1/n Fractional octave VI

Using the 1/n Fractional Octave Vi. The user manual says the averaging is continuous for exponentional averaging. It seems to be continuous no matter what the setting is, linear, peak, etc. Trying to get it to stop averaging so I can write the data to file. Please give advice.
R/Scott

Hey chad,
Yes, I'm taking mulitiple channels of 1/3 octave data in parallel with narrowband data. I have a switch on the front panel that allows the user to take either or (case structure). To clarify, I'm using the 1/n fractional octave vi with settings of 10-20kHz. I can write data to file at any time however would like to do some analysis before I take Narraowband data. To do the analysis, I would prefer the 1/3 ocatve spectrum to stop averaging so I can determine true levels. I sort of found a way around this from NI engineer, I've put a For Loop around my code with N= to the # of averages. This is ok but what if I want to view the data real-time for an indefinite period of time. Still need help on this issue. Thanks, Scott

Similar Messages

Vibration fractional octave analysis

Please provide support!
How can you analyze acceleration data g's or m/s^2 from an accelerometer text data thorugh the fractional octave analysis on labview, I've tried a lot of stuff like scaling the units but the fractional octave analysis gives -INF result that is actually not true. Also I've tried moving the range of the frequencies and nothing happen, please let me know if some of you have some idea on how to analyze .TXT acceleration data through the fractional octave analysis
I'm Attaching the TXT file that I'm trying to analyze
Please Help!
Attachments:
sample.txt ‏3364 KB

Hello Anuar
Thought nobody will help on this matter, thanks a lot for your reply, here is a little background, I acquired a signal from an accelerometer at a sampling rate of 10 Khz during 30 seconds, the attached text data posted before is an actual reading from the application, the problem tham I'm dealing with is that over the frequency range from 20 to 20,000 hz I have no values for my fractional octave analysis (attached VI), actually what I'm trying to do is to go from accleration to decibels, thats why I'm doing the fractional octave analysis. Please let me know what I'm doing wrong.
I'll wait for your response
Thanks a lot
SergeArmz
Attachments:
Fractional Octave Analsys challenge 20-may-2013.vi ‏29 KB

Fractional Octave Analysis

My current application reads from six microphones in a reverb room, averages the signals and reports the data as a single source. In the interest of tonal diagnostics we would like to be able to record data in full and 1/3 octaves at the same time. Since I could not find a single vi in the sound and vibration tool-kit that does this I wrote a quick program that processes the same signal through the SVT Fractional-octave Analysis.vi, one defaulted to read full octave and the other is user selectable but will generally be used to read 1/3 octave. My issue occurs when I go to check the accuracy of the readings, it is my understanding that the log sum of the bands for the 1/3 octave for example should equal the value given for the frequency in the full octave band. So if i look at 50, 63, and 80 in the 1/3 octave band their sum should be the value given at 63 for full octave band. I'm using the equation Lp = 10*log(10^(L1/10)+10^(L2/10).......+10^(Ln/10)). A set of readings I've taken looks like this:
Full Octave
63 - 43.6
1/3 Octave
50 - 37.3
63 - 37.3
80 - 39.4
Lp = 10*log(10^(37.3/10)+10^(37.3/10)+10^(39.4/10))
Lp = 42.9
My calculated value of 42.9 and read value of 43.6 are close but I don't understand why the discrepancy is even there if its off the same signal. Any suggestions? I know this is a fairly long post, thanks in advance.
LabVIEW 2012 - Windows 7
CLAD

Hi MeCoOp,
The reason for these discrepancies is because of how octave analysis is implemented. Doing a straight sum of the bins assumes a brick wall filter between the different bands whereas in actuality these filters have skirts. These skirts overlap and to sum up the powers would need to take into account these filter characteristics. Since these skirts level out over an infinite bandwidth, you'll see that the power amongst the whole signal is the same when calculated as either full octave or 1/3 octave.
For more information regarding Octave Analysis and the ANSI/IEC standards, please look at this link.
http://zone.ni.com/devzone/cda/tut/p/id/101
PBear
NI RF

