2.4GHz-Friendly Phones? 386
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?"
Yes, I have (Score:3, Informative)
900MHz (Score:1, Informative)
Vtech (Score:5, Informative)
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.
2.4 GHz phones == bad idea (Score:5, Informative)
You can also get 5 GHz phones, too. Either 900 MHz or 5 GHz is fine, just keep 'em off 2.4 GHz.
By the way (Score:2, Informative)
http://www.vtechphones.com/vtechui/shop/productdet ail.cfm?itemID=1299
WiFi and 2.4GHz Don't Mix (Score:5, Informative)
http://www.wi-fiplanet.com/tutorials/article.php/
Of course, the best solution is a 900MHz or 5.8GHz Cordless Phone.
Re:My microwave (Score:5, Informative)
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:5.8 (Score:4, Informative)
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.
Re:5.8 (Score:3, Informative)
Re:Why YES, I have had problems (Score:4, Informative)
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.
Re:I get interference (Score:4, Informative)
Just stick to 900mhz for the best range and wireless reliability.
Re:No problems in my house (Score:5, Informative)
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....
Re:I have always had one or more of these wireless (Score:5, Informative)
Re:Why YES, I have had problems (Score:2, Informative)
Re:2.4 GHz phones == bad idea (Score:2, Informative)
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.
There isn't any significant inherent difference in range either (note, lurkers, I said significant), but 2.4 GHz phones tend to be lossier than 900 MHz phones. That is, their power output tends to be lower and their receive sensitive not as good for stuff designed for the same money.
So, yeah, 900 MHz phones are pretty good. The older 49 MHz phones are sucky in that the inherent wavelength is over 6 meters, and so their antennas are notoriously inefficient. At 900 MHz, the wavelength is just 30cm, making it really easy to build efficient omnidirectional antennas, and 2.4GHz doesn't really have much of an advantage there.
Re:5.8 (Score:5, Informative)
So odds are a 5.8GHz phone would mess with the upper range of 802.11a.
Re:why 0.9Ghz is better (Score:3, Informative)
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
Nope, wrong again! (Score:3, Informative)
Joining the 900 MHz crowd.. (Score:5, Informative)
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
Re:5.8 (Score:5, Informative)
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:
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.
Re:why 0.9Ghz is better (Score:1, Informative)
L(f,d)=20.log(f*d)+92.5
(got it from http://www.geocities.com/senol_gulgonul/linkbudge
f is frequency, d is distance.
So obviously L(2.4GHz,d) > L(0.9GHz,d). Meaning lower frequency leads to less loss (further reach).
Re:why 0.9Ghz is better (Score:3, Informative)
(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 a few years ago)
Re:why 0.9Ghz is better (Score:3, Informative)
Hmm... base, plugged into wall outlet, plenty of power... handset, running on battery, probably using less energy for transmission in order to conserve energy.
I'd say the transmission power *might* play a factor in there somewhere. And I, too, recall that lower frequencies tend to travel further.
In addition (Score:3, Informative)
Thank you, come again.
Why 47 MHz is even better (Score:2, Informative)
Re:5.8 (Score:2, Informative)
Re:Joining the 900 MHz crowd.. (Score:5, Informative)
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.
Re:why 0.9Ghz is better (Score:5, Informative)
The variable L is often called "free space path loss". This sort of path loss increases with frequency. But where is the actual loss? This is supposed to be in free space, i.e. vacuum. Since there isn't anything in vacuum to heat up or whatever the loss can't be in the actual path between the antennas (which is why the "path loss" bit is misleading).
It's because of the antennas. An efficient omnidirectional transmitting antenna will radiate pretty much all the power you feed it. An omnidirectional receiving antenna will receive power proportional to it's size. Obviously larger antennas will collect more power. Rather than giving each antenna a separate transmit gain and receive gain the RF engineering types just fudge it with the idea of "free space path loss".
So yes, you will end up with more signal at the receive antenna of a 0.9GHz as opposed to a 2,4GHz phone. The formula is correct in that. After all the receive antenna is 2.7 times bigger. That's a whole 8 dB more signal. Of course the larger antenna will receive noise that much better too (and there tends to be a lot at 900MHz). The 900 MHz antenna will probably be so large that you will only be able to get one in a handset (some 900MHz phones actually have an extendable antenna). If the 2.4GHz faction puts more than one antenna in their handset and then has the phone pick the one with the best signal, they will probably win in practice.
