Virtual Audio Patching in Windows

I first found Jack audio on Linux, this video shows it on Windows. Simple use may only need the ASIO Bridge, for that skip to 10m49s

HERE ARE THE LINKS MENTIONED IN THIS VIDEO:
1. download for windows version of JACK AUDIO CONNECTION KIT
http://jackaudio.org/downloads/
2. tutorial on installing JACK AUDIO on windows
http://www.jackaudio.org/faq/jack_on_windows.html
3. download for KXSTUDIO Carla, and Cadence(Catia) for windows
http://kxstudio.sourceforge.net/Downloads
5. download VB-AUDIO ASIO BRIDGE
http://vb-audio.pagesperso-orange.fr/Cable/
6. download ASIO4ALL (optional) if you don't have a "true" ASIO SOUND CARD
http://www.asio4all.com/

In SDR, you may need to patch from one application to another. Here are some other ways to do it:
http://www.rtl-sdr.com/a-list-of-5-free-virtual-audio-cable-software-programs/

R820T with HDSDR

I went to Radio Club and a few people were interested in the use of the R820T with HDSDR so this post is for them.

1. Visit http://hdsdr.de/ and click the download link at the bottom of the page.  Download and install.  
2. Play around with it using pre recorded I/Q base-band files to decide if this is for you.   
3. Order:  I have purchased a few of these, the best quality and fastest delivered unit came from nooelec.com I used the ebay store to get free shipping, total cost $17.95.  I also purchased from China seller on ebay same chips, larger package, $8.75 delivered.  Frequency was off by more in the China version but both need to be adjusted in software anyway so it did not make much difference in the end.  While both of the units come with an antenna, you will likely want to attach your own, so you will need MCX Male adapter or connectors.  My favorite wide band RX only antenna is the amplified TV antenna that is already plumbed in every room of the house. For that I purchased 6in F female jack to MCX right angle male Jumper pigtail RG316 cable
4. Once the unit arrives, do not install the software that comes with it.  Follow these instructions to get it going.  http://hdsdr.de/RTLSDR_with_HDSDR.pdf

Other links you might like:

1. RTL-SDR AS A CHEAP PANADAPTER
2. My other posts on R820T
3. http://www.rtl-sdr.com/about-rtl-sdr/
4. http://superkuh.com/rtlsdr.html
5. http://sdr.osmocom.org/trac/wiki/rtl-sdr
6. http://www.sdrsharp.com/
7. SDR# Demo by Clayton Smith VE3IRR
8. http://greatscottgadgets.com/sdr/
9. http://greatscottgadgets.com/hackrf/
10. http://www.ettus.com/kb/detail/software-defined-radio-usrp-and-gnu-radio-tutorial-set
11. http://www.ettus.com/product/details/UB200-KIT
12. http://sdr.5sn.com/
13. http://www.websdr.org/
14. ModeSDeco2

Rafael Micro R820T tuner as USB SDR source for hold music in asterisk PBX

So you want to play a local radio station, HAM repeater or other radio source 24MHz-1700MHz as hold music in asterisk. $8-$18 buys you the USB radio, antenna and all depending on source. Here is how you do it.

# Install git and libusb
$ sudo apt-get install git-core libusb-1.0-0-dev

# Change to your build directory
$ cd /usr/src/

# Download the source
$ git clone git://git.osmocom.org/rtl-sdr.git

# Build with autotools
$ cd rtl-sdr/
$ autoreconf -i
$ ./configure
$ make
$ sudo make install
$ sudo ldconfig

# In order to be able to use the dongle as a non-root user, you may install the appropriate udev rules file by calling
$ sudo make install-udev-rules

# Plug in the USB radio, and check if it is detected
$ lsusb
Bus 001 Device 008: ID 0bda:2838 Realtek Semiconductor Corp.

#Test by playing FM 91.1MHz to local speaker
$ rtl_fm -f 91.1M -W -r 32k - | aplay -r 32k -f S16_LE

# Update your Asterisk Music On Hold config
$ vi /etc/asterisk/musiconhold.conf

[default]
mode=custom
application=/usr/local/bin/rtl_fm -f 91.1M -W -r 8k -

# Restart
/etc/init.d/asterisk restart

http://sdr.osmocom.org/trac/wiki/rtl-sdr
http://kmkeen.com/rtl-demod-guide/
http://www.nooelec.com/store/software-defined-radio/sdr-receivers/nooelec-nesdr-nano-sdr-dvb-t-usb-stick-r820t-w-antenna-and-remote-control.html

Software Defined Radio

I am getting a $18 RX only Software Defined Radio but expect to be able to do many of the same things as in this b200 video with the cool GNURadio software.

http://b200.ettus.com/
http://www.nooelec.com/store/software-defined-radio/sdr-receivers/nooelec-nesdr-nano-sdr-dvb-t-usb-stick-r820t-w-antenna-and-remote-control.html
4 Jan 2014 $8.75 http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItemVersion&item=141115437304&view=all&tid=908074057004
http://www.rtl-sdr.com/about-rtl-sdr/
http://sdr.osmocom.org/trac/wiki/rtl-sdr  rtl_fm -f 96.3e6 -W -s 200000 -r 48000 - | aplay -r 48k -f S16_LE
http://www.rtl-sdr.com/tag/r820t/
http://sdrsharp.com/index.php/downloads
http://www.sm5bsz.com/linuxdsp/linrad.htm
http://www.sm5bsz.com/linuxdsp/usage/newco/newcomer.htm
http://www.sm5bsz.com/linuxdsp/hware/rtlsdr/rtlsdr.htm
http://freedv.org/
http://www.rowetel.com/blog/?p=2782
http://www.rowetel.com/blog/?page_id=452