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Wireless Networking Communications Hardware

2.4GHz-Friendly Phones? 386

Posted by timothy
from the phones-are-mostly-bad dept.
da3dAlus writes "When I first bought my 2.4GHz wireless phone system several years ago, it was a rather new technology, and wi-fi wasn't even on the scene. Now it appears that all wireless phones are on the 2.4 or 5.8 GHz spectrum, and I've got neighbors with wi-fi (with myself included). While checking out new phones recently, I've noticed some are carrying a "802.11 Friendly" sticker. The question is, are there any trully 802.11 friendly phones? Has anyone really ever had a problem with these types of phones interfering with their wi-fi network?"
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2.4GHz-Friendly Phones?

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  • 900mhz? (Score:4, Interesting)

    by Anonymous Coward on Saturday August 07, 2004 @04:35PM (#9910201)
    Mine 900mhz cordless phone even has spread spectrum. Works great, excellent range.
  • by cflorio (604840)
    The other question is, will the 5.8 interfere?
    • Not unless you find a way to run your wireless network at 5.8Ghz.
      • Re:5.8 (Score:4, Informative)

        by Glonoinha (587375) on Saturday August 07, 2004 @04:54PM (#9910318) Journal
        You mean like the 802.11a wireless networks?

        But the first guy hit it right on the head. 900MHz phones are the best bet if you are running a regular wifi network and don't want interference.
        • Well technically 802.11a runs at 5Ghz; maybe that's close enough to cause interference, I don't know.

          But the real question is, considering the speed and price of 802.11g these days, why would you ever choose to run 802.11a?
          • Have you checked ebay for 802.11a devices recently? You can get a card for $10 and an access point for ~$25.
          • Re:5.8 (Score:4, Informative)

            by TWX (665546) on Sunday August 08, 2004 @01:29AM (#9912111)
            "But the real question is, considering the speed and price of 802.11g these days, why would you ever choose to run 802.11a?"

            Multiple reasons:
            • Less people on it. Channels will be available until the end of time, and even if everyone in your neighbourhood has an access point, you won't have network problems.
            • Less interest with wardrivers. While "security through obscurity" isn't the best idea if you're going to pick only one way to secure your systems, if you combine the fact that most people aren't looking for 802.11a networks with the fact that there are tons of open 802.11b and 802.11g networks you won't be looked upon as a potential victim nearly as much. It's not the end of security, but it's a good beginning.
            • No protocol issues. 802.11b and 802.11g frequently have issues sharing, where the "g" features dumb down to "b" speeds if anything "b" is talking. This is bad in my opinion.
            • Few, if any consumer devices in the 5GHz range. Nothing running in the house on 5GHz means nothing interfering with the network. Since everyone seems to be making 900MHz and 2.4GHz devices, including microwaves, telephones, and other things, using the currently lightly-used 5GHz area makes a lot of sense to me.
            I was really sad that 802.11a never really made it to prime time in Linux while it was still commercially viable to manufacturers. I'd have bought into it in a heartbeat.
    • Re:5.8 (Score:3, Informative)

      by imp (7585)
      No. 5.8GHz won't interfere with your wireless network. 802.11[bg] is at 2.4GHz, and 802.11a is at 5.4GHz.
    • by imp (7585)
      I have 5.8GHz phones. They don't interfere with 802.11[bg] at all. They don't even interfere with 802.11a because the frequencies there are approx 5.4GHz.
    • Re:5.8 (Score:5, Informative)

      by stilwebm (129567) on Saturday August 07, 2004 @05:43PM (#9910556)

      The other question is, will the 5.8 interfere?

      I have an AT&T 5840 phone that uses 5.8GHz but if you read the fine print in the specifications, it also uses 2.4GHz:

      • RF Frequency Band (Handset to base): 2400 MHz - 2483.5 MHz
      • RF Frequency Band (Base to handset): 5725 MHz - 5850 MHz

      All 802.11b/g devices use channels within 2412 MHz - 2483.5 MHz, so there is quite a bit of overlap there. When shopping around, I noticed that many 5.8 GHz phones actually use 2.4 GHz as well. In my limited use of 802.11b in the vicinity of this phone, I noticed no interference, but ymmv.

