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• UNIX Signal lost

  - by user309506

  Hello, Is there any situation in which classic UNIX signals are lost? Thank you!

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• Filter design for audio signal.

  - by beanyblue

  What I am trying to do is simple. I have a few .wav files. I want to remove noise and filter out specific frequencies. I don't have matlab and I intend to write my own code for all the filters. Right now, I have a way to read the .wav file and dump out the structure into a text file. My questions are the following: Can I directly apply the digital filters on this sampled data?{ ie, can I directly do a convolution between my input samples and h(n) for the filter function that i choose?). How do I choose the number of coefficients for the Window function? I have octave, so if someone can point me to anything that gives me some idea on how to process the .wav file using octave, that would be great too. I want to be able to filter out the frequency and then listen to the sound again. Is this possible with octave? I'm just a beginner with these kinds of things, so please bear with me if my questions are too naive. Any help will be great.

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• Laptop with Intel Graphics: external VGA monitor only gets signal on boot (no "hot plugging")

  - by iveand

  I am able to get an external VGA monitor (or projector) to work if I start my laptop with it connected. However, if I start the laptop with it disconnected there is no signal on the external. The Displays screen shows the external, and thinks that it is active, but there is no signal being sent to it. This has been a persistent problem since 10.04 (I am now on 12.04.... each upgrade hoping something is improved). I should note that even when it works (starting with display connected), Displays still says the monitor is "unknown" (but it sends the signal). For the correct resolution to display, I have had to add a few xrandr lines for my monitor to my .xprofile file... otherwise resolution is limited to default 1024x768. So, resolution issues can be worked around, but the main issue is that the external doesn't get a signal without starting the machine with it connected. I have tried: adding i915.modeset=1 to grub (also i965.modeset=1 since someone posted that this helped even though lshw shows i915) adding following ppa and doing a dist-upgrade: sudo add-apt-repository ppa:xorg-edgers/ppa Here are the details: Laptop: Toshiba Tecra M10 lspci listings for video: 00:02.0 VGA compatible controller [0300]: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller [8086:2a42] (rev 07) sudo lshw -C video listing: *-display:0 description: VGA compatible controller product: Mobile 4 Series Chipset Integrated Graphics Controller vendor: Intel Corporation physical id: 2 bus info: pci@0000:00:02.0 version: 07 width: 64 bits clock: 33MHz capabilities: msi pm vga_controller bus_master cap_list rom configuration: driver=i915 latency=0 resources: irq:46 memory:ff400000-ff7fffff memory:e0000000-efffffff ioport:cff8(size=8) *-display:1 UNCLAIMED description: Display controller product: Mobile 4 Series Chipset Integrated Graphics Controller vendor: Intel Corporation physical id: 2.1 bus info: pci@0000:00:02.1 version: 07 width: 64 bits clock: 33MHz capabilities: pm bus_master cap_list configuration: latency=0 resources: memory:ffc00000-ffcfffff "System Info" shows my graphics as the following Mobile Intel® GM45 Express Chipset x86/MMX/SSE2

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• The physical working paradigm of a signal passing on wire.

  - by smwikipedia

  Hi, This may be more a question of physics, so pardon me if there's any inconvenience. When I study computer networks, I often read something like this in order to represent a signal, we place some voltage on one end of the wire and the other end will detect the voltage and thus the signal. So I am wondering how a signal exactly passes through wire? Here's my current understanding based on my formal knowledge about electronics: First we need a close circuit to constrain/hold the electronic field. When we place a voltage at somewhere A of the circuit, electronic field will start to build up within the circuit medium, this process should be as fast as light speed. And as the electronic field is being built up, the electrons within the circuit medium are moved, and thus electronic current occurs, and once the electronic current is strong enough to be detected at somewhere else B on the complete circuit, then B knows about what has happend at A and thus communication between A and B is achieved. The above is only talking about the process of sending a single voltage through wire. If there's a bitstream and we need to send a series of voltages, I am not sure which of the following is true: The 2nd voltage should only be sent from A after the 1st voltage has been detected at B, the time interval is time needed to stimulate the electronic field in the medium and form a detectable electronic current at B. Several different voltages could be sent on wire one by one, different electronic current values will exists along the wire simutaneously and arrive at B successively. I hope I made myself clear and someone else has ever pondered this question. (I tag this question with network cause I don't know if there's a better option.) Thanks, Sam

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• No video signal after install

