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Toups
EVDO Newbie
Joined: 30 Jan 2006
Posts: 6
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 Posted: Tue Mar 11, 2008 1:48 pm Post subject: Limit transmit power |
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Greetings,
I am currently awaiting shipment and delivery of a PHS-300 but had a question in regards to transmit power of the 802.11g radio. Is there a setting to lower the transmit power to say 10, 20, 30%....
I plan to use this setup in a booth at one of our conferences, but do not want to add any more "background" to the already crowded 802.11 frequencies in use, not to mention limit usable range to the area immediately surrounding our booth.
Any advise is greatly appreciated. |
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mfisch
EVDO User
Joined: 17 Dec 2007
Posts: 27
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| Posted: Wed Mar 12, 2008 12:56 pm Post subject: Re: Limit transmit power |
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| Toups wrote: | Greetings,
I am currently awaiting shipment and delivery of a PHS-300 but had a question in regards to transmit power of the 802.11g radio. Is there a setting to lower the transmit power to say 10, 20, 30%....
I plan to use this setup in a booth at one of our conferences, but do not want to add any more "background" to the already crowded 802.11 frequencies in use, not to mention limit usable range to the area immediately surrounding our booth.
Any advise is greatly appreciated. |
You could stick it in a mylar bag or similar, you'll have to experiment to get the reduction you need.
That said, you probably don't want to reduce signal unless you're trying to evade the conference-wifi police. You'll just get stomped by your neighbors.
This is the reason convention police usually restrict adhoc wifi networks.
Maybe you should get a CTR350 or MB1000 instead and run real ethernet. |
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Toups
EVDO Newbie
Joined: 30 Jan 2006
Posts: 6
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| Posted: Wed Mar 12, 2008 4:45 pm Post subject: |
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Received the router today and there is a power setting option for "low, medium, high) but does not have any actual EIRP reference i.e. 15dbm, 12.5dbm...
You are entirely right about the "conference police" but we are often allowed to use "short range" 802.11 routers as long as transmit power is limited to the lowest setting i.e. 25% or EIRP of 7.5dbm give or take. this will usually limit the range significantly , especially when placed inside of a booth or small structure. This allows local access withing 10 meters or so, but also limits interference with nearby radios even if transmitting on the same channel. Not ideal but in cases where wireless is not provided can prove most helpful for VPN and other tools in between demos. |
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mfisch
EVDO User
Joined: 17 Dec 2007
Posts: 27
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| Posted: Thu Mar 13, 2008 7:05 am Post subject: |
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| Toups wrote: | Received the router today and there is a power setting option for "low, medium, high) but does not have any actual EIRP reference i.e. 15dbm, 12.5dbm...
You are entirely right about the "conference police" but we are often allowed to use "short range" 802.11 routers as long as transmit power is limited to the lowest setting i.e. 25% or EIRP of 7.5dbm give or take. this will usually limit the range significantly , especially when placed inside of a booth or small structure. This allows local access withing 10 meters or so, but also limits interference with nearby radios even if transmitting on the same channel. Not ideal but in cases where wireless is not provided can prove most helpful for VPN and other tools in between demos. |
It's possible noone knows at 3gstore or cradlepoint the power of these settings. I'm sure its a relative power setting and you would need a spectrum analyzer to figure that real output of the radio.
Many wifi cards (and toolsets you can download) allow you to poll statistics reporting dBm of the infrastructure AP on a laptop. This is how people often perform site surveys (I know its what I did instead of using expensive analysis tools).
You might also record the dBm output at 2 or 3 meters for all three settings and see what the difference is. Then use an inverse square ratio algorithm to determine how that affects the range reduction, this is easily done on a pocket calculator.
All that said, I'm sure the conference police will understand if you perform due diligence (set power to low) and your router still transmits with slightly too much punch.
If this is the case, you may follow up with cradlepoint and suggest a new power setting. |
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yonnie
EVDO Fledgling
Joined: 06 May 2008
Posts: 14
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| Posted: Wed May 07, 2008 12:01 pm Post subject: |
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| I haven't been able to find what the range is on a ctr350. Anybody know? There doesn't seem to be an external antennae, so can I assume it's reach is less than a typical wireless router? Will it reach 300ft? |
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mfisch
EVDO User
Joined: 17 Dec 2007
Posts: 27
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| Posted: Wed May 07, 2008 12:20 pm Post subject: |
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| yonnie wrote: | | I haven't been able to find what the range is on a ctr350. Anybody know? There doesn't seem to be an external antennae, so can I assume it's reach is less than a typical wireless router? Will it reach 300ft? |
The range really depends what you are beaming through. I'm fairly certain it'll do 300ft if you have radio line of site in an open space, I'm equally certain no wifi device I know of can beam 300ft through an office building.
If range is your chief concern, the MBR1000 supports MIMO and will increase throughput at distance. You can also setup additional access points and use WDS to repeat the CTR350 signal far beyond its base range. |
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yonnie
EVDO Fledgling
Joined: 06 May 2008
Posts: 14
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| Posted: Wed May 07, 2008 1:23 pm Post subject: |
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could you elaborate? Don't know about WDS or usage.
I may need to use the neighbors house which is about 40ft higher elevation to get a signal. Of course, they'll probably want access too. Barriers would be their window and my window and about 200ft of air. Other choice would be a tall tree in my yard, but then I'd have to figure out how to weather and critter-proof it. |
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mfisch
EVDO User
Joined: 17 Dec 2007
Posts: 27
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| Posted: Wed May 07, 2008 1:32 pm Post subject: |
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| yonnie wrote: | could you elaborate? Don't know about WDS or usage.
I may need to use the neighbors house which is about 40ft higher elevation to get a signal. Of course, they'll probably want access too. Barriers would be their window and my window and about 200ft of air. Other choice would be a tall tree in my yard, but then I'd have to figure out how to weather and critter-proof it. |
If you're looking for range your best bet is to turn the wireless feature off, buy a second device that can take external APs, and beam a sector antennae toward your house.
Better yet, call the people at 3gstore and explain to them your situation. Though they're mostly EVDO experts (and not necessarily WiFi) I'm sure there is somebody there willing to help you spec a solution, or assist you in purchasing additional equipment if the router isn't enough. They're really very helpful. |
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