Answer to Question #191132 in Electrical Engineering for sambasiva

Question

Design a 400Hz hum eliminator for an Airline radio transmission with the following specifications: Pass band: 0-400Hz Pass band ripple: 2dB Sampling frequency: 10 kHzStop band: 2.1 kHz- 4 kHz Stop band attenuation: 20dB 

Answer 1

By international agreement, the radio spectrum is divided into major bands in frequency decimal

multiples of three. The radio spectrum was originally defined in terms of metric system wavelengths. The three multiple came into use because the speed of light and electromagnetic propagation is about 300 million meters per second in free space. The length of a full wavelength is 3 x 108 meters per second (m/s) divided by the frequency in Hz. Noting this frequency/wavelength relationship, a frequency of 3 MHz calculates to 100 meters for a full

wavelength.

These decade bands of frequencies have international defined names, using common terms. For

For example, the band of frequencies from 30 kHz to 300 kHz is named Low Frequency (LF) and 300 kHz to 3 MHz is designated Medium Frequency (MF). The bands continue from LF and MF to High (HF), Very High (VHF), Ultra-High (UHF) and Super High (SHF) with continuations above and below these ranges. The frequency band names are divided by decimal breaks defined in wavelengths; e.g., 300 kHz is 1000 meters, 3,000 kHz is 100 meters, etc. The United States uses frequency in Hz as the unit for specific administrative tracking of spectrum assignments.