  • Yes, I have (Score:3, Informative)

    by Lordofohio (703786) on Saturday August 07, 2004 @04:37PM (#9910213)
    We had to stop using our brand new 2.4Ghz phones at work because our wi-fi stuff wouldn't hold a signal when the phones were in use. Keep in mind this was 2 years ago, haven't tried anything since.
    • I was browsing at a relative's house recently when the phone rang. The moment someone answered it I lost my 802.11 carrier. As soon as the phone was hung up, it came back. Coincidence? I think not.
  • by johncel (196614) on Saturday August 07, 2004 @04:37PM (#9910217) Homepage
    So, I had a linksys wifi router and an AT&T 2.4 gHz phone... They fought like dogs! If the phone rang, wifi was out for at least 5 mins after you hung up. What a pain. I finally just bought a 5.8 gHz phone.
    • by prockcore (543967) on Saturday August 07, 2004 @05:04PM (#9910382)
      So, I had a linksys wifi router and an AT&T 2.4 gHz phone... They fought like dogs!

      I'm willing to bet that the linksys you've got is the first generation BEFW11S4. I had problems with my 2.4ghz phones but when I upgraded to linksys's 802.11g router, all my problems went away.

      I'd recommend upgrading because if a 2.4ghz phone causes your router to die, then its likely that your router won't play well with others. If your neighbors get 802.11b/g, your router will die a horrible death.
    • hmm, i have 2.4ghz phone and it never compleatly knocks down the network, it just slows to about 5.5mbps(i have 802.11g)the trick is to get an older(about 2001) panasonic phone, my friend got one of these and it never takes his network down either(same one i have)
    • by jht (5006) on Saturday August 07, 2004 @10:14PM (#9911565) Homepage Journal
      Interestingly, many of the 5.8 GHz phones (like the one I use at home, it's an AT&T) actually only receive from the base station at 5.8 GHz. In order to save on their power budget, they transmit back in the good old 2.4 GHz band.

      Though they do play much nicer with 802.11x than older generation stuff did.

      In general, I've seen that newer phones coexist nicely, and also 802.11g devices seem to be less interference-prone than 802.11b. Also, 900MHz phones play pretty nicely because they aren't even in the same neighborhood.
  • by Anonymous Coward on Saturday August 07, 2004 @04:38PM (#9910219)
    It interoperates. If it finds an open port on your wifi network, it will handover and use VoIP to complete the call.

    This saves you money in the long run because VoIP is much cheaper cost-wise than typical cell service.

    The main thing is to make sure that the phone is SAR-approved. You don't want those microwaves heating up your neural tissue! :-)
  • by Pan T. Hose (707794) on Saturday August 07, 2004 @04:38PM (#9910223) Homepage Journal
    24GHz?! Who the hell would need such a fast phone is beyond me! I have a 500MHz AMD in my desktop (Debian) and it works just fine, thank you.
  • Not a myth. (Score:2, Interesting)

    by genixia (220387)
    My inlaws' 2.4GHz 'phone (sorry, can't recall the brand) totally screwed up their Linksys WLAN until I changed the WLAN channel (now it degrades link quality but doesn't drop it).

    OTOH, My Panasonic 2.4GHz 'phone has never interfered with my Netgear WLAN.

    I suspect that the 'phone brand has more of an effect than the WLAN brand.
    • wish i could change the channel and get the airplanes flying overhead to stop knocking my wi-fi network offline.. sheesh.. who decided to move directly under the flight path, anyhow?? oh. yeah. me.

      pm
  • Vtech (Score:5, Informative)

    by jcostantino (585892) on Saturday August 07, 2004 @04:41PM (#9910239) Homepage
    We just bought a Vtech 2.4ghz phone system - two handsets, one base w/ answering machine and a base with a charger. The system said "2.4ghz Friendly" and it replaced a Vtech 2.4ghz phone bought earlier in the year (and subsequently killed during a storm) which would knock the 802.11 offline unless I set my AP to channel 6.

    I haven't bothered to change the AP to a different channel but so far it's working fine.

