Measurements

Explanation of question 31

A digital frequency meter of accuracy 4 parts per 100,000 is used to check the frequency of operation of a transmitter in the 10m band. The most accurate reading will be

1. 28.09MHz
2. 28.094MHz
3. 28.0946MHz
4. 28.1MHz

The answer is :- 1

4 parts per 100000 is 40 parts per million,

i.e. 40Hz per 1 MHz = 1120 Hz per 28 MHz

= 1.12 kHz per 28 MHz

The most accurate reading is 28.09MHz. However, 28.094 MHz would be a useful reading, although this could be subject to an error of ± 1.12kHz at this frequency.