I am trying to implement a simple pseudo-noise (PN) ranging simulation. I have used this GNU Radio example, and I have adapted it a bit to suit my needs.

Here is a screenshot of my flowchart: enter image description here

The most important change is that I have introduced a new variable called 'bps' (bits per second). I use it and the 'samp_rate' to calculate the samples-per-symbol by the following formula:

sps = int(samp_rate/bps)

Here is where the sps variable is used (see the red blocks): enter image description here


Why increasing the bits per second (bps) and therefore decreasing the samples per symbol (sps) gives better correlation between the reference and "transmitted" signals?

Correlation with bps = 1.2k: enter image description here

Correlation with bps = 4.8k: enter image description here


1 Answer 1


Your sync word is the sample points of your symbols. That being said, before you use a correlation estimator, you need to use a symbol timing synchronization block to decrease your sample/symbol=1. What you observed is quite expected since you look at the consecutive samples of an oversampled modulated signal!


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