    Worthy of mention is that the new handsets come with speakerphone and use three NiMH AAA cells instead of a shrinkwrapped battery with a lead. Plus they sound great and I don't have the problem I used to have on the older phone where the microphone was too sensitive and I heard background noise at too high a level in the earpiece.

    • By the way (Score:2, Informative)

      by jcostantino (585892)
      Link to the phone:

      http://www.vtechphones.com/vtechui/shop/productdet ail.cfm?itemID=1299

    • I've got a VTech 5.8 Ghz phone system [amazon.com] -- also two handsets (the system supports up to six) and one base (w/o answering machine). It rocks. My VTech 2.4 Ghz phone had problems going through aluminum siding, but the 5.8 Ghz phone has tremendous range, through all of the trouble-spots I had before. And if you're using 5.8 Ghz, you know you're not going to hurt your 802.11? connection.
  • Kills my wifi. My 2.4ghz phone does not however. Kinda strange.
    • Re:My microwave (Score:5, Informative)

      by John Miles (108215) on Saturday August 07, 2004 @04:53PM (#9910313) Homepage Journal
      Household microwave ovens spew a lot of 2.4 GHz energy all over the band (enough that after looking at it on a spectrum analyzer, I no longer feel like pressing my face up to the window to see if the cheese on my pizza has melted yet).

      However, they radiate only on alterating half-cycles of the 60 Hz line frequency. There may be a config option in your WLAN hardware's client utility to make it more resistant to microwave-oven leakage by forcing transmission of smaller packets. You'll lose some performance if you enable it, but it should keep your WLAN from going down altogether.
      • Re:My microwave (Score:3, Interesting)

        by j1m+5n0w (749199)

        Interesting - that gives a window of about 8.3 milliseconds. (1/120th of a second, if I understand you correctly.) A full size packet takes about a millisecond to transmit at 11mbps, plus a few hundred microseconds for the ack. That should be well within the window.

        Unfortunately, after repeatedly losing packets, most 802.11 gear will probably drop the transmission rate to its slowest rate: 1mbps. 1500*8 bits at 1 mbps is about 12 milliseconds (plus a few hundred microseconds for the header), which no l

    • by Anonymous Coward
      Thats cuz you are supposed to take your router out of the microwave before use!
  • by Anonymous Coward on Saturday August 07, 2004 @04:42PM (#9910242)
    I've gone back to the older 900 MHz phones since installing a WiFi network at home. The WLAN didn't interfere with the 2.4 GHz cordless phones we had, but the phones knock the network down hard. I haven't heard anything about "802.11 friendly" labels on newer 2.4 GHz phones, but I'd be skeptical. If they work at all, they work by adaptively locating an empty part of the 2.4 GHz spectrum, and around many crowded residental areas, there ain't no such thing no mo'.

    You can also get 5 GHz phones, too. Either 900 MHz or 5 GHz is fine, just keep 'em off 2.4 GHz.
    • I agree. I've never had a bit of problem with my 900 MHz phones. I suspect the only reason they came out with 2.4 GHz phones is to get customers to use the "2.4 gig is bigger than 900 meg, so it must be better!" line of reasoning.
      • Isn't sound quality better on the 2.4s, but range much shorter?

        (greater bandwidth, but shorter signal distance at higher frequency, right?)
        • Isn't sound quality better on the 2.4s, but range much shorter?

          Sound quality has nothing to do with the carrier frequency used. Consider broadcast FM; it's at around 100 MHz, or 0.1 GHz, yet I'm sure you'd admit it sounds quite a bit better than your cordless phone does.

          You are correct that higher bandwidth == higher fidelity, but my point is that bandwidth is independent of the band you choose to use, as long as the bandwidth is available on that band. And it is on both 900 MHz and 2.4 GHz.

          Ther

    • What's the deal with 802.11 and cordless phones intefering anyways? I thought this was the problem spread spectrum was supposed to solve: Direct sequence radios should be relatively immune to narrow band interference, and frequency hopping radios should not be affected much by direct sequence signals.

