Month: January 2014

Posted on

Software Defined Radio in Pd

This is based on the Max tutorials. I have only written one external (for Soft66LC2). But everything seems to be working well with minimal filtering. After watching the video, I think the next feature should be an AGC (automatic gain control) on the input stage.

Posted on

converting IQ audio files using sox

To get information about a file:

# sox --i 10meter96.wav


Input File : '10meter96.wav'
Channels : 2
Sample Rate : 96000
Precision : 16-bit
Duration : 00:00:16.50 = 1584387 samples ~ 1237.8 CDDA sectors
File Size : 6.34M
Bit Rate : 3.07M
Sample Encoding: 16-bit Signed Integer PCM




#




To convert the sample rate:




# sox 10meter96.wav -r 44100 10meter44.wav




More useful hints about sox by Selvaganeshan at “The Geek Stuff”


http://www.thegeekstuff.com/2009/05/sound-exchange-sox-15-examples-to-manipulate-audio-files/


Here are the commands that worked to get the raw IQ data from rtl_sdr into Max




rtl_sdr -f 94900000 -s 1024000 -g 50 iq.raw




To convert the above to 96k 16bit wav format




sox -e unsigned-integer -r 1024k -t raw -b 8 -c 2 iq.raw -r 96k -b 16 iq.wav




Note: I could not get the above conversion to work with device sampling rates below 1024k. Didn’t try anything higher.


 


 

	


	







		

		
Posted on 
return of Pluggo
	


	
	

		
Pluggo, running in Max 4.6, on a Macbook, inside a VirtualBox instance of Windows XP.


to be continued…




Notes:




update 1/26/2014 – audio input and Max search path




For audio input to work in a windows XP virtual box inside of Mac OS, the sample rate of the microphone in Mac OS (utilities/audio midi setup) must be set to 441000. I spent hours trying to figure this out. Then found this post: https://forums.virtualbox.org/viewtopic.php?f=8&t=56628


The strangest thing is that if you activate audio input in Max without setting the above sample rate, you will get no audio output either.


Also, note that switching default sound cards in the host OS can cause the sample rates to reset back to 96 kHz – requiring them to be reset again before using VirtualBox.


The second issue was that the [vst~] object wasn’t finding names passed with the plug message. Turned out to be a simple matter of setting the path to the plugin directory in the Max file preferences.


Almost forgot – I set a shared drive to be on the E: drive – which was the original location of the plug go project directory – this eliminated need for updates in the patch.


The Pluggo authorization worked.


I was able to use the Behringer UCA202 (audio device) just by plugging it in. Although I couldn’t use any sound cards that required drivers.


http://www.amazon.com/Behringer-Latency-U-Control-UCA202-Interface/dp/B000J0IIEQ


Note: I am running plugv4r6 (the version from 2006)




 original post 




Instructions for installing Windows XP to run max 4.6 in VirtualBox on mac OS 10.8


    

  • Download and install VirtualBox
    • 

  • create new VirtualBox instance (1 Gb of memory)
    • 

  • install Windows XP from CD
    • 




    

  • install Firefox (or some reasonable browser)
    • 

  • install “guest additions CD image” from device menu select  (inside the virtual machine)
    • 



    

  • install Max 4.6 from c74
    • 



For Midi devices:


    

  • virtual machine – settings -usb – add the midi device – then unplug and replug – windows should find and install
    • 

  • also activated windows over internet –
    • 

  • installed and tested Pluggo
    • 



    

  • activated drag and drop (doesn’t seem to work)
    • 

  • setup shared folders 
    •