gsm
Cable test is first understanding for any RF Engineer here i write how to test cable integrity and Cable loss and testing of Transmitter in gsm. Cable Integrity Test Cable integrity is checked by measuring VSWR. A good known cable is connected from the test transmitter to the wattmeter. The cable under test is placed … Read more
INTRODUCTION Predesign drive test for measurement integration This is at beginning of design when no site has been built or even selected. All test sites are temporary. Drive test is performed mostly for characterization of propagation and fading effects in the channel. The object is to collect field data to optimize and adjust the … Read more
Hata Model is applied for GSM Link Budget,here i write about its formula and Cell Size Estimation. Hata´S Empirical Formula PL = 69.55 +26.6log10fc – 13.82log10hb + (44.9 – 6.55log10hb)log10R – a(hm) -CF Where , fc – Frequency in MHZ hb – Transmitter antenna height hm – Receiver antenna height R – Radius in Km … Read more
Receiver sensitivity is the ability of the receiver to receive signals in the sense that any signal below the sensitivity is considered as noise and is not usable. Receiver sensitivity is given by S = Antenna Noise (dBm) + Receiver Noise Figure (dB) + C/N (dB) S = the receivers sensitivity C/N = Carrier to … Read more
The Mobile Equipment and SIM are the only parts of the GSM network which the subscriber will really see. Let’s see what inside it. GSM Mobile Equipment There are three main types of ME, these are listed below: Vehicle Mounted These devices are mounted in a vehicle and the antenna is physically mounted on the … Read more
Repeater units are designed to receive signals from a donor site, amplify and rebroadcast the donor sites signals into poor coverage areas or to extend the coverage range of the donor site. Repeater : These repeaters are bi-directional and do not translate frequency and subsequently are limited in output power and gain. Repeaters provide between … Read more
To protect the logical channels from transmission errors introduced by the radio path, many different coding schemes are used. The diagram below illustrates the coding process for speech, control and data channels; the sequence is very complex. The coding and interleaving schemes depend on the type of logical channel to be encoded. All logical channels … Read more
What is Echo Canceller and why it require in GSM – as from name Echo canceller is nothing but the process to remove duplicate signal or delayed signal, let’s see how it in GSM. An EC is used on the PSTN side of the MSC for all voice circuits. Echo control is required at the … Read more
To Improve Error Protection and Security of Data the Data is Interleaved and its type is Diagonal let’s check how it works. The diagram below illustrates, in a simplified form, diagonal interleaving applied to a 9.6 kbit/s data channel. The diagram shows a sequence of ‘data blocks’ after the encoding process previously described, all from … Read more
As All Channel Interleaving in GSM but control channel is some different interleaved its interleaving rectangular lets understand how it. The diagram below illustrates, in a simplified form, the principle of rectangular interleaving. This is applied to most control channels. The diagram shows a sequence of ‘control blocks’ after the encoding process. Each block contains … Read more