Wednesday, October 28, 2009

DVB-S on the spectrum analyzer

Here's what DVB-S looks like on a spectrum analyzer:

This is with the modulator configured for a 4500 kilobaud signal, which results in a 6 MHz wide channel. With a FEC rate of 3/4, that's about 6 MB/sec or so of available MPEG bandwidth.

Compared to 8VSB, the envelope isn't quite so square - it rounds off a bit on either end. And, of course, there is no pilot at the bottom end like with 8VSB.

This is another SA view - this time it's calculating the channel average power and the adjacent channel power. Taking into account the 20 dB attenuator on the input of the SA, it's seeing a channel average power of about 4 watts, and the adjacent channels are 30 dB down from there.

1 comment:

Radio Frequency Test Equipment said...

Great post. Its easier to read and calculate frequency in waveform presentation.