  - by tW4r

  Today I tried to install Ubuntu 12.10 to my machine, but all the time I encountered the same problem, I successfully boot from Ubuntu 12.04 DVD, and a purple background comes up with accessibility and keyboard icons at the bottom of the screen, then when you wait a while a monitor text comes up "No signal" (Keep in mind that this signal is only shown when there's cable in the monitor HDMI plug), and nothing happens, a little later disk drive stops flashing meaning that disk finished being read. Even if you reset the computer you still get no signal, you have to turn the power of and on again, and plug HDMI out and put it in again. My info: Graphics card: ATI/AMD Radeon HD 4850 Connection to monitor: HDMI Monitor: Samsung SyncMaster T220HD

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• ubuntu server 12.10 get input signal out of range on HP DL380 G4

  - by lix

  After installed ubuntu 12.10 server on HP DL380 G4, I can't boot into it. And the LCD got message "Input signal out of range, recommened settings is 1280x1024". I can't see the terminal and tried several LCDs and still can not work either. How can I should do now? I tried 12.04 but got fail message when installing (select and install software). Is that signal push me to change another os instead of my favorite ubuntu?

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• half-sine pulse shaping

  - by kos

  hi, i wanted to know what is the pulse shape of the modem.oqpskmod? and if it is not half-sine pulse shape, how is it possible to make it half-sine pulse shape as it is stated in ieee 802.15.4(zigbee) standard where it shows it as follows p(t)=sin(pi*t/2*Tc) if 0<=t<=2Tc p(t)=0 if otherwise ? thanks a lot!

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• Generating data on unlevel background

  - by bluejay93

  I want to make an unlevel background and then generate some test data on that using Matlab. I was not clear when I asked this question earlier. So for this simple example for i = 1:10 for j = 1:10 f(i,j)=X.^2 + Y.^2 end end where X and Y have been already defined, it plots it on a flat surface. I don't want to distort the function itself, but I want the surface that it goes onto to be unlevel, changed by some degree or something. I hope that's a little clearer.

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• Wireless signal changes from strong to weak after connecting

  - by gibberish

  Router (primary AP) is a WRVS4400N, WAP (signal booster) is a WAP4410N. Problem: User is physically located within ten feet of WAP (200 feet from main wireless router). Signal is at 5 bars as user connects to wireless network. Within seconds, signal is at or below two bars and connection is poor. Background: Trying to solve problem of weak wireless signal in back offices. Desired result is for client laptops to automatically switch to the stronger signal. WAP is connected to network via Ethernet cable. WAP is set to AP mode (instead of Wireless Repeater mode) WAP does appear to boost signal. Using Windows 7 sys tray Connect To A Network applet, can observe signal boost as laptop approaches the WAP. Above-described problem happens to users located near or beyond the WAP. It does not happen to users in close proximity to the router. Secondary Question: If using WAP in AP Mode, do WAP and Router (primary AP) need to be on the same channel?

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• The Truth About Wi-Fi Signal Strength

  - by Jason Fitzpatrick

  Whether it’s the structural layout of your home or just ghosts in the machine, we’re all familiar with inexplicable Wi-Fi dead spots. One extra puzzling situation, unseen in the comic here, is when the addition of another wireless node actually causes issues with your Wi-Fi connectivity. There’s nothing more frustrating than having twice the Wi-Fi node power and half the actual signal at your laptop. If you’re looking to extend your Wi-Fi network coverage headache free, check out our guides to doing so with Tomato-powered routers and DD-WRT-powered routers. Your Wireless Internet Signal Strength [via FailDesk] How to Factory Reset Your Android Phone or Tablet When It Won’t Boot Our Geek Trivia App for Windows 8 is Now Available Everywhere How To Boot Your Android Phone or Tablet Into Safe Mode

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• How To Get a Better Wireless Signal and Reduce Wireless Network Interference

  - by Chris Hoffman

  Like all sufficiently advanced technologies, Wi-Fi can feel like magic. But Wi-Fi isn’t magic – it’s radio waves. A variety of things can interfere with these radio waves, making your wireless connection weaker and more unreliable. The main keys to improving your wireless network’s signal are positioning your router properly — taking obstructions into account — and reducing interference from other wireless networks and household appliances. Image Credit: John Taylor on Flickr How To Get a Better Wireless Signal and Reduce Wireless Network Interference How To Troubleshoot Internet Connection Problems 7 Ways To Free Up Hard Disk Space On Windows

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• Broadcom 4313 Signal strength very low on an HP Pavilion dv4

  - by thegreyspot

  I have a HP pavilion dv4 4141US laptop running fresh ubuntu 11.10. This laptop has a broadcom 4313gn chipset for the network card. The network card is using the brcmsmac driver. Which, I heard else where on askUbuntu that its the best driver to be using for this card. I can connect to my network, however I have extremely low network signal. Right now I am right in front of the router, and I only get 72%. If i go to the room directly behind the router's wall, i get no signal, where as with windows 7 I get a nice 70% percent. UPDATE: I use WEP at home and an open wireless connection at work. Both have same result. Both are completely different routers. Also you G What can i do?

