Statistics express vi

When using the statistics express vi in LV7.1, I get wrong results for standard deviation. I particular, the VI outputs the mean value instead, but only for certain data sets. Most of the times it works fine. I can not see any problem in this very simple VI. Any ideas?
Thanks
Dirk
Attachments:
statistics_problem.vi ‏565 KB

Hello Dirk,
I think you found a bug on the LabVIEW's statistical functions...
I removed that set of data from the array and tried the normal (not express) statistical functions and they return NaN and for the others it's ok!
See attached code.
Paulo
Attachments:
statistics_problem[1].vi ‏600 KB

Similar Messages

How do I get the statistics express to read more than 10 segments when reading from a .lvm

I have tried 2 ways of doing this. I had an for loop set up with a "Read labVIEW Measurement FIle" then a xy chart to plot the 2 measurements vs. each other. The chart works and will plot everything great but the "Statistics" express will only take 10 samples at a time and will keep redoing the statistics for each subsequent segment of 10 samples. I tried to change this to a while loop but then the same thing happens with the stats and the xy chart does not graph. How do I get the stats calculate for the entire file?

Richard,
Thank you for contacting National Instruments. I think I understand what you are looking to do here, but it might be easiest for myself and others to help you more specifically if you post a screenshot of your code, or your actual VI. However, I looked into trying to achieve something similar, and used a loop structure to bring the information in from a file. Then, outside the loop, I used the Statistics Express VI from the Mathematics palette to obtain some statistical values. What type of statistics are you looking to receive from this program?
Jason W.
National Instruments
Applications Engineer

Statistics Express VI - help

Under the help option in the statistica express VI this is given to explain the time between samples (dt)
Time between samples (dt)
—Bases the calculation on the time between samples in
Signals
My design is two micophones and one sound and finding the time delay between the two.
Now does this mean it takes the difference from when one signal starts and the other starts
(say when microphone 1 first picks up a signal and then microphone 2)
Or does it show the time difference between the two signals ?
(as in the delay between the samples)
I'll attach the VI's below to see it that helps makes sense
Solved!
Go to Solution.
Attachments:
VI.zip ‏980 KB

dt is the time spacing between sampled points. In your case, dt=0.001.
If you convert to plain 1D arrays, the sampling information is lost, meaning the cross correlation in in units of the array indices. Given dt, you can calculate the the spacing in seconds from the spacing in index units.
You can also set the dt of the x-axes of the graphs so the display is in seconds.
LabVIEW Champion . Do more with less code and in less time .

Statistics Express Kurtosis inconistency Labview 2011 (Bug 215683)

Hi All,
I am currently working with a data collection program from which I need to output the skew and kurtosis values for an array of 30 data points. As I was already using the Statistics Express VI to calculate mean, s.d. etc. I just added the skew and kurtosis outputs to that VI. I then set up a basic VI to generate a 1D array of random numbers to let me compare the Express VI to the skew and kurtosis VI on the mathematics > probability and stats. palette.
The skew and kurtosis values are inconsistent between the two VIs. If I calculate the skew and kurtosis by hand I can see that the non-express VI appears to be giving the correct answer. I did some digging and found that this has been labelled as bug no. 215683 and is described as having been fixed as part of Labview 2011. I am running Labview 2011 with SP1 so I'm not quite sure why the two VIs are still inconsistent.
I realise that I can simply use the VI which is giving the correct answer but I am curious as to why a bug which should be fixed still appears to be active in my version of Labview.
Any thoughts/ input would be greatly appreciated.
Many thanks in advance

Hi cat,
why don't you get rid of that buggy (as it seems) ExpressVI?
The remaining data (StDev, variance) are provided by just another function from math->statistics palette…
You can also opne the ExpressVI to see, how it calculates those data and why it does produce different results!
Best regards,
GerdW
CLAD, using 2009SP1 + LV2011SP1 + LV2014SP1 on WinXP+Win7+cRIO
Kudos are welcome

I found Error in Statistics Express about the algorithm for mode

LabVIEW 7.1 was used. today I acquired a lot of data and analyzed using Statistics Express in LabVIEW 7.1, whereas the results of mode were not correct because I analyzed the data using both Excel and SPSS. so I think there must be something wrong with Statistics Express in LabVIEW 7.1. Attached is the data which mode is 57.24 by SPSS, but the result of Statistics Express showed the result of 32.608.
will someone please help me?
thanks
Attachments:
data.xls ‏29 KB

