Pick a card, any card. [Andrew Quitmeyer] and [Madeline Schwartzman] make sure that any card you pick will match their NYC art installation. “Replantment” is an interactive art installation which invites guests to view full-size leaf
molds casts from around the world.
A receipt file with leaf images is kept out of range in this art installation. When a viewer selects one, and carries it to the viewing area, an RFID reader tells an Arduino which tag has been detected. Solid-state relays control two recycled clothing conveyors draped with clear curtains. The simple units used to be back-and-forth control but through dead-reckoning, they can present any leaf
mold cast front-and-center.
Clothing conveyors from the last century weren’t this smart before, and it begs the question about inventory automation in small businesses or businesses with limited space.
We haven’t seen much long-range RFID, probably because of cost. Ordinary tags have been read at a distance with this portable reader though, and NFC has been transmitted across a room, sort of.
Continue reading “Long-Range RFID Leaflets”
While most of you reading this have broadband in your home, there are still vast areas with little access to the Internet. Ham radio operator [emmynet] found himself in just such a situation recently, and needed to get a wireless connection over 1 km from his home. WiFi wouldn’t get the job done, so he turned to a 433 MHz serial link instead. (Alternate link)
[emmynet] used an inexpensive telemetry kit that operates in a frequency that travels long distances much more easily than WiFi can travel. The key here isn’t in the hardware, however, but in the software. He went old-school, implemending peer-to-peer TCP/IP connection using SLIP — serial line Internet protocol. All of the commands to set up the link are available on his project page. With higher gain antennas than came with the telemetry kit, a range much greater than 1 km could be achieved as well.
[Editor’s note: This is how we all got Internet, over phone lines, back in the early Nineties. Also, you kids get off my lawn! But also, seriously, SLIP is a good tool to have in your toolbox, especially for low-power devices where WiFi would burn up your batteries.]
While it didn’t suit [emmynet]’s needs, it is possible to achieve extremely long range with WiFi itself. However this generally requires directional antennas with very high gain and might not be as reliable as a lower-frequency connection. On the other hand, a WiFi link will (in theory) get a greater throughput, so it all depends on what your needs are. Also, be aware that using these frequencies outside of their intended use might require an amateur radio license.
Continue reading “Long Range Wireless Internet”