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Mr. Bill
MAGNETIC GROUND SIGNAL
Posted by: Eric Foster
Date: March 10, 2004 03:05PM
I thought I would repeat the test that I did on the magnetic ground signal and tidy things up a bit to give a more conclusive result. My contention was, that the magnetic decay signal is independent of transmitter pulse width (within certain limits), which is at variance with some other results that have been acquired, both theoretical and experimental.
To ensure that only the pulse width varies and that the field from the coil is steady state for a period of time before the switch off, a special coil arrangement was used. The coil was wound on a ferrite core of 3/4in diameter and 4in long. The core used gave no magnetic relaxation signal of itself and was used so as to give a more concentrated field, so as to get maximum signal from the sample being tested. Coil inductance was 100uH and a series resistance of 10 ohms was used. This gives a coil rise time constant of 10uS and a total rise time to the point where the current is limited by the resistance, of 60uS. The control that varies the pulse width has a range of 150
Mr. Bill
MAGNETIC GROUND SIGNAL
Posted by: Eric Foster
Date: March 10, 2004 03:05PM
I thought I would repeat the test that I did on the magnetic ground signal and tidy things up a bit to give a more conclusive result. My contention was, that the magnetic decay signal is independent of transmitter pulse width (within certain limits), which is at variance with some other results that have been acquired, both theoretical and experimental.
To ensure that only the pulse width varies and that the field from the coil is steady state for a period of time before the switch off, a special coil arrangement was used. The coil was wound on a ferrite core of 3/4in diameter and 4in long. The core used gave no magnetic relaxation signal of itself and was used so as to give a more concentrated field, so as to get maximum signal from the sample being tested. Coil inductance was 100uH and a series resistance of 10 ohms was used. This gives a coil rise time constant of 10uS and a total rise time to the point where the current is limited by the resistance, of 60uS. The control that varies the pulse width has a range of 150