Last month I've upgraded my first generation Mac Mini to Intel Core Duo. I have been bother by its wireless network issues ever since. It is a late 2009 model with Snow Leopard. It is connected to a Linksys WRT110 router. The problem is its poor reliability. Packets are dropped frequently. Sometimes it disconnects from the access point altogether. This means a very frustrating experience for some applications. VNC session are dropped frequently to the point it is unusable. Directory browsing and file transfer with Samba is a hit or miss. It unreliable and often incurs lengthy delay.

It seems mine is not an isolated problem. Wireless issue is a frequent topic on Apple support forum. I find many message like this one:

Topic : New Mac Mini Wireless Internet - Slow, Disconnects frequently

I use ping to test its connectivity. Pinging the gateway from the Mac gets result like below. There are plenty of missing packets.

64 bytes from 192.168.1.1: icmp_seq=7 ttl=64 time=1.219 ms
64 bytes from 192.168.1.1: icmp_seq=8 ttl=64 time=3.698 ms
64 bytes from 192.168.1.1: icmp_seq=9 ttl=64 time=3.862 ms
Request timeout for icmp_seq 10
Request timeout for icmp_seq 11
64 bytes from 192.168.1.1: icmp_seq=12 ttl=64 time=3.671 ms
64 bytes from 192.168.1.1: icmp_seq=13 ttl=64 time=3.766 ms
Request timeout for icmp_seq 14
64 bytes from 192.168.1.1: icmp_seq=15 ttl=64 time=3.997 ms
64 bytes from 192.168.1.1: icmp_seq=16 ttl=64 time=5.394 ms

Pinging the Mac from a PC, both are connected wirelessly, is even worst. Besides loss packets, the response time is pathetic. Sometimes it takes hundreds of millisecond.

Reply from 192.168.1.120: bytes=32 time=609ms TTL=64
Reply from 192.168.1.120: bytes=32 time=632ms TTL=64
Reply from 192.168.1.120: bytes=32 time=655ms TTL=64
Request timed out.
Reply from 192.168.1.120: bytes=32 time=97ms TTL=64
Reply from 192.168.1.120: bytes=32 time=1ms TTL=64
Reply from 192.168.1.120: bytes=32 time=93ms TTL=64
Request timed out.
Reply from 192.168.1.120: bytes=32 time=640ms TTL=64
Request timed out.

Note that this is not a wireless signal problem. I have moved the access point to only 15 feet away from the Mac with a direct line of sight. The test does marginally better at best. Besides, none of other wireless devices on the network have any connectivity problem.

After several false start using different suggestions from the Internet, I have found a config that dramatically improve the Mac's connectivity. I set the router to use Wireless-G only. The default of Linksys WRT110 is in "Mixed" mode. It includes some proprietary Linksys enhancement that none of my device can take advantage anyway. And it is not even Wireless-N. Setting it to Wireless-G only improve the Mac's connectivity with no loss of performance for other devices.

2010.01.26 [tech] - comments (0)

SF Appeal has published the Muni onboard video recording of the collision between a Muni #19 bus and a pickup truck on Jan 5th morning. The intersection is controlled by four way stop sign. Question has been brought about who's at fault. I have reviewed the video frame by frame. I come to a clear conclusion that the truck driver was at fault. While the bus driver technically did not made a complete stop, it has the right of way. The accident was caused by the truck running the stop sign at a high speed.

The four frames below captured the action during a span of 2.8 s until the moment they collided.

• Frame 1 - 00:02:34.22
• Frame 2 - 00:02:35.02
• Frame 3 - 00:02:36.02
• Frame 4 - 00:02:37.02

At frame 1, using the trash can as a reference point, it shows the bus was right at the intersection. The truck was about half a block away. It should be immediately obvious that the bus has the right of way.

At frame 2, the bus rolled forward. The truck was still some distance away.

At frame 3, the bus proceeded across the intersection slowly. The truck still have not arrive at the intersection. It should stop and yield to the bus.

At frame 4, truck ran the stop sign at high speed and caused the collision.

Base on the video frames, I plotted the estimated position and the movement of the vehicles during this 2.8 s on a map. I estimated the bus has rolled through the stop at 8 mph. In contrast, the truck has flown through the intersection from half a block away at 32 mph.

The verdict is clear, the truck driver was driving recklessly and caused the accident.

San Francisco Chronicle has published an article with the release video titled "Crash video shows bus, pickup ran stop signs". It implies they are equally at fault. I think this is wholly a mischaracterization by failing to unambiguously call out it was the truck's fault. The bus had the right of way. Actually had the bus made a complete stop the same accident could still happen.

2010.01.07 [San Francisco] - comments (3)

My niece was visiting us from Peru. So we had an active holiday week showing them around in San Francisco. She brought her 1 year old baby daughter along. I setup some old infant gear for her. It all worked out quite well.

This is the first time Tatchee has a baby visitor. I'm delighted to see him act like a big brother. He spontaneously bring her toys and other stuff for her comfort. Other times I saw him act with a sense of fairness. When the baby try to grab things from him, he hold it away from her and told her that you shouldn't grab things from others. Tatchee is a little boy to us. We only realize how much he has grown up when he is together with his little niece.

2010.01.02 [personal] - comments (0)