Notifications
Clear all
Search result for: id10=WA 0859 3970 0884 Harga Borongan Taman Rumah Vertical Garden Terpercaya Tanon Sragen
| # | Post Title | Result Info | Date | User | Forum |
| RE: What is the MagArrow GPS accuracy in position/elevation/altitude? | 19 Relevance | 2 years ago | Magnetics SW | Hardware | |
| Here are a few additional details relating to the measurement of elevation: GNSS AccuracyAccuracy depends on multiple aspects of the GNSS system: among them are clock accuracy, atmospheric effects, and satellite geometry. Satellite geometry"Satellite geometry" refers to how the currently visible satellites are distributed in the sky - close to each other or scattered around. The best satellite geometry includes satellites that are near the axes on which you hope to locate your receiver; for example, to locate your receiver on the East/West axis, it's helpful to have good reception from satellites low in the sky in the East and in the West. If you also have satellites that are low in the sky near the South and North horizons, you will have good accuracy on the horizontal (latitude/longitude) plane. It's best to have satellites scattered around the sky, overhead as well as near the horizon all around. HDOPMagArrow records HDOP, a standard measure of satellite geometry's effect on horizontal (or latitude/longitude) accuracy. A smaller number (less than 1.0 is very good) indicates that the visible satellites are in good positions to contribute to accuracy. Vertical AccuracyThe reason that GNSS systems aren't as accurate on the Vertical axis as on the horizontal axes is that no satellites are visible in a full half of that axis: the half that is below the horizon. Consequently, Vertical accuracy is on average about half that of horizontal accuracy; calculated offset from true elevation is on average about twice that as on the horizontal axes. While on average HDOP can therefore be used to estimate VDOP (the similar measurement of the effect of satellite geometry on the Vertical axis), that estimate is only a rule of thumb; it is possible to have an excellent HDOP, reflecting very good horizontal satellite geometry, while having poor Vertical satellite geometry. In those cases, good HDOP does not indicate good VDOP. Keeping in mind that possibility, a combination of good HDOP and many satellites in view usually indicates good VDOP. Practical effects Some data processing techniques (upward continuation, for example) can include elevation as an input. Customers who are considering using GNSS elevation in those techniques should conduct a careful analysis of their data and develop test routines to verify that all their data meet the requirements of the technique and its application to a particular survey. Some customers who require very accurate elevation data incorporate LIDAR data and drone elevation data into their analyses. | |||||
| Environmental seismic refraction survey considerations | 4 Relevance | 2 years ago | Gretchen Schmauder | General Seismograph Info | |
| Can I do refraction on pavement? It is exceedingly difficult to do this, because the pavement is generally has a much higher velocity that the materials below it. It is generally not recommended. Can I do refraction on a hillside? Yes. The slope of the surface is not relevant (at least in theory, although there may be obviously practical limits). Can I survey in the rain? Rain won’t hurt the seismographs. If you are using a StrataVisor or SmartSeis and it starts raining, they should be fine as long as they are kept Vertical, with the screen pointing up. But acquiring data in the rain should be avoided, especially if there is lightning. Even in the absence of lightening, rain can be a significant source of noise, especially those raindrops striking the geophones directly. Obviously, the harder the rain, the more noise. If waiting the rain out is impractical, shielding the geophones themselves can reduce the noise significantly. If for some reason the seismic system must be left on the ground during an electrical storm, it is advisable to disconnect the trigger and geophone cables from the seismograph. | |||||
| Stacking waveform data (SEG2) files using Pickwin | 4 Relevance | 2 years ago | Gretchen Schmauder | Software | |
| Stacking waveform data (SEG2) files using Pickwin Make sure your dimension size is large enough. To start, select "option", then "Dimension size". If the maximum traces is smaller than the total number of traces, increase the maximum traces, check “Change dimension size” and click “OK” to change dimension size. Open one waveform file as usual. Open another waveform file as usual. Choose “Append to present data”. If you want to change the color of traces depending on files, change component (2 to 10), check “Change” and click “OK”. Note that color does not affect stacking. Trace color is shown below. If you uncheck the “Change”, all traces are shown black. Confirm total number of traces. Two waveform files are shown together. Make sure there is no time difference between shots. After importing 3rd file. After importing 4th file. Make sure there is no time difference among shots. Confirm total number of traces.. All waveform files are shown together. Make sure there is no time difference among shots. Select “Processing”, “Vertical stack”. Select “a. Average” and click “OK”. You may select “Semblance” or “Semblance weighted stack” to emphasize coherent signal. Stacked data is shown. | |||||