Hi,
I agree the 2 places of decimals is a cosmetic property and I have no issue with that....
I have my vi setup such that at one call it gets the mode of distances between points on lines. The second time I call the mode it is to get the mode of distances between another set of points. Two separate arrays in a fairly large program. I've attached a shortened sample hopefully the error still appears. Also I was wrong about wiring the intervals wire, this did not change anything.
If I run the 2nd mode operation on it's own without the previous call it works fine, only when there is a previous mode operation does it fail to "re-initialise" and returns the result of the first mode operation.
The only thing I can think of is that the first set of data has many different distances and gives a clear mode, whereas the second set has values approximately the same, with the odd multiple (ie 20,22,19,41,62,20,21,23). However, going against this is the Express Statistics vi which calculates the correct values in the Express Window (double clicking on it and selecting the statistics) but when wiring these to an indicator the result from the first mode operation is returned.
Any suggestions welcomed.
Kind regards,
Leeser
Attachments:
mode_error_example.vi ‏143 KB

RMS calculation in Statistics Express

Hi all,
I want to figure out whether the RMS calculation in Statitics Express will output a signal with a different "number of samples" than the raw signal. I read about the following knowledgebase:
http://digital.ni.com/public.nsf/allkb/862567530005F09C862567210074EA10
but still not quite sure if averaging will reduce the number of samples. Can anyone help me out?
Thanks in advance for any answers!

It is getting away from the Express VIs, but you could use the RMS PtByPt VI inside of a FOR loop. Then it is a question of how large of an RMS window do you want. Same idea as a moving average.
There are only two ways to tell somebody thanks: Kudos and Marked Solutions
Unofficial Forum Rules and Guidelines

DAQmx drivers needed to calculate statistics in a standalone application ?

Hi!
My standalone application analyzes measured data and saves statistics into Access database. It uses Statistics express VI, among the others. It does not use any data acquisition library. I've made an installer to install it on my customer's computer. After installation I tried to run the application but an error occured (see below).
Well, it works now (after few hours). But my opinion is that my solution is a little bit strange: I simply installed DAQmx drivers.
1. Is this a bug ?
2. How to explain my customer why does he need 1GB of hardware drivers ?
Fortunately, It was not necessary to use any special procedure tu run Database Connectivity Toolset: see this link, for example
Best regards ,
Ljubo.
P.S.: Developer Suite 8.6, Win XP Pro, DAQmx 8.8, MS Office 2003.

Hi Dennis,
let me repeat the whole story once again:
About
two years ago the same problem occured (with LabView 7.0 or 8.0, I
don't know exactly). Our local NI representative happened to be present
and we discussed the problem but we didn't find the solution. Instead
of using Statistics Express VI I made my own subVIs and the problem was
solved (and forgotten).
I've already checked my
customer's computer this morning and everything seems to be OK. DLL
library lvanlys.dll is installed in "data" folder.
To eliminate unnecessary details I've created a new project (see the attachment, please).
I
installed the program on my colleague's PC (my colleague never used
LabView in his life). The result is the same. You can see the error
report in the second attachement.
Then I've copied lvanlys.dll
file to all folders where programs usually search libraries: Windows,
Windows\system, Windows\system32 and Program Files\Mean4V. But program
can't find the library NI_AALBase.lvlib.
Obviously,
installation of DAQmx drivers adds something which is missing in my
build specification. I hope someone could explain what I'm doing wrong.
With best regards,
Ljubo.
Attachments:
Mean4values.zip ‏50 KB
Error_missing_subvi.jpg ‏62 KB

"real" RMS

Hi all
I use SCXI-1000 and module SCXI 1313,1125...
I want to measure "RMS" current, from square signal. I use DAQ Assistant, from which I get out voltage and current! All working, tested with constant DC.
I tried in this way:
But RMS Value is incorrect(I know that, because I measure with TRUE RMS MULTIMETER.....). The signal is square and look's like this:
Any ideas or "hint's".

robinson wrote:
Voltage is from 0-16V, "RMS" give values about 8-12, which is incorrect, it must be about 50-70mA...(don't look at signal picture, it's just "example").
robinson wrote:
From 'statistics' I get 'RMS' output , which I connect into DC-RMS, and soo one, from that I can see value of signal(look at RMS value,DC avarage, RMS avarage...), so why I will need additional indicator, if I see value from that...
You know, we try to be professional and polite on this forum. We really try. Sometimes, though, we read responses like this which simply make our head shake. in disbelief.
You know what the difference is between voltage and current, right? If so, how in the world can you say that a VOLTAGE between 0 and 16V with an RMS value "about" 8-12 (whatever "about" is supposed to mean in engineering terms) should actually be 50-70 mA??? That's simply inane. If you are getting a voltage which is proportial to a current then you obviously have to perform the same proportianal calculation to convert the voltage to a current!
Also, the "RMS" output of the Statistics Express VI IS the RMS value. Why are you trying to calculate the RMS value of an RMS value? We cannot "look at RMS value,DC avarage, RMS avarage". We don't have your VI, and you're not showing the front panel. Look at the picture you posted. Do you see the values of "RMS value,DC avarage, RMS avarage" anywhere on that picture?
EDIT: It seems that Dennis pretty much said the same thing at the time I was posting.

