Abbreviations

[Lacey]

We are newbies to metal detecting. We are trying to learn all we can as we are definately HOOKED!! We read many of the forums and enjoy the articles and advice. I only have one suggestion. Many times I have read questions and responses using abbreviations in them, such as BFO. I have no idea what a BFO is.


It would be really helpful if when posting, the abbreviated item would be spelled out at least once. Then we beginners would know what you are talking about. Just an idea.......and thanks for all the good info that you are putting out. I love to read the forums and you have helped me tremendously.


HH Lacey

[Don]

Re: Abbreviations

BFO: Beat Frequency Oscillator.


In order to hear a frequency that is beyond audible range, such as 50,000 Hertz (Hz), you must mix it with another signal. Beat is technoslang for Mix. When I beat two frequencies together in an electronic "mixer" the mixer output contains the sum and the difference of the two signals. If I beat 50,000 Hz and 49,500 Hz, the mixer will output 99,500 Hz and 500 Hz. Since I want to hear the 500 Hz tone, I will amplify it and send it to a speaker or hearphone. 50,000 Hz might be the frequency being generated by the metal locator, and when it is reflected electromagnetically to the receiver which has the BFO at 49,500 Hz. I will hear the 500 Hz. tone.

[Carl]

Re: Abbreviations

Here's a few:


BFO: Beat Frequency Oscillator


TR: Transmit-receive


IB: Induction Balance


VLF: Very Low Frequency (defined to be 3-30KHz)


PI: Pulse Induction


VCO: Voltage controlled Oscillator


PLL: Phase-locked loop


GB: Ground balance


GEB: Ground exclusion balance


Hz: Hertz (cycles per second)


KHz: KiloHertz (thousands of Hz)


MHz: MegaHertz (millions of Hz)


When I (finally) get around to writing up the IB theory most of these will get explained in detail.


- Carl