QUISK SDR 40 metre RX

To test the previous GNU radio apps and evaluate the linux SDR QUISK software, the following 7MHz SDR was quickly assembled from available parts. The heart of the hardware is the modulator section of a Marconi QPSK modem using Watkins Johnson M6E mixers with a 90 deg phase shift circuit modified for the xtal frequency of 7035kHz.

Using the Softrock .quisk_conf.py file for QUISK with:

fixed_vfo_freq = 7035000
sample_rate = 96000

The following daytime spectrograph was obtained on 40 metres.

The SDR hardware (90% not used, including the 741 or TL081 op amps as they were noisy + insufficient gain-BW). The PC was a Toshiba Satellite L650 laptop with Ubuntu 11.10 OS.

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