Potential Problems and Possible Solutions

Below is a list of potential problems as well as some more concrete ones.

• Antennas may not have been pointing at each other. The compasses were highly impacted by the metals around us when placed on the antennas and therefore prevented us from getting accurate readings and alignment.
• Make sure that the compass is being read while positioned clear of any metal.


• Both machines may have been on opposite channels and we must therefore make sure that we are set to the same one. It would be wise to choose one end of the spectrum in hope that most UMass networks use the middle channels.
• Adjust the /etc/network/interfaces file to include - channel 1


• We could use some binoculars to visually locate the other group however since we are attempting to establish communication over long distances, potentially out of visual range, we shouldn't rely on them since the distances may be larger.

• It would be helpful to figure out the angle between us and the other group with respect to north prior to an outing. Once we have an angle and the compasses aligned properly we can point the antennas with greater accuracy.
• I believe the compass shows magnetic north. Magnetic north is -14.86* from True North.

• We should try and figure out the height distance between us and the other group so that we may attempt to figure out the vertical angle between us. This may be difficult but as long as we get an idea as to whether we are pointing up or down, it would be helpful to try.
• Sugarloaf - 625ft
• UMass tower - 388ft + tower height


• It is possible that the dozens of UMass networks were interfering with our communication. It would be worth a try to attempt this communication with the same distance only without as much interference in the middle. However the differences in link quality as measured by the Sugarloaf group and the UMass group make this more of an assumption than fact.

Setup Instructions

Physical Setup:

1. Attach antennas to mount.
2. Attach N-Male to N-Male cable from antenna to computer networking card pigtail.
3. Attach monitor and keyboard to computer.
4. Turn on computer.

Network Interface Setup:

1. Log into computer (root/umass)
2. Open /etc/network/interfaces
1. Modify ath0:
   auto ath0
   iface ath0 inet static
   address 192.168.1.x
   netmask 255.255.255.0
   wireless_mode Ad-Hoc
   wireless_essid CS496
3. Restart the interface by bringing it down and then back up:
ifconfig ath0 down
ifconfig ath0 up
4. Adjusting bitrate:
iwconfig ath0 rate 54M

Aligning the Antennas (Possible options):

• Run ping -b 192.168.1.255
• This will tell you all the machines that are in the subnet.
• If other machines are replying, transport layer connectivity exists.
• Run wavemon
• Switch to "access points" view
• This view displays statistics (link quality, signal/noise strength and signal-to-noise ratio) on all access points detectable by the antenna.
• If other machines are seen, link layer connectivity exists.
• Run iperf:
• UDP
• Server - iperf -s -u -i 1
• This runs iperf as a server, in UDP mode, with a display update interval of 1 second.
• Client - iperf -c [server addr] -u -b 54M
• This runs iperf as a client , in UDP mode
• TCP
• Server - iperf -s
• Client - iperf -c [server addr]