Beware of the DFS band if you want gigabit Wi-Fi

▼ I got an Apple Time Capsule 802.11ac "gigabit Wi-Fi" base station this summer, and then a new 802.11ac-capable MacBook Pro (read my review) a few months ago. Those two can communicate wirelessly at a blistering 1.3 Gbps. Sweet!

However, after my initial testing I would never see speeds faster than 878 Mbps when clicking on the Wi-Fi symbol in the menu bar while holding the alt/option key. For a while I thought there was a software issue and I even waited to see if the MacOS 10.9.1 update would resolve the issue. It didn't.

But then I noticed something. I had my Time Capsule set for automatic channel selection, and it selected channel 100 (DFS). Then at some point it switched to one of the lower channels. And suddenly I was back to 1300 Mbps! (Although fallback to 1053 Mbps still happens regularly.)

I then tried switching channels a few more times, with fairly conclusive results: I would never get more than 878 Mbps on a DFS channel, but on channels 36 - 48 I'd often get 1053 or 1300 Mbps. Also, on DFS I would sometimes have really poor network throughput, which disappeared after switching to 36 - 48.

DFS is dynamic frequency selection. As you can see here, in the US, on all available channels except 36, 40, 44 and 48, dynamic frequency selection is required so the Wi-Fi equipment changes channels if it detects other stuff, most likely radar, getting in the way. Apparently Apple enforces this in Europe, too. So it could be that some radar installation is keeping me from getting my full 1.3 Gbps. Or perhaps the antennas or radios are less efficient at these higher frequencies.

In any event, I'm using channels 36 - 48 from now on, even though two of them are also used by neighbors.

Bonus tip: if you alt-click on the Wi-Fi icon in the menu bar and then hover over a network name, you get to see additional information:

(Yikes, I wrote "Time Machine" instead of "Time Capsule" twice originally!)

Permalink - posted 2014-02-14

Railroad nostalgia in Rotterdam

▼ A couple of days ago, I posted this picture:

De hef, 1/30 sec, f/3.8, ISO 1600, 12 mm (x 1.5)

Turns out, this railroad bridge from the 1920s across the Meuse river in Rotterdam has its own documentary film: De brug (Wikipedia link) or The Bridge, by Joris Ivens, 1928. (It's 15 min and silent). Watch it on Youtube or Vimeo, but not on the Internet Archive, because their copy is much lower quality.

In 1993, the bridge was closed and most of it was removed after a new tunnel had been built. As you can see in the photo, the remaining part of the bridge is left in the open position. I wasn't a very frequent rail traveler back then, but I still remember that the "luchtspoor" (something like "air track", link is a nice history in Dutch with many photos) provided a very nice view of Rotterdam, most notably this building:

Witte Huis, 1/30 sec, f/4.5, ISO 200, 24 mm (x 1.5)

The Witte Huis (White House) is a 43 meter, ten story high building from 1898. At that time it was the tallest building in Europe.

A couple of additional photos: this is the old Hofplein station, back in 2009 shortly before it closed. It was the terminus of the Hofpleinlijn, a second rail link between The Hague and Rotterdam, which was the first electrified rail line in Holland in 1908.

Station Rotterdam Hofplein (2009), 1/60 sec, f/4, ISO 200, 11 mm (x 1.5)

For some strange reason they built this station within easy walking distance of the Rotterdam central station. In 2006, it was converted to a metro (subway/underground) line, and a few years later it was connected to the rest of the Rotterdam metro network so this terminus was no longer needed.

Speaking of the Rotterdam central station, this is what it looked like in 2003.

Station Rotterdam Centraal (2003), 1/20 sec, f/3.2, ISO 50, 6.6 mm (x 6.5)

It's really too bad I don't have a better photo, because I liked the 1950s style architecture. It's been completely rebuilt the past years (all of the largest train stations in the country have been under extensive construction the past decade!) and the new look isn't half bad either. So I guess I'll have to shoot some new photos and show how all of this looks today.

Permalink - posted 2014-02-09

First photo with my new camera: The Hague skyline by night

Beware of the DFS band if you want gigabit Wi-Fi

Beware of the DFS band if you want gigabit Wi-Fi

Railroad nostalgia in Rotterdam

Railroad nostalgia in Rotterdam

Have a look at my photos on Flickr

Walking around the city I ran into the peace palace

Bike and sunset