15 June 2011

Weaving Textile Engineering

Weaving is a textile craft in which two distinct sets of yarns or threads are interlaced to form a fabric or cloth. The threads which run lengthways are called the warp and the threads which run across from side to side are the weft or filling.
Cloth is usually woven on a loom, a device that holds the warp threads in place while filling threads are woven through them. Weft is an old English word meaning "that which is woven" A fabric band which meets this definition of cloth (warp threads with a weft thread winding between) can also be made using other methods, inclluding tablet weaving, backstrap, or other techniques without looms.
The way the warp and filling threads interlace with each other is called the weave. The majority of woven products are created with one of three basic weaves: plain weave, satin weave, or twill. Woven cloth can be plain (in one colour or a simple pattern), or can be woven in decorative or artistic designs, including tapestries. Fabric in which the warp and/or weft is tie-dyed before weaving is called ikat.
Though traditional handweaving and spinning remain popular crafts, nowadays the majority of commercial fabrics in the West are woven on computer-controlled Jacquard looms. In the past, simpler fabrics were woven on dobby looms, while the Jacquard harness adaptation was reserved for more complex patterns. Some believe the efficiency of the Jacquard loom, with its Jacquard weaving process, makes it more economical for mills to use them to weave all of their fabrics, regardless of the complexity of the design.


Telenor Pakistan BTS site visit - Part 2


Diversity techniques
To improve the quality of the received signal, often two receiving antennas are used, placed at an equal distance to an uneven multiple of a quarter of wavelength (for 900 MHz the wavelength it is 30 cm). This technique, known as antenna diversity or space diversity, avoids interruption caused by path fading. The antennas can be spaced horizontally or vertically. Horizontal spacing requires more complex installation, but better performance is obtained in this configuration.
Other than antenna or space diversity, there are other diversity techniques such as frequency/time diversity, antenna pattern diversity, and polarization diversity.
Splitting
The flow of power within a particular area of the cell, known as sector. Every field can therefore be considered like one new cell. By using directional antennas, the co-channel interference is reduced. A typical structure is the trisector, also known as clover, in which there are three sectors, each one served by separate antennas. Every sector has a separate direction of tracking of 120° with respect to the adjacent ones. If not sectorised, the cell will be served by an omnidirectional antenna, which radiates in all directions. Bisectored cells are also implemented with the antennas serving sectors of 180° separation to one another.

Telenor Pakistan BTS site visit - Part 1

A base transceiver station (BTS) or cell site is a piece of equipment that facilitates wireless communication between user equipment (UE) and a network. UEs are devices like mobile phones (handsets), WLL phones, computers with wireless internet connectivity, WiFi and WiMAX gadgets etc. The network can be that of any of the wireless communication technologies like GSM, CDMA, WLL, WAN, WiFi, WiMAX etc.
BTS is also referred to as the radio base station (RBS), node B (in 3G Networks) or, simply, the base station (BS). For discussion of the LTE standard the abbreviation eNB for evolved node B is widely used.

Pakistani Mechatronics Engineers