Quote:
Originally Posted by FrancoItaly
My opinion does not change, in the mixing stage there is a "mixing" between two signals, one of constant amplitude (quartz oscillator) and the other of variable amplitude (the phenomenon) and I do not see how it can improve. It should also be borne in mind that even getting an increase in sensitivity to the phenomenon, at the same time it would almost certainly be a appearance of the compass effect.
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Francoitaly keep in mind that appearance of so called "the compass effect" is due to very high dc gain. Lower overal gain and lrl going out from "the compass effect". It is artificial effect made by us not the phenomenon.
Also, you have no proof that the phenomenon amplitude is variable at a given area of prospecting. Maybe phenomenon amplitude is mainly constant, while on some unknown way rise or decay amplitude and phase of oscillator. In my opinion phenomenon noise has unknown bipolar nature, very wide bandwidth and maybe have some unknown 3rd component which change both amplitude and phase of lrl reference signal.
There are only to ways imho to explain such odd manifestation of phenomenon signal at referenced oscillator signal. They are speed up or slow down charge carriers (electrons-holes) migration through the base-emitter juntion of tr2 bc183c transistor. It means increasing or decreasing emitter current of tr2.
We should easy monitoring this variations by simply puting current transformer around emmiter leg withouth affecting amplitude of the current, and amplify that tiny current by 3 lm358 op amps in the differential configuration.
The question is one: Does phenomenon signal or phenomenon noise is current or voltage dependent or both ?
Best regards
Dubulumach