slava_edf said:
I have finishid model in simulink Conovolutional coder + Amplitude PPM model for Optical chanel... I made it for IBM enginner last summer. and we compare L-PPM and APPM but in idealy i biuld only APPM model to find best result in Conv coder wich worked with A-PPM. Pls send me specification or more info.... I think this is the same project. If need I can rebuild project for you task. Let me know if you are agree
HI
Thank you -
L-PPM, also called as L-arry PPM. PPM is an orthogonal modulation scheme that offers a decrease in average-power requirement compared to OOK, at the expense of an increased bandwidth requirement. L-PPM utilizes symbols consisting of time slots, which can be referred to as chips. A constant power
L.Pt is transmitted during one of these chips and zero power is transmitted during the remaining (L-1) chips, thereby encoding Log2(L) bits in the position of the “high” chip. 4-PPM are shown in Fig. attached. 2PPM is like OOK. For a given bit rate, L-PPM requires more bandwidth than OOK by a factor
L/Log2(L), e.g., 16-PPM requires four times more bandwidth than OOK. In the
absence of multipath distortion, L-PPM yields an average power requirement that decreases steadily with increasing ; the increased noise associated with a
L/Log2(L), -fold wider receiver noise bandwidth is outweighed by the L-fold increase in peak power. This decreased average-power requirement makes PPM especially suitable for portable infrared transmitters. Fig. as short block level is also given.
In fact, from this I plan to develop Sub Carrier PPM (SC-PPM) in which in each of this L-PPM pulse a carrier frequency will be sent instead of rectangular pulses. If you can give some hint or model, I shall be grateful to you. Thanks