Software Defined Radios are all the rage these days, and with a cheap USB digital tv tuner card with the RTL2838 chipset, its very easy. My dongle cost $10.99 and took a week to arrive from Hong Kong via this eBay seller. You can find these dongles cheaper, I choose this seller as a friend had used them before me and the device arrived promptly. The device is a simple usb stick, some PC software for the tv tuner on a mini CD and a mag antenna with a MCX connector. This is a quick post to show my first toe into the SDR world, using TV Tuner SDR on a Mac and will write more when I undertake further exploration.
Being a mac user, the options for this SDR stuff are a little more limited, but since most of the development work seems to be done is Linux, getting a version to work on mac(bsd) is generally pretty easy.
If you are a PC/windows user, best to head over to the HDSDR main website and download the latest windows version. its the same software, just a more recent version.
Download the MAC software package (its 115mb) and copy the 2 applications to your local machine.
First you need to start the GNU Radio Server, Click that program and it will start. This allows HDSDR to interact with the USB Dongle. This loads the Python (linux) environment and makes it all work.
Next, start HDSDR mac. It can take a short while to load, (if its slow, move your mouse over ExtIO to resolve- thanks Alain) and comes up with a configuration window, ExtIO, for my device, i have to select the RTL device and then hit Create, it connects and starts the device. Sample rate and offset can be configured, I’m still to fully explore the options.
Once the device is correctly configured, (its best to make sure the Gain is set to MAX) as default is Min, and you wont hear anything – the HDSDR window loads, and all that is left to do is to hit start, and you can start listening to the device. Click tune to modify the receive frequency, or click the waterfall to tune to the desired signal. Again lots of options to explore when I have more time.
Observations, my device is a little off frequency, about 500kHz high at 146mhz. The software has a configuration menu in the options tab that allows you to calibrate the device. Additionally, given the wide front end and very limited (if any) real filtering, i get a lot of pager break through from 148Mhz, (I’m about 2km line of sight to a major Melbourne pager site, so thats understandable, even my icom IC9100 experiences some pager break through at the top of the 2m band on the big antenna. Im still learning how to use the device, and its real purpose for me will be very limted, its a neat tool and a nifty thing to play with, from a tinkering point of view.
This is just a quick video of the local morse training beacon on the provided magnetic antenna from last night. I have a MCX to N connector adaptor on its way to allow me to connect to the big antennas at home, that should really unlock its functionality.