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 Subject :Question on using RM Online for plotting 2.4ghz, and 900mhz... 2015-02-16- 04:06:46 
KK4TGV
Member
Joined: 2015-02-15- 15:26:54
Posts: 15
Location: Mendota, VA

Hello all,

I am trying to use Radio Mobile Online to try to get an idea on coverage from various locations in my area.

I am a little unsure about the RX threshold, and the strong signal margin.

What would you suggest setting those to for 2.4ghz and 900mhz?

Thanks!

73,

KK4TGV

 

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 Subject :Re:Question on using RM Online for plotting 2.4ghz, and 900mhz... 2015-02-16- 09:04:45 
K6AH
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Joined: 2012-03-05- 10:47:45
Posts: 181
Location: San Diego, CA
Assuming you're planning to use Ubiquiti nodes, then you can use "4μV" Rx threshold and "15dB" for Strong Signal. You'll find everyone has their own opinion on this last parameter. I treat it the same as "Fade Margin" when I'm modeling in Radio Mobile. Andre, K6AH
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 Subject :Re:Re:Question on using RM Online for plotting 2.4ghz, and 900mhz... 2015-02-16- 09:09:01 
KK4TGV
Member
Joined: 2015-02-15- 15:26:54
Posts: 15
Location: Mendota, VA
Thinking about using WRT54GL. I have some around. I have been doing my modeling with the defaults. 0.5μV and 10db. What about the "required reliability" and "use two rays"?
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 Subject :Re:Question on using RM Online for plotting 2.4ghz, and 900mhz... 2015-02-16- 09:23:22 
K6AH
Member
Joined: 2012-03-05- 10:47:45
Posts: 181
Location: San Diego, CA

.5μV is equal to -133 dB receiver sensitivity.  Ubiquiti devices are all around -95 dB (about 4μV).  I don't recall exactly, but I believe Linksys are in the -85dB range (14μV).


Andre, K6AH

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 Subject :Re:Re:Question on using RM Online for plotting 2.4ghz, and 900mhz... 2015-02-16- 09:27:25 
KK4TGV
Member
Joined: 2015-02-15- 15:26:54
Posts: 15
Location: Mendota, VA
Thanks! What about the "use two rays"?
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 Subject :Re:Re:Re:Question on using RM Online for plotting 2.4ghz, and 900mhz... 2015-02-16- 10:14:27 
K6AH
Member
Joined: 2012-03-05- 10:47:45
Posts: 181
Location: San Diego, CA

I'd leave both the 2 Rays and Land Cover boxes checked. They are options embedded deeply in the theoretical method used in computing path loss. Andre, K6AH

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Last Edited On: 2015-02-16- 10:14:57 By K6AH for the Reason
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 Subject :Re:Question on using RM Online for plotting 2.4ghz, and 900mhz... 2015-02-16- 12:12:45 
KG6JEI
Member
Joined: 2013-12-02- 19:52:05
Posts: 516
Location

Also make sure to work with the data and understand what it says.

I've been planning at 10db above minimum sensitivity as my goal for a link before I really even contemplate testing it. Even then it likely may not be a great link.

One also has to rembering that local noise floor comes into play.  I've got one link with 25dbm + above receiver specs to RX signal but the noise floor is 15dbm+ above receiver specs meaning I really only have 10dbm on that link (and I actually can't establish on it because of a few local noise sources that wipe me out).

In the end the more pessimistic you plan the better your network qualitiy will be.

In my mind anything less than 100% LQ is a bad link as it only takes a couple of them to really kill out a network max speed.  

I have seen networks work with bad paths, and in a disaster a bad path is better than no path but I really dislike any bad links as they don't get better until another node shows up.

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