On the block diagram, clicked Express - Signal Analysis, I don't see Statistics.

On the block diagram, I clicked EXPRESS - SIGNAL ANALYSIS , then all I get are SIMULATE and HISTOGRAM. What happened to the rest like SPECTRAL, TONE, STATISTICS, etc.?
Solved!
Go to Solution.

(Well, if you get a sine wave, you are probably simulating one. )
Where do the temperature readings come from? Please show us your actual VI. This seems almost trivial.
LabVIEW Champion . Do more with less code and in less time .

Getting statistics from multiple tables using conditional expressions (e.g. combining min, count, sum, etc) in PHP/MySQL

Hi,
I'm trying to get statistics from a variety of related tables
where the statistical counts are based on comparing the value on
one table with an equivalent value on a second table (and I want to
view the results grouped by time period, day, week, month, etc);
e.g.
Consider two tables - Customer & Customer_Action which
are related as a one-to-many (one customer can take many actions):
Customer: id, create_date, customer_name, etc.
Customer_Action: id, customer_id, create_date, action, etc.
If the customer took their first action at the same time as
they registered on the system (i.e. if the customer record was
created at the same time as the very first action record)
YES_count is incremented by 1 else
NO_count is incremented by 1
So running the query against the database the report would
look something like:
Customers Yes No
January 8 5 3
February 14 9 5 .... Etc.
I've tried this around a number of different ways but always
seem to end up with double counting in one way or another: see this
sample data
Customer Create_Date Action_Date
01 05/07/2008 12:36 05/07/2008 12:36
01 05/07/2008 12:36 28/08/2008 22:22
02 10/07/2008 12:04 10/07/2008 12:04
03 10/07/2008 12:12 10/07/2008 12:12
This should give me
Count Yes No
July 3 3 0
...... but I get always get a customer counts of 4 2 2!
My current statement is .....
SELECT count( m2u_Customer.id ) AS Customer,
min( m2u_Customer_Action.action_date ) AS 'Action_Date',
DATE_FORMAT( m2u_Customer.create_date, '%m-%M' ) AS Month,
sum(case when m2u_Customer.create_date =
m2u_Customer_Action.create_date then 1 else 0 end) as Yes,
sum(case when m2u_Customer.create_date !=
m2u_Customer_Action.create_date then 1 else 0 end) as No
FROM m2u_Customer
LEFT JOIN m2u_Customer_Action ON ( m2u_Customer.id =
m2u_CustomerAction.customer_ id )
WHERE m2u_Customer.create_date > '2008-07-02'
AND m2u_Customer.create_date < '2008-08-01'
GROUP BY DATE_FORMAT( m2u_Customer.create_date, '%m-%M' )
Can this be done?
Regards.
Patrick

In the default php.ini is set open_basedir which limits work with php only to few directories (and directories bellow them). There is set /srv/http, /home,/tmp and /usr/share/pear by default.
To allow your vhost you should add /data/www or set empty value.

Bandwidth Statistics in Airport Extreme/Express

Before I buy airport extreme ... I want to know is there a way in airport extreme that will let you know how much bandwidth is utilized in total over a specific period of time and/or that also group by device types ... my ISP just billed me for 150 GB/month usage ... needed the auditing stuff badly

Sorry, but the AirPorts do not have this type of capability.

