1 modern electronic
1. Define Modulation Modulation process of putting information onto a high-frequency carrier for transmission.
2. What is carrier frequency? In essence, then the transmission takes place at the high frequency (the carrier) which has been modified to “carry” the lower-frequency information.
3. Describe the two reasons that modulation is used for communications transmission. The modulated stage accepts two inputs, the carrier and the information (intelligence) signal.
4. List three parameters of a high-frequency carrier that may be varied by a low-frequency intelligence signal. 5. What are the frequency ranges include in the following frequency subdivision: MF ,HF, VHF, UHF,SHF?
MF= 300 kHz-3MHz
HF= 3-30MHz
VHF= 30-300MHz
UHF=300 MHz-3GHz
SHF= 3-30 GHz
9. Convert the following powers to their dbm equivalents:
(a) p=1W (30 dbm 0
(b) p= 0.001 W (0 dbm)
(c) p=0.0001 w (-10 dbm)
(d) p=25uW (-16 dbm)
15. Define electrical noise, and explain why it is so troublesome to a communications receiver.
Electrical noise may be define as any undesired voltages or currents that ultimately end up appearing in the receiver output. To the listener this electrical noise often manifests itself as static.
16. Explain the difference between external and internal noise. External noise in a recived radio signal that has been introduced by the transmitting medium and the internal noise in a radio signal that has been introduced by the receiver.
17. List and briefly explain the various types of external noise. Human-Made Noise It is often produced by spark-producing mechanisms such as engine ignition systems,fluorescent lights, and commutators in electric motors. Atmospheric Noise Is caused by naturally occurring disturbances in the earth’s atmosphere, with lightning discharges being the most prominent contributors.
23.Calculate the S/N ratio for a receiver output of 4v signal and 0.48v noise both as a ratio and in
2. What is carrier frequency? In essence, then the transmission takes place at the high frequency (the carrier) which has been modified to “carry” the lower-frequency information.
3. Describe the two reasons that modulation is used for communications transmission. The modulated stage accepts two inputs, the carrier and the information (intelligence) signal.
4. List three parameters of a high-frequency carrier that may be varied by a low-frequency intelligence signal. 5. What are the frequency ranges include in the following frequency subdivision: MF ,HF, VHF, UHF,SHF?
MF= 300 kHz-3MHz
HF= 3-30MHz
VHF= 30-300MHz
UHF=300 MHz-3GHz
SHF= 3-30 GHz
9. Convert the following powers to their dbm equivalents:
(a) p=1W (30 dbm 0
(b) p= 0.001 W (0 dbm)
(c) p=0.0001 w (-10 dbm)
(d) p=25uW (-16 dbm)
15. Define electrical noise, and explain why it is so troublesome to a communications receiver.
Electrical noise may be define as any undesired voltages or currents that ultimately end up appearing in the receiver output. To the listener this electrical noise often manifests itself as static.
16. Explain the difference between external and internal noise. External noise in a recived radio signal that has been introduced by the transmitting medium and the internal noise in a radio signal that has been introduced by the receiver.
17. List and briefly explain the various types of external noise. Human-Made Noise It is often produced by spark-producing mechanisms such as engine ignition systems,fluorescent lights, and commutators in electric motors. Atmospheric Noise Is caused by naturally occurring disturbances in the earth’s atmosphere, with lightning discharges being the most prominent contributors.
23.Calculate the S/N ratio for a receiver output of 4v signal and 0.48v noise both as a ratio and in