What do these dBm numbers mean? Are they reasonable?

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I'm a Trusted Enthusiast
Posts: 143

What do these dBm numbers mean? Are they reasonable?

Installed an 8dBm gain antenna for my Rocket hub.

 

In the 3G section of the hub I see:

Signal Strength : -83 dBm

RSCP fluctuates from -96 dBm to -103 dBm

 

Wondering what these numbers mean in reference to performance and if they aren't all that good , would a Yagi (??) antenna be beneficial?

 

txs

 

 

*** Edited Labels***

I'm an Advisor
Posts: 842

Re: What do these dBm numbers mean? Are they reasonable?

@BeerHunter125:

 

dBm  is an absolute measure of radio frequency (RF) power/signal strength.  See the Wikipedia article:

 

http://en.wikipedia.org/wiki/DBm

 

for the definition of what it means.

 

The reason I mention the above is because you mention as well " Installed an 8dBm gain antenna".  Normally, antenna gain specs are stated in dB, which is a signal strength ratio, and not an absolure measure, as explained in this Wikipedia article:

 

http://en.wikipedia.org/wiki/Decibel

 

Antenna gain specs as stated in Decibels are a measure of ratio, in other words the increase in signal amplitude you can expect when using the antenna.  So if you are thinking of a Yagi antenna, it should help, but do remember that the signal gain of the antenna is achieved through directionality,  The antenna is designed to be more sensitive to RF signals in one direction, while much less sensitive in all other directions.  Most antennas will have a polar graph published for them that illustrates this for that particular antenna.

 

The result is, that when you use a directional antenna, it is critical that you point the antenna at the cell tower with some care to take advantage of the antenna's directional characteristics.

 

The Wikipedia articles referenced above also give info on what those numbers mean in practical quantities.  For example, a 3 dB difference in signal strength, depending on which direction, is a signal either 2 times as strong, or 1/2 as strong.

 

I hope that the above helps.

 

skinorth

 

I Plan to Stick Around
Posts: 10

Re: What do these dBm numbers mean? Are they reasonable?

Those are pretty weak signals - sitting on the line of bare minimum connection

 

A Yagi style antenna will definately boost them, although by how much depends on landscape and line of sight.

 

You can order relatively affordable ones from amazon.ca that come with connections for different rocket hubs, depending on which one you got.

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I'm a Trusted Enthusiast
Posts: 225

Re: What do these dBm numbers mean? Are they reasonable?

Lower DBs are better 70's is medium and average for a decent connection (yours are rather poor)

 

check out this guy he is $30 cheaper than canadian seller selling the same antenna, which I can vouch will give you 2 bars extra.. as long as you have a decent line of site

 

http://www.ebay.ca/itm/24db-gain-yagi-cell-phone-external-antenna-Free-Adapter-/260837436324?pt=PDA_...

 

just ask seller if he can ship USPS instead of UPS, and if he has an FME Male to SMA Male  connector

 

to check where you should be pointing check out this site

 

http://www.ertyu.org/steven_nikkel/cancellsites.html