WIDEBAND (BROADBAND) TECHNOLOGY

[mikebg]

The Russian scientist Lev Matveevich Fink is author of very intersting books. When in 1970 appeared his book
"Theory of Transmitting Discrete Messages", the US department of defense immediately translated and published it.
Unfortunately, his book "Signals, systems, errors" was not translated in English, despite in Russia there are two editions in 1978 and 1984. In this forum I see a lot of errors described by Lev Fink in that book.

I will post in the forum several questions. Please think clearly and look WEB for information before you post a reply in the forum. Even I recommend that you do not post the answers direct, but first send them to me via email or private mesages. Keep in mind that this is a worldwide forum. Radio amateurs say that

Forums are a place where you can easy become the laughing stock of the world.

Here's the first question:
Showed rectangular wave generates series of odd harmonics. Modify signal parameters so to obtain both odd and even harmonics. It is necessary to obtain the frequencies used by MINELAB: 1.5kHz, 3kHz, 4.5kHz, 6kHz, ... etc.

[mikebg]

ENERGY EFFICIENCY OF RECTANGLE PULSE TECHNOLOGY

Attached diagram shows that energy efficiency of waveform in post # 1 is worsened.
See what is the difference between this diagram and that in post #1.
Remains you to insert the difference in the frequency spectrum.

[Bill512]

The Russian scientist Lev Matveevich Fink is author of very intersting books. When in 1970 appeared his book
"Theory of Transmitting Discrete Messages", the US department of defense immediately translated and published it.
Unfortunately, his book "Signals, systems, errors" was not translated in English, despite in Russia there are two editions in 1978 and 1984. In this forum I see a lot of errors described by Lev Fink in that book.

I will post in the forum several questions. Please think clearly and look WEB for information before you post a reply in the forum. Even I recommend that you do not post the answers direct, but first send them to me via email or private mesages. Keep in mind that this is a worldwide forum. Radio amateurs say that

Forums are a place where you can easy become the laughing stock of the world.

Here's the first question:
Showed rectangular wave generates series of odd harmonics. Modify signal parameters so to obtain both odd and even harmonics. It is necessary to obtain the frequencies used by MINELAB: 1.5kHz, 3kHz, 4.5kHz, 6kHz, ... etc.

the simplest way is to "modify" the duty cycle of the square waveform, but depending from the this ratio at some harmonics there will be a hole.
Another way is to use a sawtooth waveform.
For "random" TX freq take a look at this:
http://terraplus.ca/products/electromagnetics/gem2.aspx

[mikebg]

DUTY CYCLE

the simplest way is to "modify" the duty cycle of the square waveform, but depending from the this ratio at some harmonics there will be a hole.
Another way is to use a sawtooth waveform.
For "random" TX freq take a look at this:
http://terraplus.ca/products/electromagnetics/gem2.aspx

I can't see the hole.
Please show suitable duty cycle for frequencies used by MINELAB: 1.5kHz, 3kHz, 4.5kHz, 6kHz, ... etc.
Here is a drawing for editing.
To spare your time, I will make and post a drawing with parameters of sawtooth waveform.

[Bill512]

[Bill512]

[Aziz]

BTW guys,

if you make the FFT spectrum of the TX coil current, don't forget, that the RX coil won't sense the same frequency spectrum.
dI(TX)/dt -> U(Target) -> dI(Target)/dt -> U(RX)

The voltage at RX coil U(RX) is direct proportional to the TX coil current frequency.
Aziz

[mikebg]

BTW guys,

if you make the FFT spectrum of the TX coil current, don't forget, that the RX coil won't sense the same frequency spectrum.
dI(TX)/dt -> U(Target) -> dI(Target)/dt -> U(RX)

The voltage at RX coil U(RX) is direct proportional to the TX coil current frequency.
Aziz

This is known and was showed:
http://www.geotech1.com/forums/showt...505#post163505

[mikebg]

SAWTOOTH AS AN ASYMMETRICAL TRIANGULAR WAVEFORM

To bill512 and all,
Does anyone have a signal generator that can show the frequency spectrum of this asymmetric triangular waveform?

[WM6]

Here you are:

[Tinkerer]

To bill512 and all,
Does anyone have a signal generator that can show the frequency spectrum of this asymmetric triangular waveform?

Here is the FFT of the TINKERERS TX, a saw tooth wave form with the long ramp of about 90us and the short ramp of 9us

[mikebg]

I need software that can show me what happens in Frequency domain when amended parameter "b" (explained in post # 9).

Can somebody show me a link where I can download for free a signal generator with Frequency analysis similar to that used by Bill512 in posts #5 and #6?

In next posts I should show the frequency spectrum of a "ringing" TX pulsation (underdamped PI metal detector or without damping resistor).

[vbeeeks]

???? http://www.geomatrix.co.uk/tools/app...notes/tn30.pdf

[mikebg]

????

Vbeeks, I'm sure that Mr. J.D. McNeil is not at all familiar with the method for identification of target, method for suppression of GND signal and method for suppression variations of AIR signal, described in patent US 4,506,225. The patent was issued in 1985, which means that Mr. J.D. McNeil was able to read the patent for 10 years. If he were familiar with the theory described in the patent, he never would have written Technical Note TN-30 in 1996.
http://www.google.com/patents/US4506225

[Bill512]

I need software that can show me what happens in Frequency domain when amended parameter "b" (explained in post # 9).

Can somebody show me a link where I can download for free a signal generator with Frequency analysis similar to that used by Bill512 in posts #5 and #6?

In next posts I should show the frequency spectrum of a "ringing" TX pulsation (underdamped PI metal detector or without damping resistor).

Hi Mike,
nothing fancy,just simple,free and useful :http://www.zeitnitz.de/Christian/scope_en
("... free of charge for private and non-commercial use in educational institutions ...")