Working GNU Radio Receiver

Working live GNU Radio Receiver for Medium wave and HF

Here is my complete working am broadcast and shortwave receiver using gnuradio code, the USRP, a tuned magnetic loop antenna, a couple of rf amplifiers and a filter. I was suprised after assembling the units that it works as good as my TenTec RX320 - good enough that I use it for SWL'ing a lot now!

The Antenna:

made from the plans published here, the top pickup loop goes to the TenTec RX320 and the bottom loop to the gnuradio setup. The pickup loops are designed to couple directly to RG-58.

The amplifiers:

The RG-58 from the antenna connects to the breadboard on the far left, which holds a AM BCB reject filter, then to a single transistor amp built from the plans published here which is connected thru a filter for 3.5-4.0Mhz, then to a Ramsey Electronics PR-2, then the USRP. The software is what I call the HF Explorer The Ramsey amp replaces a Minicircuits ZHL-32A, losing about 9db but still has enough power to bring the noise floor up to 0db in the gnuradio software. The Ramsey PR-2 is more readily available and much less expensive. Also, a prebuilt commercial version of the w7iuv amp is available for about $43 from Advanced Receiver Research, the P0.5-30/20VD covers 500Khz to 30Mhz (the also have 100Khz and 1Mhz lower cutoff versions). Advanced also has special frequency GaAsFET preamps for single band (3.5-4Mhz, 7-7.4Mhz, 21-21.5Mhz, 28-30Mhz) with 0.5db noise figure and 26db gain. The first BCB filter is necessary in my qth with a 5Kw (daytime, 1Kw night) AM transmitter 3 miles away. With the AM BCB filter in line the 80meter bandpass filter is not necessary. The only risk of aliasing would be from any strong signals over 32Mhz, such a TV transmitters, etc.