Frameless version of this page

This page was primarily made for help in timing evaluation of astronomy video records. To get results as accurate as possible we have to know about the relationship between exposure time and inserted time.

All values in the tables below are given under two important preconditions!

1.)	Inserted times from any used Video Time Inserter are within +/- 1 millisecond.
2.)	Used VTI device stamps a current video field on camera output with times
	of the two previous video Vsync pulses (see diagram below).

Thus my Video Time Inserter KIWI-OSD is working. I think many other VTI are timestamping in this way too but surely not all. So before using the tables of this page the behaviour of the used VTI must be well known.

Video cameras measured until now:

Video camera WAT-120N (camera with integrating functions)

Video camera WAT-902H2 Ultimate

Video camera modul SK-1004XC/SO

Video camera Mintron 12V1E - an external Link to a paper from John Menke about the Mintron timing

Download all correction tables in a small PDF - file

Video camera WAT-120N

This integrating video camera has an internal delay.
Many thanks to Stefano Sposetti from Gnosca - Swiss (MPC code 143) for test recordings with his WAT-120N+. The measurements confirmed that WAT-120N and newer WAT-120N+ are working identical in the same modes.

Correction tables for selection:
Use the correction value from a table below to calculate the real event time from inserted video time. Moving throught the video in steps of fields or frames you can also select the right tolerance value.

If a WAT-120N+ camera works with shortened exposure times (High 2-6), the shortened exposure window will always be placed at the end of a video field. Because an event could have occurred or started in the unexposured part of a video field before the exposure part it may be appropriate to give correction and tolerance times in Modes High 2-6 to the same values as in Mode High 1.

Important notes:
All times used for video evaluation in step by step are assumed to be the mid time of a video field or a video frame. The only difference between working in field or frame step is that the given tolerance has to be expanded by one video field time if frame timing is used. So for this difference two tolerance time columns are included in every correction table.

Example
WAT-120N+ (CCIR) in Mode Slow 4 (Integrating 8 video frames)
Event frame times from video: 22:05:17.654 and 22:05:17.694
Event frame video mid time:   Vt = 22:05:17.674
Values from the table:        It = 0.320s, Ct = -0.190s, Tolerance = ±0.170s
Real event time to report:    Rt = Vt + Ct = 22:05:17.484 (±0.170s)

WAT-120N  (CCIR)

WAT-120N+ (CCIR)

WAT-120N   (EIA)

WAT-120N+  (EIA)


Video timing diagrams for all types of WAT-120N cameras

WAT-120N   (CCIR)
Mode	Integration time [s]	Correction time [s]	Tolerance value [s]
			Evaluation in fields (0.020s)	Evaluation in frames (0.040s)
Off	0.020	-0.040	±0.010	±0.020
Frame 1	0.040	-0.050	±0.020	±0.030
Frame 2	0.080	-0.070	±0.040	±0.050
Frame 4	0.160	-0.110	±0.080	±0.090
Frame 8	0.320	-0.190	±0.160	±0.170
Frame 16	0.640	-0.350	±0.320	±0.330
Frame 32	1.280	-0.670	±0.640	±0.650
Frame 64	2.560	-1.310	±1.280	±1.290
Frame 128	5.120	-2.590	±2.560	±2.570
Frame 256	10.240	-5.150	±5.120	±5.130

WAT-120N+   (CCIR)
Mode	Integration time [s]	Correction time [s]	Tolerance value [s]
			Evaluation in fields (0.020s)	Evaluation in frames (0.040s)
High 6	0.0005	-0.040	±0.010	±0.020
High 5	0.001	-0.040	±0.010	±0.020
High 4	0.002	-0.040	±0.010	±0.020
High 3	0.004	-0.040	±0.010	±0.020
High 2	0.008	-0.040	±0.010	±0.020
High 1	0.020	-0.040	±0.010	±0.020
Slow 1	0.040	-0.050	±0.020	±0.030
Slow 2	0.080	-0.070	±0.040	±0.050
Slow 3	0.160	-0.110	±0.080	±0.090
Slow 4	0.320	-0.190	±0.160	±0.170
Slow 5	0.640	-0.350	±0.320	±0.330
Slow 6	1.280	-0.670	±0.640	±0.650
Slow 7	2.560	-1.310	±1.280	±1.290
Slow 8	5.120	-2.590	±2.560	±2.570
Slow 9	10.240	-5.150	±5.120	±5.130

WAT-120N   (EIA)
Mode	Integration time [s]	Correction time [s]	Tolerance value [s]
			Evaluation in fields (0.017s)	Evaluation in frames (0.033s)
Off	0.017	-0.033	±0.008	±0.017
Frame 1	0.033	-0.042	±0.017	±0.025
Frame 2	0.067	-0.058	±0.033	±0.042
Frame 4	0.134	-0.092	±0.067	±0.075
Frame 8	0.267	-0.159	±0.134	±0.142
Frame 16	0.534	-0.292	±0.267	±0.275
Frame 32	1.068	-0.559	±0.534	±0.542
Frame 64	2.136	-1.093	±1.068	±1.076
Frame 128	4.271	-2.161	±2.136	±2.144
Frame 256	8.542	-4.296	±4.271	±4.279

