20 node 24 hours

This is a screenshot of a 24 hour cycle of 20 motes measuring temp, light, battery, mic, accel and mag. Motes are micaz, sensor boards are MTS300 and 310’s. Gateway is an MIB510 connected via serial to USB converter. Data being captured into Postgres db on sony laptop. Code on gateway is XMeshBase as shipped with moteworks 2.0. Code on motes is xmts310 from xmesh folder, again shipped with moteworks 2.0 – the only change was my addition of the following to hard code into the application a timer interval of 30 seconds:

(in static void initialise after timer_rate has been set, inserted at line 169)

timer_rate = 1024 * 30;

Curious observation – why does the temp sensor readings oscillate so much during the day but then do not between 9.30pm and 3.00am? The fluorescent lights are on timers so they would have gone out at around 9pm but would not have come back on continuously at 3.00am (might have come on intermittently as security walked through the building…) Is this sensitivity on the analogue sensor? Am i getting intereference. I seemed to get the same 4 degree oscillation at home where there are no fluorescent lights. Could it be the 60Hz power?