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Wireless Signal

Discussion in 'Cisco/Linksys Wireless Routers' started by michsu, Dec 15, 2005.

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What is your Wireless Signal? (Signal Strength -dBm) about 5-10 feet away

  1. -100 to -80

    97.8%
  2. -80 to -60

    0 vote(s)
    0.0%
  3. -60 to -40

    1.1%
  4. -40 to -20

    1.1%
  1. michsu

    michsu Network Guru Member

    What is your Wireless Signal? Please answer the poll if you can... Thanks for your help... just wondering if my connection now with the new setup is good ...

    http://www.linksysinfo.org/modules.php? name=Forums&file=viewtopic&t=11199
     
  2. NateHoy

    NateHoy Network Guru Member

    Conditions:

    WRT54G, V4 hardware, HyperWRT Tofu 10. Stock antennae.

    Antenna strength: 25% (21mW), automatic antenna selection.

    Mode: WPA/Personal TKIP, Mixed AP mode

    Interference: no known interference (I'm way off in the boonies, in a house with aluminum siding).

    Distance: 6-10 feet

    Testing client: Status screen built into Odyssey Network Client.

    Results: Varied between about -34 and -42. I called it "-40 to -20" because it stayed in the -30's range more than it went into the -40's.

    Boosting antenna strength to 50% (42mW) kept me firmly in the -30's, but never got better than -34 or so.

    Hope this helps you out, whatever you're looking for.
     
  3. SteelersFANinMA

    SteelersFANinMA Network Guru Member

    I have a WRT54G v2 with Linksys 7dBi antennas running tofu11 Hyperwrt. I have the TX power set at 100%/84mW. At close range I usually get between -45 & -29. The -29 is my all time record. Usually my best signal is in the low -30's. I recently modded the router with heatsinks and an internal fan while OC'ing the cpu at 216. I also have a Linksys WPC54G v1.2 adapter in the PCMCIA slot of my laptop.

    I saw your other poll and I'll say that if you want to get a better signal for your dad, you may have to get a better adapter/NIC for his computer/laptop. You can set the router's TX power as high as you want, but if the clients connecting to it don't have the power to send the signal back, then it won't help much.
     
  4. michsu

    michsu Network Guru Member

    Thanks!!

    http://www.linksysinfo.org/modules.php?name=Forums&file=viewtopic&t=11199

    Here was my original post which no one replied to... In summary, I bought Linksys SRX router WRT54GX v2 (3 removable antennas),

    Original : 3 stock antennas (2.16 dBM?)

    New Setup :
    1) RA24J (Amp 500mw) + 9dbi Omnidirectional High-Gain
    2) 9dbi Omnidirectional High-Gain (same for diversity, hopefully)
    3) Linksys Stock (left one there in case something goes wrong, I can still get connection)

    Signal:
    Old Setup: about -30 dBM (5-6 ft) (other side of house : -89 dbM (100 ft + 4 walls ; connection "VERY LOW")
    New Setup: about -15 dBM (5-6 ft) (other side : haven't tested )

    dbM:
    with a 15 dbM increase , I read from articles, that in theory 3dbi doubles space ( so in theory 5x as far ), but some articles say that you need 9dbi to actually double... so 15 / 9 = 1.666 so about 150% increase in signal...??

    Assumption :

    other side of house (-89 + 15 = -74 dbm), is that a good connection signal? I know that -89 , I can't get much download speed (have Adelphia 6MB down / 800K up), with original setup, I get about 100-300K down with his laptop (connection off and on)... hopefully with the new setup, it will improve a lot.. How much does a wall decrease the signal?

    Thanks
     
  5. NateHoy

    NateHoy Network Guru Member

    Re: Thanks!!

    I doubt that assumption will turn out to be correct. Signal drops as the square of the distance, not linearly. So pumping out another 15dB of signal is not going to give you the exact same gain on a distant connection.

    However, if it made THAT much difference at the base station, then the new antenna, etc, is obviously working, so you'll see some improvement. My question is: Why are you asking (no offense, merely curious)? Test it out, move the remote client around a bit to make sure the connection is reasonably solid, and if it's not, then you need to be looking at boosting signal strength on the client, or getting a repeater somewhere, or relocating your wireless router.
     
  6. michsu

    michsu Network Guru Member

    thanks for all your replies... I'm just curious too, haha... curious to see how much improvement he can get... I gave him my old PC Card (Linksys WPC54AG) to use, but I read that Linksys receive sensitivty is bad... so I opted for the better high-gain antennas (which supposedly improves receiving and sending signals)... well, with a -15 dBm at about 5 feet off, it seems to work out pretty good... although there seems to be high radiation (just like a microwave??)...
     
