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
Refractive index of ionosphere is :
Zero
more than one
less than one
one
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
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
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
Modulation is the process of superposing:
low frequency audio signal on high frequency radio waves
low 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
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
The mobile telephones operate typically in the range of :
1- 100 MHz
100 - 200 MHz
1000 - 2000 MHz
800 - 950 MHz
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)
