One RSU acquires data from 4 channels. Each RSU requires a battery. The battery packs contained 2 x 7.2AH lead acid types inside a cast Aluminum case. Batteries would last around 16 hours if minimal line checks were done and noise monitoring is used sparingly.
Each line of RSUs is controlled by an SLCU (Slave Line Control Unit). This device controls and collects data from the RSUs and communicates with the MLCU (Master Line Control Unit) in the recording truck. There are 2 MLCUs, one for lines each side of the recorder if recording 3D.
The biggest criticism I have of the system is that real time monitoring of the line was not possible because of the battery capacity. For me, real time display of the line is a requrement, not an option. I'll forgive JGI for now though, as I see the GDAPS4 more as a development system than one they really intended to make a fortune from.
According to the manual (which isn't exactly the best) the system can record SEGY or SEGD to tape. On the job I was involved with, we used SEGD. I created a viewer for the GDAPS4 SEGD format. It is very much like the 408 Viewer described here
but I am making it freely available for download
, with the usual disclaimer that you use it at your own risk. The amount of information displayed reflects what is in the header. JGI do a better job than IO, but no where near as good a job as Sercel.
Anyone who requires a description of the file formats can contact me.
I will not post them here, as although they are probably not secret, they are copyright JGI.
I also wrote a quick test display program that will read the test result file and display a histogram reflecting the results. You can read about it and download it here