hi guys,
i need help from you anyone know any idea or somthing can help please tell me directly
i have 1 watt access point 11b <---- very old board TI chipset and its been Amp to 1 watt
i want to change it to 400mw that comes with mikrotik.
whats better for me my old 1 watt OR the new 400mw SR2
btw i dont have any problems with the bandwidth"wireless bandwith"
i have problems with the range and stablity
please advice me guys ASAP
thaaaaaaaaaaanks
“I am alive and on planet Earth. What should I do next?”
More information needed to be of help, but generally speaking an SR2 w/a Mikrotik is a pretty romantic marriage, especially compared to a union between a geriatric unsupported chipset and an amplifier of unknown provenance…
When it comes to distance there are many factors that come into play and it is a case by case analysis but generally speaking our tests and research have found that when comparing 802.11b with 802.11g the modulation used is very important. While 802.11b typically boasts better receive sensitivity and power output the QPSK and QAM modulations used in 802.11g (>12Mbps) allow for much greater distances then the BPSK and CCK modulations used in 802.11b. The becomes very apparant in NLOS (near line of sight) situations. So I would wager that a newer SR2 would outpreform the older gear + 1W Amp in both speed and distance.
As a side note if bandwidth is not of great importance, and both ends are Mikrotik you could lock down the SR2 at 24Mbps, and run in the newer Atheros 5MHz modes this would provide the best modulation to speed to distance. In this mode you can expect true bandwidth’s of ~4.5 Mbps.
Keep in mind that the 400mW cards (at least the ones from Ubiquiti) only give you 400mW when your transmit rate is set to 24Mb or lower (hence the locking them down to 24Mb as mentioned).
If you are having problems with range and performance, chances are you are trying for N(on)LOS links? There’s only so much you can get away with…you might need to consider 900MHz if this is the case.
You still need to post more information if you want any kind of feedback relating specifically to your network.
no one give me clear answer guys,
now i m making 7km from omni 15db to 20db CPE client 11g (73mw) < from aircord.com
ok for example i m using 400mw with MT -----> to the 20db (73mw) can i make it 7 or more or less if we consider the same enviroments
Just pop those numbers into a calculator and you’ll do fine. Here’s a decent one that’s simple to use, and there are many others available by googling:
http://www.zytrax.com/tech/wireless/calc.htm
Intuitively speaking, ignoring factors such as noise (other operators), fresnel interference, massive cable losses etc. the system you describe ought to work with a reasonable margin.
thanks dbstrom,
i know all of these but i want you experinse in actual site
As the other posters say, it varies hugely depending on circumstances. Here’s an example:
Some time ago we had a WRT54G-- equipped with standard rubber duck antennas, sitting in a 2nd story window and set to 50mw-- accidentally associate and actually pass traffic via another site that was some 19km distant. That remote site-- which we were using as an emergency backhaul substitute AP for another location and which was configured in great haste-- happened to have a 24dBi grid pointed in the exact direction of the WRT and was located at about 500 meters elevation with a clear shot to the WRT. The customer using the WRT called in to complain about “a slow connection” but in fact still was able to use their connection to the network. People having only dialup as an alternative probably would have found the connection to be really terrific. Bizarre but true.
We have a number of configurations that are roughly similar to what you describe, successfully running in fairly noisy environments. In part, your satisfaction depends in part on what is your definition of “success”. For us, we only sell connections up to 512k, most of our customers buy 256k connections, so “success” is very easy. In some ways the greatest trick to misapplying 802.11-whatever gear in the WISP market is expectation management. Don’t expect miracles, and especially don’t lead your customers to expect miracles. 
Any answer to your questions is going to be in the “generally speaking” realm because there are a lot of variables in this squishy mess that are totally dependent on your context. Generally speaking, we get good results with APs running less than a watt into omni or sector antennas with gains varying between 8 and 16dBi that are talking to CPE running 200mw and working 24 or 19dBi antennas. Sometimes these work excellently, sometimes they fail to work due to context. Sometimes the failures can be rectified with enough work.
If it’s specifically the SR2 you’re wondering about, who could wish for a better chipset than Atheros? Assuming the amplifier incorporated on the SR2 card is reasonably designed and constructed, there’s no reason not to use 'em. We do and we’re quite happy. We’ve got a pair running a 48km Nstreme backhaul link in 5Mhz mode to a comically weird tree-mounted AP/relay we inherited from a failure and we get the bandwidth we need out of that rig.