 | Radio and Electronics (DED Philippinen, 66 p.) |
 |  | (introduction...) |
|  | 1. INTRODUCTION |
| | (introduction...) |
| | 1.1. A TRIAL TO STATE A DEFINITION OF ELECTRONICS |
| | 1.2. A SHORT HISTORY OF ELECTRONICS |
| | 1.3. CLASSIFICATION OF ELECTRONIC DEVICES |
| | 2. PRINCIPLES OF RADIO COMMUNICATION UNICATION |
| | 2.1. BASICAL IDEAS ABOUT COMMUNICATION |
| | 2.2. DEVELOPMENT OF LONG DISTANCE COMMUNICATION |
| | 2.3. FIDELITY AND DISTORTION |
| | 3. TRANSDUCERS |
| | (introduction...) |
| | 3.1. MICROPHONES |
| | 3.2. LOUDSPEAKERS |
| | 3.3. THE TELEPHON SYSTEM |
| | 3.4. PROBLEM OF FREQUENCY RANGES |
| | 3.5. BANDWIDTH |
| | 4. RADIOWAVES |
| | (introduction...) |
| | 4.1. ORIGIN OF RADIOWAVES |
| | 4.2. PARAMETERS OF ELECTROMAGNETIC WAVES |
| | 4.3. PROPAGATION OF RADIOWAVES |
| | 4.4. SPECTRUM OF RADIOWAVES AND BANDS OF RADIOWAVES |
| | 5. MODULATION OF RADIOWAVES |
| | (introduction...) |
| | 5.1. THE AMPLITUDE MODULATION (AM) |
| | 5.2. FREQUENCY MODULATION (FM) |
| | 5.3. SIDEBANDS |
| | 5.4. TRANSMISSION OF RADIOSIGNALS |
| | 6. RECEPTION OF RADIOSIGNALS (AM - TYPE) |
| | 6.1. AERIAL |
| | 6.2. THE TUNED CIRCUIT |
| | 6.3. INCIDENTAL REMARK ON BLOCK DIAGRAMS |
| | 6.4. DETECTOR OR DEMODULATOR |
| | 6.5. POWER SUPPLY |
| | 6.6. AMPLIFIER |
| | 6.7. SUPERHET RECEIVER (the SUPER) |
| | 6.8 INCIDENTAL REMARK ON MIXING FREQUENCIES |
| | 6.9. CONSTRUCTION OF A SUPERHETRADIO |
| | 7. COMPONENTS OF MODERN RADIO RECEIVERS |
| | 7.1.1. HANDLING OF ELECTRONIC COMPONENTS |
| | 7.1.2. HANDLING OF PRINTED CIRCUITS |
| | 7.1.3. DIFFERENTIATION OF COMPONENTS |
| | 8. PASSIVE COMPONENTS |
| | 8.1. RESISTORS ELECTRICAL CHARACTERISTICS |
| | 8.2. CAPACITORS |
| | 8.3. INDUCTORS |
| | 8.4. COMBINATION OF PASSIVE COMPONENTS |
| | 8.4.1. SERIES CONNECTION OF R AND C, OR R AND L |
| | 8.4.2. COMBINATION OF L AND C, RESONANT (TUNED) CIRCUITS |
| | 8.4.3. TUNED CIRCUIT CONNECTED TO AN AC-VOLTAGE |
| | (introduction...) |
| | 8.4.4.1. QUALITY OF TUNED CIRCUITS |
| | 8.4.4.2. BANDWIDTH |
| | 9. ACTIVE COMPONENTS -1- DIODES |
| | 9.1. CHARACTERISTICS OF SEMICONDUCTORS |
| | 9.2. THE PN-JUNCTION OR DIODE |
| | (introduction...) |
| | 9.2.1. PN-JUNCTION CONNECTED TO VOLTAGE |
| | 9.2.2. CHARACTERISTICS OF A PN-JUNCTION OR DIODE |
| | 9.2.3. ZENERDIODE |
| | 10. BLOCKS OF RADIOS / -1- / POWER SUPPLIES |
| | 10.1. GENERAL CONSIDERATIONS |
| | 10.2. TRANSFORMER |
| | 10.3. THE RECTIFIERS. |
| | 10.4. SMOOTHING AND FILTER CIRCUITS |
| | 10.4.1. THE RESERVOIR CAPACITOR |
| | 10.4.2. FILTER CIRCUITS |
| | 10.5. STABILIZATION |
| | 10.5.1. GENERAL REMARKS |
| | 10.5.1.1. LOAD VARIATIONS |
| | 10.5.1.2. INTERNAL RESISTANCE OF VOLTAGESOURCES |
| | 10.5.1.3. PROBLEMS CAUSED BY THE SMOOTHING CIRCUIT |
| | 10.5.5. METHODS OF STABILIZATION |
