TECH 1002TECH 1002

Radio Project AssignmentRadio Project Assignment

Katie Rhodes – P09290071Katie Rhodes – P09290071

Joshua Coyne – P09305892Joshua Coyne – P09305892

Anthony Gale – P08253822Anthony Gale – P08253822

IntroductionIntroduction

Our objective in this assignment is to build Our objective in this assignment is to build a working radio receiver and audio a working radio receiver and audio amplifier. amplifier.

Once constructed we will experiment with Once constructed we will experiment with what AM transmissions our radio can what AM transmissions our radio can receive.receive.

EquipmentEquipment

• Soldering EquipmentSoldering Equipment• Circuit BoardCircuit Board• IC MK484IC MK484• Transistor BC548BTransistor BC548B• Ferrite Rod & Enamelled Copper Ferrite Rod & Enamelled Copper

WireWire• Two 100k Resistors, 1K Resistors Two 100k Resistors, 1K Resistors

and one 270R Resistorand one 270R Resistor• Slide SwitchSlide Switch• Two 100nF capacitors, one 10nF Two 100nF capacitors, one 10nF

capacitor and one 47uF capacitorcapacitor and one 47uF capacitor• Headphone SocketHeadphone Socket• AA Battery HolderAA Battery Holder

• Soldering EquipmentSoldering Equipment• Circuit BoardCircuit Board• Three 1K resistors, two 470R Three 1K resistors, two 470R

resistors and one 1R resistorresistors and one 1R resistor• Two 330uF electronic capacitates Two 330uF electronic capacitates

and one 10uF electrolytic and one 10uF electrolytic capacitorcapacitor

• One 150pF ceramic capacitorOne 150pF ceramic capacitor• One 100nF polyester capacitor One 100nF polyester capacitor

and One 47nF polyester capacitorand One 47nF polyester capacitor• IC TBA 820MIC TBA 820M• One 8 Ohm speakerOne 8 Ohm speaker• 100mm of speaker cable100mm of speaker cable• One slide switchOne slide switch• One 3.5 plug to plug cableOne 3.5 plug to plug cable• One 3.5mm stereo jack socketOne 3.5mm stereo jack socket

Components for the Radio Receiver Components for the Audio Amplifier

MethodMethod

The construction of our radio receiver The construction of our radio receiver took place over a course of lab sessions took place over a course of lab sessions in the University’s Radio Labsin the University’s Radio Labs

MethodMethod

• An aerial was created An aerial was created consisting of wrapping the consisting of wrapping the enamelled copper wire enamelled copper wire loosely around the ferrite loosely around the ferrite rodrod

• This procedure took time This procedure took time as the wire was required to as the wire was required to be wrapped around the be wrapped around the rod, with no overlapping, a rod, with no overlapping, a total of 55 times in order to total of 55 times in order to guarantee the best quality guarantee the best quality of transmissionof transmission

• The next step was the The next step was the circuit boardcircuit board

• All the circuit components All the circuit components required soldering into required soldering into placeplace

• Smaller components such Smaller components such as the resistors and as the resistors and capacitors were soldered capacitors were soldered firstfirst

• Next were the BC548B, Next were the BC548B, MK484, radio IC and MK484, radio IC and variable tuning capacitorvariable tuning capacitor

• The larger components The larger components such as the aerial, battery such as the aerial, battery hold and headphone hold and headphone socket were then attached socket were then attached

MethodMethod

• The construction of the The construction of the Audio Amplifier followed Audio Amplifier followed a similar processa similar process

• The smaller The smaller components such as components such as the resistors and the resistors and capacitors were capacitors were soldered first followed soldered first followed by the components like by the components like the battery snap, the battery snap, speaker and switchspeaker and switch

TestingTesting

• The radio receiver was The radio receiver was first tested using first tested using headphone to headphone to determine its qualitydetermine its quality

• The use of a audio The use of a audio amplifier at this stage amplifier at this stage could distort the could distort the quality of the sound if quality of the sound if there were circuit there were circuit imperfectionsimperfections

• The first transmission The first transmission received by our received by our receiver was mainly receiver was mainly one of noise and one of noise and interferenceinterference

• By moving the copper By moving the copper wire up and down the wire up and down the ferrite rod however we ferrite rod however we began to receive a began to receive a signal from a local signal from a local radio stationradio station

TestingTesting

Sabras RadioSabras Radio BBC Asian NetworkBBC Asian Network

Local station Sabras Radio’s transmission was received. The signal was quite distorted and unclear though

BBC’s Asian Network was the other signal we were able to pick up. Once again the signal received was distorted and very difficult to listen to.

The quality of both station’s transmissions was worsened when the audio amplifier was attached

Results ExplanationResults Explanation

The three integral sub-systems which The three integral sub-systems which must be working for the radio must be working for the radio receiver to be successful are the receiver to be successful are the tuning, demodulation and tuning, demodulation and amplification ones.amplification ones.

