Instrumental TransCommunication by nature seeks to establish some form of contact, often in real time, with a spirit or other entity. In that regard the concept is worthy of continued research. Some include EVP research into the ITC field among other more exotic methods as well. For purpose of this discussion I am going to consider those methods which involve some form of feedback loop. It is not the intent of this discussion to negate all ITC or EVP work. Rather it is to define why the popular idea of creating a feedback loop to achieve these ends is unwise and in fact a detrimental concept to your goals.
To understand how ITC in a feedback mode operates you also need to have a basic understanding of the electronic equipment used in such an endeavor. All signals, either audio or visual as we see them or hear them are of an analog nature. They may vary in intensity or frequency, but they still must be considered linear. For example a light may be dim or bright, and may be somewhere in between in intensity. This would be a definition of a linear signal. Electronics such as video cameras, must operate within this range of intensity to properly display an image.
These devices use class A linear amplifiers. A simplified example of how such an amplifier works is shown in the graphs below. The curve represents the response of a linear class A amplifier. You will note that at either end of the curve the amplifier deviates from the linear response. These areas are known as cutoff (low levels) and saturation (high levels). All linear amplifiers exhibit this characteristic; there is a point where no current flows (cutoff) and a point where current flow reaches a maximum limit and can go no higher (saturation).
Figure 1A represents an ideal situation, you can see from the voltage (input signal level) at the bottom a low signal level is amplified and the corresponding output voltage is shown on the right. Since the amplifier has a gain of 5, it is clear that a 2 volt peak to peak sine wave input results in a 10 volt sine wave peak to peak output. There is little distortion because the entire operation remains within the linear portion of the response curve.
But what happens if we overdrive the amplifier, using an input signal of 5 volts or more? Figure 1B represents how this same amplifier would react under such a condition. The input is well above and below the linear region. The amplifier is driven into cutoff on the low side and saturation on the high side. Notice how any signal deviation that might take place near either cutoff and saturation is lost. Under these conditions the amplifier becomes unstable, and any small signals which might contain information are lost.
When one puts an amplifier in a feedback mode, it quickly reaches a point where it has entered an overdriven state. If we start with a signal of 1/10 Volt and amplify it using this example (gain of 5) it results in a 1/2 volt output. This is within acceptable limits. But because it is configured in a feedback loop that 1/2 volt output wraps around and becomes the input. Now with 1/2 volt of input it generates 2 volts of output. Still acceptable, and again it feeds back on itself. we have a situation seen it Figure 1A. Acceptable, but one can see where this is going. We have all heard a microphone sqeal on a PA system. It starts quietly then continually builds to a deafening howl. Now look at Figure 1B and we can see where continued feedback drives the amplifier into distortion. This is unacceptable, severe clipping will take place, and the output becomes unstable. This is exactly what happens when an ITC experiment uses a feedback loop.
But How Does This Affect ITC?
If we consider the level of most alleged contact we can see it generally is of a low amplitude. EVPs are generally low volume; Ghost images when they appear are generally very dark; video is as a rule faint impressions. Seldom does anyone get anything that is in-your-face clear. Signal levels are as a rule very low. If you look at Figure 2A below, you can see how such a low level signal might be passed through an amplifier. It could be either an audio or a video signal, the important thing is that it must be amplified, yet reproduced accurately. Compare this to Figure 1A above, and you can see how the distortion is kept to a minimum as the signal is amplified. one can easily see how this is maintained as some waves are higher than others, yet the output is a faithful reproduction of the input. Those with higher amplitude follow the same order input to output.
Now let's assume a feedback situation is created. The signal is still present, however it is riding on top of a very large signal created by the feedback loop. (Note the regions highlighted in yellow.)
The desired, let's assume the ghost generated, signal you seek is seen here along with the much larger feedback generated signal. It is exceeding both cutoff and saturation points of the amplifier. Note what happens. Since the amplifier is being overdriven the desired signal is lost. Thus, not only are we unable to amplify such a weak signal under these conditions, what little is present is removed in the process! Your ghost, if it exists at all, is completely unable to communicate with you. Feedback methods such as these actually are a sure way to not succeed at communication.
So what constitutes a feedback loop? Any closed loop where energy is received and placed back into the loop to be re-processed again is a feedback loop. Placing a microphone in front of a speaker is a feedback loop. Using a camera to take an image of a monitor to which it is connected is a feedback loop. The important aspect though is how the devices are connected. The output must be fed back to the input to be considered a feedback loop. Simply placing a camera in front of a monitor showing some other image is not feedback. Only if that camera is feeding the image to that stated monitor or TV is it considered feedback.
The same logic applies whether it is a video feedback or audio feedback loop. Non-linear operation results in unreliable and unstable signals. These become very easy for anyone to read in whatever they want to the output. Consider the audio equivalent, if you had a PA system where the microphone was too close the speaker and it starts squealing. Now if you turn down the gain it generally quits and things work fine. But consider how hard it would be to hear the speaker if he simply talked with this squeal building up to maximum intensity.
Amplifiers can react in other ways too when they operate in a non-linear mode. One such condition results if the signal shifts more into either cutoff or saturation than it does in the opposite direction. This can make the amplifier respond as an RF detector. When this happens it can actually receive radio broadcasts and convert them to audio. It is plain to see how under these conditions the radio broadcasts can be mistaken for voices from the spirits!
As stated at the outset it was not the intent of this article to either validate nor condemn all ITC or EVP research. Rather it was to point out how a popular method used is flawed. Hopefully those researchers involved in this area will consider the known laws regarding how electronics operates and accept these constraints before going out and using methods which clearly violate the laws which govern electronics and physics.