Die Aufnahme einer Echosignalspur
The methods for recording the path the signal takes differ in the
various sonar systems. However, only SOCON delivers recording and
documentation of the signal trace. Only SOCON and one other service
provider supply signal-related interpretation, no other provider
world-wide offers this. EDO
WESTERN systems use a threshold switch in the tool. If a sonar signal
exceeds a preset threshold, pulses related to a trigger signal are
transferred to the surface. These pulses are used on the one hand for
streaking the monitor (echo sounding principle) and on the other for
information on distance for further-processing systems. Depending on
the company, either the values from the streaked screen prints or the
threshold time pulses are used for further processing. Signal
processing, stacking or correlation are not carried out and neither is
adjustment of the necessary parameters for each single point of
measurement.The so-called DOWELL TOOL - which has been used for downhole cavity surveying in the USA for over 30 years - works similar to the EDO WESTERN system. In the USA systems are also used which digitally transfer the data that exceed a threshold instead of transferring analog pulse data. If the rotation and tilt commands are also transmitted digitally, this would represent a very economic system - tool, power source, interface and laptop computer. But here, too, signal processing, stacking or correlation are are not carried out and neither is optimization of the requisite parameters from measurement point to measurement point. In principle the method is identical to the "EDO WESTERN" method. All these simplified methods that base value determination on threshold value interpretation and not on the more complicated method of peak value interpretation produce errors, which, depending on the signal amplitude, generate different and variable measured values! Using the overstepping of a threshold to determine the echo time values generates different measured values, depending on the amplitude (reflection condition)!  The figure shows the range of variation of measurement values for threshold interpretation depending on signal amplitude (reflection condition) and the amount of energy sent to the measurement point on the cavern wall. Echo time value calculation based on the determination of peak values produces identical measurement values depending on amplitude (reflection condition)!  Calculating echo times from the peak values of the signal waveforms. The example shows that the peak values - as long as the signals are not overamplified - generate correct, reproducible measurement values independent of signal amplitude. For this reason and in view of the explanations provided below SOCON systems are generally based on peak analysis. In all systems overamplified signals produce too short echo times (distances). This demonstrates the importance of accurate optimization, recording and documentation of all signals. The only way of verifying that errors are avoided is by optimizing parameters measurement point for measurement point. World-wide, only SOCON systems deliver optimization measurement point for measurement point. In SOCON systems the sonar signal including trigger (to) and transmit signal is continuously transmitted differentially to the surface via two cable cores. The differential signal transmission delivers a noise-free, high-quality signal. Digitizing the sonar signal in the tool with digital transmission to the surface does not make much sense when using standard well-logging cables, as these only permit low data-transmission rates. Only extremely sophisticated and expensive fiber-optic cables would get around this problem and allow even more possibilities. The advantages of SOCON technology:
The quality of digital transmission is greatly reduced using
standard well logging cables! To get a fairly usable transmission of
the measurement signal the data volume and the information content has
to be significantly reduced. Basically, this can be done using two
methods: Whereas the SOCON system is based on 12 bit (1/4096) amplitude
resolution, other systems commonly implement only 8 bits (1/256) for
digital transmission. |
| Sonar in caverns |
 SOCON SONAR CONTROL The World-wide leading engineering company specializing in the surveillance of underground caverns and voids. |
| Blanket surveying |
 BCS Value microC (Generation 4)
|
| Old mine mapping |
 In many parts of Europe underground cavities created by mining exist under surface areas that are now populated.
|