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Linksys WRT54GL lost its wireless performance/range

Discussion in 'Tomato Firmware' started by oddis64, Jun 17, 2008.

  1. oddis64

    oddis64 Network Guru Member

    I have an WRT54GL with tomato version 119 firmware.. i have a neighbour who is 100 meter away from me and he was logged on to my net earlier but suddenly my net is not visible anymore at his place.. i even tried to raise the transmit effect to 100 but still no signal at his place.. i earlier had the effect on 60 and that was enough.. is there any thing i can do to fix the effect loss? or is there any other firmware that is better. i run system with wpa-tkip and only G on wireless.
    Any tips or solution here?
  2. jersully

    jersully LI Guru Member

    Build or buy a couple of directional antennas or cantennas. There's a really good website that has instructions, cut-outs, diagrams, etc. but right now the address escapes me. It'll come to me, or someone else will post it. In the meantime just do a websearch.
  3. M_ars

    M_ars LI Guru Member

    I can recommand you the Linksys HGA7T-EU HIGH GAIN ANTENNA KIT. You would ne 2 pair of them of course. I assume your neighbour has also a WRT54XX. The bad news is, they are not cheap, round about 40 euros.. --> 80 total;
    I can not guarantee that the antenna kit will work for you as desired, but its certainly an option.
  4. LLigetfa

    LLigetfa LI Guru Member

    While I always advocate better antennas over cranking up the power, there still is the question of why suddenly the OP has a reduction of signal and why adjusting the power appears to have no effect.

    There are three possible causes. Loss of transmit power. Loss of receive sensitivity. Loss of signal due to path.

    Loss of transmit power could be from a diversity chip gone bad. Well known issue and some have been known to remove and solder a bypass.

    Loss of receive sensitivity could be from a new source of interference.

    Loss of signal due to path could be that someone moved the camper parked in the driveway that was reflecting the signal. My office at work is right downtown and I watch the signal strength from distant APs go up and down depending on what is parked where.
  5. HennieM

    HennieM Network Guru Member

    I'd say try different channels first before you think of stronger antennas, etc.

    It could be that that bush or tree that was between your router and the neighbor, has now grown leaves, and that's killing the signal. Stonger antennas could solve that.

    However, I think most likely you are now picking up interference from something that started in your neighborhood, so try some other channels.
  6. Kiwi8

    Kiwi8 LI Guru Member

    Before buying anything, perhaps u would like to confirm that the wireless failure is due to range and not the equipment, by bringing your router to your neighbour's place to test whether he could still connect?
  7. ndoggac

    ndoggac Network Guru Member

    When you say "raise the transmit effect to 100", are you actually setting the transmit power to 250 mW, cause that is actually running the wireless at 100%. If you put 100 in the wireless power setting, you are only running at 40%. Did you reset to defaults, because I think by default Tomato only runs the wireless power at 50 mW (20%) power.
    I could be wrong on the default setting....If you look to the right of the box, it gives you the setting range (1-251mW I believe). It's not %, but actual mW signal strength values.
  8. Dragon2611

    Dragon2611 LI Guru Member

    I think 100mw is the legal limit in the UK.
  9. HennieM

    HennieM Network Guru Member

    @Dragon: You are not wrong, but you are not right...

    The Legal limit "for a 2.4GHz unlicensed transmission" in ETSI countries is 20dBi. That means the total radiation you put out, may not be more the 20dBi.
    Further, dBi for the "Transmit power of the AP", is calculated as dBi = 10 log(mW)

    So, if you have a 0dB antenna, your total transmission power would be
    10 log(mw) + 0dB; For 100mW, this is 10 log(100) + 0 = 20dB

    Your normal pigtail antenna on APs is about 2.2dB, so if you tune your router to 100mW:
    10 log(100)+2.2 = 22.2dBi

    For pigtails, you max Tx power would thus be:
    10^[(20-2.2)/10] = 60.2mW

    If you use say a 9dB antenna, it becomes
    10^[(20-9)/10] = 12.6mW
  10. ndoggac

    ndoggac Network Guru Member

    I was not aware of this law...we don't have it in the US that I know of. Hmmm? Maybe I should look that one up before the cops beat down my door :). Honestly though, even if you crank the mW value all the way up to 251

    10 log (251mW) = 23.996 dbi

    less than 4 dbi over the limit, is anyone really going to come after you for that? Doubtful!
    I would rather have a strong clean signal that I didn't have to mess around with. But like I said, I don't have any experience with this law, so my opinion is a bit ignorant i suppose.
  11. LLigetfa

    LLigetfa LI Guru Member

    In the US, the EIRP limit is 36dBm for a PtMP system. PtP links can enjoy slightly higher depending on antenna.
  12. ndoggac

    ndoggac Network Guru Member

    Thanks LLigetfa, So I don't have to worry if I max out the signal to 251 mW....except for the extra internal heat of course.
  13. HennieM

    HennieM Network Guru Member

    O but you do! They are just not as stupid/senseless/brainless as the ETSI ones. It's FCC Part 15, which basically let you turn up the power as your antenna gets more directional and stronger. A quick one I could find here http://www.qsl.net/kb9mwr/projects/wireless/pwr.html There are probably much clearer ones out there.

    ETSI reckons 20dB 360deg in all directions is less than 24dB over say 30deg. Morons. But so be it.
  14. LLigetfa

    LLigetfa LI Guru Member

    It is a common misconception that the deciding factor is directional versus omnidirectional but that is not the case. The deciding factor is PtP versus PtMP.

    The AP on a PtMP is always bound to 36dBm but the client side of the PtMP is actaully allowed the limits of PtP with the same 2 out 3 dB rule mentioned above.

    Don't forget that an omni has direction gain, just that the beamwidth is only on the E-plane.
  15. HennieM

    HennieM Network Guru Member

    I'm no expert, and agree with the "deciding factor" LLigetfa, but I think the intent of Part 15 is that a non-omni type directional antenna would be used for PtP. I.e. directional is defined relative to a dipole, not an isotropic radiator, viz ERP, and not EIRP. I may of course be wrong...

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