[SOLVED] TX Power Setting Not Working?

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Ivo_K
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Joined: 12 Jan 2018
Posts: 29

PostPosted: Sun Apr 10, 2022 19:22    Post subject: [SOLVED] TX Power Setting Not Working? Reply with quote
I have a Linksys WRT1200AC running DD-WRT v3.0-r48607. I use the 5 GHz wireless channel 149 which the European legislation assigns for use by SRDs and limits the EIRP to 25 mW. I have therefore set the TX Power on the Wireless/Basic Settings page to 14 dBm (which roughly equals 25 mW) and left the Antenna Gain field at zero.

Then I experimented a little bit with different settings but I could not see any difference in strength/quality or range of the signal. So, for the hell of it, I tried the TX Power settings of 300 dBm and also of 0 (zero, which defaults to 1 when applied) dBm and still saw no change whatsoever. My signal strength, its quality, range or the speed/bandwidth and S/N ratio achieved on the client devices were practically unchanged.

Am I missing something here? Is there something more I should do in order to modify the TX power?
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SurprisedItWorks
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Joined: 04 Aug 2018
Posts: 1354
Location: Appalachian mountains, USA

PostPosted: Mon Apr 11, 2022 15:50    Post subject: Reply with quote
It has been awhile, but I have done similar experiments with my WRT1900ACSv2 and have concluded that the transmit power level cannot actually be changed by the user. (For measurement I used the Wi-Fi Scan feature of the AirPort Utility app on an iPhone to get RSSI receive power in dBm at a fixed location near the router.)

And thanks for the chuckle: 300 dBm is 10 to the 18th Gigawatts, which per the numbers floating around the internet (correct?) is a bit more than the power output of the sun.

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4 Linksys WRT1900ACSv2 routers on 49081, 2 on 48141: VLANs, VAPs, NAS, client mode, OpenVPN client (AirVPN), DDNS, wireguard servers and clients (AzireVPN), three DNSCrypt DNS providers (incl Quad9) via VPN clients.
Ivo_K
DD-WRT Novice


Joined: 12 Jan 2018
Posts: 29

PostPosted: Mon Apr 11, 2022 18:43    Post subject: Reply with quote
Indeed. If you look at the Status/Wireless page it will always show TX Power of 13 dBm regardless of your input on the Wireless/Basic Settings page. Even if you aim for the sun Smile
buboleck
DD-WRT Novice


Joined: 06 Jan 2022
Posts: 4

PostPosted: Tue Apr 12, 2022 13:10    Post subject: Reply with quote
If I'm not mistaken in version 2 of WRT1900ACS and 1900ac the transmit power can not be modified and is build in the firmware to comply with regulatory requirements. I have 1900ACSv1 but I can't test now. I found that EU regulations lower the max transmit power (23 dBm) and resorted to using US region 30 dBm.

FYI, I'm right:

https://openwrt.org/toh/linksys/wrt1200ac

WRT 1200AC v2 can not modify Wifi power

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