Monday, July 17, 2017

Aliasing and Noise

The word "trigger" has come to be used in colorful ways in recent years. For me, the neural paths responsible for religious thought and those responsible for math, science, and engineering do tend to run a little separate. That is, until I am "triggered," causing these paths to short and ideas to free-flow. This little piece is about my most recent experience.

As a preface and as supplemental material to my remarks, I strongly encourage the reader to view this video based on the words of the late James E. Faust, a leader in our church that I remember frequently giving very powerful sermons:


I watched this video yesterday with the relatives I am boarding with this summer, the missionaries serving in our area, and a wonderful couple they have been meeting with recently. We watched this video and talked a little more about the analogy then President Faust makes between the voice of the Spirit and dealing with an old radio.

"...Tune in..."
"...Wrong frequency..."
"...Deception..."

Somewhat seemingly unconnected statements aligned in succession became to me, you guessed it:

TRIGGER!!!!!!!!

My mind began to race at a million miles a minute. I could hardly control the speed with which I thought of connections between this message we were sharing and a very important concept in terms of engineering measurement systems. For you, the reader, I will attempt to slow it all down as you may not be quite as enthused in or aware of sampling frequencies, Nyquist frequencies, or, most critical of all, Aliasing!

For a general definition, Aliasing, in terms of science and engineering, is the phenomenon that occurs when a frequency that enters your measurement system appears to have a different frequency. Like, a frequency alter-ego. Or, like, an alias. Everyone has seen an example of aliasing. Have you ever seen a movie or video with a helicopter or car or something else turning and then the propellers or spokes look to slow down and then go backward? That, my friends, is aliasing. In the case of the helicopter or car example, the camera recording the scene didn't have a high enough frame rate to capture the motion properly. This is where those other words, sampling frequency and Nyquist frequency come in, but those are things I had multiple lectures on, so I will spare you the low-level, awesome details.

I will, however, explain why I thought of this during our discussion. Our God will speak to us through his spirit and transmits at a certain frequency. If the resolution of our receiver is too low, his message to us will alias and we will not receive the guidance we need. To properly sample the input God is transmitting, we need to increase our resolution and apply both physical and digital (spiritual) filters.

High resolution data acquisition systems are expensive! There is a lot of engineering and attention to very acute details that goes into each system. There must be a controller that oscillates on the order of millions to billions of times every second in addition to high-functioning electrical components (including the physical filters I will address later). We need to be sampling (taking data, or receiving a frequency) faster and faster all the time. We should, as Alma says, "let [our] hearts be full, drawn out in prayer unto [God] continually..." (Alma 34:27). If we follow this direction and always have a prayer in our hearts and seek for God's guidance at all times, our resolution will increase and the messages God sends to us will come through closer and closer to exactly as he intends.

Signal filtering is a very big topic that I cannot hope to explain in great detail. Much like aliasing, I will leave you with a working definition and proceed to the connection. All real signals have some amount of unexpected interference or imperfection in transmission or reception components. These errors that come through our sampling are called "noise." Noise is the name we give for frequencies that come through but don't contribute to the data collection and distract us from the actual frequency we want to read. Examples include vibrations in support systems and static. One way to filter signals is through a physical filter you (well, maybe not necessarily you reading this, but humans) can physically build with capacitors, resistors, and other electrical components. These will serve as a barrier to block out the frequencies we consider noise. Similarly, physical barriers can be effective in our lives if we want to remove the different noises President Faust listed in the video. We can, to an extent, physically remove ourselves from locations and situations that make it difficult for us to read God's signals. We can also have reminders such as pictures or quotes that can amplify the signal we do want making it easier for us to recognize when the spirit is speaking to us and when it is just Satan's noise.

Digital filtering is a separate beast that involves writing a program to work through the data gathered and extract the frequency of interest. For the most part, these programs can be generalized for specific situations, but require hands-on calibration. After some time, after many samples, and after staring at graphs that just seem to be noise, we can apply an algorithm that pulls out the signal of interest. It takes time. It takes experience. And, unfortunately, different systems will have different noise patterns associated with them requiring new calibration and a new code. However, if we persevere and fight through the distracting noise, we can extract the intended frequency and collect the message we were meant to receive.

My friends, let us increase our resolution and apply filters so that we can push through the noise that grows louder and louder every day and sample the true frequency that our Heavenly Father is transmitting to us through the Holy Ghost.

I wish I could say I am perfect. I wish I could say my sampling rate was on the TBS order of magnitude, but it isn't. I wish I could say I have such high order filters that God's message comes through clearly and the noise around me is brutally attenuated. Though I am weak, I am trying. Thank you for making it this far into my nerd ramblings. This means so much to me because I truly think that, at the heart of everything, this is key to our success in life. God speaks to man today. He speaks to me and he speaks to you. I go to church to learn different experimental ways to filter. Some filters work for other people in their circumstances, some have different noise they need to filter. But in every case, if we can have the courage to apply our signal conditioning, accept the data we receive, and act, God will not lead us astray. 

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