Changes

The length of a streamer cable ranges from 3000 to [[depth::6000 m]]. Shorter cables can be deployed in areas with obstructions to improve control and thereby avoid damage. The length of cable required for a job depends on the objectives of the survey. In general, the deeper the objective, the longer the cable should be. A rule of thumb is that ''x'', the length of the cable, should equal z, the depth of the objective.

The length of a streamer cable ranges from 3000 to [[depth::6000 m]]. Shorter cables can be deployed in areas with obstructions to improve control and thereby avoid damage. The length of cable required for a job depends on the objectives of the survey. In general, the deeper the objective, the longer the cable should be. A rule of thumb is that ''x'', the length of the cable, should equal z, the depth of the objective.

Some streamer cables contain electronics to convert the analog signal from the hydrophones to a digital form. These are called ''digital cables'', while the traditional streamer cables are called ''analog cables''. In an analog cable, there must be a pair of wires for each group. As the number of groups increases, the number and weight of the copper conductors increase, which necessitates that the diameter of cable gets larger and larger. There are analog cables with as many as 240 channels<ref name=pt07r4>Carlini, A., Mazzotti, A., 1989, Optimized receiver array simulation based upon resolution constraints: Geophysical Prospecting, v. 37, p. 607–621., 10., 1111/gpr., 1989., 37., issue-6</ref>. Digital cables, however, can multiplex data onto one or a few conductors, so there is not a weight problem due to conductors. Some digital cables have as many as 1000 channels. Analog cables may be more susceptible to electrical leakage, but a well-maintained analog cable can gather data equal in quality to that gathered using a digital cable.

Some streamer cables contain electronics to convert the analog signal from the hydrophones to a digital form. These are called ''digital cables'', while the traditional streamer cables are called ''analog cables''. In an analog cable, there must be a pair of wires for each group. As the number of groups increases, the number and weight of the copper conductors increase, which necessitates that the diameter of cable gets larger and larger. There are analog cables with as many as 240 channels<ref name=pt07r4>Carlini, A., and A. Mazzotti, 1989, Optimized receiver array simulation based upon resolution constraints: Geophysical Prospecting, v. 37, p. 607–621., 10., 1111/gpr., 1989., 37., issue-6</ref>. Digital cables, however, can multiplex data onto one or a few conductors, so there is not a weight problem due to conductors. Some digital cables have as many as 1000 channels. Analog cables may be more susceptible to electrical leakage, but a well-maintained analog cable can gather data equal in quality to that gathered using a digital cable.

In 3-D seismic surveys, the seismic boat commonly tows two and even three parallel cables spaced laterally apart so that two or three seismic lines are collected per traverse of the vessel. In a two-cable application with a single source, two seismic lines spaced ''L'' meters apart in the subsurface will be acquired if the streamer cables are spaced 2''L'' apart.

In 3-D seismic surveys, the seismic boat commonly tows two and even three parallel cables spaced laterally apart so that two or three seismic lines are collected per traverse of the vessel. In a two-cable application with a single source, two seismic lines spaced ''L'' meters apart in the subsurface will be acquired if the streamer cables are spaced 2''L'' apart.