DVTI v2b prototype camera
EXTA measurement results
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Overview
Images from camera and EXTA measurement setup
Table with EXTA measurement results - DVTI v2b
Two members from the Stellar Occultation Timing Association Switzerland (SOTAS) http://www.occultations.ch/index.html (Andreas Schweizer and Stefan Meister), have developed new digital USB cameras with GPS time insertion for occultation observation http://www.occultations.ch/equipment#DVTI.html. Beside the camera hardware also all needed software components were developed by this team.
Because I have developed an Exposure Timing Analyzer device EXTA years ago, I was interested to test the accuracy of the camera exposure and the GPS times inserted. After my measurements of a first prototype version DVTI 1 in 2019, a further developed version DVTI v2b was tested with EXTA in 2020. In addition to a different camera hardware with IMX174 image sensor, also a different camera software version was used in this DVTI v2b version. The camera control and recording software for the PC "DVTI CamControl" has also been completely revised and equipped with many new features.
During the test phase of a few months, the camera firmware and the control and recording software for the PC were continuously revised and improved. A firmware update of the camera is carried out directly with the DVTI CamControl software and the existing USB connection within a few seconds. And a new version of the DVTI CamControl control and recording software file can be started immediately after download without installation.
In March 2020, my measurements were completed. The camera, GPS and PC system delivered recordings with accurate time stamps within the system limits.
A great advantage of this newly developed DVTI v2b camera system is, that settings in the recording software cannot lead to incorrect time stamps in the recordings.
In the year 2019 I made EXTA measurements on a commercial digital camera product with the same image sensor. Several times I got time value errors apparently dependent on some setting values in the recording software. This time stamp errors were not visible and would not have been detectable by me without EXTA.
The DVTI v2b camera works without active cooling. But this is not necessary for the relative short exposure times typically used in occultation recordings. Because of this, the DVTI v2b camera is powered via USB and there is no need of an additional external power source. And the biggest advantage of this DVTI v2b camera system is "You always get what you set" if you are working within the system limits. One can always trust the exposure times and the GPS inserted time stamps. This is independent on the settings used in the PC camera control and recording software.
Additional information from the developer team:
There is a https://groups.io/g/d-vti-cam project group where further details about the camera, including a Wiki, are available. It will also be published there later when the DVTI camera can be pre-ordered.
Finally, I would like to note, that I only carried out these camera tests out of my own interest and as an amateur astronomer. I have no business relationship with the camera project or the development team. Therefore, the test results can only be used without any guarantee.
| Digital camera DVTI v2b, GPS and USB3 cable |
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| Digital camera DVTI v2b and EXTA measurement setup |
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| To record the EXTA LED matrix display with the DVTI v2b camera, a Canon 17-85mm DSLR lens and a bayonet/T2 adapter was used. |
| Digital camera DVTI v2b and Notebook with software for control and recording |
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PC Hardware: HP ProBook 6570b with Intel core i5 2.6GHz CPU, 8GB RAM, Samsung SSD, EVO 840, 500GB, 512MB Cache, SATA III
PC Software: Windows system W7P/64 (all updates) + Dvti CamControl 4.8.6
Camera: DVTI v2b Prototype connected via USB3.0; GPS connected with camera; no additional external Power supply
Firmware 0.4.35
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| EXTA measurement setup diagram |
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Table with EXTA measurement results - DVTI v2b
Download the measurement results in a pdf file
Software Version
DvtiCamControl settings
EXTA (=reference) measurement results
(Evaluation software Tangra v3.6.23)
Comment
Camera
FirmwareDVTI
CamControlBit Depth
Resolution
Binning
Exposure set
[s]Real Exposure
(EXTA)ADV State
Channel time stamp error
Video inserted time stamp error
(time = exposure start and end)Gaps in
image sequenceMeasurement tolerance
(= EXTA resolution)
(time =
Central Exposure Time)
0.4.35
4.8.6
16
960x600
2x2
0.001
0.001
0.000
0.000
0.032
+/-0.001
Gap as expected due to max. frame rate of Prototype 2b =
30fps, exposure window before the gap
0.4.35
4.8.6
16
960x600
2x2
0.002
0.002
0.000
0.000
0.031
+/-0.001
Gap as expected due to max.
frame rate of Prototype 2b = 30fps, exposure window before the gap
0.4.35
4.8.6
16
960x600
2x2
0.005
0.005
0.000
0.000
0.028
+/-0.001
Gap as expected due to max.
frame rate of Prototype 2b = 30fps, exposure window before the gap
0.4.35
4.8.6
16
960x600
2x2
0.010
0.010
0.000
0.000
0.023
+/-0.001
Gap as expected due to max.
frame rate of Prototype 2b = 30fps, exposure window before the gap
0.4.35
4.8.6
16
960x600
2x2
0.020
0.020
0.000
0.000
0.013
+/-0.001
Gap as expected due to max.
frame rate of Prototype 2b = 30fps, exposure window before the gap
0.4.35
4.8.6
16
960x600
2x2
0.030
0.030
0.000
0.000
0.003
+/-0.001
Gap as expected due to max.
