C'è un aggiornamento al software per Linux (ma ricompilabile per Windows e, forse, chissà, per Mac) jSDR, che l'olandese Jan van Katwijk ha reso disponibile qualche tempo fa per rendere possibile, tra l'altro, la decodifica di segnali in FM con front end SDR di tipo QSD, come il PMSdr. La nuova release, 3.04, si apre per la prima volta anche alle diaboliche chiavette DVB-T ultraeconomiche e a quanto mi comunica il solito amico che la sa lunga, funziona incredibilmente bene.
Il pacchetto contiene tre diversi programmi: un ricevitore HF, il ricevitore FM e un semplice visualizzatore di spettro pensato appositamente per le chiavette. Tutti i software sono testati sotto Fedora e Ubunto ma l'esecuzione dovrebbe essere possibile anche in ambienti Windows su cui girino le seguenti librerie: MINGW, Qt, Qwt and libusb-1.0 (commenti sulla possibilità di ricompilare sotto Mac sono ben accetti). La descrizione sintetica che segue aiuta a farsi un'idea delle possibilità di questo software, ma Jan ha preparato un dettagliato manualetto che si può prelevare qui. Per scaricare il tarball con il codice, invece, bisogna essere iscritti al gruppo Yahoo "soft_radio".
The package contains three programs, a simple spectrum viewer for use with the rtl2832u based dongles, a fairly complete sw receiver and an am/fm receiver running without problems under Ubuntu and Fedora, and - for the advanced user who has MINGW, Qt, Qwt and libusb-1.0 running under Windows - under Windows.The programs contain quite some improvements since the march 5 version, the most important one being that all three programs now support the DAB sticks with the rtl2832u as sdr device. DAB sticks provide 8 bit I and Q data with a data-rate of up to 3.2 M. While the spectrum viewer provides a view on a user selectable spectrum of up to 3 MHz, and therefore needs the full bandwidth, the FM receiver supports strong filtering of the incoming data to a data rate usable for WFM. Although the I and Q sample are only 8 bits, it turns out to be quite possible to receive WFM in stereo mode with decoding of (some of the) RDS signals. Just to give an idea of what turns out to be possible with a 26Euro DAB stick, I attach a recent screenshot of the FM receiver, while listening to a (dutch) station.So, the sw receiver supports the elektor card (2007), the pmsdr (basic version but up to 165MHz) and the DAB stick with a predefined rate of 2880000 (filtered and decimated to either 96 or 192K) The fm receiver supports the pmsdr (basic version but up to 165 MHz) and the DAB stick. Selection can be made of the decoding bandwidth and DAB sample rate. A pretty strong filter is used to select an appropriate subband of what is coming out of the DAB stick. Some of the command line parameters will set the samplerate used in decoding and the samplerate used by the DAB stick.The spectrum viewer supports the DAB stick. A command line parameter can be used to specify the rate of the incoming samples and the width of the spectrum. The package contains some scripts that are helpful in establishing the right environment (i.e. loading the libraries and development packages needed) in a directory "installation". The package contains a general description of the programs, including sections how to set frequencies, and about some important command line parameters in the directory "docs".
