency with the most noise in it then because i was selecting the one with the lowest like -64dBm for my AP frequency instead of like -94dBm...hopefully this will help with some of my speed issues and SMs dropping connection

thanks again

Just to reiterate the -64Dbm reading is the HIGHER reading and the -94Dbm reading is the LOWER . So for interference purposes, always pick one of the lowest readings. If you are using the tool to located the AP with the strongest signal, the pick the channel with the highest reading

Let us know how it works out :)

Here is a relatively quiet site (note bleed from paging):

Here is a site near where we have 900 MHz deployed:

I can’t quite read the numbers, but that bulge in the middle of the graph is typical of a canopy transmitter around 915Mhz. You can see the width of the frequency spread and understand how much quiet space you need to fit in.