| | (introduction...) |
| | 10.5.5.1. PARALLEL-STABILIZATION |
| | 10.5.2.2. SERIES STABILIZATION |
| | 11. ACTIVE COMPONENTS -2- / TRANSISTORS |
| | 11.1. CONSTRUCTION OF A TRANSISTOR |
| | 11.2. CHARACTERISTICS OF TRANSISTORS |
| | (introduction...) |
| | 11.2.1 HANDLING OF CHARACTERISTICS OF TRANSISTORS |
| | 11.2.1.1. CONSTRUCTION OF THE STATIC-MUTUAL-CHARACTERISTICS |
| | 11.2.1.2. CONSTRUCTION OF THE DYNAMIC MUTUAL CHARACTERISTICS |
| | 11.2.1.3. CONSTRUCTION OF THE MAXIMUM-POWER-LINE |
| | 12. AMPLIFIERS |
| | (introduction...) |
| | 12.1. STRUCTURE OF A CLASS A AMPLIFIER |
| | 12.2. FUNCTION OF A SIMPLE CLASS A AMPLIFIER |
| | 12.3. ADVANCED CLASS A AMPLIFIER |
| | 12.4. STABILIZATION OF THE QUIESCENT VOLTAGE |
| | 13. CLASS B AMPLIFIERS |
| | 13.1. LIMITS OF CLASS A AMPLIFIERS |
| | 13.2. CLASS B AMPLIFIERS WITH TRANSFORMERS |
| | 13.3. CLASS B AMPLIFIERS WITHOUT TRANSFORMERS |
| | 13.4. POWER AMPLIFIER WITH COMPLIMENTARY TRANSISTORS. |
| | 14. DETECTOR OR DEMODULATOR |
| | 15. AGC-AUTOMATIC GAIN CONTROL |
| | 16. IF-AMPLIFIERS |
| | 17. FEEDBACK |
| | 18. OSCILLATORS |
| | 19. FREQUENCY CHANGERS MIXERSTAGE |
| | 20. DECOUPLING CIRCUITS |
| | 21. MATCHING OF AMPLIFIERSTAGES |
| | 22. COUPLING OF AMPLIFIERSTAGES |
| | 23. RADIO SERVICING |
| | 23.1. IMPORTANCE AND SUBJECT OF FAULT FINDING |
| | 23.2. FAULTS AND FAULT FINDING |
| | 23.3. FAULT FINDING METHODS |
| | 24. THE USE OF THE OSCILLOSCOPE |
(introduction...)
Let us first sum up, what we know till here:
1. Our ears are able to receive frequencies within the so called audio-frequency spectrum which starts at about 30 Hz and ends below 20 000 Hz.2. Only frequencies of a minimum of about 30 000 Hz can be transmitted in form of electromagnetic waves.
3. Therefore it is easy to understand that we will hear nothing if a radio receiver is picking up a very strong transmission of a certain radiostation unless....
4. ... there is an audio signal transmitted as well.
HOW TO TRANSMIT THEN THE WANTED AUDIOSIGNAL BY MEANS OF RADIOWAVES?
The technical solution for this problem is: to let the radio frequency signal “carry” the audiosignal.
The process of charging the “lorry” (putting the audiosignal on the carrierwave) is called MODULATION.
fig. 26
Modulation means actually “varying”. So modulation of the carrierwave means to change the carrier-wave in one of its aspects, proportionally to the amplitude of the audiosignal.
The carrierwave has two main characteristics which determine its shape: the FREQUENCY and the AMPLITUDE.
To ENCODE a message (here to encode the audiosignal on the carrierwave) it is enough to change one of these two factors. Considering this fact, it is easy to understand why there are two methods of modulation.
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