The map shows the rough locations of our basestations which are spread across five office buildings. In addition to the roads visible on the map, there are some smaller streets on which the vans travel.
Both BSs and clients are small form factor desktops with two WiFi radios. BSs are placed on top floors of the buildings, with their antennae are mounted on the roofs. Low-loss coaxial cables (LMR-900 and LMR-240) connect the radios (inside the desktops) and antennae.
Similarly, the clients are placed inside the vans and their antennae are mounted on the roof. The computers in the van are powered by a dedicated deep cycle battery which powers the computers for about four hours after the van is switched off. This time is used for software updates through a wireless connection with another computer located near the van’s overnight parking space.
- EnGenius’ EMP-8602 mini PCI modules, which are based on the Atheros 5213 chipset, are used as radios. Their output power is 400 mWat 1Mbps and lower at higher transmission rates. The modules are inserted into the desktop using a mini-PCI to PCI adapter and connected to a U.FL to N Female pigtail.
- HyperLink’s HG2403MGU antennae are used for the vans and HGV-2404U antennae are used for the basestations. Both types are omnidirectional in the horizontal plane but radiate less energy directly above and below.
- The vans also have GlobalSat’s BU-353 GPS unit which is based on the SiRF Star III chipset and outputs data once per second. The uncertainty in the location estimate of this chipset is considered to be under three meters 95% of the time.
- All basestations are connected to Dataprobe’s iBoot which is used to kickstart stuck up machines