The testing of our receiver helps us The testing of our receiver helps us identify any problems with theseidentify any problems with these

Results ExplanationResults Explanation

• The picked up radio The picked up radio station proved the station proved the tuning element to be in tuning element to be in orderorder

• Our ability to identify the Our ability to identify the signals showed the signals showed the demodulation part to be demodulation part to be within working orderwithin working order

• Interference and Interference and distortion on the signal distortion on the signal however showed that however showed that the MK484 integrated the MK484 integrated circuit component may circuit component may not have been soldered not have been soldered correctlycorrectly

• Low volume on the Low volume on the output to the output to the headphones means headphones means amplification element amplification element of our radio wasn’t in of our radio wasn’t in full working orderfull working order

• The BC548 transistor is The BC548 transistor is a crucial component for a crucial component for the amplification the amplification element and the element and the incorrect installation of incorrect installation of that could of caused that could of caused the problemsthe problems

Results ExplanationResults Explanation

• The poorer quality of The poorer quality of the BBC Asian the BBC Asian Network signal could Network signal could be connected to its be connected to its lower broadcasting lower broadcasting frequencyfrequency

• Both station’s signals Both station’s signals are transmitted from are transmitted from the Freemans the Freemans Common transmitter Common transmitter in Leicesterin Leicester

• The differing The differing receptions despite the receptions despite the fact both signals fact both signals travelled the same travelled the same amount of distance to amount of distance to where we tested our where we tested our radio led us to believe radio led us to believe there was a difference there was a difference in the broadcasting in the broadcasting frequencyfrequency

• BBC Asian Network -BBC Asian Network -837 kHz837 kHz

• Sabras Radio – 1260 Sabras Radio – 1260 kHzkHz

The higher frequency on the Sabras Radio station explains it being the better of the two signals

AM Transmission AM Transmission DemonstrationDemonstration

The aim of this experiment is to show The aim of this experiment is to show the amplitude modulation of a carrier the amplitude modulation of a carrier wave by an audio information signal. wave by an audio information signal.

The objective is the demonstrate the The objective is the demonstrate the technique of amplitude modulation technique of amplitude modulation used in radio transmissions.used in radio transmissions.

AM Transmission AM Transmission DemonstrationDemonstration• Equipment required for Equipment required for

this demonstration was an this demonstration was an Oscilloscope, a Function Oscilloscope, a Function Generator, a Wire Aerial Generator, a Wire Aerial and a AM Radio Receiverand a AM Radio Receiver

• The wire aerial was The wire aerial was connected to the function connected to the function generator and then into generator and then into the oscilloscopethe oscilloscope

• This allows the signal to be This allows the signal to be transmitted from the transmitted from the generator but also viewed generator but also viewed on the screen on the on the screen on the oscilloscopeoscilloscope

• The carrier wave transmitted The carrier wave transmitted by the generator was set to by the generator was set to 500Hz and the Modulation 500Hz and the Modulation wave frequency was 600 kHz. wave frequency was 600 kHz.

• The radio receiver was tuned The radio receiver was tuned to this frequency to narrow to this frequency to narrow the amount of signals collect the amount of signals collect down to our chosen onedown to our chosen one

• As soon as the modulation As soon as the modulation was applied to the carrier was applied to the carrier wave the monotone sound is wave the monotone sound is demodulated and amplified demodulated and amplified by the radio receiver.by the radio receiver.

Explanation of ResultsExplanation of Results

The change in waveforms on the The change in waveforms on the oscilloscope shows the technique of the oscilloscope shows the technique of the amplitude modulation for radio transmission. amplitude modulation for radio transmission. This is that the carrier and the modulation This is that the carrier and the modulation wave are merged to transmit information. wave are merged to transmit information.

The carrier wave is stripped away by the The carrier wave is stripped away by the receiver’s demodulation and then carries the receiver’s demodulation and then carries the remaining audio information in the remaining audio information in the modulation wave to the amplifier.modulation wave to the amplifier.

ConclusionConclusion

In conclusion the construction and testing of In conclusion the construction and testing of our Am radio should be deemed a success. our Am radio should be deemed a success. The circuits and components were all The circuits and components were all assembled to a level where we were able to assembled to a level where we were able to receive and identify two transmissions. receive and identify two transmissions.

The poor quality on both of the The poor quality on both of the transmissions means the quality of our transmissions means the quality of our output could be improved. This is achieved output could be improved. This is achieved through taking more care when soldering through taking more care when soldering the circuits and attaching the components.the circuits and attaching the components.

PhotographsPhotographs

1 2

3 4

PhotographsPhotographs

5 6

7 8

PhotographsPhotographs

• Image 1- The Image 1- The soldering processsoldering process

• Image 2 - Completed Image 2 - Completed radio circuit board radio circuit board with aerialwith aerial

• Image 3 - Radio circuit Image 3 - Radio circuit boad (back view)boad (back view)

• Image 4 - Ferrite Rod Image 4 - Ferrite Rod and wire acting as the and wire acting as the aerialaerial

• Image 5&6 - Amplifier Image 5&6 - Amplifier circuit boardcircuit board

• Images 7&8 – Images 7&8 – Completed amplifier Completed amplifier with speakerwith speaker

BibliographyBibliography

• BBC Asian Network image in slide 8 – BBC Asian Network image in slide 8 – http://simplybangra.com/albumcoverhttp://simplybangra.com/albumcovers/Sept09/bbc_a.jpgs/Sept09/bbc_a.jpg

• Sabras Radio image in slide 8 – Sabras Radio image in slide 8 – http://www.sabrasradio.com/sabras.phttp://www.sabrasradio.com/sabras.phphp

• DMU logo in slide 4 - DMU logo in slide 4 - http://www.cogain.org/cogain2007/dhttp://www.cogain.org/cogain2007/dmu-logo.gifmu-logo.gif