DRB 30
Functional Description
Working Principle
The external hardware converts the RF input signal to a low frequency IF signal. This IF signal is fed to the input of a PC soundcard. Filtering, demodulation and sound processing is done by the chosen SDR software. This principle is also state-of-the-art used for professional communication receivers.
Circuit Description
The DRB 30 is a dual conversion superhet receiver including a direct digital synthesizer (DDS) for the local oscillator. The DDS principle combines small tuning steps with very low pase noise and excellent short-time stability. The last-mentioned criteria is absolutely important for distortion-free DRM reception.
A high-IP actice mixer converts the RF signal to a high IF frequeny of 45 MHz. Two cascaded monolithic crystal 4-pole filters guarantee in combination with a selective input low pass filter for extraordinary performance concerning selectivity and mirror frequency supression.
Next conversion is done to the very low second IF of 10KHz, which can be handeld by a standard PC soundcard. An integrated automatic gain control ( AGC ) always delivers the optimum level for the soundcard.
The unit is controlled by the parallel interface (LPT) or via optional USB interface (DRB USB ADP). Application software (Control Panel) is available.
