The project name ADAT (All Digital Amateur Transceiver) denotes an ongoing development of an amateur transceiver which consequently uses digital signal processing. Therefore, all relevant functions are performed by software providing a very high degree of flexibility. Similar products are available on the market as Software Defined Radios (SDR), but all those use the ressources of a PC extensively. In contrast, the ADAT transceiver ADT-200A allows stand-alone operation . The ADT-200A is the first amateur transceiver in the world where the signal spectrum is fed from the antenna directly to an A/D converter and all subsequent signal processing is done d igitally. The advantage is, that linearity, noise and reproducability are near ideal.
The ADT-200A Transceiver
The ADT-200A is world’s first amateur radio transceiver with completely digital signal processing. The device is equipped with the latest DSP technology, moreover it is produced professionally with state-of-the-art technology.
The receiving portion uses a 14bit A/D converter which offers a S/N ratio of 74dB over the half Nyquist bandwith of 36.86MHz. After the subsequent decimation, a blocking dynamic range of 120dB will be achieved. The ADT-200A uses the latest generation of high performance DSP manufactured by Analog Devices Inc. capable of up to 2 billion instructions per second leaving room for future options.
The power amplifier is equipped with high voltage MOS-FET’s capable of producing 50W within the range of 1.8MHz to 30MHz with an efficiency of up to 70%. Adaptive predistortion delivers an undistorted transmission signal, which is a first in amateur radio application.
The ADT-200A has a front end, along with four parallel receivers and can be enhanced with a VHF/UHF module as an option. Eight independent VFO’s provide many split band operations. Further design highlights include an audio recorder, capable of recording up to 1 hour, an automatic fine tuning for SSB, an antenna scope which allows measurement of the complex antenna impedance and an optional Web server module.
The menu selections of the four receivers and the transmitter is accomplished with only three knobs and 18 push buttons, providing the same functionalities as other high end transceivers. Operator selections are supported by two high resolution graphic displays.