BPSK Spectrum

[molakaluri]

Hello,
Will the BPSK spectrum depends on the Random data rate and also the Randomness of data..I mean the rate of switching of data from 1-0-1.If yes..how?Is it mandatory to follow a basic architecture of 16 bit PRBS that is generally given with a feedback to an XOR gate from 14th and 15th bits of a 16 bit shift register or we can change those input bits to the XOR gate?

Thankyou

[paulob160]

Hi there,

the spectrum of a BPSK signal varies, as you
surmise, by the number of '0'/'1' transitions. Assume a
rectangular pulse and bipolar coding : if an extended
series of either '0's or '1's are sent, this will look like a
DC signal. If an alternating '0/'1' pattern is sent this
will represent the maximum bandwidth required i.e. two symbols per Hz. A random pattern will spread the
bandwidth between these limits.

The second part of your question seems to describe the
scrambler, required to break up long series of '0' or '1'
so symbol acquisition can take place. As you say this is
a PRBS, but it is usually application-specific. Looking at
one of the "V" series modem specifications might help.


Hope this helps,

Best Regards,

Paul