Real path loss caused by things like building materials and trees does tend to go up with frequency. OTOH higher frequency signals can squeeze though smaller holes. It's all a bit complicated. I personally suspect that free space path loss isn't a significant factor in the actual range you end up with.
Re:900mhz? (Score:4, Informative)
Some GSM cell phones run on the 900MHz band (880-960MHz) [thetravelinsider.info].
Some US cordless phones run on the 902-928MHz [csgnetwork.com] band. But thanks for your insightful comment anyhow, AC.
Re:Yes, I have (Score:1, Informative)
In fact, you can still find the old 49mhz phones sometimes.. They had great range, and I can tell you, since they aren't common any more, the old problem of either hearing someone else's call (the real old analog ones), or having your range drop off because of interference from another user on your channel (if it's digital) isn't much trouble anymore.
Re:I don't get it (Score:3, Informative)
My 900 Mhz handset seems to use a reasonably efficient 3" (~8cm) 1/4 wave antenna, while my base uses a nice 6" 1/2 wave antenna. Of course 2400 Mhz allows antennas that don't protrude out of even a small handset. In some applications, like very small handsets, this could be a significant design advantage, especially outside in rural areas where building penetration is least important and open space range most important).
For the old 46/49 Mhz phones the only privacy feature that I can recall is "frequency inversion" which produced Donald Duck quacking noises instead of speech. Some Uniden phones used this. However, such speech could still be monitored with the use of commonly available frequency inversion decoders. There were better "rolling" frequency scramblers for which decoders were not so easily available, but Uniden was not using those.
Keep in mind that the 46/49 Mhz phones were so low in power in comparison to modern phones that an eavesdropper needed to be much closer and/or have a much more sensitive receiver to pick up the broadcast. When 900 Mhz phones first came out they were regarded as less private until the first digital and then digital spread spectrum models were released. I am not aware of any viable method to eavesdrop on DSS calls.
Re:No problems in my house (Score:2, Informative)
And for what it's worth, Airsnort has the ability to save its place so you can stop and restart at a later point, so it doesn't have to be a continuous month long cracking session, and if it's a neighbor I don't doubt that they could leave it running in the background enough to crack a wep key. It's in his house, so it's not like anyone is going to notice a van sitting in front of their house all the time.
Re:900mhz? (Score:5, Informative)
Pot kettle black. [bizrate.com]
Someone apparently doesn't know that 900mhz cordless phones exist, and all of them are wi-fi friendly. I myself have a Panasonic 900mhz digital spread spectrum phone and have no problems at all with my wi-fi when using it.
Re:why 0.9Ghz is better (Score:3, Informative)
Re:Why YES, I have had problems (Score:4, Informative)
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.
Re:Joining the 900 MHz crowd.. (Score:5, Informative)
Re:I get interference (Score:3, Informative)
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 couldn't reach another story. The 2.4 ghz I use at home can't reach to the other end of the house while our 900mhz (digital) can penetrate the house and surrounding acreage.
Finally, I can tell when my father uses our 2.4 ghz phone [panasonic.com] when I'm on the perimeter of the linksys 802.11b/g border. Depending on what my signal strength is, it'll drop or weaken.
Re:spread spectrum hops (Score:3, Informative)
Here's a quote from that article:
The use of these special pseudo noise codes in spread spectrum (SS) communications makes signals appear wide band and noise-like.
Re:5.8 (Score:4, Informative)
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.Go DECT and be done with it (Score:2, Informative)
From what I understand this frequency range is reserved in the US - so bad luck. You are stuck with stupid phones and the imperial system
I made the mistake of getting a Panasonic 2.4GHz phone. Complete crap, and has about 60% chance of killing your (and your neighbors) wireless LAN dead when you call someone. I'm just in the process of moving to DECT/GAP myself.
More info: http://www.dect.org/toptech.html
Ironically, this wouldn't be a problem for me except my stupid IBM Thinkpads think they are in the US, and won't allow me to use the extra channels that we are given in Australia. My WAP will go all the way up to channel 13 if I tell it I live in Australia - which is well out of the range the phone uses - but the Thinkpads limit me to max channel 11.
Zilch.
900Mhz Cordless Phones Consumer Reports "Best Buy" (Score:2, Informative)