Solution to Airport Extreme Base Station + Airport Express networking probs

I've been investigating this for 3 straight days after inadvertently destabilizing my network. There are tons of posts discussing a variety of issues, all of which seem related. My goal here is to provide links to other relevant posts and explain what I ended up doing to get things to work.
First, the background. You can skip below to SOLUTION if you don't really care... However, I highly recommend you take the time to read everything, as you'll get other useful information in the BACKGROUND section. I'm guessing many of you have similar, related problems so BACKGROUND might help provide context (and solutions) to some things you are seeing...
MY SETUP:
AirPort Extreme Base Station (AEBS) of type b/g (round one, not square one), connects to the cable modem, and creates a WDS network that is then shared across two standard AirPort Express (AEX) units (100megabit, not the gigabit ones). One AEX serves as a relay unit that accepts clients, the other serves as a remote unit that also accepts clients. The intent is to show a single network throughout the house and let users log on to one network and move between networking units without having to switch from network to network.
I have a variety of networked devices throughout the house all running on the same network (2 Mac Pros, a Powerbook G4, a Mac Mini, an Apple TV, a Windows XP laptop, two iPhones, two wifi printers, and a 5-unit Sonos system, plus the AEBS and two AEXs). Yeah, I'm a geek.
The Mac Pros are both running 10.4.11, and the Powerbook is running 10.5.2.
AEBS is running firmware 5.7
AEXs are running firmware 6.3
All Macs were initially accessing configs via the recently released AirPort Utility 5.3.1. More on that later.
BACKGROUND:
I've had this network setup working for about a year now. Recently, I've been having poor network performance problems and came to the conclusion it was a LAN problem (ie. problem with my home network, as opposed to with my ISP). Upon initial investigation, I began by looking at my networking logs (via AirPort Utility 5.3.1). You get to those by selecting the unit in question, choosing "Manual Configuration", the selecting the "Advanced" tab up top with the "Logging and SNMP" sub-tab. Click the "Logs and Statistics" button therein for log details from that unit.
The first thing I noticed was "Administrative access denied to ff80::xxxxxxxxx" messages - a lot of them. I didn't recognize the ff80:: address in question, and so became concerned it was someone outside the network trying to hack one (or all) of the AEBS/AEX units. You can see threads discussing that investigation here:
"Hack or panic?" - http://discussions.apple.com/thread.jspa?threadID=1438486
"Administrative access denied" - http://discussions.apple.com/thread.jspa?threadID=1438865
Long and short of it is that the recent AirPort Utility 5.3.1 release (current as of March 13) seems to have problems (keychain) when attempting to access the AEBS and AEX units. The "Administrative access denied" logs actually refer to the client machine you are using when you try to read the logs. The ff80::xxxxxx address is simply the IPv6 address for the machine you are using; if you turn off IPv6 on your client machine, that address should switch over to begin showing a regular IP address instead (something like 10.0.1.xxx), which makes it easier to associate the IP to the machine. I explain how to deactivate IPv6 on both Tiger (10.4.x) and Leopard (1.5.x) here:
http://discussions.apple.com/thread.jspa?messageID=6814978#6814978
Anyway, in the process of investigating the "Administrative access denied" problem, I began tinkering with my AEX settings. Specifically, I ended up performing a hard factory reset (unplug unit, plug back in while holding down the little button with paper click/pen for ~10-15 seconds until light flashes green 4x then reverts to amber/yellow/orange). I began reconfiguring my entire WDS network using the newly updated AirPort Utility 5.3.1, and that's when the trouble started.
(If you are having problems seeing either your AirPort Extreme Base Station or AirPort Express, read this:)
In short, each time I thought I had properly configured things and then confirmed settings (kicking off a reboot on the AEX unit) the unit would restart with new settings but not properly join the WDS and not show up in the AirPort Utility list of units. More specifically, I would start with a "wiped" AEX and see both the AEBS and the AEX in my AirPort Utility list, but upon confirm/reboot the AEX would disappear and the AEBS would remain. However, that's not 100% correct. It seems that sometimes I would end up with the AEX and NOT the AEBS. Because both the AEX and AEBS were theoretically "hosting" the same network name (remember, WDS shares the network name across units) my auto-login feature for my client computer's wifi seemed to "jump on" whichever unit it first saw hosting the default network name for my house. In other words, it seems what was really happening was that I was ending up with two separate networks in my house, both with the same name but not talking to each other (as opposed to two units sharing the same network name and internet connection). The AEX would continue to blink orange/amber/yellow (whichever color it is to your eyes ) because it could not grab an internet connection -- and if I was on the network through that AEX unit I would not get internet. But if i was connected through the AEBS I would continue to have internet access. As far as my client computer (my Mac Pro) was concerned, I was on the home wifi network even if I was on the AEX rather than the AEBS -- it would show the home wifi network name as the name of the network it had connected to. But when I opened the AirPort Utility 5.3.1 I would see only the AEX (if I was connected through it) or the AEBS (if connected through it) -- a clear indication that the units were not truly sharing the same network.
I tried rebooting and reconfiguring the AEBS and AEX about 50 times (literally). I even tracked down an older version of the AirPort Utility 5.2.1 via this thread (see Tesserax post):
http://discussions.apple.com/thread.jspa?threadID=1067565
One interesting thing re: 5.2.1 is that the "Administrative access denied" errors summarized above disappeared. As explained in a post reference above, the going theory is that this a permissions/keychain problem new and unique to AirPort Utility 5.3.1. However, even though 5.2.1 does have a slightly different interface with different settings, I still couldn't get the WDS to work.
EVENTUALLY, I came across this post:
http://discussions.apple.com/thread.jspa?threadID=1422527
MuaddibOfArrakis walks through setting up a WDS from scratch, and the workflow is different than what is possible with either AirPort Utility 5.3.1 or 5.2.1. He's doing it with the old version of AirPort Admin Utility, which I fortunately saved a copy of many moons ago when I had somewhat-related problems with my WDS (since forgotten). In fact, it's a lot easier. What's nice about this older app is that it literally does the heavy lifting of "connecting" the AEBS and AEX units during the configuration -- it reboots both at the same time as the config is happening, and lets you choose from a list of available units to "add" to your WDS network. In short, it's a FAR SUPERIOR workflow even though some of the GUI isn't as intuitive as the newer AirPort Utilities that were designed to replace it.
SOLUTION:
If still have a copy of the AirPort Admin Utility follow the instructions from MuaddibOfArrakis here:
http://discussions.apple.com/thread.jspa?threadID=1422527
If not, try setting up your WDS network using AirPort Utility (hereafter AU), with these configs (take from my now-working network), as viewed through AirPort Utility 5.3.1.
I. Configure your AEBS.
Select the AEBS from AU, and choose "Manual Setup"
1. Under the AirPort tab up top:
a. Under "Base Station" sub-tab:
i.) assign a name for that specific unit, so you can later identify the specific unit from the list of units -- this is the name that will show up beside the unit in the AU list of configurable units. You can name it something like "kitchen", or "office". I have mine numbered, so XXXXXv1, XXXXXv2 etc where the XXXXX is the name of the shared network and the numbers help me tell the units apart. Just be sure you name each uniquely, and if you have several you might write the name on the unit itself.
