TXpower Problem

Anscheinend gibt es in der Firmware ein Problem mit der Sendeleistung.

Kieler Firmware 0.3.2.1-1

root@KNOTEN:~# iw list
Wiphy phy0
	Band 1:
		Capabilities: 0x11ef
			RX LDPC
			HT20/HT40
			SM Power Save disabled
			RX HT20 SGI
			RX HT40 SGI
			TX STBC
			RX STBC 1-stream
			Max AMSDU length: 3839 bytes
			DSSS/CCK HT40
		Maximum RX AMPDU length 65535 bytes (exponent: 0x003)
		Minimum RX AMPDU time spacing: 8 usec (0x06)
		HT TX/RX MCS rate indexes supported: 0-15
		Frequencies:
			* 2412 MHz [1] (18.0 dBm)
			* 2417 MHz [2] (21.0 dBm)
			* 2422 MHz [3] (21.0 dBm)
			* 2427 MHz [4] (21.0 dBm)
			* 2432 MHz [5] (21.0 dBm)
			* 2437 MHz [6] (21.0 dBm)
			* 2442 MHz [7] (21.0 dBm)
			* 2447 MHz [8] (21.0 dBm)
			* 2452 MHz [9] (21.0 dBm)
			* 2457 MHz [10] (21.0 dBm)
			* 2462 MHz [11] (18.0 dBm)
			* 2467 MHz [12] (disabled)
			* 2472 MHz [13] (disabled)
			* 2484 MHz [14] (disabled)
		Bitrates (non-HT):
			* 1.0 Mbps
			* 2.0 Mbps (short preamble supported)
			* 5.5 Mbps (short preamble supported)
			* 11.0 Mbps (short preamble supported)
			* 6.0 Mbps
			* 9.0 Mbps
			* 12.0 Mbps
			* 18.0 Mbps
			* 24.0 Mbps
			* 36.0 Mbps
			* 48.0 Mbps
			* 54.0 Mbps
	max # scan SSIDs: 4
	max scan IEs length: 2257 bytes
	Coverage class: 0 (up to 0m)
	Supported Ciphers:
		* WEP40 (00-0f-ac:1)
		* WEP104 (00-0f-ac:5)
		* TKIP (00-0f-ac:2)
		* CCMP (00-0f-ac:4)
		* CMAC (00-0f-ac:6)
	Available Antennas: TX 0x3 RX 0x3
	Configured Antennas: TX 0x3 RX 0x3
	Supported interface modes:
		 * IBSS
		 * managed
		 * AP
		 * AP/VLAN
		 * WDS
		 * monitor
		 * mesh point
		 * P2P-client
		 * P2P-GO
	software interface modes (can always be added):
		 * AP/VLAN
		 * monitor
	valid interface combinations:
		 * #{ managed, WDS, P2P-client } <= 2048, #{ IBSS, AP, mesh point, P2P-GO } <= 8,
		   total <= 2048, #channels <= 1
	Supported commands:
		 * new_interface
		 * set_interface
		 * new_key
		 * start_ap
		 * new_station
		 * new_mpath
		 * set_mesh_config
		 * set_bss
		 * authenticate
		 * associate
		 * deauthenticate
		 * disassociate
		 * join_ibss
		 * join_mesh
		 * remain_on_channel
		 * set_tx_bitrate_mask
		 * frame
		 * frame_wait_cancel
		 * set_wiphy_netns
		 * set_channel
		 * set_wds_peer
		 * tdls_mgmt
		 * tdls_oper
		 * probe_client
		 * set_noack_map
		 * register_beacons
		 * Unknown command (89)
		 * connect
		 * disconnect
	Supported TX frame types:
		 * IBSS: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0
		 * managed: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0
		 * AP: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0
		 * AP/VLAN: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0
		 * mesh point: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0
		 * P2P-client: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0
		 * P2P-GO: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0
		 * (null): 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0
	Supported RX frame types:
		 * IBSS: 0xb0 0xc0 0xd0
		 * managed: 0x40 0xd0
		 * AP: 0x00 0x20 0x40 0xa0 0xb0 0xc0 0xd0
		 * AP/VLAN: 0x00 0x20 0x40 0xa0 0xb0 0xc0 0xd0
		 * mesh point: 0xb0 0xc0 0xd0
		 * P2P-client: 0x40 0xd0
		 * P2P-GO: 0x00 0x20 0x40 0xa0 0xb0 0xc0 0xd0
		 * (null): 0x40 0xd0
	Device supports RSN-IBSS.
	HT Capability overrides:
		 * MCS: ff ff ff ff ff ff ff ff ff ff
		 * maximum A-MSDU length
		 * supported channel width
		 * short GI for 40 MHz
		 * max A-MPDU length exponent
		 * min MPDU start spacing
	Device supports TX status socket option.
	Device supports HT-IBSS.

Der Ausgabe zu folge wird auf Kanal 1 und 11 nur mit 18.0 statt 21.0 dBm gesendet.

Dies entspricht einer Halbierung (!) der Ausgangsleitung von 125mW auf 63mW.

Leider habe ich nicht das Equipment um die reale Sendeleistung zu messen. Evtl. hält sich die Firmware auch nicht an seine eigenen Angaben ;)