This invention relates to method and apparatus for displaying data. In a particular aspect, this invention relates to method and apparatus for displaying data from a plurality of data channels. In another particular aspect, this invention relates to method and apparatus for using substantially the entire screen of a CRT display device to display data from a plurality of data channels where the number of data channels available to supply data to be displayed varies. In another particular aspect, this invention relates to method and apparatus for preventing the overloading of an automatic gain control circuit which is used to enable substantially the entire screen of a CRT display device to be utilized to display data for a plurality of data channels where the number of data channels available to supply data, to be displayed, varies. In another particular aspect, this invention relates to method and apparatus for highlighting data from a particular data channel on a CRT display device.
In many data acquisition systems and communication systems, data is provided from a plurality of sources to a central location for processing or use. The data is usually provided through a plurality of data channels from the plurality of data sources. An example of this would be a seismic exploration system where the data from a plurality of geophones is provided to a central location for processing by means of a plurality of data channels.
Where data is being supplied to a central location through a plurality of data channels, it is often desirable to be able to check the operability of a particular data channel or to be able to check to determine that all of the data channels are operable and are supplying data from the various sources to the central location. A CRT display device provides a convenient means by which the data which is being provided by a plurality of data channels can be displayed thus providing a visual indication of whether or not a particular data channel is operable.
When using a CRT display device, it is particularly desirable from an operator standpoint that substantially the entire screen of the CRT be utilized, for ease in visual identification of the data being displayed. If only a few data channels are supplying data to the central location then the display of data on the CRT display device can be spread out if the entire screen of the CRT display device is utilized. If a large number of data channels are provided data to the central location, then the data must be compacted to get all of the data from all of the data channels on the screen of the CRT display device. It is desirable that, no matter how many data channels are providing data to the CRT display device, the entire screen of the CRT display device be utilized to display the data. It is thus an object of this invention to provide method and apparatus for using substantially the entire screen of a CRT display device to display data for a plurality of data channels where the number of data channels available to supply data to be displayed varies.
Automatic gain control circuits can be utilized to spread out or compact a display on a CRT screen. However, if the number of data channels which must be displayed varies greatly, then the capabilities of the automatic gain control circuit may be overloaded. It is thus another object of this invention to provide method and apparatus for preventing the overloading of an automatic gain control circuit which is used to enable substantially the entire screen of a CRT display device to be utilized to display data from a plurality of data channels where the number of data channels available to supply data, to be displayed, varies.
Often, only the data being supplied by one data channel will be of interest to the operator who is viewing the screen of the CRT display device. If the data from a large number of data channels is being displayed on the screen of a CRT display device, then it may be difficult to pick out the data from the particular data channel of interest. It is thus another object of this invention to provide method and apparatus for highlighting data from a particular data channel on a CRT display device to provide a means by which an operator can easily pick out data being supplied from a particular data channel of interest.
In accordance with the present invention, method and apparatus is provided whereby the data from a plurality of data channels is provided to the Y input of a CRT display device by samples. All of the first samples of the data from the plurality of data channels are first provided to the Y input of the CRT display device. Then all of the second samples of the data from the plurality of data channels are provided to the Y input of the CRT display device. This procedure continues until all of the samples of the data from the plurality of data channels have been provided to the Y input of the CRT display device.
The data is displayed as a function of the data channel which provided the particular data sample. The display will change each time another sample of the data from the plurality of data channels is provided to the Y input of the CRT display device. This provides an indication of both the quality of the data being provided by means of the plurality of data channels and also the operability of the data channel itself.
The data channels, which are supplying data to be displayed on the CRT display device, are displayed as the X coordinant of the data display. An automatic gain control circuit is provided which ensures that, if only three data channels are available, then the three data channels will be spaced essentially equally across the screen of the CRT display device to therefore use essentially all of the screen of the CRT display device to display the data which is being supplied from the three data channels. If sixty data channels are available to supply data to be displayed, then the automatic gain control circuit assures that the data from the sixty data channels will be spaced essentially equally across the screen of the CRT display device. In this manner, no matter how many data channels are available to be displayed, essentially all of the screen of the CRT display device will be utilized for displaying the data available.