ii.) pick a password for logging into that unit. This is different from the network password, its a security check to get in and change the configs on this unit later. Be sure to remember it in your keychain for the sake of simplicity, and write it down somewhere secure.
iii.) if you choose to set time automatically, pick a location that you will use consistently across all your units. I use time.apple.com.
iv.) uncheck "Allow configuration over Ethernet WAN port" unless you want to be able to remotely mess with settings -- which you almost certainly do not need to do.
v.) I left the "Options" button alone - no settings there.
b. Under the "Wireless" sub-tab:
i.) Wireless Mode: "Participate in a WDS network"
ii.) Network Name: this will be the name of your wifi network shared by all units, so be sure to remember what you pick. If you are already connected to this AEBS via wifi while you are making these changes, then you can use the same wifi name you already have set up -- you don't have to change it. Note that if you DO change it, after reboot your will LOSE connection to the network and have to reset your wifi settings on your client machine to match the new network/password in order to be able to access the network.
iii.) pick a Radio Mode. I'm using b/g compatible. You'll want to do the same, unless you are on the new gigabit AEX. I'm pretty sure about this, but not 100% -- others post if I'm wrong.
iv.) choose a Channel. This can be a more complicated procedure, but for now just pick something consistent across all your units. If you get everything working and find that you're having intermittent network problems, you could later try changing your Channel -- it can pick up interference from phones, microwaves, etc and changing it can help.
v.) I have wireless security set to WPA/WPA2 Personal.
vi.) Wireless Password is the password for access to your wifi network (not your unit itself). If you are connecting to your AEBS via wifi while doing this config, then you can use the same password you have already set up. Pick a good one unless you want other folks jumping on your wifi and stealing your bandwidth and/or credit card numbers . Remember it in your keychain and write it down someplace secure, because you'll need it for the other units too. As noted above, note that if you DO change it, after reboot your will LOSE connection to the network and have to reset your wifi settings on your client machine to match the new network/password in order to be able to access the network.
vii.) Click the "Wireless Options" button. I have my multicast rate set to 2mbps, transmit at 100%, timeout at 1 hour, and i have checked the "Create a closed network". This last step keeps your network from advertising itself to the outside world. Users can only find it by explicitly typing the network name into their wifi settings (e.g. AirPort -> Other... then enter Network Name, Security and Password). I leave interference robustness unchecked.
c. Under the "WDS" sub-tab:
i.) the AEBS should have it's WDS Mode set to "WDS main".
ii.) Check the "allow wireless clients" box on the AEBS; this lets you connect client machines to it directly too.
iii.) hit the plus button to add the Remote system (AEX). There are two types of configs for the AEX's - "remote" and "relay". Assuming you have 3 units like me (2 AEX and 1 AEBS) the key question is whether you will place each AEX within direct reach of the AEBS (remotes), or if you will have one AEX in the middle connecting to an AEBS on one side and an AEX on the other -- where the furthest AEX is out of reach from the AEBS (remote) and connects only to the AEX in the middle (relay). I'm using a relay setup. If you are using relay, you can still set up the AEX relay to serve client computers too -- it doesnt have to JUST relay. More on that later. For now, you want to add only AEX units that will talk DIRECTLY to the AEBS. So if you have a setup like mine, just add one (the one in the middle - the relay). If you have two remotes connecting directly to the AEBS, you will add them both here. When you hit the '+' button it will ask for both an ID and description. For description I use the name I'm assigning to each unique unit (as above, "kitchen" or XXXXXv1 or whatever you use). For AirPort ID, use the number listed on the AEX unit itself (not the number for "Ethernet", also on the AEX unit).
d. Under the "Access" sub-tab:
i.) I have it set to "Not Enabled". I'd suggest you start that way too, and you can go change it later if you get everything working correctly.
2. Under the "Internet" tab up top:
a. Under the "Internet Connection" sub-tab:
i.) Connect Using: Ethernet
ii.) Configure IPv4: Using DHCP
iii.) Ethernet WAN Port: Automatic (Default)
iv.) Connection Sharing: Share a public IP address
b. Under the "DHCP" sub-tab:
i.) DHCP Beginning Address: 10.0 . 1 . 2
ii.) DHCP Ending Address: 10.0.1.200
DHCP Lease: 4 hours
c. Under the "NAT" sub-tab:
i.) nothing should be checked;
ii.) nothing under Port Mappings either
3. Under the "Printers and Advanced" tabs up top:
Nothing special needs to be configured there.
THAT'S IT.
=============
I. Configure your AEX(s)
Select the AEX from AU, and choose "Manual Setup"
1. Under the "AirPort" tab up top:
a. Under "Base Station" sub-tab:
i.) pick a unique name for this unit, same logic as for AEBS
ii.) pick a password specific for accessing this unit, same logic as for AEBS
iii.) Set time automatically: be sure to use the same settings used on your AEBS
iv.) Options: no need to set any
b. Under "Wireless" sub-tab:
i.) Wireless Mode: Participate in a WDS network
ii.) Network Name: same name used for AEBS, this is the name of your wifi network
iii.) Channel: same as AEBS
iv.) All settings here (those above, plus Security and Password & in Options button) should be the same as for AEBS settings on this tab
c. Under the "WDS" sub-tab:
...if AEX is "in the middle" (as described above):
i.) WDS Mode: WDS relay
ii.) Allow wireless clients: check (unless you only want to bridge between the edges without letting folks connect on this AEX in the middle)
iii.) WDS Main: set to the AirPort ID (aka MAC address) for the AEBS. You can find it on the bottom of the AEBS, either labeled as such or at the bottom beside the logo of a wireless signal (square logo, with semi-circles mimicing a radio signal).
iv.) WDS Remotes: click the '+' to add any AEX's that will connect to this relay rather than directly to the AEBS. Same deal as above, use the name in the description and use the AirPort ID from the side of the AEX (not the Ethernet ID).
.....if AEX is connecting to a relay ("on the end", as above) or if there is no relay and AEX connects directly to the AEBS:
i.) WDS Model: WDS remote
ii.) Allow wireless clients: checked
iii.) WDS Main: if connected to a relay, use the AirPort ID of the relay AEX. If connected to the AEBS directly, use the AirPort ID of the AEBS
d. Under the "Access" sub-tab:
i.) MAC Address Access Control: Not Enabled (for now, you can change later)
2. Under the "Internet" tab up top:
a. Under the "Internet Connection" sub-tab:
i.) Connect Using: AirPort (WDS) -- should be selected and gray'ed out.
ii.) Configure IPv4: Using DHCP
iii.) Ethernet WAN Port: Automatic (Default)
iv.) Connection Sharing: Off (Bridge Mode)
3. Under the Music, Printers and Advanced tabs up top:
Nothing special needs to be configured there. You can worry about AirTunes settings later...
That should be it. I'd recommend setting up the AEBS first, then the relay (if applicable), then the remotes. Initially, you can bring each unit in the same room with you for configuring. After configured and restarted the AEX should blink then turn solid green. If it turns green you should be good to go.
HOPE THIS HELPS. As noted above, I did not config through AirPort Utility 5.3.1 so I haven't tested this procedure through that app. However, after getting my network to work I went back and transposed all settings into this post to help others. Please provide feedback on whether or not this is working, so we can collectively try to move towards a setup procedure that works for everyone....
Good luck!
Message was edited by: b.byrd

