CONTENTS INTRODUCTION DESCRIPTION OF PROJECT TASK

2. CONTENTS

This Test Project proposal consists of the following documentationfiles: a. LKS_2017_XXI_TP16_FFRM_EN.docx b. Data sheets on computer dekstop 3 Version: 1.0 Date: 20.10.2016 Test Project proposal for skills competition LKS_2017_TP16_FFRM_EN

3. INTRODUCTION

This Test Project is a Stereo Multiplex MPX and FM Transmitter test, Instead of using special purpose ICs to produce the waveforms this design uses ordinary HCMOS logic. Audio Frequency AF signals are produced using binary counters and combinational logic and then filtered to obtain two very low distortion sine waves to serve as the test tones. These audio signals are then multiplexed by a 38 KHz Sub-Carrier to form a Left+Right and a Left-Right Double Side-Band Suppressed Carrier DSBSC signal to form the Stereo Multiplex MPX. No fault and no measurement in the oscillator FM Modulation FM Block. Fig. 1 PCB FFRM TASK 4 Version: 1.0 Date: 20.10.2016 Test Project proposal for skills competition LKS_2017_TP16_FFRM_EN

4. DESCRIPTION OF PROJECT TASK

The block diagram of the Stereo Multiplex MPX and FM Transmitter is shown in Fig. 2. Fig. 2 Block Diagram of Stereo Multiplex MPX and FM Transmitter test Fig. 3: Audio Signals, Sub-Carrier and Multiplexed MPX Signals The Signal Generator generates the 38 KHz sub-carrier and 19 KHz pilot tone. It uses an ingenious technique to generate 2 sine waves audio with very low distortion at around 300 Hz and 1.2 KHz. The 38 KHz sub-carrier is used to multiplex the audio signals and then summed with the 19 KHz pilot tone by the Multiplexer Summer to form 16 different waveforms Fig 4. The audio signals being encoded as Left or Right is based on the phase of the sub-carrier. The 16 different waveforms 300 Hz right 1.2 KHz left MPX no 19 KHz pilot 300 Hz right 1.2 KHz left MPX with 19 KHz pilot 1.2 KHz left only MPX no 19 KHz pilot 5 Manual Clock Control Logic Multiplexe r Summer MPX Output Signal Generator Audio 19 KHz 38kHz Version: 1.0 Date: 20.10.2016 Test Project proposal for skills competition LKS_2017_TP16_FFRM_EN 1.2 KHz left only MPX with 19 KHz pilot 300 Hz left only MPX no 19 KHz pilot 300 Hz left only MPX with 19 KHz pilot 300 Hz left1.2 KHZ right MPX no 19 KHz pilot 300 Hz left1.2 KHZ right MPX with 19 KHz pilot 1.2 KHz right only MPX no 19 KHz pilot 1.2 KHz right only MPX with 19 KHz pilot 300 Hz right only MPX no 19 KHz pilot 300 Hz right only MPX with 19 KHz pilot 300 Hz + 1.2 KHz mono audio only 1.2 KHz mono audio only 300 Hz mono audio only 19 KHz pilot only Fig. 4. The 16 different waveforms The state of the Control Logic is advanced by the Manual Clock. In manual mode it is done by a Push Button with a de-bouncing circuit. 6 Version: 1.0 Date: 20.10.2016 Test Project proposal for skills competition LKS_2017_TP16_FFRM_EN

6. INSTRUCTION TO THE COMPETITORS Fault Finding and Repair