I'm running a SOKKIA SRX with SurveCE on Carlson Surveyor+ data collector. We mainly do Urban/ Semi-Urban cadastral surveys. In one man operation tried to use Robot mode. I've setup a tripod and set the ATP1 360 prism for backsight & foresight. In TRACKING & SEARCH modes the gun locks to slightly off the visible centre towards right. For 100-150m it's about 10-12 seconds. Approximately for 150m - 7mm, for 100m - 5mm, for 50m- 2mm off respectively. If I set 0.0000 for backsight, after locking it becomes 0.0010 - 0.0012 approximately. I need to measure it more accurately as they are my traverse lines. Even in most cases we run open traverses for detail pickup. Tried with two different ATP1 prisms but ended up with the similar results. Then I tried without the data collector but with the gun on SEARCH mode got same results. Again tried with -30mm standard prism got similar results. Could anybody give me a hint about that?
This Content Originally Published by a land surveyor to Land Surveyors United Network
Have you calibrated your station recently?
Hi, I copied this comment from my Sokkia SRX manual, hope it helps
Search operation during Auto Pointing
When the target enters the field-of-view within the set time limit for Auto Pointing completion,
the SRX stops moving and the offset between the target and telescope reticle is added to the
angle measurement value obtained from the encoder and compensated using image processing
calculation. Although this compensation reduces measurement time and increases search
accuracy, there is a possibility that the target and telescope reticle appear to be misaligned.
Compensated values are displayed in blue.
If the SRX is rotated (manually or u~ing the jog dials) more than 1 0", compensation will be
canceled, the angle reverts to that obtained from the encoder, and the angle values are once
again displayed in black. Compensation is automatically performed when performing Auto
Tracking. Terminating Auto Tracking or powering OFF the SRX will cancel the compensation
The SRX has a field collimation process that can correct this issue. Setup prism about 300ft away and go to the configuration/collimation IMAGE-SENSOR is normally the last in the list. Sight prism center and press measure and it will do an electronic adjustment for the offset. This is a document for the SX/PS series and is very similar. http://nebula.wsimg.com/18b0241bd61539dc3b4da3ab189427bf?AccessKeyI...
Good explanation, it is not an error, it is the way the station works, moreover you can check the accuracy of your targets looking the residuals of your resections, and the results of your backsights
what Ivan and Troy wrote above is absolutely correct.
Due the image processing, your SRX achieves better accuracy in angular measurements.
This is an AP1 image from SRX camera during a service inspection in my lab:
Sorry for image quality, but I took this picture with a poor camera ...
I suggest You, use a circular prism (like AP1, for instance), because the autopointing system can work better on a circular shape.
Obviously, your gun must be fine adjusted. With "Settings" menù, You can perform CCD calibration. It isn't too difficult but, if You are not enough skilled, it's better ask for Sokkia's service.