What factors does PowerTutor measure to show energy consumption? I am trying to find the impact of the signal strength on the energy consumption of WIFI in Android using an HTC NEXUS ONE. I am sending several files starting from 1 kb to 600 kb.

I use PowerTutor as a measurement application however the values are almost the same for any signal strength of wifi.

Can you please help me to find out if PowerTutor can reflect the signal strength effect and what factors in fact does PowerTutor use to show how much energy was consumed by Wi-Fi? Do you recommend the use of another android app to measure the wifi consumption?
According to the developer's documentation, WiFi signal strength is not accounted for:


  The power states we have considered in the power model includes:
  
  ...
   -Wifi: Uplink channel rate, uplink data rate and packets transmitted per second.


They have a link to a study performed by the University of Michigan (who is, as best I can tell, also connected to this app's development) that looks to go much more in depth into their thoughts on the matter, should you be interested.

I don't have any better recommendations for you as far as apps go. Has the standard Android Battery Usage information not been helpful? I imagine if you set up a test scenario where you send a continuous steam of data over WiFi for an hour, then change the distance from the device to the WAP (i.e. changing signal strength) and repeat the process, you might be able to see a difference in the battery usage attributed to WiFi.