Karls48
03-06-2007, 12:42 AM
Meteor image capture on cheap.
For some time now I was trying to devise system for capturing meteor images automatically and without spending great deal of money on it. There is an excellent meteor capture program available for free on the net but it got one big problem. It works only with Maxtor Meteor Video Capture card that cost about $1000 and it is hard to get in Australia. Program itself got many desirable features as it can calculate meteor’s magnitude, speed and the direction. But 1000 bucks is 1000 bucks that I could not justify for this application. After getting GStar CCD camera I noticed it got “Motion detection function”. I have tried to use it for Meteor detection by wiring camera ”Motion detection output” to the relays to simulate “mouse click” and to the mouse and leaving mouse pointer hovering over the “Capture” icon in AstroVideo capture software. It kind of worked but the problem was the time lag how long it took for the camera motion detection circuit to decide that there was a motion and the relays to generate “mouse click “and video capture program to start capturing and I got only tail end of the meteor. After couple weeks of trials I abandoned this system and kept looking for better solution.
I kept searching for “something” that would do the job capturing meteors from the instant they become visible. Then cheap and easy solution appears on eBay in the form of DVR2000 security video surveillance card for PC.
DVR200 is sold on eBay by various vendors for $10 to $ 30. I got mine for $10.95 including postage. The PCI card got four BNC sockets for video input from four cameras that can be switched to display on monitor either as single picture at minimum switching rate of 1 sec or as tile of four images. This function of the card does not interest us at this moment. More interesting is “Motion detection” feature of this card.
Motion Detection
The motion detection function is designed to automatically detect any activities within a selected detection area(s), and to start recording of that camera when activity is detected inside the detection area(s).
For Meteor detection “Select all” button is used to rapidly select the whole video screen for detection.
You can adjust the sensitivity by using the sensitivity control box.
Detection Interval
The occurrence of motion is detected by correlating the successive frames of the video. The “Detection interval” control box can adjust the detection interval between these successive frames. The detection interval is in unit of 100mS.
Recording Time Extension
The motion detected in the detection area(s) will be used as an event to trigger the alarm recording of the corresponding camera.
Once the recording is started, it will continue with an extension time even the motion is stopped.
This extension time can be adjusted by using the “Post motion rec.” control box.
Pre-Alarm
Second most important function of this board is ability to store recording of the event before the Motion detection is triggered.
Pre-Alarm Recording
Pre-alarm recording works together with the alarm recording, which enables you to capture images before the alarm event has happened.
Pre-alarm allows images to be temporarily recorded for a short period of time (1 to 60 second) at normal situation. Once an alarm is being triggered, the pre-alarm images become permanent files, which can be retrieved and playback.
I have been using this board to capture meteors with GEM CCD camera fitted with security 8mm F1.2 lens for three weeks. Camera is mounted on fixed tripod and pointed about 55 degrees to the North West, covering approximately 24 x 28 degrees of sky. It is set up to capture at 12.5 FPS .So far this setup captured 3 to maximum 8 meteors per night. Couple of them quite bright leaving smoke trail for few seconds. I’m looking forward to next meteor shower to see how many I will get. Unfortunately it also captures aircraft, satellites, birds, insects and sudden changed in light intensity. So it is necessary to edit your recording after night’s session, as there will be 20 to 40 false alarms triggered by above mention events. The software is bit clumsy, but it was not written for astronomical use but it is cheap works well.
For some time now I was trying to devise system for capturing meteor images automatically and without spending great deal of money on it. There is an excellent meteor capture program available for free on the net but it got one big problem. It works only with Maxtor Meteor Video Capture card that cost about $1000 and it is hard to get in Australia. Program itself got many desirable features as it can calculate meteor’s magnitude, speed and the direction. But 1000 bucks is 1000 bucks that I could not justify for this application. After getting GStar CCD camera I noticed it got “Motion detection function”. I have tried to use it for Meteor detection by wiring camera ”Motion detection output” to the relays to simulate “mouse click” and to the mouse and leaving mouse pointer hovering over the “Capture” icon in AstroVideo capture software. It kind of worked but the problem was the time lag how long it took for the camera motion detection circuit to decide that there was a motion and the relays to generate “mouse click “and video capture program to start capturing and I got only tail end of the meteor. After couple weeks of trials I abandoned this system and kept looking for better solution.
I kept searching for “something” that would do the job capturing meteors from the instant they become visible. Then cheap and easy solution appears on eBay in the form of DVR2000 security video surveillance card for PC.
DVR200 is sold on eBay by various vendors for $10 to $ 30. I got mine for $10.95 including postage. The PCI card got four BNC sockets for video input from four cameras that can be switched to display on monitor either as single picture at minimum switching rate of 1 sec or as tile of four images. This function of the card does not interest us at this moment. More interesting is “Motion detection” feature of this card.
Motion Detection
The motion detection function is designed to automatically detect any activities within a selected detection area(s), and to start recording of that camera when activity is detected inside the detection area(s).
For Meteor detection “Select all” button is used to rapidly select the whole video screen for detection.
You can adjust the sensitivity by using the sensitivity control box.
Detection Interval
The occurrence of motion is detected by correlating the successive frames of the video. The “Detection interval” control box can adjust the detection interval between these successive frames. The detection interval is in unit of 100mS.
Recording Time Extension
The motion detected in the detection area(s) will be used as an event to trigger the alarm recording of the corresponding camera.
Once the recording is started, it will continue with an extension time even the motion is stopped.
This extension time can be adjusted by using the “Post motion rec.” control box.
Pre-Alarm
Second most important function of this board is ability to store recording of the event before the Motion detection is triggered.
Pre-Alarm Recording
Pre-alarm recording works together with the alarm recording, which enables you to capture images before the alarm event has happened.
Pre-alarm allows images to be temporarily recorded for a short period of time (1 to 60 second) at normal situation. Once an alarm is being triggered, the pre-alarm images become permanent files, which can be retrieved and playback.
I have been using this board to capture meteors with GEM CCD camera fitted with security 8mm F1.2 lens for three weeks. Camera is mounted on fixed tripod and pointed about 55 degrees to the North West, covering approximately 24 x 28 degrees of sky. It is set up to capture at 12.5 FPS .So far this setup captured 3 to maximum 8 meteors per night. Couple of them quite bright leaving smoke trail for few seconds. I’m looking forward to next meteor shower to see how many I will get. Unfortunately it also captures aircraft, satellites, birds, insects and sudden changed in light intensity. So it is necessary to edit your recording after night’s session, as there will be 20 to 40 false alarms triggered by above mention events. The software is bit clumsy, but it was not written for astronomical use but it is cheap works well.