Smart-e 4K-RX9000 User Manual - 6.2
4K-9000 USER MANUAL V1.1
© 2018 Smart-e (UK) Ltd
www.smart-e.co.uk
PAGE | 12
6.2
HOW BIT ERRORS OCCUR
Bit errors can be very destructive events, completely changing an intended instruction or piece of data
rendering a data packet useless and possibly leading to a system critical state. Systems mitigate against these
kinds of situations by employing methods such as checksums on data packets to ensure any data which has
propagated with a bit error is disposed of and a new packet either requested or waited for. More advanced to
this are forward error correction systems, commonplace in most modern digital data storage devices,
whereby when an error is detected the system can identify the bit or bits which have been affected and correct
their values, this is only possible for a limited number of bit errors. If too many errors have been induced it
becomes impossible to know which bits have been affected and the data packet must be rejected.
Within a typical HDBaseT install there are three key areas where faults can be introduced to data, the
HDBaseT transmitter, the transmission medium (CATx cable) and finally the HDBaseT receiver. The
transmitter and receiver can be looked at in similar terms as they are a typical PCB assembly with surface
mount components all housed within a sealed metal casing.
The most common source of errors within a digital system are caused by electromagnetic interference (EMI)
also commonly referred to as radio-frequency interference (RFI). The most effective way to mitigate against
the effects of EMI is to house all components within an external shield, this is provided at the transmitter and
receiver ends of a HDBaseT system by the metal casing. Whilst not 100% effective products undergo
electromagnetic compatibility (EMC) testing to ensure that they (a) are resilient to the effects of external
sources of EMI and (b) do not generate a significant EMI effect themselves which could cause issues for other
surrounding devices.
With the cased transmitter and receiver protected from any major impact of interference this leaves the
transmission medium, in the case of HDBaseT the CATx cable, as the vulnerable point of the system to the
effects of EMI.
Nearly all electronic devices are a potential source of EMI, as demonstrated above with some typical consumer
electronic products. Internet connected devices using wireless are a low risk source, such as smartphones
and tablets, however they also often incorporate Bluetooth technology which is a slightly greater risk. Devices
with large switching currents such as hair dryers, fluorescent lighting and microwave ovens are a common
source of interference within domestic HDBaseT installations. Large induction effects can occur on CATx