# Differences between dB and dBm

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Differences between dB and dBm:
1. dBm
dBm is a unit measuring absolute power. Its calculation formula is: 10 x lgP. (Note: P in this formula equals power (unit: W) divided by 1 mW.
[Example 1]: If the transmit power P is 1 mW, it can be converted to 0 dBm.
[Example 2]: If the power P is 40 W, it can be converted as follows:
10 x lg(40 W/1 mW) = 10 x lg(40000) = 10 x lg4 + 10 x lg10000 = 46 (dBm).
2. dB
dB is a unit measuring relative power. To calculate the difference between two power values such as A and B, use the following formula: 10 x lg(A/B).
[Example 3]: If A is twice as much as B, the formula 10 x lg(A/B) equals 3 dB. That is, A is greater than B by 3 dB.
[Example 4] If A is 46 dBm and B is 40 dBm, A is greater than B by 6 dBm.

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Function comparison of optical spectrum analyzer units MCA and WMU on OSN 6800
1. MCA boards are classified into MCA4 and MCA8, which provide four and eight ports respectively. An MCA board is mainly used to detect channel optical power, center wavelengths, optical signal-to-noise ratio (OSNR), and the number of wavelengths on an optical path. Similar to an optical spectrum analyzer, an MCA board reports the detected information to the system control board for fault diagnosis and monitoring. In addition, an MCA board can be used together with other boards to implement the automatic power equilibrium (APE) function. 2. The core function of a WMU board is to work with the system control board to lock wavelengths and monitor the wavelength offset of the transmit-end OTU board. The monitoring information is sent to the system control board by email. Then the system control board determines whether to adjust the wavelengths based on the wavelength configuration table. If wavelength adjustment is required, the system control board sends the adjustment information to the OTU board and then adjusts the wavelength offset. 3. An MCA board can monitor both the transmit end and receive end. 4. A WMU board can be configured only at the transmit end because it must work with the system control board at the local site to adjust the wavelength offset of the OTU board at the local site. 5. An MCA board mainly facilitates maintenance and a WMU board is used for function implementation. If an OTU board with 100 GHz channel spacing is used to implement a C-band 80-wavelength system, a WMU board needs to be configured to lock the operating wavelength of the OTU board. This is because the OTU board with 100 GHz channel spacing cannot satisfy the stability requirements of an 80-wavelength system, but the WMU board can help stabilize the wavelength performance.

Differences between IN_PWR_LOW differ from IN_PWR_ABN
IN_PWR_ABN is the predecessor of IN_PWR_LOW/IN_PWR_HIGH. Due to historical reasons, both alarms exist in the OptiX OSN 8800.

Differences between TE40 and TE30 usage scenarios
Compared with TE30, TE40 has higher performance and more ports. TE40 is a good choice for holding video conferences in medium- or small-scale conference rooms and office rooms. Example: TE40 supports a maximum of 8 Mbit/s call bandwidth, while TE30 supports a maximum of 4 Mbit/s call bandwidth. TE40 supports a maximum of 1080p60 image resolution, while TE30 supports a maximum of 1080p30 image resolution. TE40 supports three video input ports, while TE30 supports two. TE30 adopts an all-in-one design that that integrates digital cameras and stereo microphones, satisfying the demand of senior managers to attend video conferences in administrative offices or small-sized conference rooms. For more differences, see TE40 Product Description and TE30 Product Description.

Differences between TE50 and TE30 usage scenarios
Compared with TE30, TE50 has higher performance and more ports. TE40 is a good choice for holding video conferences in medium- or small-sized conference rooms and office rooms. Example: TE50 supports a maximum of 8 Mbit/s call bandwidth, while TE30 supports a maximum of 4 Mbit/s call bandwidth. TE50 supports five video input ports, while TE30 supports two. TE30 adopts an all-in-one design that integrates digital cameras and stereo microphones, satisfying the demand of senior managers to attend video conferences in administrative offices or small-sized conference rooms. For more differences, see TE50 Product Description and TE30 Product Description.

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