  7. NateHoy

    NateHoy Network Guru Member

    Ah, I see. You aren't at the actual site. Sorry, my bad. Now I understand.

    Hmm. I have a Linksys WPC54G as my "backup card" (my Dell has a wireless card built in now that my company has replaced it), and I remember the Linksys card was very good about locking into signals. I could routinely reach access points that few others in the room could get to.
     
  8. michsu

    michsu Network Guru Member

    thanks for you info... I looked at some of the Linksys PC Cards specs and the receive sensitivity doesn't seem that high compared to others... also, is it wise to get a 200 or 300 mW powered PC Card? I looked at other forums talking about this, but it tends to overheat the laptop? haha, I have a dell laptop with integrated wireless card too, but it overheats already... but that's a problem for another time... the reason I'm not using a repeater , because it seems like it cuts the throughput in half? (since a repeater only has one send/receive antenna signal)... so maybe now the only option left would be to get a high-powered PC Card, or a PC Card which you can add an external antenna...
     
  9. NateHoy

    NateHoy Network Guru Member

    Daaaaamn. Dude, I would NOT want a 200mW card sitting on my lap, or anywhere near me for that matter. Screw the heat, that's some SERIOUS radiation. Units of that strength are best used with external antennas, and kept a good distance away. Unless you hope to acquire some superpower (or more likely cancer).

    According to some reviews, the WPC54G is about a 40mW card.

    If you can afford a cable run to somewhere else in the house, you can get a WRT54G and set it up with the same SSID and credentials, on a different channel, and the laptop will find the stronger one. You can also get a directional antenna and try that out.

    But a good external antenna on the client is probably your best bet, if you can pull it off.

    What kind of distance are we talking about here, and how much interference?
     
  10. michsu

    michsu Network Guru Member

    thanks for your reply... haha, I guess I won't go with the overpowered PC Card... considering I got my amp and antennas "cooking" in one part of the house already... the intereference is probably about 100 feet away with 3 or 4 walls... how much does a wall decrease? considering it still has a connection all the way on the other side (barely), then the router I bought must be pretty good...
     
  11. SteelersFANinMA

    SteelersFANinMA Network Guru Member

    For laptop heat, try a Targus Chill Mat. It comes in two flavors. One is USB powered and the other is powered by an adapter, plugs into a USB port, but has 4 USB ports built into it. They each have 2 fans and look identical except for the obvious. I got the USB powered one from Best Buy and it keeps my laptop cool. I have a Gateway Solo 5300 from Jan. 2001 and the PCMCIA slot is right next to the hard drive. So, it really started cooking once I got the WPC54G. My hdd probably would've fried by now without the Chill Mat.
     
  12. kulprit

    kulprit Network Guru Member

    Are these numbers you are getting the RSSI reading. I have 2 WRT54G's. One as my router and one as a Wireless Ethernet Bridge to my Xbox. The only reading I can get is in the Device list in tofu11 running on the AP is that the WEB is getting and RSSI of -63dbm. Is there a better reading I can get?

    I still get about 2.6 megabytes a second transfer to the hard drive.
     
  13. michsu

    michsu Network Guru Member

    Yes, that is what I am getting, I think.. -15 dbM to -20 (on bad days), nothing over that with new setup... with old setup I get -30 to -40 (bad day)... this is done with software measuring wi fi signal strength, or you can just measure it with your wireless client software... most client software (Linksys, Netgear, Belkin, and others) have software that comes with the router.. or you can try this (this is what I use to measure signal strength ) ... it is freeware that loads on your desktop (a small meter) that jumps around based on your signal received (or connected to)..

    http://fileforum.betanews.com/detail/WiFi_SiStr/1133468258/1
     
  14. SteelersFANinMA

    SteelersFANinMA Network Guru Member

    kulprit, you can also try NetStumbler to get readings of all AP's in your area. It's a great little program.
     
  15. kulprit

    kulprit Network Guru Member

    Steelers, thanks for the info, but both of my computers are connected via ethernet. Only my WRT54G running in WET mode and my Nintendo DS connect to it at the moment. Is my dbm any good at -69? And is 2.6 megabytes a second the maximum I am going to get ?
     
  16. SteelersFANinMA

    SteelersFANinMA Network Guru Member

    Sorry, I thought you were wireless. Hopefully someone else can answer your questions.
     
  17. ranpha

    ranpha Network Guru Member

    WRT54G v2.2 with tofu11. Stock antenna at 67% transmit power.

    D-Link DWL-G122 v2.03

    Reading is -69dbm.

    About 5 feet with a brick wall seperating client and access point.
     
