Generation of frequency output for instrumentation applications using digital hardware
The use of frequency output for measurement transmission remains common in the design of smart transmitters. Conventional methods of frequency generation, based on counting clock cycles, have a precision which is inversely proportional to the frequency to be generated. Consequently, frequency output precision could be much lower than the measurement precision. This paper describes a simple frequency generation technique which, when implemented in low-cost hardware, provides a precision of 10-6 per cent for all frequencies. The method represents an intermediate non-available frequency by dithering between two exact frequencies. Averaging over some reasonably short timescale provides the desired frequency to high precision.