Airspy HF + Discovery SDR receiver

Now comes the sequel to Airspy HF + which gives you great reception on short wave and VHF band. Many users believe that this receiver is significantly sharper than many HF rigs.

Airspy HF + Discovery covers from 500 Hz to 31 MHz and 60-260 MHz. Like Airspy HF + works "Discovery" as a "zero-IF" SDR. This technique avoids many of the problems with classical receivers, but also provides developers with new challenges. Airspy HF + Discovery addresses these challenges by using three analog receivers. The recipients preceded by band-pass filters and variable filters. As with the '+ HF' are mixers designed as a Harmonic Rejection Mixer, which ensures exceptionally good linearity and spectral purity of the downmixed signal. This is important for sensitivity, because the purer the signal is, the lower the likelihood of a weak signal in the noise is lost. For digitizing used very powerful AD converters. The subsequent decimation stages (DDC) using various methods to reduce (decimate) the data rate. The result is a highly effective anti-aliasing filter provides approximately 108 dBc reduction. The resulting signal has an 18-bit resolution, which is then scaled to 16 bits for transmission over USB 2 interface.

Such mottagarkoncept requires a very precise AGC to achieve optimum sensitivity and high dynamic range. Here, checks the software Airspy HF + Discovery gain in each stage of the receiver and the subsequent filters and amplifiers. The result is a dynamic range of approximately 113 dB, which practically results in 110 dB (short-wave). This is an excellent result for such a compact receiver in this price range. The user benefits from the very good linearity and high dynamic range of the received spectrum is much cleaner and free from artifacts. Manual control of the gain is not necessary, nor used attenuator, preamplifier, selective bandpass filters, etc.

Apart from the excellent RF properties, developers have also achieved a remarkable noise reduction on the LF level. This eliminates the distracting noise in a useful signal is largely without understanding suffering and without too many artifacts in the NF.

As a further highlight in Airspy HF + 'Discovery' offers the free "SpyServer" software is an easy-set remote server. Here, a small computer (a cheap Raspberry Pi, etc.) take over the function of the server to which Airspy HF + 'Discovery' is connected. Over the Internet or your local network, you can then reach the reception data in the normal way, even with multiple participants simultaneously. The difference with other web-based concept is that the actual IQ data is transmitted, which can then be further processed with the standard SDR software with all the plug-ins.