  18. michsu

    michsu Network Guru Member

    some information about antenna gain / dBm :

    http://www.cpcstech.com/dbm-to-watt-conversion-information.htm

    http://www.wlanantennas.com/wlan_faq_fcc.htm
    ( My new setup: 27dBm + 9dbi omni = 36 EIRP )


    ====== (TO ANSWER YOUR QUESTION) =======

    www.stumbler.net


    What signal level should I consider usable for a good wireless link?
    Posted in FAQ by mariusm #
    I get asked this question rather too often, so I'm posting my short answer here. The answer is rather more complex than it ought to be, and depends on a huge number of factors.

    The most important is the receive sensitivity of your equipment. Many manufacturers fail to publish this data, but those that do will generally rate their radios by dBm at various data rates. As an example, let us take the venerable ORiNOCO Gold 802.11b "Classic" card. Its receive sensitivity is:
    -94 dBm at 1 Mbps

    -91 dBm at 2 Mbps

    -87 dBm at 5.5 Mbps

    -82 dBm at 11 Mbps

    In theory this means, in order to operate at 11 Mbps, this card must be consistently receiving a minimum signal level of -82 dBm. Any less and it is likely to drop to one of the lower rates; if you get as low as -94 dBm then the connection may drop altogether. As I mentioned before, many manufacturers do not quote their receive sensitiviy for their adapters; if you have one of these, I suggest picking a conservative figure such as -76dBm at 11 Mbps, which is the number for the Belkin F5D6020.
    The signal level you receive in an unobstructed environment depends on the transmitter power, the gain of the two antennas involved, and the distance between them, as well as any loss between the antenna and the radio at each end.

    In practice, radio waves behave unpredictably in a number of ways. First, the signal will fade out due to multipath effects (radio waves that bounce off objects and increase or decrease the signal that you receive). The further the receiver is from the transmitter, and the more objects between them, the higher this effect will be. Walls, people, electronic equipment, rain/snow/ice/fog are all quite effective at decreasing your signal level. In a typical home or small office environment without too many obstructions, a 10dB variation in signal level is quite normal. So, if you are looking at a NetStumbler scan and the signal is consistently around -65 dBm, it could drop to -75 dBm when somebody comes over to talk to you.

    Summary so far:
    (Received signal) = (transmit power) - (loss between transmitter and antenna) + (transmit antenna gain) - (path loss) - (multipath and obstruction loss) + (receive antenna gain) - (loss between antenna and receiver)
    In order to operate, (received signal) must be greater than (receiver sensitivity).

    Another factor is noise. This is "background" radio-frequency junk that your receiver can "hear" but needs to reject. Sources of noise include other wireless networks, cordless phones, microwave ovens, radio hams, medical equipment, Like other radio phenomena, noise may be highly variable. Many wireless network adapters do not report noise, so if you're using NetStumbler with them then you can't even tell how much noise you have in your environment. A typical urban location these days might have an average noise level around -95 dBm. When you switch on the microwave oven or take a call on your 2.4GHz phone, this value will increase. I've seen a 2.4GHz phone produce -50 dBm of noise, which is enough to saturate some Wi-Fi radios and thus kill their connection completely.

    Let's take these concepts and combine them. In order to operate, the actual signal level at your receiver needs to be higher than the noise level. The actual signal level varies depending on signal fade, so if you measured -75 dBm one day, it might drop to -85 dBm occasionally. On most radios this is sufficient to make it drop to a lower data rate, and on some it will cause the connection to drop altogether. Likewise your background noise might be around -98 dBm, but then your neighbor takes a call on her cordless phone and it jumps to -78 dBm. With multipath effects, this is sufficient to make your connection drop randomly.

    My conclusion, therefore, is:
    Q: What signal level should I consider usable for a good wireless link?
    A: Depends on your equipment and your environment.
     
  19. Private-Cowboy

    Private-Cowboy Network Guru Member

    I've -68db around 15-20feet way from the router and through one wall. The router is a WRT54GC with FW 1.04.5. Just bought an external antenna, lets see how this boosts the signal.
     
  20. michsu

    michsu Network Guru Member

    -68 dbi from 15 ft thorugh 1 wall seems bad... I'm getting -89 dbi through 4 walls + 100 ft (so if with the new setup -89 + 15?? = -74 dbi??) maybe that's right, maybe wrong...have to assume different factors everyday (weather, cordless phones (they make a difference), and also programs you are running)...

    For example :

    MSN Messenger + Webcam (stock antennas drop from -30 to -60 when using it)...

    Skype usage (100%, yes I have that problem) the signal jumps around.... maybe both problems have antenna diversity issue...s

    :cheering: :cheering: YAY, I got a new record from my close range just a couple days ago... -10 dbi... whew... awesome... can't quite reach 0 yet... but good enough I think... but normally it's between the signal of -20 to -15... maybe cordless phone interference, so it jumped?? (have both 900mhz and 2.4 ghz at home throughout the house)..
     
