ECHO CANCELLING

ECHO CANCELLING

Our two very high-performance echo cancellers make TRedess gap fillers ideal for operation in single-frequency networks with limited isolation between the receiving and transmitting antennas. Two different versions are available: DAE and DEEC.

As general rule, it can be stated that a gap filler without echo canceller can be installed in a SFN (using the same input and output channel), but needs an echo signal level 10dB lower than the main signal.

 

A TRedess gap filler can be installed in locations where the echo signal level is up to 10dB (using DAE) or 20dB (using DEEC) higher than the main signal (recommended reference values).

01

Characteristics

Maximum Gain Range: DEEC (-24dB) & DAE (-15dB)

Cancelation window: DEEC (0,5-18,5μs*) & DAE (0-8μs)

Features: DEEC (Doppler Cancellation) & DAE (Spectrum Equalization)

* The cancellation coverage is based on three temporal windows of approximately 6μs wide each. Placed in continuous mode, they fully cover a range from 0,5μs to 18,5μs. The three windows can shift independently in a range going up to 37,6μs.

02

Advanced Features

Digital Adaptive Equalizer

The DAE echo canceller is indicated to be used under moderate echo conditions, supports a 10dB gain margin level and performs spectrum equalization.

 

In addition to cancelling the echo produced by the coupling between the transmitting and receiving antenna, it is able to cancel any echo of the input signal whose delay with the main beam is between 0 and 8μs.

 

Thus, the echo canceller circuit allows correcting the distortions in amplitude of the input signal of the gap filler when they are caused by multipath propagation, in the case of rays that are within the cancellation window.

The DAE echo canceller performs the spectrum equalization in the entire cancellation window.

Input signal
Output signal
03

Advantages & Benefits

Doppler Enhanced Echo Canceller

The Doppler Enhanced Echo Canceller can suppress Doppler effect and echoes with greater gain margin, giving a better MER performance:

 

Output MER > 27dB for a 20dB gain margin.

Output MER > 24dB for a 24dB gain margin.

For the cancellation of an echo 24dB higher than the main signal provides an output MER > 24dB.

Gap-filler input
Gap-filler output