I'm not convinced that the problem lies in Airport Utility. This same thing was happening to me, nearly exactly as you describe it. The thing is that with me, the problems clearly started when I updated the firmware in my Airport Express (n). That's when all the wacky stuff started happening. Sometimes it would show up in AU, sometimes it didn't and even if it didn't, I could still access the internet through it.
But as you said, the problems got really bad when another Express (b/g) was put on the network with it. Even when it did work, the (b/g) would make it impossibly slow.
You know more about this than me, and clearly have more patience if you've restarted the network fifty times. I gave up at about ten.
In any case, your solution is more of a work around and if you're still having that slow connection problem, I'm not sure you've got it. But thanks for your reporting of this. At least I know I'm not crazy.

How to read the statistics graph?

Hi,
I'm trying to troubleshoot some network issues. I have an AirPort Express connected to a DSL modem and acting as a wireless router. One computer connected is a Mac Pro with an AirPort Extreme card, and the other is a PC laptop with an Intel 2200BG wireless card. Both computers are connected, using the internet, sharing files, etc. I am using WPA2 encryption.
The Mac has a good stable connection while the PC disconnects frequently. The thing is that the PC is just a few feet away from the router, while the Mac is in the other room. Moreover, both computers show an excellent connection in their status.
I've opened Airport Utility in order to diagnose the problem. Looking at the statistics graph, I cannot seem to understand how to read it. I'm confused by the negative signals vs. noise signals, etc.
Unfortunately, I cannot post a screenshot here, but here are the readings:
PC: Signal: -24, Noise: -95, Rate: 54
Mac: Signal: -73, Noise: -84, Rate: 78
This is cryptic to me, so I'd appreciate any explanation of the data.
Thanks!

