Label: CCD analog monitoring
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The complexity of current image specifications is confusing, and the most frequently asked by customers is - "What is the difference between the two?" Since the Sony Effio 960H series was launched in 2009 and shines in various exhibitions, since then The support of the end products is not enough, and there is little opportunity to further explore the new generation 960H specifications and the traditional D1. Seeing that the 960H trend will start this year, it is imperative to refit the existing monitoring system, but in the transition from the traditional D1 to 960H, the mix of various specifications of the camera and the back-end D1/960H Decoder is feasible. How many differences are there? This is the topic that this article wants to explore today.
Can the 960H camera be connected to the D1 Decoder? In conclusion, there is no problem. According to the company's products, the 960H or 760H camera can be connected to the D1 or 960H Decoder. But is there any difference? To explain this problem, you may want to review the analog and digital image specifications first. The following table is based on NTSC:
On the surveillance camera side, the ISP converts the signal obtained by the CCD into an analogy and transmits it to the Decoder at the back end via the coaxial line. The Decoder's built-in ADC digitizes the analog signal sample sent by ISP, and after Decoder internal detection, demodulation and correction mechanism, finally converts the digital signal into BT.656 format output to the back end of the compressed chip (Codec) for storage. .
The biggest difference between the 960H and the traditional D1 is that the effective pixels taken by Sony Effio's CCD and ISP are nearly one-third more than the average D1. However, to fully extend the image quality of Effio to the back-end DVR, you must rely on the support of the back-end Decoder and Codec. First, the Decoder's ADC must support a sampling frequency of 36MHz, allowing Effio to generate a high-frequency analog signal that can be completely sampled into digital data. Second, the Decoder must support the 960H digital signal format (BT.1302), and the final Codec must also increase the bandwidth and speed to handle this amount of data that is one-third more than D1.
For example: In Decoder, the ability of the ADC is like the speed limit of a highway. The resolution and effective pixels of CCD+ISP are the top speed of a car. How fast you can run in the end is the result of the final DVR recording.
In other words, the final image quality will depend on which of the Decoder and Camera's high-frequency attenuation (resolution) first reaches the point where the image quality is affected. The following will analyze the various conditions:
1. When the 760H Camera transmits the analog signal to the D1 Decoder:
The resolution of the traditional 760H is about 540 TVL (which starts to decay at about 6.75 MHz), and about 580 for the Decoder of D1 (the attenuation starts at about 7.25), so the theoretical resolution of the imaging resolution. The date is around 540TVL. However, due to the length of the wire, the material, the quality of the Sensor itself and the ability of the Decoder ADC, the digital signal of the Codec end will be affected. It's like the D1 Decoder running on the speed limit of 75 (760H Camera), the specifications on both sides will not cause the image gap, the car (camera) itself will be different.
2. When the 760H Camera signal is transmitted to the 960H Decoder:
In terms of frequency response, the analog signal of the 760H generally begins to decay at approximately 6.75 MHz, while the 960H Decoder has a significant effect at 8.1 MHz. That is, on the highway with a speed limit of 120 (960H Decoder) running a car with a limit speed of about 75 (760H Camera), the theoretical impact on the picture quality will be the quality of the Camera itself.
However, since the 960H Decoder samples the analog signal of the Camera at 36MHz, the digital image quantized by the ADC will be closer to the signal transmitted from the Camera than the signal after the 27MHz sampling of the D1. So when the 760H camera is connected to the 960H Decoder, the actual picture quality is improved. In addition to improving the resolution of the high frequency of the 760H, it can also be more realistic than the Decoder of the D1 and the signal of the Camera. I have colleagues who even watched D1's Camera see 600 TVL records on the 960H Decoder.
3. When the signal from the 960H camera is transmitted to the D1 Decoder:
Under such circumstances, the Decoder of the backend D1 cannot completely sample the signal of the high frequency part transmitted by the 960H camera, and the high resolution of the 960H cannot be fully utilized. Take the previous analogy as an example. When the top speed 120 car (960H camera) runs on the road of the speed limit 80 (D1 decoder), it can only run to 80; and the difference of the car with the highest speed of 75 (760H decoder) Very small. Strictly speaking, if there is a gap, it will be because the 760H camera is particularly sensitive to high-frequency attenuation. For a better-quality 760H camera, there is even no difference.
4. When the signals of the 960H camera are transmitted to the 960H Decoder:
When the car with the top speed of 120 speeds on the road with the highest speed limit of 120, the resolution of both sides can reach the limit, and the attenuation of high frequency and the degree of signal is also much better than that of D1. When the good Video Decoder takes the advantage of the Sony Effio 960H system to the limit, the gap between D1 and 960H is unquestionable.
From the user's point of view, first purchase the 960H support DVR, and then replace the camera one by one to Sony Effio is a relatively high C / P. First, the 960H Decoder has improved the picture quality of the old camera itself. In addition, the 960H's Camera price cut will take a little longer. The first purchase of the 960H DVR will make the entire monitoring system change smoothly.
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