      If they work at all, they work by adaptively locating an empty part of the 2.4 GHz spectrum

      IIRC the FCC part 15 rules forbid this: for frequency hopping radios, they must hop to every channel in the hopp

  • by pbwiz (803505) on Saturday August 07, 2004 @04:46PM (#9910273) Homepage
    WiFi (802.11b) and 2.4GHz Phones almost always will clash -- but there is a good article on wifi planet that gives some things that can be done to lessen interference.
    http://www.wi-fiplanet.com/tutorials/article.php/2 191241/ [wi-fiplanet.com]
    Of course, the best solution is a 900MHz or 5.8GHz Cordless Phone.
  • I have used my 2.4ghz phone while on my 54g wireless net with no issues. In fact my microwave messes-up my phone more than it does my wireless. I have two Linksys AP's running on a mostly wired net. They give me great coverage, sometimes too good... damn nieghobr with NetStumbler..oh well.
    • by jwcorder (776512) on Saturday August 07, 2004 @05:07PM (#9910396)
      Not to nig your post here, but there is no way he cracked YOUR WAP with NetStumbler unless he just left it for about 2 months.

      The way NetStumbler works is that it looks for "special" packets that have weak keys. Once it gets enough of these (a million is a good number) it can crack your WEP. The only problem with this is that the average home with one or two wireless connections would have to send constant data for months and months before there would be enough packets sniffed to crack it.

      A business would do it in a week probably if they had say 25-50 wireless users, but 1-3 wireless connections wouldn't be enough data to even bother sniffing out.

      Not like I know ANYTHING about doing this kind of stuff though....

  • Yes,

    My D-Link 614+ wireless router has a heck of a time communicating with my wife's iBook whenever we use the 2.4GHz wireless phone.

    I've read suggestions that the intereference will lessen if you set the wireless router to Channel 11, but we've tried that and only seen small to no improvement.

    My plan is to buy a 5.8 GHz phone, which is widely reported [google.com] to clear this up.
    • I've had the interference problem with a Linksys 802.11B router and now an Airport Express with a Seimens phone and an AT&T phone (both 2.4GHz).

      When I change the routers to channel 11, I get no problem whatsover. I guess you just need to find the right combination of gear.

    • by Cyberop5 (520141) * on Saturday August 07, 2004 @05:05PM (#9910387) Homepage Journal
      I've tried a few 5.8ghz phones. They have horrible range and still pollute 802.11a. The quality is better, but not being able to leave the room with the base antenna doesn't really help.

      Just stick to 900mhz for the best range and wireless reliability.
      • by Cyberop5 (520141) *

        My suggestion, if you have the money to spend, is an engenius [smarthome.com]. We use a pair at work and aside from a flakey power system they get great reception and distance. Analog I believe. We get through 5 stories of concrete building plus the perimeter and into the neighboring buildings.

        We tried most consumer products before purchasing these and nothing came close to the performance of these. The 5.8 ghz phones, from panasonic, could hardly get reception down the hall. All of the 2.4 ghz phones we tried cou


  • I haven't looked into it too much, but from what I understand newer 2.4ghz phones use an adaptive frequency response to get around interference from other devices. In essence they detect other devices on "locked" channels and maneuver their way through the mine field without causing any real problems for everyone else.

    As for actual signal strength, the phones aren't usually the problem. 2.4ghz phones have 2.4ghz transmitters in the base station, but the phone itself is often just 900mhz. That being the
  • A while back every time someone at my house used the cordless phone, my 802.11b network would get hosed. I ended up finding a channel which doesn't get hosed as badly, but there is still packet loss.
  • why 0.9Ghz is better (Score:5, Interesting)

    by infonick (679715) * on Saturday August 07, 2004 @04:51PM (#9910303) Homepage
    900Mhz phones:

    1) are inexpensive;
    2) do no interfere with the 5Ghz and 2.4Ghz wifi channles;
    3) do no interfere with Bluetooth;
    4) are inexpensive;
    5) will get better range because of the lower frequency used.
    • by CMRichar (610129) <exentric@charte r m i.net> on Saturday August 07, 2004 @05:03PM (#9910368)
      i think you forgot:

      6)are inexpensive.

