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802.11 RF Amp
MikeLRoy writes "Linksys has announced a signal amp, to be available soon, for their wireless ap's/routers. While many people have been using commercial rf amps hacked onto their ap's, linksys now has a commercial solution!" I wonder when ISPs are going to stop soft-pedaling the anti-NATing provisions in their terms of service.
While many people have been using commercial rf amps hacked onto their ap's, linksys now has a commercial solution!
Now if they could just come up with a commercial solution, we'd be all set.
And I'm not even a SpeakEasy customer. I wish RoadRunner would implement similarly "with-it" policies...
"BSD: Free as in speech. Linux: Free as in beer. Windows 10: Free as in herpes." --Man On Pink Corner in #52607549.
Actually, this device increases the RX sensitivity and power as well as that of the TX, thus giving a greater range regardless of what you have in your laptop.
Erm, no... it's a signal amp... so if you stick it halfway between a laptop and a wireless AP, it will amplify the signal from both. It's just like using a repeater in a cabled network.
"If at first you don't succeed, lower your standards."
Because this device emmits at the FCC max, something most APs do not. Yeah, this thing would rock inside a Pringles can, but it's likely even the worst designed can will put the setup over the limit.
Unless you start snooping into the data packets, looking for User-Agent strings, etc (if you're NATting 2 different OSes behind it). You can make educated guesses (why do all TCP connects come from port 61000+?) but you really can't KNOW if someone is NATting.
I want to delete my account but Slashdot doesn't allow it.
Balam
...but ours goes up to 11.
The entire point of 802.11b is that it is low power, allowing a lot of use in a small area. If my neigbours all start to boost their signals (both ways of course), my 2.4 GHz RF environment is going to be be useless. X.10, cordless phones, bluetooth, 802.11b all share this frequency (and I have all four of those at home...)
In the UK, until recently 802.11b was illegal for commercial use because it was full, making it useless. My car the other day would not open in a high-RF environment (near Toronto's CN tower).
Can we please keep this frequency useable? Amplifying will kill it. An RF signal of this type can carry 30 miles very easily, making it useless if we all start amplifying.
Michael (radio amateur, VA3MVW)
---
BDOS ERR ON A:>
I dumped my Comcast cable modem for SpeakEasy DSL just about a year ago, and I've never been happier with an ISP.
I've never had an outage, I can (and do) run servers in my house to handle my own mail, www, etc. Their phone reps are courteous and don't suffer total brain shutdown when I mention the magic sentence, "I'm using a Mac."-- not that I've needed support beyond a little help sorting out a password issue when I wanted to configure the INCLUDED dial-up access in case I needed it.
When I needed an additional IP address last year, I called them up and had one in a couple minutes. I just upgraded my service from 608K down/128K up to 1.5M down/384K up, and it was not a hassle at all. Since my employer chips in $50/month of my ISP charges, this higher speed service now costs me $40 per month, the same I was paying a year ago for my cable modem with all of its restrictions.
To all Slashgeeks who are able: If you have a choice, go with SpeakEasy-- you won't regret it!
~Philly
I'd be a lot happier if the FCC got rid of some of those UHF TV channel frequency monopolies and gave the spectrum back to the public that rightfully owns it, to try to lower contention over the narrow strip of bandwidth that 802.11 uses. There's also much more use of wireless these days by non-mobile devices than there really needs to be, when those devices could perfectly well use wired ethernet, or maybe a much lower-powered shorter-range wireless scheme (like a higher-bandwidth Bluetooth) to an access point that's nearby (i.e. in the same room or close to it, not far away in the building). However, that last part is harder. Tragedy of the commons and all that.
A while ago on slashdot there was breathless coverage of a Linksys hardware 'hack' that raised their 30mw AP to 100mw. Some knowledgeable RF engineer took a look and it *was* putting out 100mw - 31mw in channel, and 69 mw of crap spattered all over 2350 - 2550 MHz. All that 'hack' accomplished was giving more ammunition for those satellite radio folks that want to regulate the ISM band.
Instead of building a 100mw radio with good sensitivity, Linksys is building a cheesy amp to go with their cheesy AP.
If you genuinely need some amplification I've used YDI.com and Teletronics.com amps in the 250mw to 1 watt range and not had much trouble with any of them. RFLinx or RFLynx(sp?) has come out with a 750mw amp for $200, but I haven't tried that product yet.
FYI half of the reason to deploy an amp is for the LNA (low noise amplifier) effect - besides boosting output they pump up the return signal by 10 - 14 dB. There is a real call for a 150mw output amp with a solid LNA for client side problems, but that is a story for another day.