Third octave operations with "sound and vibration toolkit"

Hi!
I’m working about third octave decomposition with a vibration signal.
I’m using the sound and vibration toolkit.
The sample frequency of my signal is 2400 Hz.
And I’m working with a 1 second vibration signal (so 2400 points).
Fs = 2400
N = 2400
I need to understand the different and successive operations that the “SVT Fractional-octave Analysis [IEC].vi”VI do.
In fact, I think that my frequency resolution (df = Fe/N=1Hz) is too low.
Do you have a solution?
Maybe I could turn into my 1 sec signal in 10 sec signal with 10 recopies and assemblage of my previous signal?
N’ = 10N so df = Fe/10N = 0.1Hz.
Thanks for your help.
Bastien of paris

Hello,
The first thing you have to do is to read the Chapter 7 of the user manual of the Sound and Vibration Toolset.
You can find it in : program -> National Instruments -> LabVIEW Sound and Vibration Toolset -> User Manual
This chapter discusses fractional-octave analysis, including fractional-octave analysis theory, averaging modes supported by the
Octave Analysis VIs, settling time, and ANSI and IEC standards.
regards,
Marc L.
NIF

Third octave decomposition

Hi!
I’m working about third octave decomposition with a vibration signal.
I’m using the sound and vibration toolkit.
The sample frequency of my signal is 2400 Hz.
I use the vi “1/n octave IEC decomposition” and I would like to know if I can selected the frequency range “1 to 400 Hz” in third octave decomposition? I think the results are strange in a low frequency (1 to 4 Hz)
In fact, for example, the BW of the first 1/3 octave is less of 0.3 Hz!!!!
So it’s possible to begin the third octave decomposition at 1 Hz?
Thanks for your help.
Bastien

thank...
But I would like to analyse a short signal (5 to 10 second) in the frequency range [1Hz to 400Hz].
When you begin the third octave analyse at 1 Hz you must to have a vibration signal with 17.24 s minimal length in time.
this minimum time is say in the user manual of the toolkit "sound and vibration":
Filter Settling Time :
When starting or resetting the filtering operation of the fractional-octave
filters, a certain time is required before the measurements are valid.
This time is called the settling time and is related to the bandwidth of any
particular filter. The lowest frequency band has the smallest bandwidth and
defines the settling time required before you can consider the complete
fractional-octave measurement valid. In the Sound and Vibration Toolkit,.......
settling time is defined as five divided by the bandwidth of the filter used
for the lowest frequency band.
..........The filter settled indicator returns TRUE as soon as all the filters are settled.
When you begin analyse at 1 Hz, the first BW is 0.29. So, 5/0.29 = 17.24 second.
My vibrations signals are too short (5 to 10 second) and I can't have more long because this signals are due to train course and it’s very fast.
I don’t know how to catch information in a low frequency (1 Hz) with a short signal.
Thank for your help
bastien

Fractional transfer function

Hello
I am using Frequency response function from sound and vibration toolkit and getting Magnitude, Phase and Linear frequency. I want to do the frequency response function in such a way that I get my results in fractional octave analysis (meaning I want the magnitude, phase averaged for that particular frequency band octave, 1-3 octave).
Again Frequency response function where the frequency scale is not linear but represents 1-3 octave bands and the appropriate values for magnitude and phase.
Any suggestions
Thanks
Ankit

Hello Ankit,
The Sound and Vibration toolkit contains several VIs and examples for performing octave analysis. The manual for this toolkit has several pages of information on octave analysis (start at page 10-1). There are also several shipping examples with the toolkit that provide some great getting started information. From LabVIEW click Help -> Find Examples. This will open the NI Example Finder that locates all of the shipping examples installed on your computer. Follow the path Toolkits and Modules -> Sound and Vibration -> Analyzing and Processing Signals -> Octave Measurements. In this folder there are several examples that use the octave analysis VIs for performing a magnitude measurement.
You can find the VIs used for octave analysis by searching for “octave” from the functions palette or by following the path Addons -> Sound and Vibration -> Octave Analysis in the functions palette. These VIs do not perform a phase measurement for the octave analysis, so it would necessary for you to write your own algorithm to analyze the phase of the octave bins.
Regards,
Browning G
FlexRIO R&D

