LEARNING OUTCOME :
Student be able to : -
Understand AM & FM block diagram
Describe function each block
Identify Radio Fault and Flow Chart
Troubleshoot and Report
Basic CD Player Block Diagram
and Function Each block
EXIT
RADIO is….
An electronic equipment which received
modulation radio frequency from transmitter
station and convert to audio signal.
Is one way communication.
Have 2 type of modulation :-
1) Amplitude Modulation (AM)
2) Frequency Modulation (FM)
AM & FM
AM – a process FM – a process which
which carrier signal carrier signal
amplitude change frequency change
according to according to
information signal information signal
amplitude frequency.
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Characteristic AM Radio FM Radio
Frequency Band 535 - 1700 KHz 88 - 108 MHz
IF frequency 455 KHz 10.7 MHz
Circuit Simple Complex
Bandwidth 10 KHz 200 KHz
Noise High Low
Efficiency Low High
Control Circuit AGC AGC & AFC
Rx & Tx Efficiency Low High
Transmission Distance Long Range Short Range
AMPLITUDE
MODULATION
[ AM ]
FREQUENCY
MODULATION[ FM ]
Freq. RF 1000 Khz
Freq. LO(Fo) = 1000Khz + 455Khz = 1455Khz
RF + Fo = (1000Khz + 1455Khz = 2455 Khz
IF = (Fo – RF) = (1455 Khz – 1000 Khz)= 455 Khz
Freq. RF 100 Mhz
Freq. LO(Fo) = 100 Mhz + 10.7 Mhz = 110.7 Mhz
RF + Fo = (100 Mhz + 110.7 Mhz = 210.7 Mhz
IF =(Fo – RF)= (110.7 Mhz –100 Mhz)= 10.7 Mhz
Function Each Block Of FM Radio
Continue…
Testing technique
2
Tracing
signal
1 3
- Search the fault on the
Signal radio block diagram
Alignment
Injection
- inject the 1 kHz signal Two conditions needed alignment:
1) For a new radio that is made in a factory,
it was do on the last production
2) While fix the radio (change IF coil), or
during alignment was disturbed by a user
Testing Method
RF RF RF AF
Generator Generator Generator Generator
- audio (1 kHz),
- radio freq (10.7 MHz-fm) Testing Equipment
(455 kHz-AM)
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A CD is a high - precision, compact, circular disk with a high storage
capacity.
On one side of the disk signals are recorded and on the other side of the
disk the label indicating the contents is printed.
Signals are stored on the CD in the form of digital data comprising
combinations of ‘on’ and ‘off’ signals (1’s and 0’s), recorded as pits and flat
areas on the disk surface, commencing from the centre of the disk.
Signal recording on the CD in digital format offers greater advantage
than in analogue format, Where signal loss and disturbances are
completely eliminated.
The main advantage of using a CD is that its fine track is not easily
damaged and does not wear out in use because There is no direct contact
between the reading mechanism and the disk surface.
The signals being read from the disk through a reflected beam of laser
light.
RF Amplifier • Choose and Amplified the RF signal
Decoder • Control the spindle motor and capture the digital signal
RAM • Store the temporary digital signal and to prevent signal loss
Digital Filter • Reduce hissing noise and disturbance
Digital to Analog • Convert and amplified digital signal to audio signal.
Converter
Audio Amplifier • Amplified audio signal to level that can drive the speaker.
