Discrepancy on reported AirPort 'PHY mode' & channels

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Level 1

67 points

Discrepancy on reported AirPort 'PHY mode' & channels

About This Mac assures me my current AirPort PHY mode is 802.11n and that I'm on both channels 157 and 1. The third-party WiFi Scanner app tells me my PHY mode is 802.11a (and, appropriately for 802.11a, on the 5 GHz band) and detects me on channel 157 only. Another app, iStumbler, agrees with About This Mac that I'm on 802.11n but, as with WiFi Scanner, finds me on just channel 157.

With these discrepancies, how can I confirm my PHY mode and channel(s)?

The wifi network has an Airport Express (also on channels 157 & 1), and Apple TV (not sure of channels or how to check them but it works) and a couple of iPads.

24 inch Intel Core Duo iMac, Mac OS X (10.6.8), 2.8 GHz, 4GB ram

Posted on Jul 6, 2013 9:55 PM

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Answer 1

Best reply

LaPastenague

Level 9

67,226 points

Jul 7, 2013 4:59 AM in response to duncantho

When I look at the available wireless, in the Mac it will show all the AP's available to which the wifi can connect.

hence

Status: Connected

Current Network Information:

TG782T:

PHY Mode: 802.11n

BSSID: fc:75:16:e9:69:b8

Channel: 6

Network Type: Infrastructure

Security: WPA2 Personal

Signal / Noise: -46 dBm / -91 dBm

Transmit Rate: 145

MCS Index: 15

Other Local Wireless Networks:

Tardis24ghz:

PHY Mode: 802.11n

BSSID: 28:cf:da:b5:98:49

Channel: 11

Network Type: Infrastructure

Security: WPA2 Personal

Signal / Noise: -54 dBm / -85 dBm

Tardis5ghz:

PHY Mode: 802.11n

BSSID: 28:cf:da:b5:98:4a

Channel: 36,1

Network Type: Infrastructure

Security: WPA2 Personal

Signal / Noise: -70 dBm / -91 dBm

frednog:

PHY Mode: 802.11n

BSSID: 0:1f:5b:87:d5:43

Channel: 1

Network Type: Infrastructure

Security: WPA2 Personal

Signal / Noise: -43 dBm / -85 dBm

That simply means the card is dual band and sees all those wireless signals.. but it can link to only one. At the moment it is linked to my modem.. TG782T.. on 2.4ghz.

If you set the express as normal it transmits the 2.4ghz signal and 5ghz signal on the same wireless name.. and the computer can join to one or the other.. but not both.

The actual PHY mode is the top of the list.

Or type in terminal airport -I

macproie-5:ATV Ray$ airport -I

agrCtlRSSI: -44

agrExtRSSI: 0

agrCtlNoise: -84

agrExtNoise: 0

state: running

op mode: station

lastTxRate: 145

maxRate: 144

lastAssocStatus: 0

802.11 auth: open

link auth: wpa2-psk

BSSID: fc:75:16:e9:69:b8

SSID: TG782T

MCS: 15

channel: 6

That tells you precisely what wireless and what channel it is using.

THere is also a wireless tool in new Mountain Lion.. what actual OS are you running??

Oh and you can also hold down the option key when you click the wifi (airport) icon.

In this case I have swapped over to the TC but i have named the two bands differently because I am ever a doubter of wireless and need to know precisely what I am doing.. hence I can see I am joined to 5ghz and deliberately choose it.

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Answer 2

duncantho Author

Level 1

67 points

Jul 7, 2013 10:00 AM in response to LaPastenague

Holding down the option key when clicking the wifi icon does indeed confirm I'm on channel 157. Thanks for that — much clearer than what 'Current Network Information' shows in Snow Leopard's About This Mac. It lists both my channels, "157, 1".

The only remaining discrepancy would be between iStumbler and my Mac. iStumbler had me on 802.11a, but I see it's changed its mind and now has me on 802.11n.

By the way typing airport -I into Terminal gives me "Command not found." Must be another difference between 10.6 and Mountain Lion.

Thanks, LaPastenague.

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Answer 3

Jul 7, 2013 3:07 PM in response to duncantho

They took the airport command and hid it in the directory so it is not on the path.

http://reviews.cnet.com/8301-13727_7-57566448-263/how-to-adjust-network-settings -in-os-x-via-the-command-line/

So to get that via the terminal you need to access the directory.. and then use the command.. ML.. sigh!! why do they do this??

In ML there is a new diagnostics .. well half new.. it did exist in Lion but was hidden.. now they have swapped the command line utility airport for this diagnostics.. so same as before holding down option key you click the wifi fan.

Open the diag program.

You need to give it root access and it will then monitor.. that is not much use..

But you can open the utilities.

And that has some scan function and a graphical output of wireless connection running the wrong way.

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Answer 4

duncantho Author

Level 1

67 points

Jul 8, 2013 8:01 AM in response to LaPastenague

Thanks for the CNET link. I shall steer clear of playing with Terminal for now but will clip the article. The Open Wireless Diagnostics looks interesting .. and if I ever upgrade from Snow Leopard (I'm a resister), I imagine I'll poke around in there.

By the way I messed up trying to give you a 'This solved my question' score — instead accidentally giving it to myself. Didn't think I could do that, and there's no way I can see to undo it.

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