    • "5) will get better range because of the lower frequency used."

      Sorry but not true. If this statement where true, companies would stick to 900mhz. T0he 2.4 and 5 Ghz offer more range that's the whole point of upgrading. That's also why when you walk away from the base of your 2.4 Ghz phone and reach it's transmission limit, you can still hear the person on the other end long after they can no longer hear you. From the base to the phone is 2.4, from the phone to the base is 900. 900 has a shorter range.

      • Christ, does the difference really matter? I can carry a 900mhz phone all around my property and it is an acre of land!
      • Sorry, but I don't think you know too much about RF. All things equal (same effective power output, same obstacles), low frequencies travel further.

        This is part of the reason why low frequency radio has such a reach (well, that and it can be bounced off the ionosphere whereas higher frequencies often break-through).

        -psy
        • My personal experience with phones suggests that 900MHz is better because it tends to travel through walls better, thus making it appear like it works further away. If you only used your phone outside, or in a large empty warehouse, then you'll likely find that the 2.4GHz phones work equally well.

          (IIRC, a few years ago, 2.4GHz phones were allowed to operate with more power, thus making those phones appear to work better...however, (again IIRC), the FCC up'd the max. allowable power of the 900MHz phones
        • You are almost right. Low frequencies only travel farther (transmissions are attenuated less) when there are obstacles involved. Higher frequencies are better for line-of-sight transmission. Since most people (at least the ones who buy cordless phones) don't live outside on flat open land, microwave transmitters are less efficient for cordless phone applications. The use of 5.8 Ghz for cordless phones only makes sense if you live in a studio (one room) apartment.
      • ^Quoting Rafiki from the lion king... The base has longer range because it has a higher power output. The physicaly properties of EM waves dictate that a 2.4ghz wave requires more energy to produce than a 900mhz wave. This is in part why AM radio stations are lower power, and the range is a lot better.
      • by bogie (31020) on Saturday August 07, 2004 @07:12PM (#9910978) Journal
        Companies went with 2.4GHz so they could sell the same products to people again. Although the latest 2.4 phones are probably ok for years 2.4GHz phones had shit reception compared to their 900MHz predecessors. There is zero doubt in my mind that most 2.4GHz phones were not equal to their 900MHz counterparts when they first came out. I used to hear echo and bad reception constantly on 2.4GHz phones while 900MHz just worked. Plus even now 2.4GHz models can have a nack of interfering with wireless which you and especially your neighbors probably won't like.
    • 47 MHz phones (you remember them, right? -- the *original* cordless) may be your best option yet! They're on such a low frequency that they don't have a chance of interfering with anything in your house, except maybe your neighbor kid's walkie-talkies or the garage door opener, and those are both very unlikely. Get a set with voice scrambling and you've got some privacy too. And lastly it has a terrific range and because it's analog, sounds good even when the reception is getting poor (you will get a lit
  • We saw the interference problem coming, even before we went wireless with the network, so we thought ahead and bought a 900 MHz DSS phone (with digital answering thingy) a couple of years ago. Thus, no issues with 802.11 or even the older Proxim Symphony stuff we used to have.

    I don't know if Toshiba still sells the SX-2981, but it's a great phone... Headphone jack, good range, DSS for clarity/security, etc. Answering machine is sometimes a little unclear (unsure what audio codec they use for voice recor
  • I've been told that Sony has some wireless home speakers available. And of course, they run at 2.4Ghz. From what I've been told at work, they are most often used in appartment complexes not to mention along with Wireless 802.11 b/g stuff.

    I guess 2.4 is only going to get more crowded as more and more devices offer wireless ability on this spectrum. Maybe I will have a need to go back to 10/100/GB Eithernet soon :( Oh well, at least I will have a constant connection *shrug*

  • I have a D-link 614+ that will reset each time my Panasonic 2.4Ghz phone rings.

