I just walked around my place measuring signal strength on my x61s's Intel 5100 AGN.
At the place where I usually work signal was 49dBm. Moving 2 steps to the left, which put a wall and a metal door frame between the x61s and the wifi router, signal dropped to 61dBm! As realblackstuff pointed out, rotating the machine also has a dramatic effect on reception.
In the cafe try to seat yourself so you've got an unobstructed view of the router.
In linux you can watch signal strength with this one-liner:
Code: Select all
while true; do iwconfig|grep uali;sleep 0.3;done
A summary of the readings taken in the 4m X 5m room I'm in:
# readings Link Quality ----- Signal Level
1 Link Quality=29/70 Signal level=-81 dBm
2 Link Quality=32/70 Signal level=-78 dBm
1 Link Quality=34/70 Signal level=-76 dBm
3 Link Quality=35/70 Signal level=-75 dBm
1 Link Quality=36/70 Signal level=-74 dBm
1 Link Quality=37/70 Signal level=-73 dBm
1 Link Quality=38/70 Signal level=-72 dBm
4 Link Quality=39/70 Signal level=-71 dBm
3 Link Quality=40/70 Signal level=-70 dBm
2 Link Quality=42/70 Signal level=-68 dBm
2 Link Quality=43/70 Signal level=-67 dBm
2 Link Quality=44/70 Signal level=-66 dBm
2 Link Quality=45/70 Signal level=-65 dBm
6 Link Quality=46/70 Signal level=-64 dBm
5 Link Quality=47/70 Signal level=-63 dBm
9 Link Quality=48/70 Signal level=-62 dBm
8 Link Quality=49/70 Signal level=-61 dBm
14 Link Quality=50/70 Signal level=-60 dBm
5 Link Quality=51/70 Signal level=-59 dBm
7 Link Quality=52/70 Signal level=-58 dBm
8 Link Quality=53/70 Signal level=-57 dBm
8 Link Quality=54/70 Signal level=-56 dBm
11 Link Quality=55/70 Signal level=-55 dBm
6 Link Quality=56/70 Signal level=-54 dBm
8 Link Quality=57/70 Signal level=-53 dBm
2 Link Quality=58/70 Signal level=-52 dBm
11 Link Quality=59/70 Signal level=-51 dBm
8 Link Quality=60/70 Signal level=-50 dBm
3 Link Quality=61/70 Signal level=-49 dBm
7 Link Quality=62/70 Signal level=-48 dBm
9 Link Quality=63/70 Signal level=-47 dBm
1 Link Quality=64/70 Signal level=-46 dBm
8 Link Quality=65/70 Signal level=-45 dBm
1 Link Quality=66/70 Signal level=-44 dBm
1 Link Quality=68/70 Signal level=-42 dBm