WAT-120N+   (EIA)
Mode	Integration time [s]	Correction time [s]	Tolerance value [s]
			Evaluation in fields (0.017s)	Evaluation in frames (0.033s)
High 6	0.0005	-0.033	±0.008	±0.017
High 5	0.001	-0.033	±0.008	±0.017
High 4	0.002	-0.033	±0.008	±0.017
High 3	0.004	-0.033	±0.008	±0.017
High 2	0.008	-0.033	±0.008	±0.017
High 1	0.017	-0.033	±0.008	±0.017
Slow 1	0.033	-0.042	±0.017	±0.025
Slow 2	0.067	-0.058	±0.033	±0.042
Slow 3	0.134	-0.092	±0.067	±0.075
Slow 4	0.267	-0.159	±0.134	±0.142
Slow 5	0.534	-0.292	±0.267	±0.275
Slow 6	1.068	-0.559	±0.534	±0.542
Slow 7	2.136	-1.093	±1.068	±1.076
Slow 8	4.271	-2.161	±2.136	±2.144
Slow 9	8.542	-4.296	±4.271	±4.279

Timing diagrams for all types of WAT-120N cameras

This diagrams will show how the WAT-120N camera types are working in timing of exposure and signal output. An internal basic delay of two field times is visible. And in integration modes additional delay times must be considered. Exact time values can be taken from several tables on this page.

Note about other integration modes 16, 32, 64, 128 and 256:
In all other modes with 16, 32, 64, 128 and 256 integrated frames this camera works always with the same procedure and the same delay of two video fields between the last exposured field and the first output field. But we have to consider that the length of integrating and output sequence depends on used mode.

WAT-120N with CS/T-2 Adapter und external control box		Listed modes on the back side

The EIA values printed on the back side of the WAT-120N cable controll are based on a calculation with 30 fps and not 29.97 fps.

Video camera WAT-902H2 Ultimate

No internal delay in this video camera.
In electronic shutter mode OFF the two KIWI-OSD timestampes in the video fields on output specify exactly the start and the end of optical exposure time in this video field. As in most video cameras a time shift between exposure window and V-sync signal of around 0.84 millisecond exists (value determined with VEXA). But no correction of time is necessary because inserted time is equal to the time of optical event +/- 1ms.

In electronic shutter ON/Mode 0-7 exposure times can be set to different shorter values. If working with shortened exposure times it is possible that a short event is missed by the video camera.

In electronic shutter ON/Mode 8-9 exposure time is automatic controlled. Because the exact exposure time is unknown we have always to assume and use the longest possible exposure time with the largest tolerance value. If camera is working in automatic controll with shortened exposure times it is possible that a short event is missed by the video camera.

If a WAT-902H2 Ultimate camera works with shortened exposure times (ON/0-9), the shortened exposure window will always be placed at the end of a video field. Because an event could have occurred or started in the unexposured part of a video field before the exposure part it may be appropriate to give tolerance times in Modes ON/0-9 to the same values as in Mode OFF.

Important notes:
All times used for video evaluation in step by step are assumed to be the mid time of a video field or a video frame. The only difference between working in field or frame step is that the given tolerance has to be expanded by one video field time if frame timing is used. So for this difference two tolerance time columns are included in every correction table.

Example
WAT-902H2 Ultimate (EIA) in Mode Off (normal timing)
Event frame times from video: 17:38:09.243 and 17:38:09.276
Event frame video mid time:   Vt = 17:38:09.260
Values from the table:        It = 0.017s, Ct = 0s, Tolerance = ±0.017s
Real event time to report:    Rt = Vt + Ct = 17:38:09.260 (±0.017s)

WAT-902H2 Ultimate  (CCIR)

WAT-902H2 Ultimate  (EIA)


Video timing diagrams for all types of WAT-902H2 Ultimate cameras

WAT-902H2 Ultimate   (CCIR)
Mode	Integration time [s]	Correction time [s]	Tolerance value [s]
			Evaluation in fields (0.020s)	Evaluation in frames (0.040s)
Off	0.020	0	±0.010	±0.020
ON/0	0.008	0	±0.010	±0.020
ON/1	0.004	0	±0.010	±0.020
ON/2	0.002	0	±0.010	±0.020
ON/3	0.001	0	±0.010	±0.020
ON/4	500 µs	0	±0.010	±0.020
ON/5	200 µs	0	±0.010	±0.020
ON/6	100 µs	0	±0.010	±0.020
ON/7	10 µs	0	±0.010	±0.020
ON/8	10 µs - 20ms	0	±0.010	±0.020
ON/9	10 µs - 8ms	0	±0.010	±0.020

