Signal level alignment and in-band noise measurements

May 2, 2006.

Signal level alignment and in-band noise measurements (OP-170-E option)

Blanking a set of contiguous carriers within the COFDM spectrum can help in measuring the levels of in-band noise (intermodulation products, Gaussian noise). The digital DVB-T modulator MO-170 allows to vary the width of the spectrum hole as well as its location within the channel.

COFDM signal power is measured by taking the average of the power within the channel. To simplify the process of aligning signal levels across a transmission or reception chain, the MO-170 can generate a single central carrier whose peak power is 3 dB above the average power of the DTT sign

Spectrum hole unveilling the presence of intermoduation products within the channel
Spectrum hole unveilling the presence
of intermoduation products within the channel

In case a moving picture is required the GV-998 TV generator can be used to supply a test pattern through the ASI or SPI input.

DTT complete test set using GV-998 as an encoder
DTT complete test set using GV-998 as an encoder