Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
Q. Advanced Mobile Phone System?
Cellular systems employed cells with a radius in the range of 5-18 km. The base station usually transmitted at a power level of 35 W or less, and the mobile users transmitted at a power level of about 3 W, so that signals did not propagate beyond immediately adjacent cells. By making the cells smaller and reducing the radiated power, frequency reuse, bandwidth efficiency, and the number of mobile users have been increased. With the advent of small and powerful integrated circuits (which consume very little power and are relatively inexpensive), the cellular radio concept has been extended to various types of personal communication services using low-power hand-held sets (radio transmitter and receivers).
With analog cellular,or AMPS (Advanced Mobile Phone System), calls are transmitted in sound waves at 800 MHz to 900 MHz. This was the first mobile phone technology available in early 1980s. Digital cellular,or D-AMPS (Digital AMPS), transmits calls in bits at the same frequency as analog cellular, with improved sound quality and security. To send numerous calls at once, D-AMPS phones use either CDMA (Code Division Multiple Access) or TDMA (Time Division Multiple Access) technology; but CDMA phones won't work in TDMA areas, and vice versa. A dual-mode unit can switch to analog transmission outside of the more limited digital network.
PCS (Personal Communications Service) phones transmit at 1800 MHz to 1900 MHz and are smaller and more energy efficient. To get around the limited coverage, a dual-band digital phone (which switches to the lower digital frequency) and a trimode phone (which works in AMPS, D-AMPS, or PCS areas) has been developed. The GSM (Global System for Messaging communications) is the most widely accepted transmission method for PCS phones.
The per-phase synchronous reactance of a three-phase, wye-connected, 2.5-MVA, 6.6-kV, 60-Hz turboalternator is 10. Neglect the armature resistance and saturation. Calculate the vo
Draw layout of hydro-electric power plant and illustrate it briefly. Explain the following: a. Types of power plants b. Selection of power Plants
Normal 0 false false false EN-IN X-NONE X-NONE
Name the switching schemes used in a digital exchange
speed control of single phase ac motors
Q. Find load resistance and voltage? Let the amplifier block be connected to a current source at the input terminals, as shown in Figure(a), and to a load resistance R L at it
Static scherbius Drive By using this scheme, below and above synchronous speed can be obtained for an induction motor. There are two possible configurations to obtain s
Q. Introduction to power systems? Thomas A. Edison's work in 1878 on the electric light led to the concept of a centrally located power station with distributed electric power
Explain ferrites and its uses in high frequency devices. A group of magnetic alloys show the property of magnetisation that change, with percentage of various constituent atoms
For sign flag RP ( Return on Plus ) and RM ( Return on no minus ) Instructions RM returns from the subroutine to the calling program if sign flag is set (S=1). The in
Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd