smart-e 4K-RX9000, User Manual

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4K-9000 USER MANUAL V1.1
© 2018 Smart-e (UK) Ltd www.smart-e.co.uk PAGE | 34
13 INTERPRETTING BIT ERROR RATES
Bit error rate readings are available on both the TX and RX variants of the 4K-9000, one on the 4K-TX9000
the total BER and four on the 4K-RX9000, video BER, audio BER, blank BER and control BER.
The bit error rate of digital communications is calculated using cyclic redundancy checks (CRC). HDBaseT uses
a variant of CRC32 commonly employed in Ethernet communications. It works by adding bits to a section of
data at the source and checking this data at the receiving end. Using these bits, the data can be checked for
errors and where minor errors are encountered the code is used to correct the bits received incorrectly.
In the case of HDBaseT transmission the CRC code is added to section of data at the transmitter end of the
system, these CRC codes are then checked at the receiver end, errors incurred are then output as the video,
audio, blank and control BERs at the receiver end. These four different readings are obtained by reading the
individual streams within the originally encoded TMDS signal.
The video BER is the most important reading, the vast majority of the data being transmitted is video data. If
errors are present in the video data errors are likely to be seen as interference on the screen. The perfect
reading shown by the 4K-9000 is 10^-10, any value more than this (10^-10 is a smaller number than 10^-9)
and errors are being encountered and are of a measurable level. The video BER is the reading on the 4K-
RX9000 used to give the relative signal quality seen in the top right of the LCD display.
This quick signal strength reference is placed here so whilst observing any other reading the user has the quick
ability to see the video BER state at a glance, this reading is updated in real time, approximately every 3
seconds. Below is a guide to the signal strength bars and the video BERs they indicate.