DDWRT Xmit Power and FCC Regulations

Discussion in 'DD-WRT Firmware' started by Severeth, Jul 26, 2007.

  1. Severeth

    Severeth Guest

    I have a question. We run systems at sporting events and would like to boost our signal a bit to cover the entire area. I have installed DDWRT on a linksys Router and have done some tested raising the Xmit power and testing our connection. We find that using the DDWRT firmware and boosting the XMIT power we would acheive the distance we need for the events without buying any additional harware to go with the router. Now my question is this. Does boosting the XMIT power still stay within guidlines of the FCC? The default is 30 I beleive and we boost the XMIT power to 75-80. If anyone has any knowledge that might be helpful in this situation please let us know so we can move foward with this or go another route. Thank you for your time.
  2. GeeTek

    GeeTek Guest

    Your linksys router is not physically capable of exceeding FCC limits no matter how high you set it.
  3. ifican

    ifican Network Guru Member

    I would say dont worry about it, your not going to get enough xmt to cause any undue grief to any surrounding receivers (ultimately what the power limitations are there for). The thing i would be more concerend with is if there is going to be more devices in the area thus limiting your coverage area and also having some sort of backup plan. Upping transmit creates alot more heat and some of the routers dont do so well when they are getting hammered on. If you really are concerned with power, there should be a rule compliance number on the device and all you would have to do is look it up. Though i think the rule will stipulate mostlike milliamps of wattage and i am not sure how you would convert the number in the browser to the actual output wattage.
  4. supervillain

    supervillain Guest

    Could someone who actually knows the FCC laws please respond to this post? I have a business right next to Los Angeles International Airport (LAX) and I was thinking of setting up a chillispot wifi service with hotspotsystem.com. But I do not want to get into any type of trouble with the FCC or interrupt air traffic control communication. Also what would be the best router / antenna system that I could set this up with?
  5. fudge55

    fudge55 Guest

    Hello, you can easily set the xmit power to 90-100dB, without breaking the FCC regulations.

    Hotspotsystem is a good choice, i believe they have operators in a few airports in Mexico already.

    I'd try the Linksys WRT54GL with a powerful external antenna.
  6. Quijy

    Quijy LI Guru Member

    Well, should not have any problems operating WiFi near or next to an airport. WiFi operates at 2.4Ghz, in the ISM band, most air port communications are at 108Mhz-142Mhz VHF band running in AM mode. And the airlines are in the 400Mhz-420Mhz FM, 450Mhz-512Mhz in the UHF band running in FM mode. Militaly traffic at any airport will be anywhere from 225mhz-400Mhz VHF cross over to UHF using a mulitude of formats, (SSB, AM, FM, etc...). The power limits are not really the issue with WiFi, it is ERP which is a combination of Power output from the AP + antenna system Loss + Antenna Gain. In truth it would be very hard to exceed these limits using any comerically available Wireless AP and antenna combination. If you want details and speciifics, go to FCC.Gov and seach around. There is a ton of articale here on WiFi. You are looking for 2.4Ghz, ISM band materials then look for Wifi and Bluetooth articles.
  7. HennieM

    HennieM Network Guru Member

    FCC limits are different (and pretty lenient vs. ETSI!) for point-to-multipoint and point-to-point links - the idea being that a more directional antenna is used in P-t-P. It also encourages you to use a strong antenna rather than high and noisy Tx power. Here some rules

    the most descriptive one IMO (3/4 down the page)

    and some other
  8. Quijy

    Quijy LI Guru Member

  9. HennieM

    HennieM Network Guru Member

    @Fudge55: Could you show us how to
    Reading Trevor's article again, I can't see how you could do that, as your max _xmit-power_ is set at 30dBm.
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