    Changing from factory default channel 6 to channel 10 clears the problem up

  • I've got a Linksys WRT54G router and a Panasonic 2.4GHz phone. Haven't had any problems yet, and they're both in the same room. In fact, as I type this, my laptop's directly in between the two. I think if you make sure not to use both devices on the same channel, you should be all set.
  • I had to set my wi-fi to channel 1 in order to prevent interference with my 2.4 GHz spread spectrum phone. I thought I was just having random driver anomalies until one day I couldn't connect at all while my wife was on the phone then finally connected the instant she hung up. Watching the signal to noise ratio when I turned the phone on and off finally proved it.

    What a lot of people don't realize is that both 802.11 and cordless phones are part 15 devices, meaning they have no spectrum allocated to the

  • I have a Uniden 2.4 GHz cordless phone from like a year or two ago. There's two problems with my D-Link DI-624 Wi-Fi router and it. One, if I use the cordless phone anyway remotely in the same area of the house as the router, I get an audible rapid clicking. Also, I discovered that by turning the phone on, and placing it next to my wireless card, it drops the signal. AND then Intel's ProWireless software says an unknown device is trying to communicate with the card. Go figure... =p
  • I think the phone is this [epinions.com]. It came with a warning that it shouldn't be near a PC. I thought it meant something like not near a WiFi base station. Well, when I used it near one, the static was REALLY bad - even when the computer had no component running anywhere near 2.4GHz (466MHz Celeron, 66MHz FSB (which means 66MHz RAM), 33MHz PCI bus).
  • by mrbrown1602 (536940) <(mrbrown) (at) (mrbrown.net)> on Saturday August 07, 2004 @05:12PM (#9910426) Homepage Journal
    I have a PowerBook G4 which is equipped with an Airport Extreme card. The Airport Extreme (802.11b/g) has a feature called "Interference Robustness" which prevents any problems I would normally encounter using my 2.4GHz phone. Does anybody have any insight into how this works and does anybody know if any other wireless adapters include it?
  • This is why when I recently bought new cordless phones, I bought 900mhz phones instead of 2.4 so I couldn't have any worries. I've never been at all displeased with 900mhz and the range is excellent.
  • You are doing nothing but using a low bandwidth device to pollute a frequency range that is better used on 802.11 networks.

    2.4GHz phones does not mean that:

    1. The sound quality is better. This is entirely dependent on the encoding algorithm the phone uses (if at all). The 2.4GHz is simply a carrier signal.
    2. You get better range. You don't because 2.4GHz doesn't propogate as far.

    And also, given that some 2.4GHz phones probably don't use spread spectrum, they are likely to interfere with several channels.
  • I'm lucky that right now, I own a Panasonic (KX-TG1000N) 2.4Ghz cordless phone, and it never seems to cause my wi-fi network any problems at all. (I'm using a Linksys WRT-54G router, but also used a Lucent RG-1000 residential gateway before that, and had no problems with it either.)

    A good friend of mine, also using a Linksys WRT-54G has terrible problems with a 2.4Ghz cordless phone at his house. (I don't know the model, or I'd post it.) I was over there on his wi-fi network, and as soon as you'd pick t
  • A friend of mine has an Apple Airport, and an AT&T 2.4 phone, and whenever the phone was turned on the wireless network disappeared TOTALLY. You could be 10 feet from the Airport and it would still disappear. They did not work and play well together at ALL. You could occasionally force a new phone channel and it would have minimal effect, but still an effect. (The 802.11 connection would flicker in and out of existance). All in all, it was quickly a learned behaviour that the network was not availa
  • by Proc6 (518858) on Saturday August 07, 2004 @05:32PM (#9910509)
    Why not just overclock your phone? Put it up into the 20 ghz range and trump anyone who tries to start a conversation about them overclocking their Athlon. Weaklings.
  • Really, it does, at least here in Europe. My father had this Nokia cell phone that he brought into my (then, now it's a Cisco router) Airport network. It did not exactly interfere, instead, it hopped onto the network (it wasn't a WAP phone or whatever, it only made calls you know) and appeared as a kind of zombie client. It was present but didn't do anything. Weird. He got another phone later on (a Siemens) and I never had that problem again. Seems that European dual band cell phones also operate in the 2.
  • by cmowire (254489) on Saturday August 07, 2004 @05:36PM (#9910528) Homepage
    The cordless phone manufacturers have been playing quite a game over the past decade. They keep trying to get you to upgrade phones to a "higher" megahertz phone because they know that you are already being told by Intel to upgrade your CPU to a "higher" megahertz CPU.