Vibration octave analysis problem

I'm measuring a vibration in range of 1-80Hz, according to Iso 2631.
The problem is that I need the velocity information for each 1/3-octave bands. It should be expressed in mm/s. If fractional octave analysis is used it always ends up to psd unit (mm/s)^2. Using some basic fft-analysis the unit is correct (mm/s) but resolution is higher than 1/3 octave. Any ideas?
ps. Is there any plans to develop a weighting filter needed by Iso 2631-2?

Human vibration filters were added to the Sound and Vibration Measurement Suite in version 6.0 at the end of 2007 compliant to ISO 2631 and ISO 5439.

Enumeration conflict

I am getting an enumeration conflict with the averaging type input of the fractional octave analysis VI.
"You have two or more enumeration data types wired together, but the enumerations are different. The list of items in the enumerations must be exactly the same."
The problem is that I only want to give the user 2 options - exp or linear, I don't want option 2 or 3, just 0 or 1. Howe can I force this VI to accept my input?

There is an option of programmatically disable items on front panel control (attached)
Sergey
Attachments:
disable enum's.vi ‏25 KB

PCI 4551 for FRA application

This is regarding clarification regarding frequency responce analysis
using NI PCI 4551 add-on card, especially in the singal generation part for
stimulating the unit under test.
1. Is it possible to generate sine, step, ramp and arbitrary waveforms
using this particular card?
2. Ifso what is the range of frequencies that can be possible to
generate using PCI 4551 card?( we may require from 1mHz to 2kHZ)
3. And what is the maximum amplitude of the generated signal for full
scale value?
4. Whether real-time octave analysis for NI DSA software can serve the
purpose of following tests: Frequency response test, Step response test,
Velocity test, Strain Measurement, Linearity Test, Cyclic test.
Or any other software tool is required?

