I am not able to get position solution using simulated files

I am using software GNSS Receivers to get PVT solution for the bin/iq files generated using Skydel simulator,
However I am not able to get the PVT solution for any constellation except for GPS L1CA. The C/No for all the other constellations is below 30dB mostly even after increasing the signals strength of visible satellites during simulation of binary files. The receiver acquires exactly same satellites as simulated for all the cases but fails to track.
For GPS B1C I am using following parameters in receiver
settings.dataType = ‘int16’;
% File Types
%1 - 8 bit real samples S0,S1,S2,…
%2 - 8 bit I/Q samples I0,Q0,I1,Q1,I2,Q2,…
settings.fileType = 2;
%Intermediate, sampling, code frequency and code length
settings.IF = 0e6; %[Hz]
settings.samplingFreq = 25e6; %[Hz]
% Front-end bandwidth for calculation of weighting factor in wideband (WB)
% tracking mode (this is required only for WB tracking mode)
settings.FEBW = 20e6; % [Hz]

settings.msToProcess = 37000;
settings.skipNumberOfBytes = 8e6;

%% B1C signal parameters ============================================
% Define number of chips in a B1C primary code period.
settings.codeLength = 10230; % [Chips]
% Nominal rate of B1C primary code.
settings.codeFreqBasis = 1.023e6; % [Hz]
% Carrier center frequency
settings.carrFreqBasis = 1575.42e6; % [Hz]

%% Acquisition settings =============================================
% Skips acquisition in the script postProcessing.m if set to 1
settings.skipAcquisition = 0;
% It is single sideband, so the whole search band is tiwce of it.
settings.acqSearchBand = 5000; % [Hz]
% Coherent integration time for acqisition: sub-portion of code used to do
% correlation. This parameter should be greater than 1ms and less than 10 ms
settings.acqCohT = 1; % [ms]
% Frequency search step
settings.acqStep = 1000/settings.acqCohT/2; % [Hz]
% Threshold for the signal presence decision rule
settings.acqThreshold = 10;

% Code tracking loop parameters
settings.dllDampingRatio = 0.7;
settings.dllNoiseBandwidth = 1; % [Hz]
% Hailf of the E-L spacing should be kept below approximately 0.0765 chip
% for full-band tracking mode (see Betz 2016)
settings.dllCorrelatorSpacing = 0.06; % [primary code chip]
% Carrier tracking loop parameters
settings.pllDampingRatio = 0.7;
settings.pllNoiseBandwidth = 18; % [Hz]
% Precorrelation integration time for DLL and PLL
settings.intTime = 0.001; % [s]

%% Navigation solution settings =====================================
% Period for calculating pseudoranges and position
settings.navSolPeriod = 200; %[ms]
% Elevation mask to exclude signals from satellites at low elevation
settings.elevationMask = 10; %

Requesting to please suggest what is wrong in my approach
Thanks in Advance

Hi @Nitin ,

thank you for your question.

Would you be able to tell us which GNSS receiver software you are using?
We haven’t extensively tested Skydel with software receivers, but we are quite confident that the issue is not Skydel since our IQ data is quite reliable.



Hi Andre
I am using my own Software receiver which I have tested for data available on the internet and real time data captured using USRP.
It works well for all constellations even with the IQ files generated by Skydel software simulator but only BDS is a problem.
It is not able to track the BDS satellites as the SNR is too low… It acquires the same satellites as simulated by software but fails in tracking.
Please suggest

Hi @Nitin,

We have an idea where the problem might be, but we need to confirm.
Would you be able to send us your Skydel config as well as the Skydel version number?

If possible, please send it to us via the Simulation Support email address in this link.