FUTURE WORK: DESIGN AND ANALYSIS OF A BANDPASS FILTER

FUTURE WORK:  DESIGN  AND  ANALYSIS  OF  A  BANDPASS  FILTER

 

For faithful reproduction of signal it becomes necessary  to eliminate any kind of spurious or unwanted signals which may get introduced into the system either at the transduction stage or at the signal conditioning stage.The filters are thus designed to pass the signals of wanted frequency and to reject the signals of unwanted frequencies which may be unwanted harmonics and noise. The harmonics or noise may be due to some form of distortion.

         The band pass filter is a filter that allows a certain band of frequencies to pass through and attenuates all other frequencies below and above the pass band.This pass band is known as the bandwidth of the filters.It is obtained by cascading a high pass RC  filter to a low pass RC filter.

 

 

Ø  Experimental setup used in studying the characteristics of band pass filter:

 

         To observe the characteristics of a microwave band pass filter,the following experimental setup is used:

 

 

connector

Signal source

Power meter

Power sensor

Band pass filter

connector

                

                     −→                    −→                    −→               

 

 

 

■ Design of a Bandpass filter

     

         A microwave band pass filter can be visualized as under :

 

 

 

 

 Using XGMS we intend to design a microwave BPF  as shown in the above figure.

 

                                  Our future work will further comprise of analyzing the filter with the following specifications : Edge coupled ,Chebyshev, Microstrip type, 3^rd order and a definite BW range.

 

MICROWAVE BANDPASS FILTER

ABSTRACT

This paper deals with introduction, band range, application, topologies and design of microwave band pass filter of given specification. Microwave band pass filter of given specification is obtained from chebyshev, maximally flat and Butterworth responses. Different topologies of microwave band pass filter is also dealt. The terms like scattering matrix,VSWR,refection coeff.,return loss, insertion loss and smith chart is also dealt.Simulation based filter design is edge coupled ,microstrip type,3^rd order and a definite BW range

VOICE SWITCHING IN CELLULAR NETWORKS : Introduction

INTRODUCTION:

} In near future most computer will be portable and users will access network without wire i.e., wireless

} An acceptable level of intelligibility of speech is obtained by transmitting frequencies in the range 300-3400 Hz.

} Voice is sampled at 8000 samples per second with 8 bits per sample . This results in a digital signal of 64kbps which is sent as data frames over a circuit switched network

VOICE SWITCHING IN CELLULAR NETWORKS :History of Cellular Radio Networks

In 1946, the first car-based telephone was set up in St. Louis, Missouri, USA. The system used a single radio transmitter on top of a tall building. A single channel was used, therefore requiring a button to be pushed to talk, and released to listen. This half duplex system is still used by modern day CB radio systems utilized by police and taxi operators. In the 1960s, the system was improved to a two-channel system, called the improved mobile telephone system (IMTS). Since frequencies were limited, the system could not support many users.

Cellular radio systems, implemented for the first time in the advanced mobile phone system (AMPS), support more users by allowing reuse of frequencies. AMPS is an analogue system, and is part of first generation cellular radio systems. In contrast, second generation systems are digital. In the USA, two standards are used for second generation systems: IS-95 (CDMA) and IS-136 (D-AMPS). Europe consolidated to one system called the global system for mobile communications (GSM). Japan uses a system called personal digital cellular (PDC).

Present Day

Cellular radio is the fastest growing segment of the communications industry. Cellular companies reported a subscription base of more than 200 million people in 1997. This figure grows by an average of 150,000 new subscribers every day.

Because of Europe's early commitment to one system, it is leading the field in both its subscriber base and data transmission capabilities. GSM is used in over 100 countries by over 215 operators inside and outside of Europe. The Japanese PDC system is the second largest digital cellular system, followed by the IS-54/136 and IS-95 systems used in North America.

Current cellular radio systems are in their second generation (2G). The third generation of cellular systems (3G systems) will allow different systems to interoperate in order to attain global roaming across different cellular radio networks. The International Telecommunication Union (ITU) has been doing research on 3G systems since the mid 1980s. Their version of a 3G system is called international mobile telecommunications - 2000 (IMT-2000).

VOICE SWITCHING IN CELLULAR NETWORKS :How Does it Work?

In the following explanation, a cellular telephone or any other device that can connect to a cellular radio network will be referred to as a mobile station. This is in keeping with the literature on the subject.

A cellular network consists of both land and radio based sections. Such a network is commonly referred to as a PLMN - public land mobile network. The network is composed of the following entities:

• Mobile station (MS): A device used to communicate over the cellular network.
• Base station transceiver (BST): A transmitter/receiver used to transmit/receive signals over the radio interface section of the network.
• Mobile switching center (MSC): The heart of the network which sets up and maintains calls made over the network.
• Base station controller (BSC): Controls communication between a group of BSTs and a single MSC.
• Public switched telephone network (PSTN): The land based section of the network.
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