Hi Mallesh,
In response to your questions, I've included my responses. I highly advise referencing the NI-4551 User Manual for more details.
1. Is it possible to generate sine, step, ramp and arbitrary waveforms
using this particular card?
NI-DSA includes functions to generate standard white noise, pink noise, band-limited noise, periodic white noise, single or dual-tone sine, and chirp signals. For step, ramp, and any other arbitrary waveforms you can use NI-DSA to define and generate an arbitrary analog output signal.
There is a good example which ships with NI-DSA that demonstrates how to generate arbitrary waveforms on the NI-4551. You can find this example in the NI-DSA function palette in LabVIEW under Application Examples>>Advanced>>Arbitrary Output Example.
By default, this example outputs a swept sine wave, but you can change the waveform to whatever you need.
2. If so, what is the range of frequencies that can be possible to
generate using PCI 4551 card?( we may require from 1mHz to 2kHZ)
The maximum output frequency you can generate with NI-DSA is 23 kHz. This limit is governed by the maximum output sampling rate of 51.2 kS/s. Because the digital-to-analog converters on the NI 455x DSA devices feature sharp roll-off, anti-imaging filters, you can generate a spectrally pure sine tone up to 23 kHz with minimal quantization noise, so when using the NI 455x devices, you do not need to worry about the output signal becoming choppy or noisy when approaching the Nyquist frequency.
The minimum frequency you can set is 0.1 Hz. This is limited by the finite size of the output buffer and the minimum update rate for the DAC. The output buffer is limited to 4,096 samples, and the DAC must maintain a minimum rate of 1.25kS/s for accurate results.
In Octave Analyzer Mode, when you're inputting a certain frequency, keep in mind the input range differs for each analysis type and the two configurable center frequencies. I've included the frequency ranges for a single channel below.
1/1-octave analysis
center frequency fs=25.6 kHz:
High: 8 kHz
Low: 16 Hz
fs=51.2 kHz
High: 16 kHz
Low: 31.5 Hz
1/3-octave analysis
fs=25.6 kHz
High: 10 kHz
Low 12.5 Hz
fs=51.2 kHz
High: 20 kHz
Low: 25 Hz
1/12-octave analysis
fs=25.6 kHz
High: 10.68 kHz
Low: 11.05 Hz
fs=51.2 kHz
High: 5.34 kHz
Low: 5.52 Hz
3. And what is the maximum amplitude of the generated signal for full
scale value?
The maximum amplitude is equal to the voltage range for the selected output channel.
4. Whether real-time octave analysis for NI DSA software can serve the
purpose of following tests: Frequency response test, Step response test,
Velocity test, Strain Measurement, Linearity Test, Cyclic test.
Or any other software tool is required?
The NI-DSA Real-Time Octave Analysis software add-on for NI-DSA supports fractional-octave analysis for 1/1, 1/3, and 1/12 octave analysis, level measurements, and A-, B-, and C-weighting. You can do octave, level, or both octave and level measurements, and have the additional option of specifying the weighting if required. This is all that can be done in real-time.
To perform a frequency response test, it is preferable to use the swept-sine analysis mode of the NI-4551 rather than a broadband FFT-based frequency response. Swept-sine analysis provides two main advantages over a broadband frequency response measurement in which all frequencies are excited and measured simultaneously. The first is a wider dynamic range. The second is flexible measurements of signal distortion and nonlinearity. For more information of swept-sine analysis, please refer to the NI-DSA Software Manual downloadable off our web site. http://www.ni.com/
For the Velocity test, Strain Measurement, Linearity Test, and Cyclic Test I should ask for more information about each test before attempting an answer. However, to answer your question, there are no methods I know of in NI-DSA that would directly perform these tests. In contrast with that answer, you may be surprised this functionality may be included with a LabVIEW development environment.
Let me know if you have further questions or this does not resolve your issue!
Chad AE
Applications Engineer

ISO Human exposure vibration analysis

Good Morning,
I am trying to use LabView 7.1 with the Sound and Vibration toolkit in processing some data in accordance with ISO 5349-1:2001. In this standard, data needs to be collected in 1/3 octave bands from 6.3Hz to 1250Hz then weighted and the RMS taken. Data collection and RMS are not a problem, the challenge I am having is with the octave analysis and creating the custom weighting. Am I just missing the obvious VI's in SVT 3.1? Is there a custom weighting example? How does one perform octave analysis below the low frequency cut-offs of the existing VI's?
Thanks,
DRK

Hi DRK,
thanks for posting again. A few things:
1) In the same user manual on pages 9-9 and 9-10 there's this info:
Performing Third-Octave Analysis Outside the Audio Range
You might need to perform third-octave analysis on signals outside of the
20 Hz–20 kHz range. For example, you might need to evaluate human
exposure to whole body vibration with potential signals of interest in
the 0.5 Hz–80 Hz range. To perform third-octave analysis outside the
20 Hz–20 kHz range, use either the SVT Fractional-octave Analysis
[ANSI] VI or the SVT Fractional-octave Analysis [IEC] VI and select a
bandwidth equal to 1/3 octave, as illustrated in Figure 9-7.
2)We don't have a weighting filter according to that standard currently but we would like to discuss the standard a little more with you, if possible. Can you give us a phone number (preferably) or an email address that we can contact you at?
Thanks!
Brian Spears

