RT-N16 XMIT Power

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rakstr
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Joined: 12 Feb 2010
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PostPosted: Sat Feb 13, 2010 15:24    Post subject: RT-N16 XMIT Power Reply with quote
I recently bought an ASUS RT-N16 and installed the 13309M DD-WRT build. Very nice!

On the Wireless/Advanced Settings, the TX power defaults to 17 yet the comment says default 71, range 1-251mW.

A) is the default supposed to be 71?

B) what ranges have people tried and when do you begin to overdrive the unit?
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4512jth
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PostPosted: Sat Feb 13, 2010 16:02    Post subject: Reply with quote
Well for A, if it uses a default lower than 71 it is suppose to be like that. It is the best value found in testing.
rakstr
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PostPosted: Sat Feb 13, 2010 16:06    Post subject: Reply with quote
4512jth wrote:
Well for A, if it uses a default lower than 71 it is suppose to be like that. It is the best value found in testing.


Ordinarily I'd agree but when I see 17 versus 71 I think about it a lot harder Smile
la7dfa
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PostPosted: Sun Feb 14, 2010 1:05    Post subject: Reply with quote
There are heat issues with wireless transfers.
You have to add some kind of heatsink/cooling to the wireless module if u want to increase power.

Read the sticky regarding RT-N16 in the forum.

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rakstr
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PostPosted: Sun Feb 14, 2010 5:15    Post subject: Reply with quote
la7dfa wrote:
There are heat issues with wireless transfers.
You have to add some kind of heatsink/cooling to the wireless module if u want to increase power.

Read the sticky regarding RT-N16 in the forum.


I understand that but I'm still trying to establish what the correct baseline is; 17, 71, or somewhere in between. 17mW seems very low to me..... Been in the telecom business for 35 years.
la7dfa
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Location: Kristiansund, Norway

PostPosted: Mon Feb 15, 2010 3:41    Post subject: Reply with quote
It was also a dd-wrt ticket where 17mW were said to give the best wireless performance (speed) for this particular router.
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modervador
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PostPosted: Mon Feb 15, 2010 15:05    Post subject: Reply with quote
rakstr wrote:
I understand that but I'm still trying to establish what the correct baseline is; 17, 71, or somewhere in between. 17mW seems very low to me..... Been in the telecom business for 35 years.

I've been in related businesses for a few decades myself. My guess is that in this case, a 17 in the TX power configuration is just a number that gets copied to a programmable register in the router hardware, and that the actual power into the antenna bears some relationship to that number but nothing quite so simple as 17=17mW or 17=17dBm. Consider that this software runs on a variety of hardware; storing calibration curves for every device would be rather expensive, memory-wise and otherwise.

My advice is to set the TX power number to the minimum that yields the highest stable connection speed, plus a small margin, as established through experiment. Any higher setting than that is at best wasted, and at worst harmful.
rakstr
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Joined: 12 Feb 2010
Posts: 65

PostPosted: Mon Feb 15, 2010 15:59    Post subject: Reply with quote
modervador wrote:
rakstr wrote:
I understand that but I'm still trying to establish what the correct baseline is; 17, 71, or somewhere in between. 17mW seems very low to me..... Been in the telecom business for 35 years.

I've been in related businesses for a few decades myself. My guess is that in this case, a 17 in the TX power configuration is just a number that gets copied to a programmable register in the router hardware, and that the actual power into the antenna bears some relationship to that number but nothing quite so simple as 17=17mW or 17=17dBm. Consider that this software runs on a variety of hardware; storing calibration curves for every device would be rather expensive, memory-wise and otherwise.

My advice is to set the TX power number to the minimum that yields the highest stable connection speed, plus a small margin, as established through experiment. Any higher setting than that is at best wasted, and at worst harmful.


Totally agree with you, that's why I reached out to see if anyone had done any experimentation! I currently have settled at 40 for this setting. Seems to "match/balance" best with the receive direction and there is no noticeable heat increase on the router (by no means exhaustive scientific evaluation". FWIW, I have my router mounted on the edge of a shelf in the closet oriented vertically with the back pointed upwards. It is about 6 feet off the ground and the antennas are at least 12 inches from any walls or other obstructions oriented off vertical 45, 0, 45. Primarily connecting with Intel 5300 AGN adapters, router in mixed mode (security cameras are wireless B Sad)
davesbass
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Joined: 15 Oct 2010
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PostPosted: Fri Oct 15, 2010 19:52    Post subject: possible answer for you Reply with quote
Ive got a couple rtn12s and 16s that all seem to have this issue

I think i found some evidence 71mw is what its supposed to be not 17mw. i think 17 is a typo

looking at asus website the specs for the RTN-16 state: Output Power [all modes]:15.8~19.5 dBm

if you convert db's to mW's

15.8 dBm = 38.0189396321 mw
19.5 dBm = 89.1250938134 mw
and
71 mw = 18.5125834872 dBm
BUT
17 mw = 12.3044892138 dBm
28 mw = 14.4715803134 dBm

so it seems to me like the 17 mw default [as well as 28 mw mentioned in help] has to be too low- its clearly out of the range of the manufacturers specs.

anything between 38 mw and 89 mw is probably ok.without doing a lot of math 71 is right in the middle there.

