A
Anonymous
Guest
For a description of continuous-current pulse induction, please refer to my posts beginning 29 Dec 01.
If the transmitter coil is low-Q (substantially less than unity) at the fundamental frequency, it can be driven by unipolar pulses rather than the bipolar arrangement described in prior posts. In this case there would be two timing phases, Phase I (transmit pulse), and Phase II (flyback period). There is no reversal of current in the transmitter coil. DC current will build up over the first few cycles until all the energy being delivered during Phase I is being dissipated as heat rather than being stored in the field.
Even though the signal is not bipolar, the demodulation will usually be bipolar (full wave) in order to cancel earth field. However, the CCPI system allows the AC amplifying system to be AC coupled, and in some cases this may eliminate the need for full wave demodulation.
The primary advantage of unipolar excitation of the transmitter is that the circuitry is simpler. This advantage may be significant in products which are a step down from the high end, and in the early stages of prototyping low-Q designs where learning is more important than perfection.
--Dave J.
If the transmitter coil is low-Q (substantially less than unity) at the fundamental frequency, it can be driven by unipolar pulses rather than the bipolar arrangement described in prior posts. In this case there would be two timing phases, Phase I (transmit pulse), and Phase II (flyback period). There is no reversal of current in the transmitter coil. DC current will build up over the first few cycles until all the energy being delivered during Phase I is being dissipated as heat rather than being stored in the field.
Even though the signal is not bipolar, the demodulation will usually be bipolar (full wave) in order to cancel earth field. However, the CCPI system allows the AC amplifying system to be AC coupled, and in some cases this may eliminate the need for full wave demodulation.
The primary advantage of unipolar excitation of the transmitter is that the circuitry is simpler. This advantage may be significant in products which are a step down from the high end, and in the early stages of prototyping low-Q designs where learning is more important than perfection.
--Dave J.