Karteikarten
02Handout1
Karten in diesem Stapel (34)
- 1Analog signalswhich include speech, audio, and video, have an infinite number of values. These are represented as a sine wave.
- 2Digital signalsare predominantly binary in nature and thus are represented by two (2) values or bits: 0 and 1. These are represented as a square wave.
- 3two (2) forms of analog and digital signalsPeriodic signal
Nonperiodic signal - 4Periodic signalIt completes a pattern within a measurable time frame, called a period, and repeats that pattern over subsequent identical periods. The completion of one (1) full pattern is called a cycle.
- 5Nonperiodic signalIt changes without exhibiting a pattern or cycle that repeats over time. Both analog and digital signals can be periodic or nonperiodic.
- 6Parts of a Signal
- 7Wavelengthis directly related to the frequency of a given waveform. Formula for Wavelength
𝜆 =𝑐 / 𝑓 - 8𝜆 – wavelength (𝑚) 𝑓 – Frequency (𝐻𝑧) 𝑐 – wave speed or speed of light (𝑚/𝑠)𝜆 –
𝑓 –
𝑐 – - 9Frequencyrefers to the number of waves that pass a given point in each time period and is often expressed in terms of hertz (𝑯𝒛) or cycles per second.
𝑓 = 1/𝑇 - 10𝑓 – Frequency (𝐻𝑧) 𝑇 – Period (𝑠)𝑓 –
𝑇 – - 11Amplitudeis a measure of how big the wave is, which
- 12crest troughThe height from the equilibrium point to the highest point of a ____
The depth from the equilibrium point to the lowest point of a ____ - 131.) What is the wavelength of a radio wave with a given frequency of 900 𝑘𝐻𝑧?
- 142.) What is the frequency of violet light with a wavelength of 400 𝑛𝑚?
- 153.) What would be the frequency of a signal with a period of 0.00235?
- 164.) If a sampling signal with frequency 50 𝐻𝑧 is to be passed in a modulator, what will its period be over 1 second?
- 17modemis a contraction of the words “modulator” and “demodulator.” The sending modem modulates the data into a signal that is compatible with the phone line, and the receiving modem demodulates the signal back into digital data.
- 18Modulationis the process of converting data into radio waves by adding information to an electronic or optical carrier signal. A carrier signal is one with a steady waveform—constant height, or amplitude, and frequency.
- 19Amplitude modulation (AM)It is the modulation technique in which carrier amplitude varies based on analog baseband information signal to be transmitted in a wireless medium.
- 20Frequency modulation (FM)it is the modulation technique in which carrier frequency varies based on analog baseband information signal to be transmitted in a wireless medium.
- 21Phase modulation (PM)It is the modulation technique in which the carrier phase varies based on analog baseband information signal to be transmitted in a wireless medium.
- 22ADC (Analog-to-Digital Converter) thatconverts the analog value to a digital (binary) equivalent.
- 23Analog-to-Digital Conversion Process: From PAM to PCMSampling - lays out of the analog signal in a graph. The sampling process essentially converts analog amplitudes to discrete levels and is a type of modulation called pulse amplitude modulation (PAM).
Quantize the digital pulses- means to approximate the amplitude value of a pulse to the nearest integer on a predefined set of permitted integers. Quantization layers the discrete signal in the analog signal with less margin of error.
Encoding (pulse code modulation [PCM]) - converts discrete signals into highs (1) and lows (0), making these the binary equivalent of a time-bound discrete signal. Line coding is the process of converting digital data into digital signals. It is the representation of the digital signal to be transmitted by a digital waveform. - 24Channel ImpairmentsAttenuation
Noise
Atmospheric noise
Man-made noise is
Extraterrestrial noise
Thermal noise
Shot noise
Distortion - 25AttenuationThe strength of a signal decreases as it travels along a transmission medium. The amount of attenuation depends on the medium, but in general, it increases with distance.
- 26NoiseIt is usually defined as an unwanted signal that is superimposed on a desired signal.
- 27Atmospheric noiseis the noise that is caused by such natural atmospheric phenomena as lightning discharge in thunderstorms and other electrical disturbances that occur in nature.
- 28Man-made noiseis an electromagnetic (EM) noise that is caused by human activities, which are associated with the use of electrical equipment. High-voltage wires and fluorescent lamps also produce this type of noise.
- 29Extraterrestrial noiseis the noise that comes from outside the earth and includes solar noise and cosmic noise. Solar noise is the noise that originates from the sun, while cosmic noise is generated by distant stars.
- 30Thermal noiseoccurs in electrical conductors and is caused by the thermal agitation of the charges in the material.
- 31Shot noisearises from the time-dependent fluctuations in electrical current. This is caused by the discrete nature of electron charges. It is particularly noticeable in semiconductor devices.
- 32Signal-to-Noise Ratio 𝑆/𝑁 𝑟𝑎𝑡𝑖𝑜 = 𝑆/𝑁 𝑟𝑎𝑡𝑖𝑜 = 𝑆/𝑁 𝑟𝑎𝑡𝑖𝑜 = 𝑃𝑠 – 𝑃𝑛 – 𝑉𝑠 – 𝑉𝑛 –
- 331.) A signal of 2.5 𝑣𝑜𝑙𝑡𝑠 𝑟𝑚𝑠 is corrupted by 10 𝑚𝑉 𝑟𝑚𝑠 of noise in a circuit. What is the 𝑆/𝑁 𝑟𝑎𝑡𝑖𝑜 at this point?
- 342.) A signal with 350 watts is transmitted through a cable medium with 60 watts of noise. What is its 𝑆/𝑁 𝑟𝑎𝑡𝑖𝑜?
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- easy Data and Digital Communications Karteikarten am 02Handout1, erstellt von Eljin Aguilar am 12/08/2024.
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