Reporter: Raymundo Múnoz
This presentation was given to the NASA SHARP students to inform and educate as to what DSP is. All the students were present.
The speaker’s name was Jeffrey Y. Beyon. He began the presentation by introducing himself and his assistants for the Labview and then asking us to introduce ourselves. After individual introductions, Dr. Beyon asked us a few questions about ourselves as a group, such as how long we were participating in the program for and how we had heard about NASA SHARP. Also, Dr. Beyon asked us if we knew about the selection process for the shuttle for passengers who were non-astronauts and if any of us wanted to be engineers.
After this brief period of ease so we could all get comfortable, Dr. Beyon asked us if we knew what DSP (Digital Signal Processing) was and informed us that it has many uses. He told us that NASA Langley has a laser that is used to measure Carbon Dioxide levels in the atmosphere, and then asked if we knew how a radar gun worked. A radar gun works by using the Doppler Effect to bounce waves off of moving objects and then calculating the speed of the vehicle with the information acquired using the waves that have bounced back. Theoretically, since this method is most effective when measuring an object approaching head on, a radar gun cannot accurately gauge the speed of an object on a path perpendicular to the gun’s aiming line. He also told us that lasers, such as those used to guide advanced missiles more accurately, cannot target an object if an obstacle is blocking the path of the laser between the laser’s origin and its intended destination. That is why GPS satellites lose track of vehicles when they enter tunnels and satellite television reception is knocked out by unfavorable weather conditions. Following this background information and introduction to some uses of DSP, he explained further what it is and that it is a great part of our everyday world.
DSP is the Processing of signals that are in digital format. Its technology provides benefits to us in almost every part of our lives. Automobiles use DSP in the systems used for airbags, seat belts, traction control, navigation systems, and features such as the volume of audio coming through the vehicle’s speed increases as the vehicle’s speed increases. Airplanes use DSP in the auto pilot functions, turbulence detection, radars, etc. all which help improve safety. Weather forecasters use DSP in their Doppler radars that let them inform us of upcoming weather conditions. Even things we have at home use DSP everyday: our refrigerators use DSP for temperature control and touch-screen functions in newer models, television sets that automatically adjust the volume when changing to a channel that is programmed to be louder at its station, VCRs’ auto-tracking feature uses DSP to clear up video, as well as camcorders using DSP to stabilize the picture when recording, and even hearing aids use DSP in their amplifiers to help give our hearing impaired back the gift of being able to hear.
The goal of DSP is to improve our lives by means of what we know and what we can build upon that knowledge. After Dr. Beyon told us some of the different devices that use DSP, we discussed analog vs. digital. There are many things we use and do not stop to think about whether they use digital or analog technology to function. Many of our regularly used possessions have both a digital and an analog version: cameras, TVs, radios, watches, and guitars are just a few. To better understand the differences between the use of analog and digital we must know what each is. Analog is all real information; digital uses the method of “steps” to calculate information.
A sinusoidal wave, shown in Fig.1, is an example of analog data. Digital data is comprised of many steps, shown in Fig.2. The steps capture points on the sine wave. They may not capture the wave identically, but the more steps used, the better the representation of the analog data. The conversion of analog data to digital data in this way is called quantization. A flaw in this process is the aforementioned loss of data by not capturing the sine wave identically. Thus, quantization, though producing more technologically advanced data in more compact form, invariably gives data with some degree of error, however small it may be.
After this Dr Beyon went more in depth on the explanation of the function of DSP in some devices. An automobile’s traction system moves power to the outside tires and applies a brake to the inside tires on turns. This is to balance out the turn of the car so that it does not slide off the road. Digital cameras use steps to capture images. Since more steps gives us a better picture, steps can be thought of as similar to pixels in relation to digital cameras. This example shows well that the more steps used to capture an image, the clearer and more true to life it is.
Fourier’s formula of transformation states that any sine wave can be made from the sums of various other sine waves and vice versa.
He believed that everything can be explained with waves.
After the discussion on waves and we actually got to see waves in action by monitoring the waves and amplitude produced by our voices and a waveform generator on some of the equipment. Also, we learned that telephones, at least land lines, do not generate connections from one phone to another because we press the buttons on the keypad, but because the tones produced when we press the keys create waves that initiate the connection.
Equipment in the DSP Lab:
• NI-PCI-4451 Data Acquisition Board by National Instruments
– Two simultaneous sampling analog input channels
– Two analog output channels
– 5 to 204.8 KHz sampling rate capability
– 90 dB dynamic range
• Miscellaneous Peripherals
– BNC to RCA converters
• LabVIEW Professional Development 7.0 by National Instruments
– Graphical Programming for DSP implementation
Overall the experience was educational and enjoyable. I believe all the participants learned something new and got a closer look at this field of engineering.