Sources of Noise: SID Monitor

1. Sources of Noise: SID Monitor By Szu-chiech Lu and Mathieu Evans

2. Project Objectives: In addition to investigating potential sources of noise from everyday electronic devices in school or office settings, our hope was to create a catalog of sorts that would visually portray different types of noise both quantitatively and qualitatively. Why? Our own SID monitor back home was experiencing frequent signal disturbance during the daytime that was unexplainable. When we came to Stanford and began to brainstorm potential project directions, the noise problem we had on our hands back home was at the forefront of our mind. So, there was some element of personal satisfaction in problem-solving in our motivation.

3. Experiment: Sources of Noise Successful • Fluorescent Light Bulbs • Vacuum Cleaner • Microwave Oven • CRT Monitor • Gas Lamp

4. CRT Monitor • The reason the old computer monitor we used generated noise was because cathode tubes were present in the monitor. • Loud noise generator via the power speakers utilized by the SID monitor. • Noise/Interference ceases when the computer monitor is approximately 4-5 meters away from the antenna.

5. CRT Monitor • Old CRT Monitor • 1m away • Values were high, but not quite to the rail • Placed perpendicular to the antenna

6. CRT Monitor 2 • Moved the monitor to 2m away • Reduced effect • Appears to have ¼ noise strength • Seems to follow the inverse square law

7. Gas Lamps • Very strong noise generator and the most noise is present when the tubes themselves face the antenna in a perpendicular fashion. • Placing the gas lamps in this fashion, the noise ceases at approximately 3 meters from the antenna. • Placing the gas lamps in line with the antenna, the noise ceases at only 2 meters from the antenna. • The graph showed an unexplainable oscillation of noise levels. In other words, the voltage reading would drop back down into the value range we’d previously calibrated for no apparent reason and without turning off the gas lamp. It would also rise back up near the value rail only slightly lower than its first sudden increase. In one test, the high value was maintained. It is unknown whether or not this process of oscillation would occur again, much less perpetually.

8. Gas Lamp Noise • Turned on the gas lamp at 1m away • Sharp rise followed by a dip • Then rose again and maintained

9. Gas Lamp Noise 2 • Gas Lamp at 2m away from antenna • Appears to have no effect at 2m • Optimum Distance

10. Vacuum Cleaner • The reason we felt a vacuum cleaners was an important device to test was because school and office settings have janitors that might be less than considerate as to where and when they vacuum. • The vacuum’s noise performed much like the CRT monitor in the sense that the further it got from the antenna, the weaker the noise. Noise appeared to disappear after about 13m for certain so it was significantly stronger than the CRT monitor and twice as likely to pose a threat.

11. Vacuum Cleaner Noise • Besides the microwave, vacuum cleaners are also very noisy • Also made the SID monitor data hit the rail

12. Vacuum Cleaner 2 • More realistic vacuum cleaner graph • We simulated vacuuming by …er…actually vacuuming the hall

13. Microwaves (a.k.a. pure evil) • When I say evil, I mean that microwaves are quite possibly the most powerful and consistent source of noise that can be thrown at the SID monitor. It seemed to have a • We tested the SID with microwaves about four times by ourselves before we looked at our data via Logger Pro 3. The times when it was being used by others in the building throughout the day showed up on our graph as well. • As soon as the microwave was turned on, the voltage value hit the rail almost instantaneously and remained there for the duration of the time it was on. • As soon as the microwave was turned off, there was a certain amount of time needed for the SID monitor to make a recovery (recovery time for a given test increased slightly after every successive test), but the voltage value returned to our previously calibrated value (-2) for every test…except one!

14. Todd came down to check our project’s progress and when we told him about how our microwave test reflected the possibility that microwaves have a noise range of more than 25m, he wanted to see it for himself. We turned on the microwave in the upstairs conference room and the voltage value hit the rail once again. After a minute, we shut the microwave off and after five minutes of waiting, the voltage values did not recede back to our previously calibrated values. In fact, for that individual monitor, the values never receded, even after unplugging it, restarting it, or practically taking it apart. Next, we tested a new monitor and the original DATAQ and this monitor worked fine and was still affected by the microwave. Its voltage values recovered properly as expected though. Next, we tested the new monitor while placing the antenna outside of the building. For one test, we placed the antenna sixty feet away from the microwave and for the second test, we placed it a little over 10m away. This concluded our microwave testing.

15. Microwaves • When used within 30ft of the antenna, a microwave will cause the signal to “rail” at ~5.00 volts • Microwaves would not have an effect on the antenna at 60ft away

16. Microwave 2 • Microwave at about 20 meters away • No effect on antenna

17. Experiment: Non-Noise-Makers Unsuccessful • Electric Fan • Refrigerator • Human Contact • Office Computer • Radio/Boom box • Horseshoe Magnets

18. Electric Fan • We thought that the fan motor would have an effect • Apparently not, even at 1m

19. Radio/Boom Box • We also though that the radio frequency that radios receive • As it turns out, the SID Monitors behave just like radios—they only receive signals

20. Future Research If the SID monitor’s malfunction is a direct result of repetitive exposure to microwaves, this reflects one of two possibilities: either the individual monitor had a faulty part or the entire first generation of SID monitors has an inherent design flaw. If it is possible to break a SID monitor with a microwave from significant distances, students experimenting need to be informed so they can find a proper place in their school to conduct their experiments. Also, it may be necessary to redesign the SID so that money is not wasted in their production and distribution if they are susceptible to such common devices. Future research is necessary to determine the fate of the SID monitor whether good or bad.

21. Uncompleted Project Yes, there is one. Originally, we planned to complete the noise catalogue and another project concerning how the data collected by SID monitors at different locations would differ. We were not able to complete this project was not because there was no time, but instead, the reason was that we did not have several crucial pieces of information about the SID sites around the world.

22. Needed Information • Local weather conditions • Specification of the antennas at different locations • Flare(s) that occur at EXACTLY the right time of day Without these important pieces of information, we were not able to complete this second project we had in mind to complete by the end of our two weeks (today). This may be possible in the future when there are much more sites sending information to the Stanford SID Database

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