I'm receiving a digital signal that I would like to decode.
Is there a simple way (avoiding to program by myself) to get the bit stream from a NRZ square-signal using GNU Radio ?
Thanks !
Assuming the signal is 1 sample/symbol, you can simply use the binary slicer
Related
It seems as both blocks have same function. What is difference in concept, method, etc.?
no, they don't have the same function.
One allows you to write a block in Python, i.e. to implement some functionality on a stream of data (or messages).
The other is just a snippet of code to be included in the final Python program that gets generated. That's something fundamentally different.
I'd recommend going through the chapters 1 to 5 (in that order!) of the GNU Radio academy on https://tutorials.gnuradio.org .
Is reading an input from ModelSim transcript window possible? If yes, how to read the inputs?
If you want to read input from the user, or from a file, use the Verilog Programming Language Interface (PLI) to connect your verilog to the C or C++ language; and there you can use system calls like read and fgetc to get data from a file, or from the user.
See your verilog simulator's manual, or a do a web search for ModelSim PLI for help to using the Verilog PLI.
I encountered a problem while working with the TextIO structure,
because every input waites for a newline chacter and for the buffer to be full...
How can i work with BinIO and stdIn to solve that problem?
Any helpfull input is appreciated.
BTW: I am using MLTton so there is nothing more than the usual standard libs.
As a last resort, you could write it yourself in C, and then call it from SML using the foreign function interface. You can find out more info about MLton's FFI here: http://mlton.org/ForeignFunctionInterface
I encountered a problem while working with the TextIO structure, because every input waites for a newline chacter and for the buffer to be full... How can i work with BinIO and stdIn to solve that problem?
BinIO, like TextIO, implements buffered I/O. (They both implement the IMPERATIVE_IO signature.) For unbuffered I/O, you need to go "down" a level in abstraction, and use an implementation of PRIMITIVE_IO or POSIX_IO.
Specifically, Posix.IO.readVec lets you read unbufferedly from a file descriptor. (In the case of standard input, the file descriptor is Posix.FileSys.stdin.)
However, if your standard input is from the console (as opposed to being redirected from a file, or taken from a pipe, or whatnot), then there's a very good chance that the console only provides input to MLton after the user hits Enter. Using Posix.IO will bypass the line-buffering functionality that MLton provides, but if you also need to bypass your console's line buffering, then you'll likely need to use special C libraries (specific to your operating system), with the foreign function interface that Matt mentions in his answer.
I have made a software that uses WebRTC DSP libraries (AEC, NS, AGC, VAD). Now I need to know what algorithm uses each one to write my Master´s Thesis, but I don't find any information about that.
Someone knows the algorithms of this libraries, specially the Acoustic Echo Cancellation (like for example NLMS, that I know it's commonly used, but I don't know if WebRTC also uses it).
I've tryed to know the algorithm looking into the source code, but I don't understand enough.
Thanks in advance!
I've just successfully using standalone WebRTC aecm module for android. and there's some tips:
1.the most important is the thing called "delay", you can find the definition of it in dir:
..\src\modules\audio_processing\include\audio_processing.h
quote:
Sets the |delay| in ms between AnalyzeReverseStream() receiving a
far-end frame and ProcessStream() receiving a near-end frame
containing the corresponding echo. On the client-side this can be
expressed as delay = (t_render - t_analyze) + (t_process - t_capture)
where,
t_analyze is the time a frame is passed to AnalyzeReverseStream() and t_render is the time the first sample of the same frame is
rendered by the audio hardware.
t_capture is the time the first sample of a frame is captured by the audio hardware and t_pull is the time the same frame is passed to
ProcessStream().
if you wanna use aecm module in standalone mode, be sure you obey this doc strictly.
2.AudioRecord and AudioTrack sometimes block(due to minimized buffer size), so when you calc the delay, don't forget adding blocking time to it.
3.if you don't know how to compile aecm module, you may learn Android NDK first, and the module src path is
..\src\modules\audio_processing\aecm
BTW, this blog may help a lot in native dev. and debuging.
http://mhandroid.wordpress.com/2011/01/23/using-eclipse-for-android-cc-development/
http://mhandroid.wordpress.com/2011/01/23/using-eclipse-for-android-cc-debugging/
hope this may help you.
From the code inspection of AGC algorithm in WebRtc, it matches closely with the description in http://www.ti.com/lit/wp/spraal1/spraal1.pdf
It's based on NLMS, but has a variable step length (mu).
I am trying to make an interface with another program so I have to use C++.
It's been years since I have programmed in C++ and I have been at this problem for about a week so I'm slowly starting to see how everything works.
I want to read byte data coming from a serial port device.
I have verified that I can get text through the serial port using the readline command:
For example:
String^ message = _serialPort->Readline();
Is how the data is read in an example from MSDN that I got to work successfully.
However I have tried to modify it several times and I'm having no luck coming up with something that reads the data as bytes. (I already have conversion of byte data to string so I can actually see the bytes such as the number 15 equaling 0f in bytes.)
Modifying the code to
wchar_t message = _serialPort->Readline();
gives me
error c2440: 'initializing' : cannot convert from System::String ^' to 'wchar_t'.
I'm not familiar with Readline. Is it only for strings? I have verified that it does work with strings and if I use a serial device that sends a string the first set of code does work.
Can someone explain what method I could use to read byte data? Thanks.
If you actually want to use C++ rather than C++/CLI, I recommend using boost.asio. It is well established, relatively easy to understand, and has a specific set of functionality just for working with serial ports.
Update
Pure C++ Win32 API versions:
See the following good references
CodeProject article
MSDN
Is there any specific reason you are doing this in C++/CLI code?
I thought you might not even be aware of that (otherwise, tag your questions, please).
String^, Readline etc are CLR functions (i.e. .NET, think: "you could do this more easily in C#). So, again,
If there is a need for this to be in C++, why don't you look at the native Win32 API
Otherwise, why are you bothering with C++
If you really wanted C++/CLI I suggest not mixing native/managed code when handling the serial IO. You can get an UnmanagedMemoryStream to marshal the data in/out of managed land.
$0.02