A counter is utilized to provide an indication of which data channel is supplying a particular data sample. The output of the counter will count from a count of 1 to a count representative of the total number of data channels which are available. The output of the counter is converted from digital-to-analog form by a digital-to-analog (D/A) converter. The count of the total number of data channels available is utilized, after being converted to analog form, by the automatic gain control (AGC) circuit to space the data channels across the screen of the CRT display device. However, if the number of data channels which must be displayed vary substantially, the output from the D/A converter may have a dynamic range which is too great for the AGC circuit because the output level from the D/A converter will be a function of the number of channels of data being provided to the CRT display device. A digital gain ranging circuit is provided to overcome this dynamic range problem by controlling the manner in which the channel count signal from the counter is provided to a D/A converter. If only a few channels of data are available, the channel count signal is supplied to the most significant bit inputs of the D/A converter. By using the most significant bit inputs of the D/A converter, a signal having a dynamic range compatible with the input requirements of the AGC circuit is provided.
A circuit is provided for enhancing the data from a particular data channel of interest by comparing the channel count output from the counter to a signal which is representative of the data channel which is to be enhanced. When the channel count signal equals the signal representative of the channel which is to be enhanced, the output of a comparator is provided to the Z input of the CRT data display. The Z input of the CRT data display is utilized to highlight data from a particular data channel on the CRT display device.
Other objects and advantages of the invention will be apparent from the detailed description of the invention and the appended claims as well as from the detailed description of the drawings in which:
FIG. 1 is an illustration of a possible physical arrangement of the components of the seismic exploration system;
FIG. 2a is a block diagram of a central recording station;
FIG. 2b is a block diagram of a remote telemetry unit;
FIG. 51 is a block diagram of the data display unit illustrated in FIG. 2a;
FIG. 52 is a timing diagram associated with the data display system illustrated in FIG. 51;
FIG. 53 is a timing diagram associated with the data display system illustrated in FIG. 51;
FIG. 54 is a schematic of the first-in first-out memory illustrated in FIG. 51;
FIG. 55 is an illustration of the manner in which the sample-and-hold circuits, illustrated in FIG. 51, are addressed;
FIG. 56 is a schematic of the control logic illustrated in FIG. 51;
FIG. 57 is a schematic of the data display control illustrated in FIG. 51;
FIG. 58 is a schematic of the AGC circuit illustrated in FIG. 57; and
FIG. 59 is a schematic of the full wave rectifier and the integrator illustrated in FIG. 58.
FIGS. 3-50 and 60-73 of application Ser. No. 955,905, filed Oct. 30, 1978, by Robert H. Lacy, now U.S. Pat. No. 4,257,098 are hereby incorporated by reference. The brief description of FIGS. 3-50 and 60-73 in application Ser. No. 955,905, now U.S. Pat. No. 4,257,098, is also hereby incorporated by reference.
The invention is described in terms of a seismic exploration system but it is noted that the invention is not limited to a seismic exploration system but is rather applicable to any system in which it is desired to display data which is being provided from a plurality of data sources, by means of a plurality of data channels, to a central location.
In the preferred embodiment of the invention, the data to be displayed is supplied from a charge couple device (CCD) memory. However, the invention is not limited to displaying data which is supplied by CCD memory but is rather applicable to displaying data supplied from any plurality of data sources by means of a plurality of data channels.
The invention is described in terms of a specific circuit and in terms of a specific CRT display device. Different circuit components could be utilized such as equivalent components which are supplied by different manufacturers and different CRT display units could be utilized if desired.
The invention is described in terms of a display system in which the maximum display is seventy-two data channels. The invention is however applicable to display systems in which more than seventy-two data channels must be displayed.
The detailed description of the drawings and the Appendix of application Ser. No. 955,905, filed Oct. 30, 1978, by Robert H. Lacy, are hereby incorporated by reference.