The World of Signals

One of the most iconic films of all time, Alien (1979) tells the story of the commercial spaceship Nostromo that lands on the moon LV-426 after detecting a transmission from a derelict alien ship. The crew discovers a chamber containing hundreds of large egg-like objects, one of which attaches itself to a crew member. This is how an alien creature gets into Nostromo and plays its deadly game.

A DSP problem

Assume that you develop an interest in digital signal processing (DSP) after taking this course at Educative. And many years from now, you are hired as the chief DSP scientist for an international spaceship heading for a remote galaxy. To differentiate between friendly and hostile transmissions, you are given a simple criterion by the top scientists at the Global Space Agency, which they have learned from their decades of experience: If the signal frequency at 6.8 kHz has a normalized magnitude above -20 dB, the transmission is most likely coming from an alien source. Otherwise, it will be a spaceship from another nation needing help. According to the space protocol devised through a treaty among all nations, a spaceship must go and help those in distress.

At the ship, you receive the signal shown below and concentrate on analyzing it using all your expertise (because lives are at risk).

What advice will you give to the captain?

1. Go and investigate (if humans need help)
2. Steer away in the opposite direction (if dangerous aliens are around)

We will explore questions like this (and more) in this course.

Searching for aliens

If you think the situation above is a little dramatic, remember that we actually do something like this here on planet earth. The United States has a program known as Search for Extraterrestrial Intelligence (SETI) that involves 100 plus scientists. According to their website:

It is an effort to detect evidence of technological civilizations that may exist elsewhere in the universe, particularly in our Galaxy. There are potentially billions of locations outside our Solar System that may host life. With our current technology, we have some ability to discover evidence of cosmic habitation, and, in the specific case of our SETI experiments, to find beings that are at a technological level at least as advanced as our own.

Which field do you think many of these scientists have mastered to achieve this goal?

DSP is an amazing subject to learn. You touch very little of the real world, and yet you can impact it on a disproportionately large scale. How is this possible? This is where we turn to the magic of DSP.