What is 2.5G Technology | Second And A Half Generation

2.5G, which stands for “second and a half generation,” is a cellular wireless technology developed in between its predecessor, 2G, and its successor, 3G.

01-2.5G technology-video-conferencing-with-3g-technology

“2.5G” is an informal term, invented solely for marketing purposes, unlike “2G” or “3G” which are officially defined standards based on those defined by the International Telecommunication (ITU). The term “2.5G” usually describes a 2G cellular system combined with General Packet Radio Services (GPRS), or other services not generally found in 2G or 1G networks.

Wireless telecommunication technology like CDMA200 1x-RTT, Enhanced Data Rates for GSM Evolution (EDGE) or Enhanced General Packet Radio Service (EGPRS), since they have data transmission rates of 144 kbps or higher, may qualify as 3G technology. However, they are usually classified as 2.5G technology because they have slower network speeds than most 3G services.

01-GPRS-gsm-network-cdma network

GPRS is a service commonly associated with 2.5G technology. It has data transmission rates of 28 kbps or higher. GPRS came after the development of the Global System for Mobile (GSM) service, which is classified as 2G technology, and it was succeeded by the development of the Universal Mobile Telecommunication Service (UMTS), which is classified as 3G technology.

A 2.5G system may make use of 2G system infrastructure, but it implements a packet-switched network domain in addition to a circuit-switched domain. This does not necessarily give 2.5G an advantage over 2G in terms of network speed, because bundling of timeslots is also used for circuit-switched data services (HSCSD).

Terms in Engineering Measurements


01-the weighing scale-weighing machines-balance-calibration example

If a known input is given to the measurement system the output deviates from the given input, the corrections are made in the instrument and then the output is measured. This process is called “Calibration”.


Sensitivity is the ratio of change in the output signal to the change in the input signal.



Refers to the ease with which the readings of a measuring instrument can be read.

True size:

Theoretical size of a dimension which is free from errors.

Actual size:

Size obtained through measurement with permissible error.

01-true size-actual size-feet size-example-shoe-footwear


All the energy put into the stressed component when loaded is not recovered upon unloading. so the output of measurement partially depends on input called Hysteresis.

01-tachometer-digital tachometer-hysteresis due to pressure of force


The physical variables that are measured between two values. One is the higher calibration value Hc and the other is Lower value Lc.

01-range - read values from 0 to 11000 rpm - bezel meter - tachometer


The algebraic difference between higher calibration values to lower calibration values.


The minimum value of the input signal is required to cause an appreciable change in the output known as resolution.

Dead Zone:

It is the largest change in the physical variable to which the measuring instrument does not respond.


The minimum value of input signal that is required to make a change or start from zero.

01-threshold-minimum input given to start the engine-bike kick start action


The maximum distance through which one part of the instrument is moved without disturbing the other part.

01-backlash - continuous rotation possible without applying brake-SINGLE 3-PHASE AC ASYNCHRONOUS ELECTRIC MOTOR

Response Time:

The time at which the instrument begins its response for a change in the measured quantity.


The ability of the measuring instrument to repeat the same results during the act measurements for the same quantity is known as repeatability.


It is a characteristic of a measure or measuring instruments to give indications of the value of a measured quantity for which the average value differs from true value.


It means the magnitude of output signal of measuring instrument many times increases to make it more readable.

01-magnification-objective lens-magnify-loupe-ring


If an instrument does not reproduce the same reading at different times of measurement for the same input signal, it is said to be measurement drift.


It is the consistency of pattern of variation in measurement. When individual measurements are carried out the closeness of the agreement between the results of measurements of the same quantity.


The range about the measured value within the true value of the measured quantity is likely to lie at the stated level of confidence.


It is nothing establishing a calibration by step by step comparison with better standards.

01-traceability-calibration step by step-vacuum calibration


An apparent change in the position of the index relative is to the scale marks.

01-parallax-error-measurement of length-eye view