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• How do I control Front and Back volume independently with cloned stereo signal

  - by someguy1984

  hello I have my 7.1 soundcard set to stereo and plugged in two stereo thingies (a. my desktop speakers b. my stereo) to the front respectively rear plug. Now I would like to an easy way to mute/volume control them independently - gui if possible. If I set my soundcard to 4.0, the pulse audio mixer gives me sliders for front and back but the problem is that's the input signal. so if i mute the front there and I'm listening to stereo everything remains silent. But what I'd have liked in that scenario would be the front to be silent and the back playing the full stereo signal. Is there a way to do that or something similar?

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• How to send a signal SIGINT from script to script ? BASH

  - by debugger

  I want to trap a signal send from Script-A.sh to Script-B.sh so in Script-A.sh i use the command (Send SIGINT to Script-B.sh) kill -2 $PID_Script-B.sh And in Script-B.sh i catch the signal and call function Clean trap 'Clean' 2 It does not work, instead the Script-B.sh is killed right away without performing the Clean !! What i notice also is that if i want to send SIGINT from terminal to any script that traps it, a ctrl-c will be catched correctly, but not if i specify the signal via the command kill -2 $pid_of_script Any idea about the difference between the two method to send the SIGINT (ctrl-c VS kill -2 $pid_of_script), and how i can send a SIGINT from a script to another ? Regards, Debugger

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• Second Monitor Detected, but not receiving a signal after upgrading to 12.04

  - by user62458

  After I upgraded to 12.04, my second monitor is detected (in display settings), but will not power on. I have scoured the Internet and forums for a solution and I can't find anything. I have found a couple people with the same problem, but never a solution for it. I am no expert, but I'm certainly not a noob. My computer uses AMD Radeon 6250 graphics, but I do NOT want to use the proprietary graphics drivers. They refuse to work properly with my second monitor (they ATI drivers will only mirror screens, and I've done everything to try to fix it, and I DON't want mirrored screens) Not to mention that the default open-source video drivers seem to work much better than the proprietary anyway! Again, Ubuntu's default video drivers work fine, and they even DETECT the second monitor (Dell 19'). I can drag stuff off the screen and put it on the 'space' of the second monitor and even a screen-shot shows that there are two monitors active; but the monitor is OFF. It will not power on. It goes into 'power-save' mode because it is not receiving a signal. For some reason it is not getting the signal to power on, even though Ubuntu thinks the monitor is working properly. I had this working fine on my Sony VAIO yesterday (with Radeon graphics/default Ubuntu video drivers). I upgraded to a Samsung Series 3 and now I have this issue. I can't for the life of me figure out why the monitor is connected, detected and I have screen space for the monitor, but the screen won't turn on! XRANDR Output: Screen 0: minimum 320 x 200, current 1366 x 768, maximum 8192 x 8192 VGA-0 connected (normal left inverted right x axis y axis) 1440x900 59.9 + 75.0 1280x1024 75.0 60.0 1152x864 75.0 1024x768 75.1 70.1 60.0 832x624 74.6 800x600 72.2 75.0 60.3 56.2 640x480 72.8 75.0 66.7 60.0 720x400 70.1 LVDS connected 1366x768+0+0 (normal left inverted right x axis y axis) 344mm x 194mm 1366x768 60.1*+ 1280x720 59.9 1152x768 59.8 1024x768 59.9 800x600 59.9 848x480 59.7 720x480 59.7 640x480 59.4 HDMI-0 disconnected (normal left inverted right x axis y axis)

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• Entity communication: Message queue vs Publish/Subscribe vs Signal/Slots

  - by deft_code

  How do game engine entities communicate? Two use cases: How would entity_A send a take-damage message to entity_B? How would entity_A query entity_B's HP? Here's what I've encountered so far: Message queue entity_A creates a take-damage message and posts it to entity_B's message queue. entity_A creates a query-hp message and posts it to entity_B. entity_B in return creates an response-hp message and posts it to entity_A. Publish/Subscribe entity_B subscribes to take-damage messages (possibly with some preemptive filtering so only relevant message are delivered). entity_A produces take-damage message that references entity_B. entity_A subscribes to update-hp messages (possibly filtered). Every frame entity_B broadcasts update-hp messages. Signal/Slots ??? entity_A connects an update-hp slot to entity_B's update-hp signal. Something better? Do I have a correct understanding of how these communication schemes would tie into a game engine's entity system? How do entities in commercial game engines communicate?

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• Android - How to scan Access Points and select strongest signal?

  - by Donal Rafferty

  I am currently trying to write a class in Android that will Scan for access points, calculate which access point has the best signal and then connect to that access point. So the application will be able to scan on the move and attach to new access points on the go. I have the scanning and calculation of the best signal working. But when it comes to attaching to the best access point I am having trouble. It appears that enableNetwork(netid, othersTrueFalse) is the only method for attaching to an Access point but this causes problems as from my Scan Results I am not able to get the id of the access point with the strongest signal. This is my code: public void doWifiScan(){ scanTask = new TimerTask() { public void run() { handler.post(new Runnable() { public void run() { sResults = wifiManager.scan(getBaseContext()); if(sResults!=null) Log.d("TIMER", "sResults count" + sResults.size()); ScanResult scan = wifiManager.calculateBestAP(sResults); wifiManager.addNewAccessPoint(scan); } }); }}; t.schedule(scanTask, 3000, 30000); } public ScanResult calculateBestAP(List<ScanResult> sResults){ ScanResult bestSignal = null; for (ScanResult result : sResults) { if (bestSignal == null || WifiManager.compareSignalLevel(bestSignal.level, result.level) < 0) bestSignal = result; } String message = String.format("%s networks found. %s is the strongest. %s is the bsid", sResults.size(), bestSignal.SSID, bestSignal.BSSID); Log.d("sResult", message); return bestSignal; } public void addNewAccessPoint(ScanResult scanResult){ WifiConfiguration wc = new WifiConfiguration(); wc.SSID = '\"' + scanResult.SSID + '\"'; //wc.preSharedKey = "\"password\""; wc.hiddenSSID = true; wc.status = WifiConfiguration.Status.ENABLED; wc.allowedGroupCiphers.set(WifiConfiguration.GroupCipher.TKIP); wc.allowedGroupCiphers.set(WifiConfiguration.GroupCipher.CCMP); wc.allowedKeyManagement.set(WifiConfiguration.KeyMgmt.WPA_PSK); wc.allowedPairwiseCiphers.set(WifiConfiguration.PairwiseCipher.TKIP); wc.allowedPairwiseCiphers.set(WifiConfiguration.PairwiseCipher.CCMP); wc.allowedProtocols.set(WifiConfiguration.Protocol.RSN); int res = mainWifi.addNetwork(wc); Log.d("WifiPreference", "add Network returned " + res ); boolean b = mainWifi.enableNetwork(res, false); Log.d("WifiPreference", "enableNetwork returned " + b ); } When I try to use addNewAccessPoint(ScanResult scanResult) it just adds another AP to the list in the settings application with the same name as the one with the best signal, so I end up with loads of duplicates and not actually attaching to them. Can anyone point me in the direction of a better solution?

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• how to find 3g modem signal strength with out AT commands?

  - by neckTwi

  when i try to find signal strength of my modem using AT+CSQ, the usb device is locked by the network manager. To find the signal strength with AT+CSQ i have to first disable network connection using #nmcli nm wwan off to unlock the device inode /dev/ttyUSBX. Is there any nmcli option to get signal strength or any other option? EDIT The gdbus object for NetworkManager don't have any method like getSignalStrength. Network manager is locking device file preventing to use AT commands. nm-applet was able to display signal strength in system tray. so there should be a way to get signal strength form network manager! nmcli is command line counter part of nm-applet. Can i get signal strength using nmcli? nothing about signal strength is mentioned in its man pages.

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• signal processing libraries

  - by khinester

  Are there any open source libraries/projects which work in a similar way to http://www.tagattitude.fr/en/products/technology? I am trying to understand the process. At first I thought this could work like when you send a fax to a fax machine. It is basically using the mobile phone’s microphone as a captor and its audio channel as a transporter. Are there any libraries for generating the signal and then being able to decode it?

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• Pidgin script with Python/ Get Focus Signal

  - by Mr Alles

  I am creating a script in Python to integrate Pidgin with Unity (12.04), I've managed to do the counting notifications system using the Launcher API. But I dont know what event or signal is activated when the conversation window gains focus (To clear the message counter). I've tried some of the signals available on the documentation of Pidgin but none of them worked. Is there any GTK(or anything) event that is triggered when the window chat gets focus?

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• Ubuntu 11.10 Intel controller VGA detected but no signal

  - by Fred Zimmerman

  Ubuntu 11.10 Dell vostrum Intel® Sandybridge Mobile x86/MMX/SSE2 Displays ... correctly detects and identifies Viewsonic 27" VGA monitor, but monitor says it's receiving no signal Plugged into another monitor (Sony 20"), same result. $ lspci | grep VGA 00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09) I've browsed these forums and tried everything that I can but nothing has worked. I need a stepwise troubleshooting plan.

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• Git cloning for Ubuntu Kernel gave error: index-pack died of signal 9447381

  - by LAMOHAN

  My /usr/src is found empty. So I tried to install a fresh Kernel. But was unsuccessful with some error. I did this: git clone git://kernel.ubuntu.com/ubuntu/ubuntu-precise.git but it gave this error message: error: index-pack died of signal 9447381), 802.20 MiB | 88 KiB/s fatal: index-pack failed My current Kernel version is 3.8.13-bone20 #1 in LINUX -Ubuntu-armhf Can anyone help me to solve this?

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• How to use the `itemDoubleClicked(QTreeWidgetItem*,int)` signal in qtHaskell

  - by nano

  I want to use the itemDoubleClicked(QTreeWidgetItem*,int) signal in a Haskell program I'm writing where I am using qtHaskell for the GUI. To connect a function I have at other places done the following: dummyWidget <- myQWidget connectSlot object signal dummyWidget "customSlot()" $ f Where object is some QWidget and signal is a string giving the signal, e.g. "triggered()", and f is the function I want to be called when the signaled is send. The definition of connectSlot in the API is: class Qcs x where connectSlot :: QObject a -> String -> QObject b -> String -> x -> IO () where the instances ofQcs are: Qcs () Qcs (QObject c -> String -> IO ()) Qcs (QObject c -> Object d -> IO ()) Qcs (QObject c -> Bool -> IO ()) Qcs (QObject c -> Int -> IO ()) Qcs (QObject c -> IO ()) Qcs (QObject c -> OpenGLVersionFlag -> IO ()) The first Arguments passed is supposed to be the QObject of which I'm using a signal. As you can see, there is no instance where f, the function to connect to the signal, can have two further arguments to recieve the QWidget and the integer send by the signal. Is there a way to nevertheless connect that signal to a custom function?

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• How to generate a lower frequency version of a signal in Matlab?

  - by estourodepilha.com

  With a sine input, I tried to modify it's frequency cutting some lower frequencies in the spectrum, shifting the main frequency towards zero. As the signal is not fftshifted I tried to do that by eliminating some samples at the begin and at the end of the fft vector: interval = 1; samplingFrequency = 44100; signalFrequency = 440; sampleDuration = 1 / samplingFrequency; timespan = 1 : sampleDuration : (1 + interval); original = sin(2 * pi * signalFrequency * timespan); fourierTransform = fft(original); frequencyCut = 10; %% Hertz frequencyCut = floor(frequencyCut * (length(pattern) / samplingFrequency) / 4); %% Samples maxFrequency = length(fourierTransform) - (2 * frequencyCut); signal = ifft(fourierTransform(frequencyCut + 1:maxFrequency), 'symmetric'); But it didn't work as expected. I also tried to remove the center part of the spectrum, but it wielded a higher frequency sine wave too. How to make it right?

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• What DBus signal is sent on system suspend?

  - by Paul Robinson

  Hello, I need to detect when a machine is going to sleep in Ubuntu 9.10 and Fedora 13. Both use UPower, so I've been looking on the "org.freedesktop.UPower" DBus bus for such signals. I've been listening for the "sleeping" signal on the UPower bus with the following command: dbus-monitor --system "type='signal',interface='org.freedesktop.UPower',member='Sleeping'" When I sleep the machine (either by closing the lid, selecting "shutdown - suspend" or sending a DBus message) I don't see a "sleeping" event. I notice that the "Sleeping" event is sent when the "org.freedesktop.UPower.AboutToSleep" method is invoked. I can do this manually by calling: dbus-send --print-reply --system --dest=org.freedesktop.UPower /org/freedesktop/UPower org.freedesktop.UPower.AboutToSleep And I notice the "sleeping" signal is fired. My understanding is that anything that sleeps the PC must send the "AboutToSleep" signal before hand. It doesn't seem like this is happening. I've tried these steps on both Fedora 13 and Ubuntu 9.10 and I see the same results. Can anyone explain what's happening or provide me with an alternative DBus signal to listen for? Many thanks, Paul

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