[MLB-WIRELESS] World Wifi record

Peter Berrett vk3pb at optusnet.com.au
Sat Dec 31 20:19:50 EST 2011

Two problem with using 30 dbm.

With a 20 db dish that makes 50 dbm which is above the legal limit of 36 dbm. If it is to be a legitimate record it has to be legal.

You actually have to back down your power with bigger dishes to stay within the legal limit. 

The other issue is that 1000mw sounds like something more than just off the shelf wifi.  

Your 2.4m dish will probabl;y have a gain of say 25db and you might deduct 3db for losses. So your output power can't exceed 14 dbm.

Of course  as an Amateur you can use higher power but I think the spirit of the record is that it is off the shelf wifi without the benefit of using the higher power afforded by being an Amateur. 

In any event for this record it probably is unnecessary anyway.

cheers Peter  

  ----- Original Message ----- 
  From: Ratbaggy 
  To: MW Wireless ; Peter Berrett 
  Sent: Saturday, December 31, 2011 7:29 PM
  Subject: Re: [MLB-WIRELESS] World Wifi record

  Hi Peter,

  Yes, you are right about -88 being a bit low, that leaves very little margin.

  I'd propose this setup...

  * +30 dBm transmit power (Routerboard RB711UA-2HnD) Did Mike say he was interested in sponsoring?
  (it's a dual chain radio, probably get +27 from a single port?)

  * 24 dB gain grid antennas (Hills etc) I have several
  or 2.4m dish - about 34 dB gain?

  * 1 dB loss in cables/connectors at each end, radios mounted directly to the antennas.

  *  Use CH1, where transmit spectrum is all below 2450 MHz.  EIRP not a problem.
  13 Centimetre Amateur Band is 2300.000 MHz - 2450.000 MHz (I also have an advanced license.)

  * 155 Km (Donnabuang, but will need to check the clearance over trees from the observation tower)

  Which will give about -70 dBm with the grids and if we use the big antenna at one end, maybe -60 dBm.

  Here's what Radio Mobile thinks of the hop, a couple of dB lower than my calcs.

  Radio Mobile Plot

  I'm back at work on Tuesday which really only leaves the weekends open for me.



  On 31/12/2011 12:50 PM, Peter Berrett wrote: 
    I have just done the path loss calculations assuming

    - 17 dbm transmission power (50 mw)
    - 20 db gain transmission antenna
    - 20 db gain receiving antenna
    - 3 db loss in cables
    - 2400 Mhz frequency
    - 127 km distance

    I calculate a received signal after antenna gain of about -88 dbm which is a bit low for my liking.

    We probably would need to look into higher gain antennas.

    Mind you I have assumed that each of our antennas has 20db gain. I don't know what the gain figure would be for a 90cm offset dish at 2400 mhz? Higher maybe? 

    It is possible that your 2.4m dish has a higher gain figure than 20db which would help give some margin.

    cheers Peter

      ----- Original Message ----- 
      From: Peter Berrett 
      To: David Nuttall ; MW Wireless 
      Sent: Saturday, December 31, 2011 12:35 PM
      Subject: Re: [MLB-WIRELESS] World Wifi record

      Dear Dave

      I have a 90cm offset dish that I could tack my cantenna onto and I live right by Mt Dandenong.

      I am off work until 10th January. Want to try for the record? You would head out to Ballarat and I'd park myself up at Skyhigh.

      The only issue is what dongle or router should I use at my end?  

      cheers Peter

        ----- Original Message ----- 
        From: David Nuttall 
        To: MW Wireless 
        Sent: Wednesday, December 28, 2011 1:18 PM
        Subject: Re: [MLB-WIRELESS] World Wifi record

        Hi Peter,

        How about we start out with the Australian WiFi record?  I believe the W.A. guys established a fairly long link out to Rottnest Island some time back.  However, I know of no longer link than Peter Buncle's hop from Kallista to the original Highton location at around 100 Km's.

        A Picnic/BBQ trip to Mt Buninyong would give us a path of 127 Km back to node GHO at Mt Dandenong.

        I donated a 2.4 m domestic sat dish and Rob B built up a 2.4 GHz feed and tripod for the dish.  They are still sitting in my shed ready for such a project.



        On 27/12/2011 10:30 PM, Peter Berrett wrote: 

          Hi all

          Would anyone out there be interested in attempting the world unamplified 2.4 ghz wifi record?

          The record I think is held by some Venezuelans (some Italians hold the 5.7 Ghz record).

          The strategy would be as follows

          1. Use an established MW node such as GHO North as one end of the link.

          2. Go about 400 km+ in the direction the node antenna is pointing and erect a node and directional antenna, perhaps solar powered, with a small computer and high gain antenna pointing at the MW node. Perhaps our friends at the Adelaide wireless group could set up a node in their group pointing at us?  

          3. Monitor 2.4 ghz beacons and when there is some tropospheric ducting try the link. Or better still just automate things so that when the station is heard it automatically tries to transfer a video from one end of the link to the other.

          Successful transfer of video = world record


          Peter VK3PB



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