f Effects of air gun firing time vatiations of signal stability

Air gun arrays typically contain many single air gun units. These are mechanical devices and their firing time, though remarkably accurate, cannot approach that of electrical networks in spite of the introduction many years ago of computer management systems . Gun timing variations depend upon many factors which include the size and design of the air gun itself, the interral pressure, the condition of the gun and its internal wals and veear rings, the condition of the solenoid and the degree, if any, to which electrical leakage may be present in the wiring. The magnitude of these timing variations may range from orders of magnitude below that of the seismic trace sampling period which is exceptionally good to about the same order of magnitude as the sampling period which gives cause for concern. To be more precise, timing errors may vary from numbers less than +/-0 .1 msec to numbers like 2 or 4 msec or even more in severe cases . Certainly, clearer insight into the ranges of timing errors, their causes and effects on the stability of the seismic signal would be helpful .