March 4 notes - Today we will be talking about radio!
- high level terminal/modem
- UART - arduino Maxtream
- low level serial bus protocol
FCC licensed spectrum
433 MHz, "< 1 GHz"
900 MHz, "< 1 GHz"
FCC unlicensed ISM spectrum
2.4 GHz in WiFi specturm
1) needs a larger antenna, and has a MUCH longer wavelength 2) needs only a very small antenna, and has a shorter wavelength
The Future? Maybe UWB
On the sensor, how do you speak to a radio chip? - Arduino - use UART - UART is somewhat restrictive - CC2500 - probably an SPI protocol - SPI is very low-level, more options
There is a design choice here:
Does the CPU do a lot? - Software-defined radio (SDR)
Does the radio chip do everything? - radio chip has Direct memory access (DMA)
Good information can be found on the following http://www.cens.ucla.edu/CS213/CS213-04-Slides/213-04-Diffusion.ppt
We discussed directed diffusion see http://www.isi.edu/div7/publication_files/directed_diffusion_scalable.pdf for more details.
We discussed the Publish/subscribe communication model as well.