This is regarding clarification regarding frequency responce analysis

This is regarding clarification regarding frequency responce analysis
using
NI
PCI 4551 add-on card, especially in the singal generation part for
stimulating
the unit under test.
1. Is it possible to generate sine, step, ramp and arbitrary waveforms
using
this particular card?
2. Ifso what is the range of frequencies that can be possible to
generate
using
PCI 4551 card?( we may require from 1mHz to 2kHZ)
3. And what is the maximum amplitude of the generated signal for full
scale
value?
4. Whether real-time octave analysis for NI DSA software can serve the
purpose
of following tests: Frequency response test, Step response test,
Velocity
test,
Strain Measurement, Linearity Test, Cyclic test.
Or any other software tool is required?
Regards,
Sreedhar T

Hi SreedharT,
In response to your questions, I've included my responses. I highly advise referencing the NI-4551 User Manual for more details.
1. Is it possible to generate sine, step, ramp and arbitrary waveforms
using this particular card?
NI-DSA includes functions to generate standard white noise, pink noise, band-limited noise, periodic white noise, single or dual-tone sine, and chirp signals. For step, ramp, and any other arbitrary waveforms you can use NI-DSA to define and generate an arbitrary analog output signal.
There is a good example which ships with NI-DSA that demonstrates how to generate arbitrary waveforms on the NI-4551. You can find this example in the NI-DSA function palette in LabVIEW under Application Examples>>Advanced>>Arbitrary Output Example.
By default, this example outputs a swept sine wave, but you can change the waveform to whatever you need.
2. If so, what is the range of frequencies that can be possible to
generate using PCI 4551 card?( we may require from 1mHz to 2kHZ)
The maximum output frequency you can generate with NI-DSA is 23 kHz. This limit is governed by the maximum output sampling rate of 51.2 kS/s. Because the digital-to-analog converters on the NI 455x DSA devices feature sharp roll-off, anti-imaging filters, you can generate a spectrally pure sine tone up to 23 kHz with minimal quantization noise, so when using the NI 455x devices, you do not need to worry about the output signal becoming choppy or noisy when approaching the Nyquist frequency.
The minimum frequency you can set is 0.1 Hz. This is limited by the finite size of the output buffer and the minimum update rate for the DAC. The output buffer is limited to 4,096 samples, and the DAC must maintain a minimum rate of 1.25kS/s for accurate results.
In Octave Analyzer Mode, when you're inputting a certain frequency, keep in mind the input range differs for each analysis type and the two configurable center frequencies. I've included the frequency ranges for a single channel below.
1/1-octave analysis
center frequency fs=25.6 kHz:
High: 8 kHz
Low: 16 Hz
fs=51.2 kHz
High: 16 kHz
Low: 31.5 Hz
1/3-octave analysis
fs=25.6 kHz
High: 10 kHz
Low 12.5 Hz
fs=51.2 kHz
High: 20 kHz
Low: 25 Hz
1/12-octave analysis
fs=25.6 kHz
High: 10.68 kHz
Low: 11.05 Hz
fs=51.2 kHz
High: 5.34 kHz
Low: 5.52 Hz
3. And what is the maximum amplitude of the generated signal for full
scale value?
The maximum amplitude is equal to the voltage range for the selected output channel.
4. Whether real-time octave analysis for NI DSA software can serve the
purpose of following tests: Frequency response test, Step response test,
Velocity test, Strain Measurement, Linearity Test, Cyclic test.
Or any other software tool is required?
The NI-DSA Real-Time Octave Analysis software add-on for NI-DSA supports fractional-octave analysis for 1/1, 1/3, and 1/12 octave analysis, level measurements, and A-, B-, and C-weighting. You can do octave, level, or both octave and level measurements, and have the additional option of specifying the weighting if required. This is all that can be done in real-time.
To perform a frequency response test, it is preferable to use the swept-sine analysis mode of the NI-4551 rather than a broadband FFT-based frequency response. Swept-sine analysis provides two main advantages over a broadband frequency response measurement in which all frequencies are excited and measured simultaneously. The first is a wider dynamic range. The second is flexible measurements of signal distortion and nonlinearity. For more information of swept-sine analysis, please refer to the NI-DSA Software Manual downloadable off our web site. http://www.ni.com/
For the Velocity test, Strain Measurement, Linearity Test, and Cyclic Test I should ask for more information about each test before attempting an answer. However, to answer your question, there are no methods I know of in NI-DSA that would directly perform these tests. In contrast with that answer, you may be surprised this functionality may be included with a LabVIEW development environment.
Let me know if you have further questions or this does not resolve your issue!
Chad AE
Applications Engineer

