Which of the following device is full duplex?
Mobile phone
Walky - talky
Loudspeaker
Radio
The modulation in which pulse duration varies in accordance with the modulation signal is known as :
PAM(Pulse amplitude modulation)
PPM(pulse position modulation)
PWM(Pulse width modulation)
PCM(Pulse code modulation)
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
The mobile telephones operate typically in the range of :
1- 100 MHz
100 - 200 MHz
1000 - 2000 MHz
800 - 950 MHz
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
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 frequency of audio analog signals lies in the range :
20 kHz to 20 MHz
12 Hz to 20 MHz
20 Hz to 20 MHz
20 Hz to 20 kHz
Identify the incorrect statement from the following:
AM detection is carried out using a rectifier and an envelop detector
Pulse amplitude denotes the variation of amplitude of the carrier signal varies in accordance with the message signal.
Modulation index µ is kept ≥ 1, to avoid distortion.
Facsamile ( FAX) scans the contents of the document to create electronic signals
Refractive index of ionosphere is :
Zero
more than one
less than one
one
