Transmit coil power and receiver sensitivity

[Krzychu_]

I am interested in the relationship between the power of the transmit coil and the receiver's sensitivity, and its selectivity, and the effectiveness of the detection / range for a specific resonance frequency, chosen for the characteristics of the object. Some metal detectors work on very small powers and are powered, for example, only with two 9V (6F22) batteries, while others (excluding PI) - require a battery pack of capacious batteries, which do not significantly increase their range (depth of penetration of the ground), nor will they lengthen their working time

[WM6]

while others (excluding PI) - require a battery pack of capacious batteries,

Even PI cannot be excluded.

Way back we got PI detector (Fisher Impulse) in which AA alkaline last over 100 hours.

Unimaginable even for modern VLF/IB models.

Otherwise, more power in soil - more noise from soil. Poor reward from huge power.

[kt315]

Way back we got PI detector (Fisher Impulse)
---
again?? i had answered that if CZ5/6 has absolutely same transmitter circuit like in Fisher Impulse (half bridge)
so why CZ5/6 is just VLF while Fisher Impulse is pulse induction?
then we must recall CZ5/6 also PI.
also we must recall minelab sov XS, elite, gt, excalibur also PI be cause they have full bridge (or simply bridge) transmitter.

[dbanner]

I am interested in the relationship between the power of the transmit coil and the receiver's sensitivity, and its selectivity, and the effectiveness of the detection / range for a specific resonance frequency, chosen for the characteristics of the object. Some metal detectors work on very small powers and are powered, for example, only with two 9V (6F22) batteries, while others (excluding PI) - require a battery pack of capacious batteries, which do not significantly increase their range (depth of penetration of the ground), nor will they lengthen their working time

Strictly speaking, power increases the range of TX signal, but for metal detector circuit, it is about the amount of excitation/ saturation of the target and it's rate of decay(pulse induction) or phase response at Rx( VLf induction balance). It is really the medium of the soil(ground) which makes all the difference.

[Carl-NC]

I am interested in the relationship between the power of the transmit coil and the receiver's sensitivity, and its selectivity, and the effectiveness of the detection / range for a specific resonance frequency, chosen for the characteristics of the object. Some metal detectors work on very small powers and are powered, for example, only with two 9V (6F22) batteries, while others (excluding PI) - require a battery pack of capacious batteries, which do not significantly increase their range (depth of penetration of the ground), nor will they lengthen their working time

Transmitter "power" and receiver sensitivity are independent of each other. The two together determine detection range. TX power and battery consumption are also 2 different things; a resonant TX (BFO and most VLF) is very power efficient and a non-resonant TX (PI) is very lossy.

Way back we got PI detector (Fisher Impulse)
---
again?? i had answered that if CZ5/6 has absolutely same transmitter circuit like in Fisher Impulse (half bridge)
so why CZ5/6 is just VLF while Fisher Impulse is pulse induction?
then we must recall CZ5/6 also PI.
also we must recall minelab sov XS, elite, gt, excalibur also PI be cause they have full bridge (or simply bridge) transmitter.

Similar TX circuits used in different ways. All my current VLF designs are using full-bridge transmitters, as are all my PI designs.

[kt315]

Similar TX circuits used in different ways. All my current VLF designs are using full-bridge transmitters, as are all my PI designs.
----
again we gone back in start position. where i can read that full-bridge transmitter is PI? which page (number) in ITMD i must read?

[Carl-NC]

If you want to discuss specific TX circuits, how about starting a new thread instead of hijacking someone else's?

[kt315]

no need starting new thread. there was a thread on this matter but i am not able find it at once.

PS. http://www.geotech1.com/forums/showt...Feb-2016/page7

[dbanner]

A TX of waveform energy is just what it says it is, nothing more nothing less. The oscillator generating the waveform is not the transmitter, strictly speaking, the transmitter is the coil.
Whatever topology the tx circuitry takes, it has nothing to do with the receiver.
The sensitivity of the receiver is a question of bandwidth. Not tx power.
Since in metal detectors(most), the TX and RX are co-located, the range of detection of the target is not only a function of the tx power and Rx sensitivity, but also the type of target and size of target and condition of ground medium.
A target of a specific material and size will reach maximum excitation, beyond which any increase in tx power yields no benefits of detection range, since the target energy dissipation cannot overcome the distance back to the Rx coil beyond a certain depth due to ground attenuation and absorption.( Target is just too small and no amount of increased tx power will suffice).

[dbanner]

Additionally, the wavelength of TX signal is very much a factor when it comes to type of metal targets. This is why a range of frequencies are maximized depending on what one is searching for.

[dbanner]

PI refers strictly to the method of solving the information contained within the received signal. Com'on amigo.

[dbanner]

Similar TX circuits used in different ways. All my current VLF designs are using full-bridge transmitters, as are all my PI designs.
----
again we gone back in start position. where i can read that full-bridge transmitter is PI? which page (number) in ITMD i must read?

PI refers strictly to the method of solving the information contained within the received signal. And the means by which it is collected. Com'on amigo.