Enabling Wifi 2.4 Ghz channel 12 and 13 on ar71xx (TL-WR710N, TL-WDR3600, TL-WR4300, etc.), enable all channels from 36 to 165 on 5 GHz (TL-WDR3600/4300), and get higher power on both bands.
There is a law in the US or an FCC regulation that requires all Wifi devices shipped to determine on the hardware level (in this case, in the driver) whether the desired frequency and power level is allowed.
Unfortunately, TP-Link simply sets the bit to US mode on all devices shipped worldwide. The stock firmware ignores it and offers frequency and power choice based on the selected country code. OpenWRT however (as would a stock Linux kernel) respects the bit and applies a logic AND over the selected regulatory domain and the US regulatory domain.
Luckily, someone created a binary patch called reghack that replaces the in-driver US regulations with unrestricted ones. 
All informations here: http://blog.michael.kuron-germany.de/20 … nt-page-1/
The reghack utility (tested on Barrier Breaker and Chaos Calmer for TL-WR710N and TL-WDR3600/TL-WDR-4300, it does not work on A.A. firmware) replaces the regulatory domain rules in the driver binaries with less restrictive ones. The current version also lifts the 5GHz radar
channel restrictions in ath9k.
- basically:
cd /tmp/
wget http://luci.subsignal.org/~jow/reghack/reghack.mips.elf
chmod +x reghack.mips.elf
./reghack.mips.elf /lib/modules/*/ath.ko
./reghack.mips.elf /lib/modules/*/cfg80211.ko
reboot
before on TL-WR710N and TL-WDR3600:
iw phy phy0 info
* 2412 MHz [1] (30.0 dBm)
* 2417 MHz [2] (30.0 dBm)
* 2422 MHz [3] (30.0 dBm)
* 2427 MHz [4] (30.0 dBm)
* 2432 MHz [5] (30.0 dBm)
* 2437 MHz [6] (30.0 dBm)
* 2442 MHz [7] (30.0 dBm)
* 2447 MHz [8] (30.0 dBm)
* 2452 MHz [9] (30.0 dBm)
* 2457 MHz [10] (30.0 dBm)
* 2462 MHz [11] (30.0 dBm)
* 2467 MHz [12] (disabled)
* 2472 MHz [13] (disabled)
* 2484 MHz [14] (disabled)
After applying the patch:
iw phy phy0 info
Frequencies:
* 2412 MHz [1] (30.0 dBm)
* 2417 MHz [2] (30.0 dBm)
* 2422 MHz [3] (30.0 dBm)
* 2427 MHz [4] (30.0 dBm)
* 2432 MHz [5] (30.0 dBm)
* 2437 MHz [6] (30.0 dBm)
* 2442 MHz [7] (30.0 dBm)
* 2447 MHz [8] (30.0 dBm)
* 2452 MHz [9] (30.0 dBm)
* 2457 MHz [10] (30.0 dBm)
* 2462 MHz [11] (30.0 dBm)
* 2467 MHz [12] (30.0 dBm)
* 2472 MHz [13] (30.0 dBm)
* 2484 MHz [14] (disabled)
Note: to check the 5 Ghz channels on TL-WDR3600 use the following command:
iw phy phy1 info
After applying the patch on TL-WDR3600:
Frequencies:
* 5180 MHz [36] (30.0 dBm)
* 5200 MHz [40] (30.0 dBm)
* 5220 MHz [44] (30.0 dBm)
* 5240 MHz [48] (30.0 dBm)
* 5260 MHz [52] (30.0 dBm)
* 5280 MHz [56] (30.0 dBm)
* 5300 MHz [60] (30.0 dBm)
* 5320 MHz [64] (30.0 dBm)
* 5500 MHz [100] (30.0 dBm)
* 5520 MHz [104] (30.0 dBm)
* 5540 MHz [108] (30.0 dBm)
* 5560 MHz [112] (30.0 dBm)
* 5580 MHz [116] (30.0 dBm)
* 5600 MHz [120] (30.0 dBm)
* 5620 MHz [124] (30.0 dBm)
* 5640 MHz [128] (30.0 dBm)
* 5660 MHz [132] (30.0 dBm)
* 5680 MHz [136] (30.0 dBm)
* 5700 MHz [140] (30.0 dBm)
* 5745 MHz [149] (30.0 dBm)
* 5765 MHz [153] (30.0 dBm)
* 5785 MHz [157] (30.0 dBm)
* 5805 MHz [161] (30.0 dBm)
* 5825 MHz [165] (30.0 dBm)
Note: TP-Link saved a few cents on the 2.4 and 5 GHz power amplifier, which doesn’t even do more than 100 mW ( 20 dBm) on 2.4 Ghz and 63 mW (18 dBm) on 5 Ghz.
Warning: Before you change channels and transmission power on your Wifi devices, check with the regulation authority what is legally allowed in your location. The hardware is capable of things that can interfere with radar etc. and you should never set it to a country code other than your current location. Even then, you might be able to choose options that are not legal to operate.
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Almost all countries defines power limitations for Wi-Fi devices (EIRP max).
The key to applying these rules is to understand EIRP (Equivalent Isotropically Radiated Power), which represents the total effective transmit power of the radio, including gains that the antenna provides (and losses from the antenna cable and connectors).
The EIRP is calculated using this formula:
EIRP = Effective Isotropic Radiated Power
Pout = transmitter power output (dBm)
Ct = signal loss in cable (dB)
Gt = gain of the antenna (dBi)
Pout - Ct + Gt = EIRP
When installing a wireless system with external (or internal) antenna, your EIRP calculation should not exceed the class license limit. Other wise you must adjust either the transmitter power output, the length of cable and/or the choice of antenna.
You may find the gain of a router antenna in the specification manual, this value generally includes signal loss in cable (the cable from the router board to the antenna).
The RP-SMA antenna connector (female+male) present in many routers, also has a little signal loss, but you can ignore it in the EIRP calculation.
Generally the internal antenna gain (antenna printed on PCB) of a router like the TL-WR710N is about 2 dBi.
The TL-WDR3600 has two external antennas with 2 dBi @ 2.4 Ghz and 3 dBi @ 5 Ghz gain each.
The small external antennas of many router, like D-Link 600, have 2 dBi gain,
just a few high power routers have 4-5 dBi antennas.
Most of the time you get better results (coverage and signal improvements) by increasing the gain of the antenna than increasing the output power, more power means also more EMF noise and disturbances.
(Last edited by pilovis on 27 Dec 2017, 20:53)
