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[#17] Cybershaft OCXO 10M Clock 同好會    

原子鐘個short term PN 不一定差過 ocxo。反之亦然。
乜牌子,乜原子鐘/乜ocxo, 重要的係入面個"鐘"。(當然,個鐘機的其他配套也重要。)

要將兩部鐘機比較,要比較short term PN.
If other things are equal, 相差2dBc,已唔同。


Yourcousin
個人訊息 正式會員
49.xxx.xxx.247
2020-10-25 17:55
[#18] Cybershaft OCXO 10M Clock 同好會    
通常,商業級產品不會以1Hz偏移發布性能報告,這是大多數製造商都無法達到的敏感值,大多數產品僅以10Hz偏移測量其相位噪聲。Cybershaft is using 1Hz offset to measure their phase noise, which is critical to audio. All Cybershaft will have the graph showing the phase noise characteristics and the short-term stability (Alan variance) and choose carefully to distinguish their OP level for customer to choose with respect to quality level for audio.

The OCXO installed in this product uses a stable individual after several months of calibration of a new OCXO unit. In order to perform the optimum selection as a clock for audio, we perform a comprehensive evaluation of the phase noise characteristics and the short-term stability (Alan variance) that can be scrutinized more closely.

The product cannot be evaluated by measuring only the output characteristics of the built-in OCXO unit. Our calibration measurement is not directly on the output of the OCXO unit, but is measured from the output terminal of this product in order to evaluate all the performance including the buffer circuit.
And selection reference value

phase noise: OP20A-1 offset 1Hz at -120 dBc / Hz or less offset 10Hz at -140 dBc / Hz or less
      OP21A-1 -140dBc / Hz or less offset 1Hz at -121dBc / Hz or less offset 10Hz
Allan variance short stability (Reference value)

OP20A-1 TAU = 1sec 2.5E-13 or less (0.00025ppb / s)
OP21A-1 TAU = 1sec 2.0E-13 or less (0.00020ppb / s)

The main criterion for grade selection at our company is the short-term stability value of Alan variance. For example, even if the phase noise value is -121 dBc / Hz or less at an offset of 1 Hz, OP21 will not be obtained if the short-term stability Tau = 1 sec value does not meet the standard. This is similar to the traditional OP grade selection method.

The above values ​​are not the general catalog values ​​(Typical) but the guaranteed values ​​measured individually, so the quality of the product is constant. There is no so-called "off".
* For the phase noise offset of 1Hz, an appropriate value with an offset of 1.000Hz to 1.099Hz is used to avoid averaging error. Phase noise measurements are very sensitive and have instrumental and measurement errors. The indicated phase noise values ​​include measurement errors rather than absolute values. The indicated phase noise value is a value measured under the same conditions of our company and is an index of product grading.

The short-term stability value of Alan variance is not clearly defined by international standards, so there may be a large error between calibration laboratories. The above selection values ​​will be the values ​​of our calibration equipment.



BigS
個人訊息 會員
203.xxx.xxx.198
2020-10-25 22:25
[#19] Cybershaft OCXO 10M Clock 同好會    
Thanks for your comprehensive information. No matter it is a commercial, industrial or mil products, some international standard has to be followed especially for the advanced digital application. Now, most of the products follow IEEE standard, such as the "Standard for Terminology and Test Methods for Digital-to-Analog Converters;” (IEEE Std 1696-2013) ", a new requirement (TC-10) is now proposed to address the issues of AM-PM noise as shown below. Nowadays, AM noise is observed also important to the digital signal jittering.

mcc2018
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218.xxx.xxx.114
2020-10-26 10:14
[#20] Cybershaft OCXO 10M Clock 同好會    
Phase Noise Comparison from high hand.



最後修改時間: 2020-11-07 10:53:40
BigS
個人訊息 會員
203.xxx.xxx.198
2020-11-07 10:49
[#21] Cybershaft OCXO 10M Clock 同好會    

I saw this comparison table in a overseas forum, and I read the entire thread there as well.

Yourcousin
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180.xxx.xxx.105
2020-11-07 11:49
[#22] Cybershaft OCXO 10M Clock 同好會    
Not sure why the Cybershaft's BNC output connector can be used for both 50/75 ohm. In normal practice, the 50/75 ohm bnc is certainly not the same type. Termination reflection echos may be a problem.

mcc2018
個人訊息 會員
218.xxx.xxx.114
2020-11-07 18:32
[#23] Cybershaft OCXO 10M Clock 同好會    
得嗰十幾廿MHz 條線又唔係特別長,我試過喱種 75/50 插頭之間 terminal reflection 嘅分別對 signal integrity 嘅影響可以話係無。
長長影子
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165.xxx.xxx.175
2020-11-07 18:49
[#24] Cybershaft OCXO 10M Clock 同好會    
11:11 Cybershaft 所有型號 9折

https://www.adark.co/collections/cybershaft

BigS
個人訊息 會員
203.xxx.xxx.198
2020-11-07 20:41
[#25] Cybershaft OCXO 10M Clock 同好會    
要怎樣才享有9折?

要code嗎?

taichu2
個人訊息 會員
116.xxx.xxx.245
2020-11-08 08:44
[#26] Cybershaft OCXO 10M Clock 同好會    
優惠碼: 11.11
BigS
個人訊息 會員
203.xxx.xxx.198
2020-11-08 08:54
[#27] Cybershaft OCXO 10M Clock 同好會    
用左效果明顯?
Yatchboats
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219.xxx.xxx.129
2021-10-17 12:37
[#28] Cybershaft OCXO 10M Clock 同好會    
有啲分別
tonywong
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220.xxx.xxx.158
2021-10-17 12:42
[#29] Cybershaft OCXO 10M Clock 同好會    
今年還有雙11減價嗎?
wow仔
個人訊息 正式會員
14.xxx.xxx.154
2021-10-29 14:47
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