Applying of FFT and Octaves analysis to an analog input

Is it posible to aply, in real time, with LabVIEW 5.0 an FFT and Octaves analysis to an analog input obtained with a Labpc 1200? If yes could you please give me a hinch? Thank you very much.

There is basic FFT analysis built into the libraries that ship with LabVIEW Full Development System (FDS). However I would recommend considering the Sound & Vibration toolkit as an add on for LabVIEW. This contains more complete FFT analysis solutions (including averaged FFT analysers) and has a complete range of octave analysis (full and fractional analysis).
The examples are very good and even if you haven't had much experience of using traditional boxed FFT/octave analysers you will quickly be in a position to have a good working application up and running.
This brings me onto the question of the board that you are using. Depending on the type of signals that you are working with, you may find that there are a number of limitations to using the Lab-PC-1200.
1. The board has only 12-bit ADCs which therefore gives a maximum dynamic range of approx 72dB. A 16-bit board would offer a wider dynamic range of 96dB while some of the dedicate signal/audio analyser boards on offer from NI have 24-bit ADCs and a dynamic range of 120dB.
2. If you are analysing more than one channel and are looking at phase measurements (i.e. stereo if it is audio you are acquiring) you will be limited by the architecture of the Lab-PC-1200. This board uses a multiplexer to switch from one channel to another. This will automatically insert a phase error into the measurements that you take. An example of where this might be a problem would be if you were analysing the response from two audio speakers, or trying to analyse the performace of an object to vibration using multiple accelerometers. Dedicated boards on offer from NI (NI 44xx range) have simultaneous sampling inputs and these get around these phase problems.
The analysis that you perform with such a board all takes places on the host computer i.e. your Windows PC. As such you comment "is it possible to apply, in real time..." will depend entirely on the specification of your PC. NI does offer a few boards that will allow FFT and octave analysis to be performed on the actual DAQ board itself (NI 45xx range of dynamic signal analysers).
So in summary, consider the Sound & Vibration toolkit and also consider the limitations of the Lab-PC-1200. It may not be the best choose - but if you are stuck with the board, you can still develop a suitable LabVIEW application and if possible upgrade the hardware sometime in the future (the code should not need to change if you change the board).
Jeremy

Help with calculating fractions in a program...

I'm supposed to declare to fractions and then add, subtract, mulitply, and divide them.
(3, 4)
(2, 3)
The outcome is supposed to look like this...
Number 1 is 3/4
Number 2 is 2/3
Reciprocal of 3/4 is 4/3
Reciprocal of 2/3 is 3/2
3/4 + 2/3 is 17/12
3/4 - 2/3 is 1/12
3/4 * 2/3 is 6/12
3/4 divided by 2/3 is 9/8
And I have my Fraction class all figured out, but I'm not sure how to display the calculations in the main part of my program.
Here is my fraction class
public class Fraction {
     private int numerator;
     private int denominator;
     //Constructor method
     public Fraction(int n, int d) {
          numerator = n;
          denominator = d;
//Returns the fractions numerator
     public int getNumerator() {
          return numerator;
//Returns the fractions denominator
     public int getDenominator() {
          return denominator;
//Returns the fractions reciprocal
     public Fraction reciprocal() {
          //Declare the local variables
          int newNumerator;
          int newDenominator;
          int tempNumerator;
          int tempDenominator;
          //Swap the two values
          newNumerator = denominator
          newDenominator = numerator;
          //Return a new Fraction as the reciprocal
          return new Fraction(newNumerator, newDenominator);
//Returns a string representing numerator/denominator
     public String toString() {
          return (numerator + "/" + denominator);
     public Fraction add(Fraction f2) {
          tempNumerator = (numerator * number2.getDenominator()) + (denominator * number2.getNumerator());
          tempDenominator = (denominator * number2.getNumerator());
          return new Fraction (tempNumerator, tempDenominator);
     public Fraction subtract(Fraction f2) {
          tempNumerator = (numerator * number2.getDenominator()) - (denominator * number2.getNumerator());
          tempDenominator = (denominator * number2.getDenominator());
          return new Fraction (tempNumerator, tempDenominator);
     public Fraction multiply(Fraction f2) {
tempNumerator = (numerator * number2.getNumerator());
tempDenominator = (denominator * number2.getDenominator());
return new Fraction (tempNumerator, tempDenominator);
     public Fraction divide(Fraction f2) {
          tempNumerator = (numerator * number2.getDenominator());
          tempDenominator = (denominator * number2.getNumerator());
          return new Fraction (tempNumerator, tempDenominator);
}

