Discussion in 'Tomato Firmware' started by Daky, Aug 10, 2013.
What would be the highest \ safest Transmit Power on this router? (RT-N66U?)
Thanks for replying sir.
I am from Canada, Advanced setting is set to Canada, and default power was set to 45, i increased it to 85.
Since, the maximum value is 200mW, this should be safe?
The number you enter is relative power and doesn't directly equate to mW.
There are several threads on this topic as well as the "safe" maximum power. Zero is supposed to set it to the hardware default (which one would expect was sensibly chosen by the manufacturer after some testing.) Different driver versions also perform differently. At least one recent driver gave no change in power output at all with different numbers entered in the GUI.
In general, keep the power to the minimum that allows reasonable connection. If the problem is devices not connecting or dropping connections, the problem is usually the client rather than the router.
May I ask:
You say the default power was 45mW and you increased it to 85mW.
1. How do you know the TX power? -- from the GUI or with the wl command?
2. How did you increase it? -- GUI or wl command?
3. Which Firmware are you using?
1) in GUI it was set to 45mW
3) tomato latest 112 AIO
FWIW, on Victek GUI, the Country was US, tx power setting was 0.
wl txpwr returned: 31.75 dBm = 1496 mw.
changed country to Canada, no change in wl output.
Changed tx power to 50: 17.0 dBm = 50 mw.
AFAIK, toastman did testing on this and found ~50 to be the optimal power setting. Higher power did not show an improvement.
A way around this is to upgrade the antennas on your router(if possible). That way the extra power would result in signal instead of noise.
If the 3 Antennae are functional, rather than just a random wire in a random plastic enclosure.
(Functional means expensive).
Even then, increased TX power does not increase the RX sensitivity (au contraire), nor does it do anything to increase the client's TX power.
I do not trust the wl command at all.
Tomato say that 0 means Default.
wl says that -1 means default.
But this "default" is 1496 mW:
wl txpwr1 -1
TxPower is 127 qdbm, 31.75 dbm, 1496 mW Override is Off
wl txpwr1 -1
TxPower is 127 qdbm, 31.75 dbm, 1496 mW Override is Off
The value showed in the gui or command it's not the real power delivered by the unit since the signal is boosted by the RF amplifier (SG devices) and then enhanced by the antenna gain, it's known as EIRP power, the real power.
Then you can measure the signal strenght in one FFT Spectrum Analyzer to determine the real power. Measuring using your laptop,notebook is not giving any indication since the GAC control, driver version, filters may vary these values. At last you have to take in mind electrical ground noise also masking the real power, this is the reason why FFT Spectrum Analyzer shows more accurate values since you can filter the received frequency signal by mixing a master frequency, with this method (channel settings frequency/master frequency = clean frequency to measure).
In RT-N66U, 2.4GHz, Channel 4, 40MHz width channel and Country=USA, driver 184.108.40.206 I measured EIRP 27dB = 500mW. Same unit but 5GHz band I measured 25dB EIRP. Default values. Using countries adhered to CE regulations dismiss power to 100mW, better use FCC countries.
These results are theoretical and done using Tomato RAF beta 'y', the location and neighbor radios sort big differences from user to user. Also take in consideration 2.4GHz interference over USB3.0 devices, a big issue discovered when RF power surpasses standard...
It would be useful to show wl command values along with the corresponding EIRP values.
The reason i asked for this is .. that i am having issues with some of my wi-fi devices, for example Samsung Galaxy S3, i am unable to get better rate then 54mbps, on both 2 ghz and 5 ghz, and router is in the same living room where phone is, also i am getting poor signals on ObiWifi .
I tried many channels, but, no luck, i also tried to increase power, no luck.
I dont know what to do\try any more ...
Any suggestion would be very much appreciated
I very much doubt that this has anything at all to do with transmit power.
See what data rates you can get on devices that you know to be fast enough not be be a processing bottleneck.
As an overall approach, I tend to observe, quantify, measure, diagnose *first*, in order to understand the problem. *Then* I think about creating a solution.
Another approach is to try this and that in hopes of stumbling on something that works.
Sometimes the second approach is useful too.
Do any of your devices connect higher than 54mbps? Sometimes the issue is security type (must use WPA2), advanced settings (WMM must be on) or other settings on the router. Trying 20MHz channel width on 1, 6, 11, or 13 in 2.4GHz and trying both upper and lower bands in 5GHz is also recommended.
Again, though, transmission power on the router is generally less of an issue in residential WiFi than the transmission power of the clients. The default setting is likely fine. In fact, it may be better to turn the transmission power down below the default value if the clients are close to the router.
You likely know this as well, but how many bars you get in signal strength and the RSSI on InSSIDer don't equate to throughput or stable signals. You can have very high RSSI and full signal strength on the device with terrible performance.
Last, but not least, small changes in orientation and placement of obstacles make a huge difference in wireless performance. It's not the number of obstacles but the type of obstacle and the distance through which the signal must travel. Perpendicular to a wall is better than an angle, for example. Tilting the router 45-90 degrees, moving it to higher or lower location, placing metal objects behind the router to reflect RF (metal strainer) are quick and easy ways to experiment with this issue.
On 5Ghz, the most i saw was 54 mbps for some reason.
I just returned the power to 45, as this was default.
My S3 phone is varying from 6mbps to 54 mbps and its sitting like 2 meters from the router.
I did try many different channels (upper \ lower ) etc, and the same output.
If the numbers on that screenshot are to be believed, then the problem is not inadequate transmission power. In fact, lowering the transmission power would be reasonable (and possibly helpful.)
Any chance you could post screenshots of your Basic and Advanced Wireless pages?
Sure, thank you for help!
Disable afterburner on both radios, turn transmit power down (maybe around 20)
Next step would be to change 2.4GHz channel width to 20MHz, switch to n only on both radios, forget the network on your S3, update S3 firmware if possible, then reconnect.
S3 has a reputation for problems.
I will give it a try, thanks.
I have custom ROM on S3, and i never experienced this problem before.
What Aferburner usually do, if you don't mind telling me.
Afterburner/speedboost is an 802.11g technology to try to increase throughput. Doesn't work very well. Doesn't work with 802.11n.
MAN, you ROCK !!!!!!!!!!!!!!!!!
My S3 is connected to 150 mbps now !!!!!!!!!!!!!!!!!!!!!!!!!
THANK YOU !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
I suggest checking throughput with large file downloads over wifi on 20MHz channel width, then try 40MHz again and compare.
If the S3 goes back to 54mbps on 40MHz channel width, then it may be a compatibility issue between the drivers.
Will do more tests.
Thank you very, very much.
You just made me very happy, as this was going to my nerve since couple days ago.
User ERROR (mine) ;\
I remember this a bit, but after much searching can't find that Toastman post and would like to read it. Anyone know where it is?
So is there any conclusion to all this - i.e. optimum transmit power?
Toastman settings was for other routers, drivers and wireless bands, it's not applicable for this model.