I'm getting started in occultations timing and would like to use my current ZWO cameras with the video time inserter then save AVI files using Sharpcap.
Is it possible to convert the digital signal from the zwo camera to NTSC format?
I'm guessing not or it would be done but if anyone would know if possible it would be Dr. Glover or others on the Sharpcap forum.
Thank you!
Digital to analog
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Re: Digital to analog
Hi,
no, as far as I'm aware there's no way to do that using an analog time insertion tool - the data transfer to the PC is purely digital, so cannot be used with that device.
Fortunately, SharpCap has an option to digitally insert a timestamp into each frame before it is displayed/saved to file - see https://docs.sharpcap.co.uk/4.1/#Timestamp%20Frames . There are two things to be aware of
* The timestamp added will be the time SharpCap receives the frame, which is going to be *after* the end of the exposure by some small, fairly constant, amount.
* Accuracy is no better than the accuracy of your PC clock - you can use internet time or a PC GPS adapter to set that accurately.
cheers,
Robin
no, as far as I'm aware there's no way to do that using an analog time insertion tool - the data transfer to the PC is purely digital, so cannot be used with that device.
Fortunately, SharpCap has an option to digitally insert a timestamp into each frame before it is displayed/saved to file - see https://docs.sharpcap.co.uk/4.1/#Timestamp%20Frames . There are two things to be aware of
* The timestamp added will be the time SharpCap receives the frame, which is going to be *after* the end of the exposure by some small, fairly constant, amount.
* Accuracy is no better than the accuracy of your PC clock - you can use internet time or a PC GPS adapter to set that accurately.
cheers,
Robin
Re: Digital to analog
Thanks Robbin. It's what I suspected but had to ask.
I have been gathering some data with the sharpcap timestamp vs the gps time inserted onto the analog frames. I'm using dimension 4 for now to keep the PC time closer to accurate.
If I can gather enough data and characterize the offset of sharpcap from GPS time I would go straight digital with sharpcap timestamp.
I'm afraid it's not going to be so simple, or everyone would do it.
It seems odd to me that, as a neophyte, that such archaic methods are required to get accurate time. Even the QHY174gps is a bit kludgy.
I have been gathering some data with the sharpcap timestamp vs the gps time inserted onto the analog frames. I'm using dimension 4 for now to keep the PC time closer to accurate.
If I can gather enough data and characterize the offset of sharpcap from GPS time I would go straight digital with sharpcap timestamp.
I'm afraid it's not going to be so simple, or everyone would do it.
It seems odd to me that, as a neophyte, that such archaic methods are required to get accurate time. Even the QHY174gps is a bit kludgy.
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admin
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Re: Digital to analog
Hi,
actually, when I was thinking about this, my thought was that inserting the time into the video signal has its own drawbacks. After all, the image itself cannot appear in the video signal until after the camera has finished the frame, so the time that is superimposed over the image will be the time that the new frame gets to the video timestamp device, not the time that the frame was captured. As with the SharpCap timestamp, the time you see will be the end of the frame plus some sort of delay caused by the electronics between the frame capture finishing and the image getting to the point where it is timestamped.
The QHY GPS camera should have accuracy in start/end times of the frame that is better than 1ms, and getting down to low microseconds (in theory) with careful calibration using the calibration LED that flashes on the GPS second ticks.
cheers,
Robin
actually, when I was thinking about this, my thought was that inserting the time into the video signal has its own drawbacks. After all, the image itself cannot appear in the video signal until after the camera has finished the frame, so the time that is superimposed over the image will be the time that the new frame gets to the video timestamp device, not the time that the frame was captured. As with the SharpCap timestamp, the time you see will be the end of the frame plus some sort of delay caused by the electronics between the frame capture finishing and the image getting to the point where it is timestamped.
The QHY GPS camera should have accuracy in start/end times of the frame that is better than 1ms, and getting down to low microseconds (in theory) with careful calibration using the calibration LED that flashes on the GPS second ticks.
cheers,
Robin