Radio Frequency

 Introduction to Radio Frequency

Introduction 

In this area we will look at the area of the handset responsible for Transmitting, and Receiving information. will be for the next tutorial but little breakdown in this part

PLEASE NOTE:THIS TUTORIAL IS FOR LEVEL 3 MOBILE PHONE EXPERT WITH THE USE OF OSCILLOSCOPE.

Faults in this area can lead to: 

1. Parametric testing fail

2. RF calibration fail

3. Drops calls

4. Low signal strength

5. No service

The are two core elements to the RF section:

1.The Receiver - RX

2. The Transmitter – TX 

They carry out separate functions but they use similar building blocks to do so.

The Key Blocks are: 

1. Amplifiers

2. Filters

3. Mixers

4. Oscillators

Below image will describe what amplifier and filters are:

Amplifiers 

The Amplifier is a circuit used to increase the amplitude or strength of a signal. 

One of the uses of Amplifiers is to boost a signal after it has been filtered. 

                                          Radio frequency

                     Filters reduce the amount of signal we do 

    require as well as removing 

unwanted signals. 

     Filters 

Filters pass signals of a frequency that we require through them 

and reject signals of a frequency that we don’t require. 

Filters are often used to removed unwanted signals made by Mixers. 

The next page shows the block diagrams for the 4 main types of filter 

Filters can be made from discrete components such as Capacitors, Inductors and Resistors. 

Another form of Filter is the Surface Acoustic Wave or SAW Filter. These are normally implemented as a module in its own right. 

The input signal is turned into vibrations using the piezo electric effect. 

They are then turned back into electrical signals in the desired frequency range. 

Mixers 

In the Receiver circuit (RX) the Mixer block uses a signal 

from the VCO and mixes it with the signal picked up from 

the Operator Network. 

The mixer produces several signals output signals 

the key ones being: 

1. Sum signal 

2. Difference signal

Tx Block Diagram

Putting all previous discussed modules together we can also build a transmitter which represents as shown below.

Kindly download image for clearer image

Over to you, kindly study guide a i will be posting tutorial on how you can make use of Oscilloscope to troubleshoot your mobile phones.

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