Few days ago I wrote about how I upgraded the simple double side band receiver implemented in the GNU Radio Companion to a simple single side band receiver. This initial implementation used some default values for the AGC attack and decay rates. These values were acceptable; however, I wanted to spend some time trying to find better values that would correspond to Fast, Medium and Slow AGC – just as we are used to in commercial radios.
When I presented the Simple CW Receiver few weeks ago I also mentioned and demonstrated that it is actually a double side band receiver (it’s around 2:35 in the video). This is good for AM and FM, but can be very inconvenient for receiving CW and SSB (single side band). If the station we are trying to receive is surrounded by other stations on the neighbouring channels, these will interfere via the opposite side band. Therefore, it was time to look into single side band reception.
I have been playing with GNU Radio and GRC (GNU Radio Companion) over the weekend and I ended up implementing a very simple CW receiver. This will be very handy on Tuesday when we will be testing the 5.8 GHz UNITEC-1 setup for the first time using the OZ7IGY beacon on 5.76093 GHz. Here is a quick video demo of the receiver where I use my Yaesu FT-817ND to transmit a test signal.