PC: Signal: -24, Noise: -95, Rate: 54
Mac: Signal: -73, Noise: -84, Rate: 78
In general, the greater the value, the better. Both Signal & Noise are measured in dBm. dBm is a measure of absolute power output. An increase in 10 dBm = 10x increase in output power.
We would use these values to calculate the Signal-to-Noise Ratio (SNR). SNR = Signal - Noise.
To use your measurements for examples, the SNR would be:
o PC: -24 dBm -(-95 dBm) = 71 dB
o Mac: -73 dBm -(-84 dBm) = 11 dB
To put this into perspective, the SNR influences the instantaneous data rate (speed). The higher the SNR, the higher the data rate (up to the maximum bandwidth of the radio being used).
For reference, use the following SNR Guideline:
o 40dB+ SNR = Excellent signal
o 25dB to 40dB SNR = Very good signal
o 15dB to 25dB SNR = Low signal
o 10dB to 15dB SNR = Very low signal
o 5dB to 10dB SNR = No signal
Again, going back to the SNRs we just calculated, the PC is getting an excellent connection to the AX, while the Mac is not.
Finally, the 'Rate" value is a near instantaneous measure of the data rate or throughput. It is measured in Mega bits per second (Mbps). Its value should never exceed the maximum bandwidth appropriate for the radio mode. For 802.11g that bandwidth would be 54 Mbps; for 802.11n (2.4 GHz), 130 Mbps, and for 802.11n (5 GHz), 300+ Mbps.

-1 (Minus One) Wireless Client Rate for networked PCs with Ariport Express

Trying to figure out connection problems...
Under Airport Utility > Advanced > Logs and Statistics > Wireless Clients...
My MBP gets a Rate 54Mbps when I am beside it in my room, but sometimes drops down to 11 or so and then goes back up. I think this is why I am losing my AirTunes connection.
Both PCs on the network are farther away but are showing a Rate of -1Mbps, even when they are brought into the same room as the APX.
Any thoughts.

1. How does the client device know which Airport to connect to?
The Mac computer will automatically connect to the wireless access point with the strongest signal...which is probably the closest AirPort. An iPhone or iPad may not do this and will tend to stay connected to one AirPort.
2. How can I tell which of the Airports the attached client device is using?
On a Mac, open Macintosh HD > Applications > Utilities > AirPort Utility. Click on one of AirPorts. In the area to the right, locate the AirPort ID and jot that down. Then do the same for your other AirPort.
Move your Mac near one of the AirPorts and log on to the wireless. Hold down the option key on the Mac while you click the fan shaped AirPort icon at the top of the screen. Look for the BSSID. That is the AirPort ID of the device to which you are connected.
If you are close to the "remote" AirPort, and you see the AIrPort ID of the "main" router when you are testing, then you know that the network is not configured correctly.
Can I use this second Airport Express to extend the wireless network via "Extended Wireless Network" while the other two are in "Roaming Netowrk" configuration? Without bogging down??
There will be a modest 10-15% bandwidth loss with the "extend" setup, assuming that the Express is located where it can receive a strong wireless signal from the AirPort to which it is associated. You can avoid the bandwidth loss if the Express is also connected via Ethernet as part of the roaming configuration.

10.5.7 aiport express problems resolved - so far :)

