The mobile telephones operate typically in the range of :
1- 100 MHz
100 - 200 MHz
1000 - 2000 MHz
800 - 950 MHz
A message signal of frequency 50 Khz and peak voltage 5 volt is used to modulate a carrier frequency of 10 Mhz and peak voltage 15 volt .Determine (i) Modulation index (ii) Side bands produced.
(i) Modulation index = 1
(ii) Upper side band = 5500Khz & Lower side band = 4500Khz
(i) Modulation index = 0.45
(ii) Upper side band = 9200Khz & Lower side band = 4300Khz
(i) Modulation index =1.25
(ii) Upper side band = 11765Khz & Lower side band = 10300Khz
(i) Modulation index = 0.33
(ii) Upper side band = 10050Khz & Lower side band = 9050Khz
The modulation in which pulse duration varies in accordance with the modulation signal is known as :
PAM
PPM
PWM
PCM
Give the range of satellite communication:
Uplink: 5.925 to 6.425 GhzDownllink: 3.7 to 4.2 Ghz
Uplink: 8.25 to 9.25 GhzDownllink: 2.75 to 6.23 Ghz
Uplink: 10.925 to 11.425 GhzDownllink: 3.4 to 5.2 Ghz
Uplink: 14.215 to 15.265 GhzDownllink: 9.7 to 10.2 Ghz
Which of the following device is full duplex?
Mobile phone
Walky - talky
Loudspeaker
Radio
Modulation is the process of superposing:
low frequency audio signal on high frequency waves
iow frequency radio signal on low frequency audio waves
high frequency radio signal on low frequency audio signal
high frequency audio signal on low frequency radio waves
A 1000 kHz carrier wave is modulated by an audio signal of frequency range 100 - 5000 Hz.Then the width of the channel in kHz is :
10
20
30
40
Identify the incorrect statement from the following
AM detection is carried out using a rectifier and an envelop detector
Pulse position denotes the time of rise or fall of the pulse amplitude
Modulation index µ is kept ≥ 1, to avoid distortion.
Facsamile ( FAX) scans the contents of the document to create electronic signals