You've got the Fraction class already written and it looks not too bad. Probably there's some bugs, and it won't compile, but that's not your question. Are you saying you have written a Java class, but you don't know how to write a main program to use that class?
Okay, let's suppose you want to get the following output:
Number 1 is 3/4
Reciprocal of 3/4 is 4/3
Then your program would look something like this:public class FractionTest {
public static void main(String[] args) {
    Fraction f1 = new Fraction(3, 4);
    System.out.println("Number 1 is " + f1);
    System.out.println("Reciprocal of " + f1 + " is " + f1.reciprocal());
}

I'm having a problem with fractions and Mathematical Equations

Hi I'm to write fractions in pages like I can write ¾ as a single caracter but if i need franction over ⅞ I can just write them like 1/9 I can just write as 1 divided by 9 and not as a signle character. And i would like to write fractions like 1/36 o 1/72 as a single caracter.
second problem is that i know that I can insert Mathematical Equations doing Insert>Mathematical Equations but under Inster I don't have any Mathmetical Equations..... Any suggestions?
Thanks, luca

Hi Luca,
You can write fractions as single characters only using those single character fractions available in the character set you are using. For the 'standard' unicode set, the available "vulgar fractions" include the denominators from 2 to 8, with all numerators necessary to write fractions from 1/8 to 7/8, reduced to the lowest denominated equivalent.
The three missing fractions, 1/2, 1/4 and 3/4 are in row 00B0 of the table, where they were (and are) part of the earlier, smaller ASCII set.
Other common fractions ('vulgar' if you prefer the Latin name) can be written using the solidus, a zero-width character (shift-option-1 from the keyboard): 13⁄17
In the example, all five characters are set to the same height,
13 is set to Format > Font > Baseline > Superscript
17 is set to Format > Font > Baseline > Subscript
If you have many of these to enter, it may be worth your while to create a separate document containing a large selection which you can copy and paste into your documents
Regards,
Barry
EDIT: Formatting of the 13/17 example above appears to be badly interpreted by the forum software. Try it in pages for a better idea of how it should look.
Message was edited by: Barry

I attempted to download a podcast but it was corrupt and only a fraction downloaded. It won't download and I can't delete. How do I get it off my itouch?

I attempted to download a podcast but it was corrupt. Only a fraction downloaded and I can't download nor delete. Any ideas as to how to delete?

If a Podcast has only partially downloaded, then you need to delete that partial download before iTunes will "allow you" to begin a fresh download of that same file.
Have a look in your iTunes Media folder for the Download folder. On my Windows 7 for instance, it's Music/iTunes/iTunes Music/Downloads. In that folder, there should be a sub-folder with the name of that podcast which has the partial download in it. Delete the named podcast folder, but not the Download folder.
You should then be able to start a fresh download (if you still want it!).

1/n Fractional octave VI

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