Abstract: A data collection and transmission system for gathering high count vertical seismic data is disclosed using a sequence of vertically aligned seismic receivers, the analog outputs from which are sequentially analog sampled and time multiplexed onto a common pair of data conductors in the support and transmission cable. The data is time demultiplexed at the surface and appears substantially as digital data because of the relatively short sampling times. Such data is converted into analog data with conventional digital-to-analog converter means.A clock signal activates counters for establishing non-overlapping data gates in the respective sondes, the operation of the gates supplying the cable with the respective receiver analog signals in a sequence from bottom to top, simultaneously switching off previously gated signals until a clock reset pulse resets the entire sonde string.

Abstract: A geophone configuration is disclosed that includes an elongated extension or spike that couples with the soil in the hole made by the spike in the region near the end of the spike without hard or firm coupling with the soil above that region. A bow spring or drill bit larger in diameter than the diameter of the spike can be used for achieving predominant contact for the coupled region compared to soil opposite the remainder of the spike. Alternately, a weighted tip can be employed to achieve relative superior coupling by weight compared with the less heavy region of the spike above such weighted tip.