Skip to content Skip to navigation

OpenStax_CNX

You are here: Home » Content » The Channel

Navigation

Lenses

What is a lens?

Definition of a lens

Lenses

A lens is a custom view of the content in the repository. You can think of it as a fancy kind of list that will let you see content through the eyes of organizations and people you trust.

What is in a lens?

Lens makers point to materials (modules and collections), creating a guide that includes their own comments and descriptive tags about the content.

Who can create a lens?

Any individual member, a community, or a respected organization.

What are tags? tag icon

Tags are descriptors added by lens makers to help label content, attaching a vocabulary that is meaningful in the context of the lens.

This content is ...

Affiliated with (What does "Affiliated with" mean?)

This content is either by members of the organizations listed or about topics related to the organizations listed. Click each link to see a list of all content affiliated with the organization.
  • Rice University ELEC 301 Projects

    This module is included inLens: Rice University ELEC 301 Project Lens
    By: Rice University ELEC 301As a part of collection: "ELEC 301 Projects Fall 2009"

    Click the "Rice University ELEC 301 Projects" link to see all content affiliated with them.

Also in these lenses

  • Lens for Engineering

    This module is included inLens: Lens for Engineering
    By: Sidney Burrus

    Click the "Lens for Engineering" link to see all content selected in this lens.

Recently Viewed

This feature requires Javascript to be enabled.
 

The Channel

Module by: Brian Viel. E-mail the author

Summary: After transmission our signal enters the acoustic channel, join us as we witness what unfolds

The Channel

To characterize the channel, we input an impulse by recording the tapping of the mic with our fingers. We then played that sound through the speaker and recorded the response with the mic. The signal is below, along with its spectrum.

Figure 1: These graphs characterize the channel that we are transmitting through
Impulse Response of the Channel and its Spectrum
impulse

We did this in preparation for the receiving end of the system to divide the received signal’s FFT by the impulse response’s FFT.

Below are plots of our transmitted and received signals, along with their spectrums. You will notice a great similarity between the signals in time, however a distinct difference in frequency. Unfortunately, this loss in frequency will translate to a loss of information.

Figure 2: These are the signals in time that we transmitted (green) and that we received (red). As you can see they look very similar, and take it from us, they also sound similar.
Transmitted and Received Signals in the time domain
signals
Figure 3: The green spectrum is of the signal we transmitted, and the red is the spectrum of the signal we received. We see a much bigger visual difference than we did in the time domain.
Transmitted and Received Signal Spectrums
spectrum

Above are plots for our transmitted and received signals. Here we used a block length of half the duration of the signal and sent it through the air at 44.1 kHz.

Content actions

Download module as:

PDF | EPUB (?)

What is an EPUB file?

EPUB is an electronic book format that can be read on a variety of mobile devices.

Downloading to a reading device

For detailed instructions on how to download this content's EPUB to your specific device, click the "(?)" link.

| More downloads ...

Add module to:

My Favorites (?)

'My Favorites' is a special kind of lens which you can use to bookmark modules and collections. 'My Favorites' can only be seen by you, and collections saved in 'My Favorites' can remember the last module you were on. You need an account to use 'My Favorites'.

| A lens I own (?)

Definition of a lens

Lenses

A lens is a custom view of the content in the repository. You can think of it as a fancy kind of list that will let you see content through the eyes of organizations and people you trust.

What is in a lens?

Lens makers point to materials (modules and collections), creating a guide that includes their own comments and descriptive tags about the content.

Who can create a lens?

Any individual member, a community, or a respected organization.

What are tags? tag icon

Tags are descriptors added by lens makers to help label content, attaching a vocabulary that is meaningful in the context of the lens.

| External bookmarks