WAT-902H2 Ultimate   (EIA)
Mode	Integration time [s]	Correction time [s]	Tolerance value [s]
			Evaluation in fields (0.017s)	Evaluation in frames (0.033s)
Off	0.017	0	±0.008	±0.017
ON/0	0.008	0	±0.008	±0.017
ON/1	0.004	0	±0.008	±0.017
ON/2	0.002	0	±0.008	±0.017
ON/3	0.001	0	±0.008	±0.017
ON/4	500 µs	0	±0.008	±0.017
ON/5	200 µs	0	±0.008	±0.017
ON/6	100 µs	0	±0.008	±0.017
ON/7	10 µs	0	±0.008	±0.017
ON/8	10 µs - 17ms	0	±0.008	±0.017
ON/9	10 µs - 10ms	0	±0.008	±0.017

Timing diagrams for all types of WAT-902H2 Ultimate cameras

Video camera WAT-902H2 Ultimate

Video camera modul SK-1004XC/SO - CCIR version

No internal delay in this video modul.
The two KIWI-OSD timestampes in the video fields on output specify exactly the start and the end of optical exposure time in this video field. As in most video cameras a time shift between exposure window and V-sync signal of around 0.76 millisecond exists (value determined with VEXA). But no correction of time is necessary because inserted time is equal to the time of optical event +/- 1ms. The video timing of this video module, runs a little bit too slow, for the first three seconds after power ON.

In this video camera modul the exposure time is automatic controlled in the range of 10µs to 20ms. Because the exact exposure time is unknown we have always to assume and use the longest possible exposure time with the largest tolerance value. If working with shortened exposure times it is possible that a short event is missed by the video camera modul.

Example
SK-1004XC/SO (CCIR)
Event field times from video: 20:07:44.038 and 20:07:44.058
Event field video mid time:   Vt = 20:07:44.048
Values from the table:        It = 0.020s, Ct = 0s, Tolerance = ±0.010s
Real event time to report:    Rt = Vt + Ct = 20:07:44.048 (±0.010s)

Video camera modul SK-1004XC/SO  (CCIR)


Video timing diagram for video camera modul SK-1004XC/SO

Video camera modul SK-1004XC   (CCIR)
Mode	Integration time [s]	Correction time [s]	Tolerance value [s]
			Evaluation in fields (0.020s)	Evaluation in frames (0.040s)
Automatic	10µs - 20ms	0	±0.010	±0.020

Timing diagram for video camera modul SK-1004XC/SO - CCIR version

Videomodul SK-1004XC/SO

Equipment used in measurements:
GPS receiver Garmin 18 LVC
Video time inserter KIWI-OSD
Microcontroller circuit to generate short pulses synchron to the 1PPS
Video Exposure Analyzer - VEXA with new software V2.0 so it can work now also as a running light
Xpert V-Stream Videograbber USB2.0
Notebook Dell Inspirion 510m, 1.6 GHz Centrino, 1GB RAM, HD 100GB
Video camera in test

Equipment description
For UTC video time insertion KIWI-OSD is used. Additional the internal 1PPS LED of KIWI-OSD can be used for exposure analyzing. The 1PPS LED is hardware controlled by the GPS receiver and flashes at the beginning of every UTC second. The duration of this flash is programable per RS232 with special Garmin GPS software in the range of 20 to 980 milliseconds.

In many measurement cases, a LED pulse duration of 20ms can be too long - and so the pulse can be recorded on two adjacent video fields. It is better to have short pulses well defined in a single video field. Therefore I have built a little microcontroller circuit which can be connected to the KIWI-OSD to get the 1PPS as synchronisation signal. In this circuit, a LED synchronised to the GPS 1PPS, generates a shorter pulse. With eight small DIP switches on this circuit two main features of the LED pulse can be adjusted:
a.) Duration from 0.5 to 7.5 milliseconds in 0.5 ms steps.
b.) Pulse generated only every 1, 2, 3, ....., 13, 14 or 15 UTC seconds for analyzing long exposure sequences.

Video Exposure Analyzer - VEXA with new software V2.0 now can work also as a running light with a row of ten LEDs. Every LED gets lit for 1 millisecond. The duration of darkness between every LED step can be adjusted with eight small DIP switches in the range of 0 to 255 ms. This VEXA-modes can be used to differ the integration sequences of an integrating video camera and to determine the duration of this sequences.

The USB2.0 Videograbber and the Notebook allows me to record lossless videos without a tape up to three hours and without any dropped video field. Stepping through the video in field or frame steps is done very easy by keystrokes on keyboard. Any long jump forward or backward in the video is done in a second by a mouse movement. And no extra monitor is necessary.

Measurement configuration

Recording the LED flashes with the camera in test and timestamping the video signal in UTC shows the start and the end of video fields, frames and integrated sequences. To determine the exact internal behaviour of a video camera one has to take many record sequences. It is known that the flash starts exactly on the beginning of a new UTC second. Now we have to search in timestamped records when this flash is shown in video fields of output signal.

If we are using an integrating video camera we will see this flash on multiple output fields. So it is necessary to take many records with all possible different relative positions between the flash and the beginning of the integrating sequence to determine the exact internal integrating behaviour.

Top of page