<< Chapter < Page Chapter >> Page >

Upsampling vi

From the beginning, we knew that there would be restricted sampling rate of the DAQ card, and the buffer would be effectively decreased by a factor of eight for any one signal (since the data from all eight signals comes into the same buffer). Whatever sampling rate was left would meet the most basic Nyquist requirements and avoid aliasing in that fashion; however, the resultant signal was unlikely to possess much resolution beyond that. Thus, upsampling would be a necessity.

We initially searched Labview itself for a premade upsampling VI, presuming that one would exist, as it is a fairly common signal processing algorithm. However, we were unable to find one and so set about creating a module that would do the job. Our module takes as inputs the signal (array of points) to be upsampled and N, the amount the signal was to be upsampled, and passes as an output the upsampled signal.

Upsampling vi

Sub-VI used to upsample a signal

Following upsampling theory discussed in class ( ELEC 301: Signals and Systems ), the first step to our upsampler was to zeropad , that is, add zeros in between each point on the signal being upsampled. Instead of attempting to implement a dynamic array, this was accomplished by creating a new array of the appropriate length (N times the length of the original array, where N is the amount the signal is being upsampled) and using a for loop to place the original signal elements into the new array spaced N points apart.

This enlarged array of data is then passed back to the Waveform Generation VI where it is lowpass filtered in order to fill in ( interpolate ) the new zeroed out positions, and passed onward as an output of the Waveform Generation VI. The filter used in this operation is the Equi-Ripple FIR low pass filter.

Delay generation vi

This VI does the bulk of the mathematical analysis of the input signals. It takes as inputs the two delays between microphones one and two, and one and four (derived from the calculations of max norms in the Main Analysis VI ) and outputs an array that contains theta , phi , and the corresponding delays for the seven microphones (the delay of the first microphone is automatically set to zero). In all cases, the delays are scaled to correspond to the number of indexes the corresponding signal should be shifted, instead of the actual real-time delay. (As we cannot shift a signal by fractional indexes.)

d12 = k12 / (fs * N); d14 = k14 / (fs * N);phi = acos( sqrt (v^2 * (d12 ^ 2 + d14 ^ 2) ) / d ) * sign (d12 * d14); theta = atan (d14 / d12);d13 = d12 * 2; d16 = d14 * 2;d18 = d13 + d16; d15 = d13 + d14;d17 = d16 + d12;

The first part of the above code is calculates the angles based on the spatial relations between the three microphones (microphone 1, used, as we said before, as the origin, and microphones 2 and 4, which can be found directly adjacent to microphone 1 in both directions). As you can see, it is fairly simple geometry, complicated primarily by the scaling necessary to match the 'k' values (integer values used to iterate the for loop) to their corresponding 'd' value (actual delay in time).

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
Privacy Information Security Software Version 1.1a
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get the best Algebra and trigonometry course in your pocket!

Source:  OpenStax, Investigation of delay and sum beamforming using a two-dimensional array. OpenStax CNX. Feb 04, 2006 Download for free at http://cnx.org/content/col10315/1.3
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Investigation of delay and sum beamforming using a two-dimensional array' conversation and receive update notifications?