Filtering Noise by LaShonda Torbert https://padlet.com/ltorbert/gbofilter lesson for rising ninth grade students to introduce filters. courtesy of TeachEngineering resources en-us 2017-07-31 17:48:41 UTC 2025-09-24 19:11:21 UTC hello@padlet.com https://padlet-assets.s3.amazonaws.com/icons/Planets.png Example ltorbert https://padlet.com/ltorbert/gbofilter/wish/179785427 The band-pass filter is set to around 400 to 2300 Hz with six notch filters at around 900 Hz, 1100 Hz, 1300 Hz, 1500 Hz, 1700 Hz and 1900 Hz. Once filters are added to remove all the noise in the signal, students may need to turn the volume up further to hear the message.]]> 2017-07-31 18:04:39 UTC https://padlet.com/ltorbert/gbofilter/wish/179785427 Key vocabulary ltorbert https://padlet.com/ltorbert/gbofilter/wish/179785607 band-pass filter: A filter that only keeps a certain range of frequency components and blocks any other frequencies outside the range.

frequency: How many times a waveform repeats per second, measured in hertz. Hz = cycles per second

high-pass filter: A filter that keeps high-frequency components and blocks low-frequency components.

low-pass filter: A filter that keeps low-frequency components and blocks high-frequency components.

noise: Any component of a signal that does not contain useful information.

notch filter: A filter that blocks specific frequency points and does not affect the rest of the signal.

courtesy of TeachEngineering
https://www.teachengineering.org/lessons/view/csm_filtering_lesson01

]]> 2017-07-31 18:07:42 UTC https://padlet.com/ltorbert/gbofilter/wish/179785607 Why do we need filters? ltorbert https://padlet.com/ltorbert/gbofilter/wish/179786195 Filters block out any information that would otherwise distract us from seeing what we want. Think about when it's really noisy and you're trying to hear someone, what do you do? You turn off some of the things that are making noise or remove yourself from a noisy environment. When we filter a signal, we essentially do the same thing. We are taking out all the noise so that we can hear what we need to hear and not all the things that we don't. ]]> 2017-07-31 18:16:51 UTC https://padlet.com/ltorbert/gbofilter/wish/179786195 ltorbert https://padlet.com/ltorbert/gbofilter/wish/179786786 2017-07-31 18:26:07 UTC https://padlet.com/ltorbert/gbofilter/wish/179786786 ltorbert https://padlet.com/ltorbert/gbofilter/wish/179786845 Water filters are placed on the water taps or in water dispensers to filter impurities.]]> 2017-07-31 18:27:00 UTC https://padlet.com/ltorbert/gbofilter/wish/179786845 ltorbert https://padlet.com/ltorbert/gbofilter/wish/179786885 Noise cancelling headphones play a tone that is the exact opposite of the noise in the immediate area so that all or most of the noise is cancelled.]]> 2017-07-31 18:27:41 UTC https://padlet.com/ltorbert/gbofilter/wish/179786885 ltorbert https://padlet.com/ltorbert/gbofilter/wish/179786921 Applying a filter to a photo can help to make it less grainy or change the coloring of the image. (Think Instagram or SnapChat filters)]]> 2017-07-31 18:28:24 UTC https://padlet.com/ltorbert/gbofilter/wish/179786921 ltorbert https://padlet.com/ltorbert/gbofilter/wish/179786941 Coffee Filters keep chunks of coffee grinds from getting into your cup of coffee]]> 2017-07-31 18:28:46 UTC https://padlet.com/ltorbert/gbofilter/wish/179786941 ltorbert https://padlet.com/ltorbert/gbofilter/wish/179788444 2017-07-31 18:55:19 UTC https://padlet.com/ltorbert/gbofilter/wish/179788444 ltorbert https://padlet.com/ltorbert/gbofilter/wish/179789255 The resulting signal]]> 2017-07-31 19:10:34 UTC https://padlet.com/ltorbert/gbofilter/wish/179789255 ltorbert https://padlet.com/ltorbert/gbofilter/wish/179789273 2017-07-31 19:10:54 UTC https://padlet.com/ltorbert/gbofilter/wish/179789273 ltorbert https://padlet.com/ltorbert/gbofilter/wish/179789364 The original signal with a band-pass filter applied]]> 2017-07-31 19:12:34 UTC https://padlet.com/ltorbert/gbofilter/wish/179789364 ltorbert https://padlet.com/ltorbert/gbofilter/wish/179789681 The original signal with a a notch filter applied to it.]]> 2017-07-31 19:19:19 UTC https://padlet.com/ltorbert/gbofilter/wish/179789681 ltorbert https://padlet.com/ltorbert/gbofilter/wish/179789686 The resulting signal]]> 2017-07-31 19:19:23 UTC https://padlet.com/ltorbert/gbofilter/wish/179789686 Instructions ltorbert https://padlet.com/ltorbert/gbofilter/wish/179830276 With a partner you will reveal several messages from popular movies, TV, and music. You will have to apply band-pass and notch filters to the spectrum to uncover the signal. You don't have to go in order. Write down what you think the messages say. Put on headphones
http://gbofiltering.bitballoon.com/]]> 2017-08-01 04:42:18 UTC https://padlet.com/ltorbert/gbofilter/wish/179830276 ltorbert https://padlet.com/ltorbert/gbofilter/wish/179833450 2017-08-01 05:43:28 UTC https://padlet.com/ltorbert/gbofilter/wish/179833450 ltorbert https://padlet.com/ltorbert/gbofilter/wish/179833604 2017-08-01 05:46:04 UTC https://padlet.com/ltorbert/gbofilter/wish/179833604 ltorbert https://padlet.com/ltorbert/gbofilter/wish/179833651 Our group, used GNU radio which is a platform that allows us to analyze  and process the data we received from our horn telescopes and the 40 ft telescope. When the telescopes collect data, it's all analog. We attached an AIRSPY Software Defined Radio to convert the signal from analog to digital, and GNU radio to interpret the data from the telescope so that we could analyze it. Below you'll see an image of the file that was created to filter and process the spectrum. The next picture shows the difference between a filtered signal and an unfiltered signal from the telescropes.]]> 2017-08-01 05:47:02 UTC https://padlet.com/ltorbert/gbofilter/wish/179833651