Blog

An ultrasound beam travels through a three-layer medium: Medium A, Speed = 1540 m/s Medium B, Speed = 2310 m/s Medium C, Speed = 1540 m/s. All interfaces in this layered medium run parallel to one another. The angle of incidence of the ultrasound at the interface between medium A and medium B is 30° from the interface normal. What angle will the ultrasound beam propagate in medium C?

Determine the thermal noise in dBW given the following information:  T=290 degrees Kelvin, Bandwidth B=36MHz

An ultrasound beam with a frequency of 5 MHz passes through three different tissues with the following characteristics: Tissue A: 2 cm thick with attenuation coefficient 0.5 dB/cm @ 5MHz Tissue B: 3 cm thick with attenuation coefficient 0.7 dB/cm @ 5MHz Tissue C: 1 cm thick with attenuation coefficient 1.2 dB/cm @ 5MHz If the initial intensity of the ultrasound beam is 100 mW/cm², what is the approximate intensity after passing through all three tissues? The reflection at each interface is not considered here.

________ is a line coding technique in which a special bipolar sequence is inserted into the electrical signal whenever eight consecutive logical “0s” are detected. 

Orthogonal frequency division multiplexing (OFDM) divides the operating spectrum into multiple subcarriers that are used to transmit data in parallel.  By using several subcarriers extended over a larger frequency spectrum, OFDM provides greater immunity from RFI compared to narrow band frequency channels (i.e., narrow band FDM).

Determine the signal-to-noise ratio (SNR) in dBs given the following information:  received signal power, S = 1E-10 mW, T (Kelvin) = 278 degrees, bandwidth, B = 36MHz.

15W = ________dBm

A binary word consisting of 16 logical bits can represent _____  symbols.

Select the correct statement(s) regarding electric, electromagnetic, and optical signals.

Given the following FM modulated signal equation and Kvco, determine the original message m(t) and frequency bandwidth:  s(t)=2cos(2π(4MHz)t + 3sin(2π(4kHz)t)), Kvco =4000 (Hz/v)