For mac users, you will use gqrx. RTLSDR Up and running in Mac OSX Yosemite with GQRX & GNURadio.First you will need the spectrum visualization software. Grig is a freeware simple Ham Radio control (CAT) program based on the Ham Radio Control Libraries (Hamlib).install Xcode is the first step to install SDR software in IOS Sigmund Freud, Eriksons. JackAudio is a virtual audio software cable that run on Windows Linux and MacOS and if Free to download and to use. Take the audio output of one piece of software and send it to another.This is a graphical interface that is built on top of gnu radio, an open source software defined radio project. Insert SDR dongle into an available USB slot on the PC (for this demo it is assumed we are using an RTL-SDR dongle).For MacOS and Ubuntu, we will use the gqrx program. We will be using a software defined radio application (gqrx), to capture these DTMF tones and save the resultant demodulated signal to a WAV file for later analysis. This video also shows you how to install the SDR program GQRX on a Mac OS X (macOS Sierra. The antenna has a male mcx plug.The following install instructions are taken from. This is the same sort of program as gqrx, but written in C# for Windows. WindowsFor Windows we will use SDR#. The program will appear in the Applications folder. This may have issues on OS X 10.12, but has been tested on OS X 10.13 with no issues.Once the file has downloaded, run the installer.Your computer and the sdr should keep up with this easily (if it does not, set it to 1000000). We'll look at gqrx here, but SDR# is very similar, and has the same settings to adjust.When you start gqrx, it will pop up a window for the device configurationSet the sample rate to 2400000 (i.e. Commercial FM RadioFirst, plug the antenna into your sdr, and the sdr into a USB socket on your computer. This worked right out of the box on a Windows laptop. Double click on SDRSharp.exe to start. This will start a command prompt that will download all the drivers required to make SDRSharp work with RTL-SDRThat should be enough to get you going.
Gqrx Mac OSX Yosemite WithWith any luck, you should be listening to KQED!The plot in the upper panel is the live spectrum that is being received, and has a range +/- 1.2 MHz, since you set the sampling rate to 2.4 MHz.The lower panel is a waterfall plot. It looks like an on/off power button. The display should look like this:Now click the big button in the upper left corner. Change the “Mode” pulldown on the right side of the screen to “Wide FM (Stereo)”. This is KQED, which is a nice clean signal. ![]() Common choice are “AM”, used for aircraft and air traffic control, “Narrow FM” used for police and fire radio, and “Wide FM” used for commercial FM radio. The middle “Mode” pulldown selects how the receiver decodes the signal. On “Normal” it chooses something reasonable for whatever modulation we are receiving, so generally leave it there. This is the shaded region on the live spectrum plot. The top “Filter” pulldown sets how wide a bandwidth we are listening to. Ps2 emulator mac playPolice, Fire, Airport and Amateur RadioThere are several frequency bands that are used for public services, such as local police and fire. Otherwise the controls are pretty much the same. Aside from the color scale, one difference from gqrx is that the SDR gain and sampling rate is set by the “configure” button. That will set the receiver offset.The SDR# version looks like this, when tuned to KQED:Choose “RTLSDR/USB” as the input, next to the stop/play button in the upper left. Often you will see several stations in the plot, as shown below:Select any of them by clicking on them in the top panel. The bottom “AGC” pulldown sets how rapidly the receiver adjusts for amplitude variations in the signal.Try setting the center frequency to other stations that you know (such as 88.5). ![]() It's located at 162.40MHz. An example of narrow FM is the NOAA weather service. The other half will be narrowband FM, and should be easy for you to decode. We'll talk about how these signals are encoded later in the class. About half of the signals are digital, and will sound like dial-up modems. ![]() One is the police and fire band at about 154 MHz. This will annoy your roommates less!There are lots of other frequencies where you can find narrow band FM signals. Then when you tune to an active frequency the signal will come through, but will blank again when the signal stops. Tune to a frequency that is only noise, and adjust the slider so that it just blanks the noise, and the speaker goes quiet. I made a video a while back showing how to manually calibrate the frequency using GSM base station signal:Another useful control is the squelch slider, labeled “SQL” on the “Receiver Controls”. AssignmentTo show you have completed this lab, Upload a screen shot to GradeScope of some frequency band where you have found narrow band FM signals. Another is the weather radio around 162.400 MHz, where different weather stations are separated by 25 kHz spacings. These are fun to listen to after a power failure. There are many commercial users, like PG&E, right above 450 MHz. Check out 463 MHz (lots of digital radio), 930 MHz (Paging), and 856 MHz (ATT cell phones).
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