What do you mean by dial pulses, Electrical Engineering

Assignment Help:

Q. What do you mean by Dial Pulses?

Dial Pulses: Dial pulsing (many times known as rotary dial pulsing) is the method originally used to transfer digits from a telephone set to local switch. Pulsing digits from a rotary switch began soon after invention of the automatic switching machines. The idea of dial pulsing is quite simple and is depicted in figure. Process begins when telephone set is lifted off hook, completing a path for current through local loop. When switching machine detects off-hook condition, it responds with dial tone. After hearing the dial tone, subscriber begins dial pulsing digits by rotating a mechanical dialling mechanism and then letting it returns to its rest position. As rotary switch returns to its rest position, it outputs a series of dial pulses corresponding to digit dialled.

Whenever a digit is dialled, loop circuit alternately opens (breaks) and closes (makes) a prescribed number of times. Number of switch make/break sequences corresponds to digit dialled (that is the digit 3 produces three switch openings and three switch closers).

Dial pulses take place at 10 make/break cycles per second (which is a period of 100 ms per pulse cycle). For illustration digit 5 corresponds to five make/break cycles lasting a total of 500ms. Switching machine senses and counts the number make/break pairs in sequence.

829_What do you mean by Dial Pulses.png

Break time is nominally 61 ms and make time is nominally 39ms. Digits are separated by idle period of 300 ms called inter digit time. It is important that switching  machine recognize the  inter  digit  time  so  that  it  can  separate  pulses from successive digits. Central office switch incorporates a special timeout circuit to ensure that break part of dialling pulse isn't misinterpreted as phone being returned to its on-hook (idle) condition.


Related Discussions:- What do you mean by dial pulses

Covalent bonding, Covalent Bonding Exhibited through the diamond la...

Covalent Bonding Exhibited through the diamond lattice semiconductors. Each atom enclosed by four nearest neighbors, each comprising four electrons in the outermost orbi

Digital frequency metre, what is digital frequency metre?working principle ...

what is digital frequency metre?working principle its operation and types application,advantages ,disadvantages

Structure of bipolar junction transistor, Structure of Bipolar junction tra...

Structure of Bipolar junction transistor:  A BJT contains three differently doped semiconductor regions that are: emitter region, base region and collector region. These regio

Mesh analysis procedure, Mesh analysis procedure : 1.  Assign a distinct...

Mesh analysis procedure : 1.  Assign a distinct current to every closed loop of the network. 2.  Apply KVL around every closed loop of the network. 3.  Solve the resulting

Find the quantum levels, A uniform quantizer is said to have 16 levels, and...

A uniform quantizer is said to have 16 levels, and hence is called a midriser. The saturation levels are to correspond to extreme values of the message of 1 V ≤  f(t) ≤ 17 V. Find

Transistor, what part the transistor plays in the circuit

what part the transistor plays in the circuit

Develop a block diagram for a bcd encoder, Q. Based on the 8421 BCD code fo...

Q. Based on the 8421 BCD code for decimal digits 0 through 9, develop a block diagram for a BCD encoder and its implementation scheme.

Explain open loop control systems, Explain Open Loop Control Systems In...

Explain Open Loop Control Systems In an open-loop control system, the controller independently computes exact voltage or current required by the actuator to do the job and send

Determine the kva rating of the synchronous motor, An induction motor takes...

An induction motor takes 350 kW at 0.8 power factor lagging while driving a load. When an overexcited synchronous motor taking 150 kW is connected in parallel with the induction mo

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

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!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd