A microprocessor controlled fast sampler

by Franz Knüttel, DC9FF

This article describes the circuit of a sampling device capable of sampling signals, under control of a PC-software, with a maximum speed of 3 Megasamples/second. The device uses a fast 8-bit ADC AD775 under control of an ATmega32-microprocessor, both clocked by the same 18.432Mhz clock source.

A possible application of this circuit is the analyzation of the fine structure of molecule lines (masers) or the Hydrogen line on 1420 Mhz.

Circuit description

The board contains the following building blocks:

The transfer speed is max. 76800 baud.

The sampling procedure is controlled by the software of the PC connected to the board. After a start command is sent, sampling is started and the internal RAM-buffer is filled. After sampling is done, the data block is sent to the PC for analysis. Different sampling rates are possible to support oscilloscope functions, though in general FFT-sampling is performed at max. speed.


The ATmega-Software can be downloaded here together with the circuit board layout, all in one zip file.

A suitable PC-Software is available at http://vlbi.wegalink.net.

Circuit Board:

Ordering informations:

Circuit Boards are not available. You may download the layout as .bmp-file to do it yourself.

An AD775 can be ordered as a sample from Analog Devices

Please visit regularly the homepage of the European Radio Astronomy Club. Comments and questions to erachq@aol.com are very appreciated. Please contact webmaster@eracnet.org if you encounter any problems with this web site.