DVB-S2 using high sampling rate encoutered Fine Frequency error estimation failed

I'm currently facing an issue with signal demodulation when using a sampling rate of 200Msps and 20 samples per symbol. I keep encountering the error: "Fine Frequency error estimation failed."

Previously, I was able to process signals with a sampling rate of 20Msps and 2 samples per symbol without any issues. I'm using MATLAB's example code from this link: End-to-End DVB-S2X Simulation with RF Impairments and Corrections for Regular Frames.

My question is: Does the provided example code support signal processing with a 200Msps sampling rate and 20 samples per symbol configuration? If not, are there any modifications needed to support these parameters?

Any insights or suggestions would be greatly appreciated! Thank you in advance.

Answer 1

[Vinay]

Hi Chen,

The DVB-S2 uses the coarse frequency synchronization algorithm which can track carrier frequency offsets up to 11% of the input symbol rate.

The symbol rate is calculated as B/(1+R), where B is the channel bandwidth, and R is the transmit filter roll-off factor.

The symbol rate limits the maximum carrier frequency offset that can be corrected up to 2.93MHz.The symbol rate can be increased by increasing the channel bandwidth or decreasing the roll-off factor to correct the desired frequency offset but the configuration does not support the bandwidth increment by larger factor to correct CFO of 200 mega samples per second.

Kindly refer to the below documentations of “DVB-S2” for more details:

https://in.mathworks.com/discovery/dvb-s2.html?s_tid=answers_rc2-1_p4_MLT&requestedDomain=

[Chen I]

Thank you for your response. We are currently using an instrument to simulate DVB-S2 signals for reception and analysis, and the sampling rate of the instrument is 200 MS/s. I would like to confirm if the symbol rate you mentioned is the same as the sampling rate I'm referring to?

[Vinay]

Hi Chen, The symbol rate defined here is the rate of transmission of the signal and this itself determines the sampling rate by the given relation.

Fsamp = Rsymb*simParams.sps;

For sampling rate of 200MHz you can adjust the symbol rate(Rsymb) to Fsamp/sps which is 10Mhz by changing the bandwidth to 13.5Mhz and the output is recieved correctly at the reciever end.