I am very easy to get along with, but I don't have time to waste being nice to people who are being stupid. -Theo
I don't think you need to worry. What Linksys is doing is not nearly as interesting as people might assume (which is I suppose is par for the course for Slashdot :-) What I'm pretty sure is going on is that the wireless access point on the linksys doesn't have a very strong radio transmitter to begin with (I'm guessing 30-50mW), and the signal amplifer just raises the transmit power to the max legal limit for the 2.4GHz band.
The Cisco 350 Access Point (and wireless cards) has better receive sensitivity (I don't know if that's due to a better built-in antenna, or better radio circuity, or both), and a stronger transmit power than most other 802.11 cards (selectable from 5mw to 100mW). In contrast, the Lucent Wavelan Silver card has a 31 mW transmitter. I don't know what the transmit power for the Linksys access point, since it's not listed on the web site or in the user's guide, but they claim an outdoor range of 1500 feet at 1 Mbps, and 500 feet at 11 Mbps. For comparison, the Orinocco access point claims 1750 feet at 1 Mbps, and 525 feet at 11 Mbps, and the Cisco 350 access point claims an outdoor range of 2000 feet at 1 Mbps and 800 feet at 11 Mbps. If we assume that both Cisco and Linksys are exagerating to an equal extent for the best case scenario, it seems pretty clear that the Lucent transmitter is less powerful than the Cisco 350.
Of course, as radio amateurs know, transmitter power doesn't have as much effect on range as some people might think. That's why QRP operators can sometimes communicate with people halfway across the globe with only a Watt or two of power. So the Linksys signal amplifier will probably not make that much of a difference.
That being said, I would recommend the Cisco 350, not because of the higher transmit power, but because the access point has better manageability (you have much finer control over how the access point operates, with various nice features such as having the AP ask your radius server whether or not a particular MAC address should be allowed, LEAP authentication/encryption, etc.). Also the Cisco 350 PC card has a full-featured Linux driver, which allows you to control the transmit power, scan for all available 802.11 networks, and so on. Another nice feature with the Cisco 350 is that you can store the WEP keys in flash memory, so that you can lend the card to house guests, without needing to reveal the WEP key. (Right now, I haven't been able to find an open source radius server that supports LEAP, so I'm using a combination of 128-bit WEP keys plus MAC address access controls. One nice thing about the 350 Access Point, as compared to the Apple airport, is that you can change WEP keys without needing to reboot the access point. So while I haven't implemented it yet, it should be possible for me to automate changing the WEP key every 24 hours, by calculating a MD5 hash of a secret plus a timestamp. That way, a shell script on my Linux laptop would allow me to get update the WEP key at the same time, automatically.)
-Ted (N1ZSU)
That amplifiers amplify everything... including the ambient noise PLUS they also insert a certain amount of noise themselves (LNA stands for "low-noise-amplifier not no-noise-amplifier). So while the signals may be amplified, the noise level might also be amplified enough to negate the effect.
In addition, the FCC has a dba limit on the amount of signal you can have so you cannot just stick power amplifiers on all the devices in the network without incurring some exposure to fines and penalties (for interference).
It makes a lot more sense to design the wireless system to use numerous low-power devices spread around the area so that you can cover just what you need to cover and not simply saturate the area with signal.
No one ever had to evacuate a city because the solar panels broke!
It is just a repeater. It doesn't broadcast at any greater strength than your typical 802.11b access point, all it does is repeat whatever it picks up, thus increasing the range.
The logic goes that you have to certify with a known antenna, so if you use standard connectors anybody could hook up a different antenna and make the device noncompliant...
and yes, it sounds screwy to me too, but those are the rules
I think you are confused as to what an amp is and what it does and doesn't do.
An amplifier takes raw signal (including noise) and amplifies the power on it in the direction it is set to amplify. There are bidirectional amplifiers to do it in both directions.
Amps are best placed as close to the antenna as possible to reduce loss and noise. As a signal travels across cable, noise and loss increase. Thus, a short "jumper" cable is ideal to connect the antenna to the amp.
Putting an amp on one side of the communication pathway will improve the signal and perhaps the distance a bit. The biggest improvement will be in the quality of the wireless link at the far reaches of the original signal.
To greatly improve distance, it is absolutely necessary to amplify on both ends. The end goal is to improve your signal to noise ratio. The weaker your signal from the other end, the worse that ratio becomes.