Engineering topics
Fedotov, Leonid
Publications and source records attributed to Fedotov, Leonid.
The New Generation Russian VLBI Network
This paper deals with a new project of the Russian VLBI Network dedicated for Universal Time determinations in quasi on-line mode. The basic principles of the network design and location of antennas are explained. Variants of constructing receiving devices, digital data acquisition system, and phase calibration system are specially considered. The frequency ranges and expected values of noise temperature are given.
The Digital Data Acquisition System for the Russian VLBI Network of New Generation
The system consists of several identical channels of 1024 MHz bandwidth each. In each channel, the RF band is frequency-translated to the intermediate frequency range 1 - 2 GHz. Each channel consists of two parts: the digitizer and Mark 5C recorder. The digitizer is placed on the antenna close to the corresponding Low-Noise Amplifier output and consists of the analog frequency converter, ADC, and a device for digital processing of the signals using FPGA. In the digitizer the subdigitization on frequency of 2048 MHz is used. For producing narrow-band channels and to interface with existing data acquisition systems, the polyphase filtering with FPGA can be used. Digital signals are re-quantized to 2-bits in the FPGA and are transferred to an input of Mark 5C through a fiber line. The breadboard model of the digitizer is being tested, and the data acquisition system is being designed.