    So, here's the thing. It's a general rule that as you go up in megahertz, the ability to penetrate walls goes down. Thus, the higher the megahertz, the lower the effective range. Consumer Reports did some tests here and showed that this carries over to reality. This is also why Verizon Wireless tends to have better reception -- they are primarily on the 850 MHz band instead of the 1900 MHz band.

    So what have you gotten by upgrading to an "advanced" 2.4 or 5.8 GHz phone? Less range, although generally enough range to make it around a "normal" house.

    Now, in order to produce a device that works in the 900 MHz, 2.4 GHz or 5.8 GHz band without a license the FCC requires you to be spread-spectrum.

    There's some upsides and downsides here. First, some of the spread-spectrum devices, most notably older ones, didn't use very good spread-spectrum methods.

    Second, in *theory* if everything's optimized properly, you can use some number of devices and they will all be perceived as "noise" to all of the other devices. So as you add more functioning devices in general, they will all start to experience interference. The problem is when devices using conflicting spread spectrum techniques are in use.

    Third, microwaves and other such RF-heating applications, are covered underneath a different set of FCC rules, which generally are built around not causing your eyeballs to be fried overeasy (your eyeballs are the first thing to suffer damage from microwaves, which is why staring at the microwave window is not the world's brightest idea) Microwaves are supposed to be Faraday cages, but sometimes there's a leak. I'd start to wonder about my Microwave's safety if it started interfering with my WiFi, mind you.

    Fourth, if there's interference and undesired performance, you have essentially no recourse. I've been thinking that they really should have allocated a frequency band that's reserved for only devices using a 802.11-standard protocol, but that decision really should have been made a long time ago. Oh, and if you start interfering with something important (That's the "Harmfull Interference" they speak of on the FCC warning on the back of a device) you can and will have government folks knocking on your doorstep. There have been documented cases of equipment interfering with aircraft navigation signals from the ground, which makes the airlines very unhappy and tends to get investigated. ;)

    I'm really wondering what the "Wifi-Friendly" cordless phones are actually. Especially given that VTech is the folks who are advertising it. As I've mentioned above, in *theory* any device on the 900 MHz, 2.4 GHz, and 5.4/5.8 GHz ISM bands (they are actually the same thing) shouldn't prevent each other from working and should just be perceivable as noise Also, *in theory*, one could "do better" by listening for 802.11b/g activity and actively routing around it. This is the big difference between Bluetooth 1.1 and 1.2. But that's more circuitry, so I'm not entirely sure if they are actually doing that, or they just put them in a test lab to see what happens. They'll probably insist that it took years of engineering time and it's a special feature, even if it's more the second. ;)

    I personally have just stuck to 900 MHz phones. Like I said, all things being equal, they tend to have longer range. Plus, I figure that having absolutely no interference is better than having a measured amount while the phone is in use. ;)

    Sure my WiFi uses 802.11b, which is 2.4 GHz, but there's some darn good reasons for why one should keep 802.11a around.

    The main one is that 802.11a is usually faster than 802.11g at close range. So I have a halfassed
    • When I went from 900Mhz to 2.4Ghz portable phone, my range went to crap. Where are you finding these 900Mhz phones? Nobody seems to make or carry them anymore. I ended up getting another 2.4Ghz multi-extension phone and this one hasn't interfered at all.
    • by 0111 1110 (518466) on Saturday August 07, 2004 @07:34PM (#9911046)
      Good post. I was going to mod you up, but I'd like to make a minor correction instead. As many have stated, the "penetration ability" of RF waves is inversely proportional to frequency (proportional to wavelength). For getting through building structures the best are 46/49 Mhz phones followed by 900, 2.4, and 5.8. What no one has (yet) mentioned is that higher frequencies do give better range for unobstructed line-of-sight transmission. Higher frequencies require less power (especially important for handsets) to propogate through empty space. The problem lies with obstructions like walls.