I have a couple RTN16s and RTN12s [almost same broadcom chip]& I set them for 70 or 71 mw and will see how that goes. so far they seem happy they dont explode or melt when i set them that high.
When i set them for 70 I notice the status page then reports the mw as 71- so it probably doesnt matter.

but I think the original poster is correct in suspecting 17mw is indeed a error.

good luck
dave
redhawk0
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PostPosted: Fri Oct 15, 2010 20:04    Post subject: Reply with quote
This model is in dBm...not mW.

Use 17 for the value on this model...NOT 71.

17dBm is ~50mW
20dBm is ~100mW

Don't go over 20 dBm.

http://www.aubraux.com/design/milli-watts-to-dbm-table.php


redhawk

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Donations have dwindled so testing is limited to C/CB and R/RB modes on just a few newer models. No old router testing performed any longer.

Looking for more test units (newer models only) for the project...got a brick?...PM me to make a hardware donation. (USA) A donation is not a debricking service....it is a way to "Give back" to the dd-wrt project.

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jumran
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PostPosted: Fri Oct 15, 2010 20:06    Post subject: Re: possible answer for you Reply with quote
The TX power is measured in dBM on the Asus RT-N16 not mW. Do a search in the forum and you will find other topics on this. Put your settings back to 17 or at least less then 25 to avoid damage.

davesbass wrote:
Ive got a couple rtn12s and 16s that all seem to have this issue

I think i found some evidence 71mw is what its supposed to be not 17mw. i think 17 is a typo

looking at asus website the specs for the RTN-16 state: Output Power [all modes]:15.8~19.5 dBm

if you convert db's to mW's

15.8 dBm = 38.0189396321 mw
19.5 dBm = 89.1250938134 mw
and
71 mw = 18.5125834872 dBm
BUT
17 mw = 12.3044892138 dBm
28 mw = 14.4715803134 dBm

so it seems to me like the 17 mw default [as well as 28 mw mentioned in help] has to be too low- its clearly out of the range of the manufacturers specs.

anything between 38 mw and 89 mw is probably ok.without doing a lot of math 71 is right in the middle there.

I have a couple RTN16s and RTN12s [almost same broadcom chip]& I set them for 70 or 71 mw and will see how that goes. so far they seem happy they dont explode or melt when i set them that high.
When i set them for 70 I notice the status page then reports the mw as 71- so it probably doesnt matter.

but I think the original poster is correct in suspecting 17mw is indeed a error.

good luck
dave

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davesbass
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Joined: 15 Oct 2010
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PostPosted: Fri Oct 15, 2010 20:42    Post subject: ok Reply with quote
wow- you guys sure popped up quick when I suggested there was an error in there. there still is a typo in the web gui obviously- if its not the 17 number its the label of mw's vs DB's.
i noticed that other N routers I have used have dbs not mw, so I believe you. Ill try setting them for 20 "mw"s then. see what happens. I do appreciate the quick responses and the work you guys do on this stuff.
thanks
dave
redhawk0
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Joined: 04 Jan 2007
Posts: 11436
Location: Wherever the wind blows- North America

PostPosted: Sat Oct 16, 2010 12:33    Post subject: Re: ok Reply with quote
davesbass wrote:
wow- you guys sure popped up quick when I suggested there was an error in there. there still is a typo in the web gui obviously- if its not the 17 number its the label of mw's vs DB's.


Hehe...if we know it isn't a real problem...we're quick to correct it...however, if it really is a problem...we're also some of the first to jump on the bandwagon and bash and talk trash about it. :lol:

Funny how that works.

Yeah...we know about the mW vs. dBm labels...I believe there is a TRAC ticket open on it...but I didn't go look for it yet.

redhawk

_________________
Donations have dwindled so testing is limited to C/CB and R/RB modes on just a few newer models. No old router testing performed any longer.

Looking for more test units (newer models only) for the project...got a brick?...PM me to make a hardware donation. (USA) A donation is not a debricking service....it is a way to "Give back" to the dd-wrt project.

I do NOT provide personal assistance through chat or phone....so please don't ask.
nim6us
DD-WRT Novice


Joined: 03 Sep 2011
Posts: 2

PostPosted: Sat Sep 03, 2011 19:19    Post subject: Reply with quote
I have an R-N16 myself and was recently doing some research into the subject. I found the below chart that shows significant signal boost pleteuas at 60mw.



Issue is there's not going to be set transmit power that works for everyone. Obviously our homes/offices are all different, with different distances to the router, different building materials, etc. My advice, start at 60mW, then take your laptop or other wireless device and go to the farthest point away from router that anyone will feasibly need access. From there increase your transmit power by 5mW until you reach your optimal signal strength. For me it was 75mw, but again it's gonna be different for everyone. While the router has the capacity for 250mW I would caution going past half of that, 125mW. Yes the router can handle it, but moving past that threshold you risk the chance of burning your router out before it's time. Of course this is only my two cents, as always do what works best for you, good luck!
WilsonB
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Joined: 10 Oct 2011
Posts: 11

PostPosted: Mon Oct 10, 2011 19:00    Post subject: Now the last post through me off.. Reply with quote
Good information.. but it through me off.
Everyone was talking about not setting the Pwr setting to high and it was actually measured in db... Now you wrote mw.

Im using the latest version of dd-wrt on Asus rt-n16.

What is the highest safest value? It is default at 17. Is the measure in db or mw ?
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