I use ALFA AWUS050NH with EDIMAX +5db antenna (or stock one - doesn't change anything in this problem), and BT4 from DVD.

Problem is, that airodump doesn't list most of networks that are available under installed openSUSE, or Windows. Actually it doesn't even list my own network (AP is aprox. 3m away from antenna), but sometimes it even "catches" extreamly weak signals from public APs located 200m away (or even more).

What I do after startup:

/etc/init.d/networking start

With effect:
Code:
root@bt:~# /etc/init.d/networking start
Configuring network interfaces...Internet Systems Consortium DHCP Client V3.1.1
Copyright 2004-2008 Internet Systems Consortium.
All rights reserved.
For info, please visit URL

Listening on LPF/eth0/00:26:18:08:c2:2d
Sending on   LPF/eth0/00:26:18:08:c2:2d
Sending on   Socket/fallback
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 5
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 11
DHCPOFFER of 10.0.0.12 from 10.0.0.2
DHCPREQUEST of 10.0.0.12 on eth0 to 255.255.255.255 port 67
DHCPACK of 10.0.0.12 from 10.0.0.2
bound to 10.0.0.12 -- renewal in 41818 seconds.
if-up.d/mountnfs[eth0]: waiting for interface eth1 before doing NFS mounts
if-up.d/mountnfs[eth0]: waiting for interface eth2 before doing NFS mounts
if-up.d/mountnfs[eth0]: waiting for interface ath0 before doing NFS mounts
if-up.d/mountnfs[eth0]: waiting for interface wlan0 before doing NFS mounts
eth1: ERROR while getting interface flags: No such device
Internet Systems Consortium DHCP Client V3.1.1
Copyright 2004-2008 Internet Systems Consortium.
All rights reserved.
For info, please visit URL

SIOCSIFADDR: No such device
eth1: ERROR while getting interface flags: No such device
eth1: ERROR while getting interface flags: No such device
Bind socket to interface: No such device
Failed to bring up eth1.
eth2: ERROR while getting interface flags: No such device
Internet Systems Consortium DHCP Client V3.1.1
Copyright 2004-2008 Internet Systems Consortium.
All rights reserved.
For info, please visit URL

SIOCSIFADDR: No such device
eth2: ERROR while getting interface flags: No such device
eth2: ERROR while getting interface flags: No such device
Bind socket to interface: No such device
Failed to bring up eth2.
ath0: ERROR while getting interface flags: No such device
Internet Systems Consortium DHCP Client V3.1.1
Copyright 2004-2008 Internet Systems Consortium.
All rights reserved.
For info, please visit URL

SIOCSIFADDR: No such device
ath0: ERROR while getting interface flags: No such device
ath0: ERROR while getting interface flags: No such device
Bind socket to interface: No such device
Failed to bring up ath0.
wlan0: ERROR while getting interface flags: No such device
Internet Systems Consortium DHCP Client V3.1.1
Copyright 2004-2008 Internet Systems Consortium.
All rights reserved.
For info, please visit URL

SIOCSIFADDR: No such device
wlan0: ERROR while getting interface flags: No such device
wlan0: ERROR while getting interface flags: No such device
Bind socket to interface: No such device
Failed to bring up wlan0.
done.
It doesn't start my ALFA, but at least I get eth0 working. Then I do:

Code:
root@bt:~# airmon-ng start ra0


Found 1 processes that could cause trouble.
If airodump-ng, aireplay-ng or airtun-ng stops working after
a short period of time, you may want to kill (some of) them!

PID     Name
10907   dhclient3


Interface       Chipset         Driver

ra0             Ralink 2560 PCI rt2500 (monitor mode enabled)
So I got ALFA working, green lights flashing, etc.
Next I try to dump what's going on in the air with airodump-ng ra0:

Code:
 CH  5 ][ Elapsed: 1 min ][ 2009-11-24 19:43

 BSSID              PWR  Beacons    #Data, #/s  CH  MB   ENC  CIPHER AUTH ESSID

 00:1F:C6:43:38:A6    0       22       14    0   1  54e  WPA  TKIP   PSK  brzozkaiczmuchuf
 00:1D:0F:EF:81:B8    0      572       23    0   1  54 . WPA2 CCMP   PSK  KKRUSZEWSKI
 00:22:75:06:F2:16    0        3        1    0   1  54e  WPA2 CCMP   PSK  Narwik_MZ

 BSSID              STATION            PWR   Rate    Lost  Packets  Probes

 (not associated)   00:19:D2:71:B5:76    0    0 - 1      0        1
 (not associated)   00:14:A5:6B:F6:F5    0    0 - 1      0        2
 (not associated)   00:16:44:E2:27:3C    0    0 - 1      0       14
 (not associated)   00:1C:BF:0D:D6:6B    0    0 - 1      0       40
 (not associated)   00:1D:0F:E8:C6:D1    0    0 - 1      0       66  AMWIR
 (not associated)   00:0E:2E:96:60:59    0    0 - 2     14        2
So I can see a lot of not associated stations, but only few BSSID (and my own network is not there). It seems that problem is with ALFA because, when I use my old laptop (Acer 3690 series) with build-in Broadcom BCM94318MPG it sees much more associated stations.

My iwconfig:

Code:
root@bt:~# iwconfig
lo        no wireless extensions.

eth0      no wireless extensions.

ra0       RT2870 Wireless  ESSID:""  Nickname:"RT2870STA"
          Mode:Monitor  Frequency=2.432 GHz  Bit Rate=1 Mb/s
          RTS thr:off   Fragment thr:off
          Encryption key:off
          Link Quality=10/100  Signal level:0 dBm  Noise level:-88 dBm
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:0   Missed beacon:0
and ifconfig:

Code:
root@bt:~# ifconfig
eth0      Link encap:Ethernet  HWaddr 00:26:18:08:c2:2d
          inet addr:10.0.0.12  Bcast:10.0.0.15  Mask:255.255.255.240
          inet6 addr: 2002:d4b4:aeb3:0:226:18ff:fe08:c22d/64 Scope:Global
          inet6 addr: fe80::226:18ff:fe08:c22d/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:6218 errors:0 dropped:0 overruns:0 frame:0
          TX packets:3759 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:6343379 (6.3 MB)  TX bytes:501074 (501.0 KB)
          Interrupt:28 Base address:0x2000

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:264 errors:0 dropped:0 overruns:0 frame:0
          TX packets:264 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:18504 (18.5 KB)  TX bytes:18504 (18.5 KB)

ra0       Link encap:UNSPEC  HWaddr 00-C0-CA-2F-BF-59-30-30-00-00-00-00-00-00-00-00
          inet6 addr: fe80::2c0:caff:fe2f:bf59/64 Scope:Link
          UP BROADCAST NOTRAILERS RUNNING PROMISC ALLMULTI  MTU:1500  Metric:1
          RX packets:12826 errors:0 dropped:0 overruns:0 frame:0
          TX packets:618 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:953074 (953.0 KB)  TX bytes:50240 (50.2 KB)

Where is a problem?