Hello all,
Since updating my OS to 10.5.7 I have been experiencing frequents drop-outs when trying to stream music through Airtunes from my computers (duocore2 MacBook and 1st gen. intel iMac) to my Airport Express (G). I have past the last 2 days reading threads on Apple discussion board, Mac fixit, Googling, hard-resetting both my Airport extreme (N - gigabit) and Airport Express (G), pram-zapping both my computers, repairing permissions, deleting plist files, cursing all the saints names I know of (my catholic heritage ) to finally have both my computers being able to stream music normally to my Airport Express, without drop-outs. Here's what I've done, I thought I share it with you since this seem to be a common problem:
Hard-reset both my Airport (by pressing with a pen the little button intended to do so).
Important: DON'T upgrade the firmware of your airport extreme to 7.4.1, leave it to 7.3.2 (or downgrade to 7.3.2 if you already upgraded), since 7.4.1 is a not ready for prime time firmware update, it messes everything, I repeat, stay away from 7.4.1
1. Unplug the Airport Express, make sure the Airport extreme (or whatever base station you use) is on and attached to your modem (cable, dsl...). Open Airport utility and set the base station manually (Airport extreme n - attached to my cable-modem, in my case) as follow:
1st tab (Airport)
- Base station menu:
Give the airport the name you want (airportbase, in my case)
Fill the password fields
Check "Remember this password in my keychain"
Leave checked "Set-time automatically" (not important, default I guess)
Leave unchecked "Allow set-up over WAN"
- Wireless menu:
"Wireless Mode" = Create a wireless network
"Wireless network name" = the same name as the base station (airportbase, here)
"Allow this network to be extended" = unchecked
"Radio mode" = 802.11n (802.11b/g compatible)
"Channel" = 10 (VERY IMPORTANT, THAT DID THE TRICK, my express started to work normally only after I assigned a specified channel to my base station)
"Wireless security" = WPA2 Personnal
Fill the passwords field
Check "Remember this password in my keychain"
In this menu, there's a button at the bottom named "Wireless options", when clicked a new window appears in which I have the following settings:
- Country: Canada
- Multicast rate: 2 mbps
- Transmit power: 100%
- WPA group key time out: 364 DAYS
- Create a close network = unchecked
- Use interference robustness = unchecked
- Acces menu:
Mac address acces control = Not enabled
2nd tab (Internet)
- Internet connection menu:
Connect using = Ethernet
Configure IpV4 = Using DHCP
Ethernet Wan port = Automatic (Default)
Connection Sharing = Share a public IP address
- DHCP Menu:
DHCP beginning address = (from drop down list) 10.0 and then (next case) .1 and then .2
DHCP ending address = 10.0.1.200
DHCP lease = 364 DAYS
- NAT Menu:
enable default host as = unchecked (and next field is empty)
enable NAT port mapping protocol = checked
3rd tab (Printers)
unchanged (the "Share printers over WAN" option is Unchecked)
4th tab (Disks)
- I can see my attached external drive name in the Disks menu
- In the File sharing menu, "Enable file sharing" is checked, "with Airport extreme password" is selected in the "Secure shared disks" drop-down list, "Remember this password in my keychain" is checked, "Not allowed" is selected in the "Airport disks guest access" drop-down list and "Share disk over WAN" is unchecked.
5h tab (Advanced)
- Statistics menu: The "Syslog destination Address" field is empty, "Syslog Level" is set to "5 - Notice" from the drop-down list (default?), "Allow SNMP" is checked and "Allow SNMP over WAN" is unchecked
- Port mapping menu: Empty
- IPv6 menu: "IPv6 Mode" drop-down list is set to "Link-local only"
Click Update and wait for the Airport extreme base station to restart.
After the airport extreme is up and running (green light), restart all the computers that will be using your network.
Open System Preferences on all the freshly rebooted computer, click on the "Network" icon, select and add your newly created network and click "Apply". Then click the "Advanced" button and go to the TCPIP tab and make sure "Configure IPv6" is set to "OFF" and then click "Apply".
2. Plug in the Airport Express and open Aiport Utility and set the Airport express manually as follow:
1st tab (Airport)
- Base station menu: give the airport express the name you want, fill the password fields and check "Remember this password in my keychain"
- Wireless menu: Select "Join a wireless network" form the "Wireless Mode" drop-down list. Enter your airport base station name in the "Wireless Network Name" field (or select it from the drop-down list, it should be there, by default, anyway). Select the security (if not already selected after you select your network name - WPA/WPA2 Personnal, in my case), fill the password fields.
2nd tab (Internet)
Select "Using DHCP" from the "Configure IPv4" drop-down list
3rd tab (Music)
Check "Enable Airtunes.
In the "iTunes Speaker Name" field, put the same name as the one you gave to your airport express. Don't fill the password fields.
4th tab (Printers)
Unchanged (nothing there sinc no printer is attached to my express)
5th tab (Advanced)
The "Syslog destination Address" field is empty, "Syslog Level" is set to "5 - Notice" from the drop-down list (default?), and "Allow SNMP" is checked
Click the Update button and wait for the Airport express to restart.
After the airport express is restarted (green light), restart your computers, repair permission on all of them and then restart your computers again.
Now, you should be able to stream music to your airport express.
3. Finally, next time Apple issues a system update, wait a good month before updating, then go on Apple discussions boards and search for the number of the update, like 10.5.7 in this this case, along with airtunes problems, like 10.5.7 airtunes problems, that's what I will do. Chill!

Thanks for a very complete and thorough description wiiphone!
Question about your wireless channel: Are there any other competing wireless networks in your area that led you to choose channel 10?
If you don't mind doing some experimenting, does changing the channel from 10 to some other (fixed) channel, have any effect? The reason for asking is that I have reason to believe "automatic" might not be desirable, but there ought not to be anything magical about channel 10.
Please post if you experience any more dropouts. I'm glad it's working for you; I'm just doubtful this will prove to be a permanent fix.

Statistics express vi

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