  21. Private-Cowboy

    Private-Cowboy Network Guru Member

    Well my router has no external antenne and my wifi adapter on the pc side only has a very small one. I can get it to -55db when using an external antenna on the router and reposition the pc antenna.
     
  22. jot7

    jot7 Network Guru Member

    2 walls and 25 feet

    Well, I just checked the signal on my wireless bridged setup in my bedroom and it has a signal strength of -98db at close to 25 feet away going through two walls. I am using a WRT54Gv5 router with the add-on Linksys external High Gain "rabbit ear" antennae with the external antenna stand placed 1 foot from the ceiling of my pc "lab". The wireless bridge set up is on an old desktop PC with 2 NICs and a Linksys Wireless G PCI card. My neighbor can pick up a signal from router from over 200 feet away with 11Mbs transfer speed. I do have the latest firmware upgrade on the router (1.00.4), so this may have something to do with the strong signal. My old router took a dump when trying to do an upgrade of the firmware (WRT54Gv4), so Linksys replaced it with v5, but I never got this strong of a signal before. Though v5 can not be upgraded with 3rd party software, it is still an awesome router when it does work... :thumbup:
     
  23. michsu

    michsu Network Guru Member

    thanks for all the info guys (and girls?) ... I am still wondering about the connection I have... is there some sort of chart/table that says what connection/what speed?

    For example:

    -100 to -80 (how much signal and throughput, then do that for each grouping)

    Thanks
     
  24. Private-Cowboy

    Private-Cowboy Network Guru Member

    Em, isnt -98db no signal at all? I mean I've a noise level in the low 80s so such a signal cannot be picked up at all. And the closer the signal db is to 0 the better. So one in the 50s is great, one like -98db is crap.
     
  25. michsu

    michsu Network Guru Member

    yes, I just wanted to be nice... actually -98 dBm is very bad... impossible to get signal... like my previous posts say, I am getting -89 dBm from far away... so with new setup, hopefully -74... which is ok... with -89 dBm , I can pick up about 100-200k download speed, ( from 6MB max close by with -15 dBm)... so -98 dBm would not be able to get a signal at all...
     
  26. Private-Cowboy

    Private-Cowboy Network Guru Member

    Yes that what I thought but such a signal at "close to 25 feet away going through two walls" - that is not ok for sure. Misconfigured or something?
     
  27. jot7

    jot7 Network Guru Member

    Oopps.....was reading wrong signal strength settings.....it is -42db to -38db (it fluctuates)....not sure what signal strength at my neighbors house...probably close to -85db....My other neighbor behind me who uses a Motorola setup ,un-encrypted no less, I get a -50db signal from him on my desktop....


    Sorry about the wrong readinsg from earlier..... :oops:
     
  28. michsu

    michsu Network Guru Member

    does anyone know how much "reach" you can get with how much throughput (36, 54, 108?)... my reason is, I notice with my improved reception (-30 ==> -15 to -10) , my Linksys SRX drops down from 54mb to 36mb... I know about the decrease power, because it is distributed with even more distance now (same power, more distance = less overall power throughout)... anyway, 36 / 54 (66%, 33% drop in performance)... with a 6MB down, x 33% = 2 MB.. I lose about 2MB worth just on downloads..

    I have been switching back from amped antennas to stock antennas (go back to stock, it stays at 54g, which is good)... any ideas??

    Thanks :eek:
     
  29. michsu

    michsu Network Guru Member

    sometimes the speed changes, sometimes it doesn't ... why is that? (does throughoutput affect downloading/uploading speed?)... also, my reception drops from -30 to -60 when I start MSN Messenger (or Skype?), not sure which one... whenever I start using webcam (Logitech QuickCam Zoom), it starts to drop suddenly, still good connection, no drops....
     
  30. mphare

    mphare Network Guru Member

    I just installed a WRT54GC (no external antenna) and it sits about 10 feet from my laptop.
    I get about -30 to -45 dB signal and about -85 dB of noise
     
  31. Private-Cowboy

    Private-Cowboy Network Guru Member

    Ok, I now have a WRT54G v3.1 and get low 40s around 20feet away thought one interior wall. I know that's very usable but can I get it any better?

    Best I've seen yet on a good day way -37dbm with my WUSB54GP. would a PCI card perform any better given the fact that it has a 5dbm antenne (the WUSB54GP only has a 2dmb one)?

    I just wanna squeeze out the max. The problem is not the signal level itself but sometimes if moves up and down pretty badly like +-5, so I'd like to stabilize that. But I guess that gaused by interference because normally it's pretty stable at around -42dbm +-2.
     

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