BeiDou-2 (COMPASS) preliminary results

January 28, 2013  •  Leave comment (3)

On 27th of december 2012 China published full version of interface control document (ICD) for their GNSS system BeiDou-2 (COMPASS). This step opened way to building receivers that are capable of working with this GNSS.

Accuracy of FPGA receiver

July 03, 2012  •  Leave comment (0)

On the figure below coordinates variations are plotted. They are taken from FPGA+ARM receiver. The measurements were made during aproximately 1 hour with the speed of 1 measurement per second.


Variation of coordinates across each axis is about 80 meters that approximately corresponds to software GPS receiver SoftGNSS.

FPGA + ARM = new results with hardware receiver

July 02, 2012  •  Leave comment (1)

On the figure below result of hardware receiver (FPGA+ARM-based) work is shown. The same demoboard as in the note From software receiver to hardware receiver or what can be achieved from a bundle of OSGPS and NAMURU was used. Now the software part of the project is running under real time operating system TNKernel. The project is based on correlator Namuru and software gpl-gps/namuru-gpl.


For the moment the program works not stable. Sometimes incorrect synchronization for some channels happens and hence pseudoranges are calculated incorrectly. As a result wrong coordinates are calculated.

Improving the precision of the software receiver GLONASS L1

March 23, 2012  •  Leave comment (0)

Some time ago I became interested in improving the precision of GLONASS Scilab receiver. The difference between mean value and max/min values of coordinates up to 35 m for stationary receiver is too big.

PVT solution of GLONASS L1 Scilab receiver
Figure 1 PVT solution of GLONASS L1 Scilab receiver

After improving several weak parts of the code the difference between mean value and max/min values of coordinates lowered to 6 m, i.e. almost in 6 times. Results from the updated version of the receiver is on the figure 1. The same signal record as in the post GLONASS - frist experiments was used.

Successful usage cases of published projects

March 21, 2012  •  Leave comment (0)

Not long time ago I have noticed master's thesis in which materials from my blog are used :) Here is the link:



February 07, 2012  •  Leave comment (0)

After a pause in developing GLONASS L2 software receiver for SciLab I found some time to work with it. The error that didn't allow to calculate correct PVT is fixed now. So GLONASS L2 scilab receiver is fully working now. PVT solution for L2 signals recorded in the may 2011 is shown on the figure 1.

PVT Solution based on GLONASS L2 signals.
Figure 1 PVT solution for L2.

Source code for acquisition and tracking algorithms of GLONASS L3 signals

October 09, 2011  •  Leave comment (1)

Acquisition and tracking source code is available for download now. It's a reworked version of GLONASS L1 software receiver for scilab.

All source code is moving to Google Code

September 24, 2011  •  Leave comment (3)

All source code is moving to Google Code now.

Current project list includes:
1) GNSS-SDR front-end project wich include:
    a) PCB designed in KiCAD;
    b) CPLD-project made in Xilinx ISE WebPack;
    c) Firmware for USB-bridge cy7c68013a;
2) Real-time GPS receiver GPS-SDR addition to work with gnss-sdr front-end;
3) None real-time GLONASS receiver for SCILAB;
4) Console MS Windows program for streaming data to HDD from gnss-sdr front-end;
5) Hardware project wich include:
    a) Namuru based correlator ported to work with Wishbone bus;
    b) OSGPS based single channel GPS receiver (example of how acquisition and tracking is made in hardware receiver). This projects works in conjuction with Namuru based correlator;

From software receiver to hardware receiver or what can be achieved from a bundle of OSGPS and NAMURU

September 21, 2011  •  Leave comment (3)

Last 4 months were spent on experiments with hardware receivers implementation. The aim was to make a single tracking channel for 1 satellite. The base for this project are open-source projects: Namuru (correlator for FPGA) and osgps. Also gpl-gps project was used (reworked version of OSGPS for ARM7 mcu). On the following photo a device model is shown.

Hardware GNSS receiver

GLONASS L3 - new CDMA signal

April 15, 2011  •  Leave comment (0)

New generation GLONASS-K satellite was successfully launched at the end of february. During last week it started to transmit signals. Besides L1/L2 bands this satellite transmits signals in L3 band. In L3 CDMA technique is used. On the figure below signal processing results of this new signals are shown.