Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

[SOLVED] why not phase locked loop for BPSK?

Status
Not open for further replies.
S

sdc18

Junior Member level 1
Joined
Feb 26, 2015
Messages
19
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
1,425
Why don't people use a phase locked loop to recover binary phase shift key (BPSK) data? If all that is changing is the phase, why the need for a mixing and downconversion?
 

I fear you're asking too general for a meaningful answer. In some cases, BPSK will be demodulated by a PLL directly, in most cases complex receiver topologies give better performance. We should refer to specific receiver scenarios to discuss it.
 

Okay, more specifically, text books claim that the matched filter (multiplying by the source oscillator) is the optimal way to decode a BPSK signal in the presence of noise.

It seems that a PLL which is just trying to lock onto the phase of the BPSK signal near a certain frequency, would be more optimal. It is amplitude independent.

Thoughts?
 

BPSK can use various types of demodulators, and PLL is just one of them.
 

Yes. I know this. But the matched filter for BPSK does not use a PLL, and the matched filter is supposed to be optimal. I am asking if anyone has an explanation for this.
 

If you send a repeat of zeros, the PLL will try to lock to this, and when a 1 comes along, you get an output, then if a string of 1s come along the output will fall and not give an output until a 0 comes along. It would be like AC coupling the digital signal through a capacitor, where when the mean DC level shifts some 0s or 1s might get lost.
Frank
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top