      Anyone who has tried to use a handheld GPS while hiking in dense forest has seen that even 1227 or 1575 Mhz is a high enough frequency to have difficulty penetrating the leaves on trees (at least at such low power).

      So as long as you can actually see your base a 5.8 Ghz cordless phone (RF transmitter) will give you the greatest range, but in any situation with obstructions it will give you the least range per unit of output power.

      46 Mhz is such a low frequency that it penetrates walls easily without losing much power, but it is less efficient at open-space propogation (per watt). 900 Mhz seems to be a nearly perfect balance (perhaps 450 Mhz might be better). The frequency is high enough that open space propagation is very efficient, but still low enough that it will penetrate walls with some effectiveness.

      Spread spectrum is not a form of "frequency hopping" in most cordless phones. It is a form of "wideband" transmission. It does not actually "hop" per se (although there are exceptions). It does allow for greater power and range. The longest range cordless phones for most people who live indoors in a multi-room house is a 900 Mhz spread spectrum phone.

      I bought as many of these as I could because I knew that MarketSpeak would win over RF theory and that truly long range cordless phones would probably become unavailable.
      • by Anonymous Coward on Saturday August 07, 2004 @11:58PM (#9911917)
        Almost correct. 1 watt is 1 watt at any frequency. Tell hams that lower frequencies won't carry as far but stand back if you don't want get get wet from the laughter you get back. What higher frequencies do is allow higher gain antennas with less space. The least, effective, antenna is 1/4 of the wavelength of the frequency (with ground plane) 1/2 without a ground. Frequecy goes up wavelength goes down. To make a 1/4 wave antenna at 49MHz you need over 4 feet. The same 1/4 wave antenna at 900MHz needs only 3/4 inch. 900 MHz is a very good balance for cordless phone. High enough frequency for small antennas, low enough to penetrate walls and such. Also the FCC allow greater power output at higher frequencies. 4 watts EIRP (1 watt into a 6db gain antenna) at 2.4GHz and 16 watts at 5.8 GHz. The requirements at 49MHz are much lower.
  • It looks quite similar to this [avdeals.com] but is bronze colored. It was fairly inexpensive and it was purchased at Lowes. It was initially bought for my house by someone who knew nothing about computers and I gasped when I saw the 2.4ghz logo on the box. Amazingly, it has not affected my wireless setup one bit. I can sit 1 inch away from the phone with my laptop and my connectivity never drops nor does my speed. If I am on the phone and move near my WAP or laptop occasionally I'll hear a click every once in a whi
  • I put wi-fi at my sister's house, and nothing was a problem except for a video baby monitor. Turning it on would cause interference in both the 2.4ghz phones and 802.11g AP, practically disabling both. So instead we just used a 900mhz non-video baby monitor...

    Ian
  • 900 MHZ Interference (Score:3, Interesting)

    by OYAHHH (322809) on Saturday August 07, 2004 @05:56PM (#9910632) Homepage
    Given,

    All of the 900 mhz advocates on this thread seem to think there is no interference I would like to interject and say that I do have interference issues with my 900 mhz phone and my 801.11 B equipment.

    More specifically, I have a Panasonic 900 mhz gigarange telephone with some sort of digital spread spectrum technology (KX-TC1891B). The phone does not seem to impact my 801.11b equipment's (Linksys WRT54G) connectivity.

    But, connectivity isn't everything.

    As soon as I hooked a Hawking omnidirectional attenna onto my router I suddenly started hearing a beep on my computer speakers about every 5 seconds.

    It about drove me nuts one day when I took the phone handset off the base unit and placed it in another room. I didn't realize that my phone was causing my computer to beep.

    I thought something was dieing on my computer or that some program/virus was playing a cruel prank on me.

    I must have rebooted that computer 20 times that day trying to isolate the cause of the beep. Never did.

    Next day, put the phone back on the base unit and the beep went away.

    Having discovered the source of the problem, I couldn't believe it, I turned the sound off via the computer's O/S, picked up the handset and no beep.

    So, nowadays I have to turn the sound off on my computer before I answer the phone. Very annoying. But I paid a bundle for the two line phone, for which my wife was sorely irritated, so I guess I'm stuck.

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