frame rate of Prototype 2b = 30fps, exposure window before the gap
0.4.35
4.8.6
16
960x600
2x2
0.033
0.033
0.000
0.000
0.000
+/-0.001
0.4.35
4.8.6
16
960x600
2x2
0.040
0.040
0.000
0.000
0.000
+/-0.001
0.4.35
4.8.6
16
960x600
2x2
0.050
0.050
0.000
0.000
0.000
+/-0.001
0.4.35
4.8.6
16
960x600
2x2
0.080
0.080
0.000
0.000
0.000
+/-0.001
0.4.35
4.8.6
16
960x600
2x2
0.100
0.100
0.000
0.000
0.000
+/-0.001
0.4.35
4.8.6
16
960x600
2x2
0.160
0.160
0.000
0.000
0.000
+/-0.001
0.4.35
4.8.6
16
960x600
2x2
0.200
0.200
0.000
0.000
0.000
+/-0.001
0.4.35
4.8.6
16
960x600
2x2
0.250
0.250
0.000
0.000
0.000
+/-0.001
0.4.35
4.8.6
16
960x600
2x2
0.320
0.320
0.000
0.000
0.000
+/-0.001
0.4.35
4.8.6
16
960x600
2x2
0.500
0.500
0.000
0.000
0.000
+/-0.001
0.4.35
4.8.6
16
960x600
2x2
0.640
0.640
0.000
0.000
0.000
+/-0.001
0.4.35
4.8.6
16
960x600
2x2
1.000
1.000
0.000
0.000
0.000
+/-0.002
0.4.35
4.8.6
16
960x600
2x2
1.280
1.280
0.000
0.000
2.000
+/-0.002
Between some frames a small exposure gap in the range of
about 2ms is visible ***
0.4.35
4.8.6
16
960x600
2x2
2.000
2.000
0.000
0.000
0.000
+/-0.005
0.4.35
4.8.6
16
960x600
2x2
2.560
2.560
0.000
0.000
0.000
+/-0.005
0.4.35
4.8.6
16
960x600
2x2
4.000
4.000
0.000
0.000
0.000
+/-0.005
0.4.35
4.8.6
16
960x600
2x2
5.000
5.000
0.000
0.000
0.000
+/-0.010
0.4.35
4.8.6
16
1920x1200
1x1
0.001
0.001
0.000
0.000
0.032
+/-0.001
Gap as expected due to max.
frame rate of Prototype 2b = 30fps, exposure window before the gap
0.4.35
4.8.6
16
1920x1200
1x1
0.002
0.002
0.000
0.000
0.031
+/-0.001
Gap as expected due to max.
frame rate of Prototype 2b = 30fps, exposure window before the gap
0.4.35
4.8.6
16
1920x1200
1x1
0.005
0.005
0.000
0.000
0.028
+/-0.001
Gap as expected due to max.
frame rate of Prototype 2b = 30fps, exposure window before the gap
0.4.35
4.8.6
16
1920x1200
1x1
0.010
0.010
0.000
0.000
0.023
+/-0.001
Gap as expected due to max.
frame rate of Prototype 2b = 30fps, exposure window before the gap
0.4.35
4.8.6
16
1920x1200
1x1
0.020
0.020
0.000
0.000
0.013
+/-0.001
Gap as expected due to max.
frame rate of Prototype 2b = 30fps, exposure window before the gap
0.4.35
4.8.6
16
1920x1200
1x1
0.030
0.030
0.000
0.000
0.003
+/-0.001
Gap as expected due to max.
frame rate of Prototype 2b = 30fps, exposure window before the gap
0.4.35
4.8.6
16
1920x1200
1x1
0.033
0.033
0.000
0.000
0.000
+/-0.001
0.4.35
4.8.6
16
1920x1200
1x1
0.040
0.040
0.000
0.000
0.000
+/-0.001
0.4.35
4.8.6
16
1920x1200
1x1
0.050
0.050
0.000
0.000
0.000
+/-0.001
0.4.35
4.8.6
16
1920x1200
1x1
0.080
0.080
0.000
0.000
0.000
+/-0.001
0.4.35
4.8.6
16
1920x1200
1x1
0.100
0.100
0.000
0.000
0.000
+/-0.001
0.4.35
4.8.6
16
1920x1200
1x1
0.160
0.160
0.000
0.000
0.000
+/-0.001
0.4.35
4.8.6
16
1920x1200
1x1
0.200
0.200
0.000
0.000
0.000
+/-0.001
0.4.35
4.8.6
16
1920x1200
1x1
0.250
0.250
0.000
0.000
0.000
+/-0.001
0.4.35
4.8.6
16
1920x1200
1x1
0.320
0.320
0.000
0.000
0.000
+/-0.001
0.4.35
4.8.6
16
1920x1200
1x1
0.500
0.500
0.000
0.000
0.000
+/-0.001
0.4.35
4.8.6
16
1920x1200
1x1
0.640
0.640
0.000
0.000
0.000
+/-0.001
0.4.35
4.8.6
16
1920x1200
1x1
1.000
1.000
0.000
0.000
0.000
+/-0.002
0.4.35
4.8.6
16
1920x1200
1x1
1.280
1.280
0.000
0.000
2.000
+/-0.002
Between some frames a small exposure gap in the range of
about 2ms is visible ***
0.4.35
4.8.6
16
1920x1200
1x1
2.000
2.000
0.000
0.000
0.000
+/-0.005
0.4.35
4.8.6
16
1920x1200
1x1
2.560
2.560
0.000
0.000
0.000
+/-0.005
0.4.35
4.8.6
16
1920x1200
1x1
4.000
4.000
0.000
0.000
0.000
+/-0.005
0.4.35
4.8.6
16
1920x1200
1x1
5.000
5.000
0.000
0.000
0.000
+/-0.010
| *** This 2ms gap in longer exposures is caused by the IMX174 image sensor and no problem for occultation work. |
June 21, 2020 |
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