Recently I wanted to take a picture of one of my bathrooms. Unfortunately, the half bathroom is a bit small and my phone’s camera couldn’t take a shot that could show most of the bathroom. Even though my phone, a Samsung Galaxy Note 3, has a pretty impressive panoramic picture feature, it only creates horizontal panoramas. Fortunately, though, there is a free program called Panorama Plus which can take a series of photos and stitch them all together. Below are the individual pictures I took of the bathroom from different angles and below them is the panorama of all of those pictures stitched together. Not bad!
I have had AT&T U-Verse internet for some time now and my current plan is supposed to allow me to achieve download speeds of up to 24 Mbps. However, when I’d test my speed using SpeedTest, my speed would fluctuated and sometimes be as low as 9 Mbps. I was testing over wi-fi which wouldn’t give you the same speeds as over ethernet cable but still, 9 mbps was a lot less than 24. An AT&T technician came to replace the power supply brick for my modem. I asked him to check my speeds and to fix them to achieve the correct speeds. He had a special device that allowed him to see how many wi-fi networks my laptop was picking up as well as what channel they were one. To improve performance, he suggested we change my modem’s wi-fi channel to one that wasn’t currently being used by neighboring networks, I guess to minimize or eliminate collisions. By logging into your modem from a browser, you can see your current channel and be able to switch to another channel.
I was on channel 11, which no one else was on, but we changed it to channel 3, which no one else was on either, and retested the speed. The speed was better but still not great and although we were sitting right next to the modem, we weren’t getting a strong signal. We then tried channel 5, as shown above, and retested the speed. Now, I’m getting always 21+mbps down, as you can see below.
Conclusion: if you’re not getting the speeds you’re paying for, try changing your wi-fi access point’s channel. There are 11 channels in total. If you don’t know what channels your neighbors are on, you can try changing the channel from 1 to 11 and testing the speed at each channel until you find a speed that is close to what you’re paying. You can also install NetStumbler to see what networks are available and what channels they are on. Even though your access point should auto-select a free channel, that channel may still not give you the speeds you expect. Also, test you connection speeds using a direct ethernet connection as this is what AT&T uses to determine connection speed.
Recently, I needed to figure out how many 2D rectangles in different quantities I could fit in one large rectangle. (I actually needed to know how many 12″x12″, 10″x10″, 8″x8″, and 13″x8″ shooting targets I could cut out of a sheet of steel that is 315″x78″ in size while minimizing any leftover space.) I came across an algorithm online and modified it a bit to make it a easier to use and understand. Check it out at the link below.
It turns out, I can get 97% utilization with the following sizes and quantities.
Many devices are connected to each other over different cables and interfaces. But not all devices can transfer data at the same speeds. The device or connection with the lowest speed determines the maximum speed. Following are some common devices and their speeds.
Cell Phone Interfaces
- Edge (Evolution type 2 MS): 148 kB/s download
- HSPA+: 5.25 MB/s download
- LTE (2×2 MIMO): 21.6 MB/s
- LTE (4×4 MIMO): 40.75 MB/s download
Wide Area Networks
- DS1 / T1: 0.2 MB/s
Local Area Networks
- Ethernet 10BASE-T: 1.25 MB/s
- Fast Ethernet 100BASE-TX: 12.5 MB/s
- FireWire 400: 50 MB/s
- Gigabit Ethernet 1000BASE-T: 125MB/s
- IEEE 802.11a: 6.75 MB/s
- IEEE 802.11b: 1.375 MB/s
- IEEE 802.11g: 6.75 MB/s
- IEEE 802.11n: 75 MB/s
Wireless Personal Area Networks
- Bluetooth 4.0: 3 MB/s
- USB low speed: 192 kB/s
- USB full speed: 1.5 MB/s
- USB hi-speed (USB 2.0): 60 MB/s
- USB super speed (USB 3.0): 625 MB/s x 2
- Thunderbolt: 1,250 MB/s x 2