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

September 21, 2011

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


This model includes gnss-sdr front-end and digital signal processing board. Digital processing board is SK-LPC2478-S3E board of starterkit.ru. It consists of two main parts: lpc2478 mcu with ARM7 core and FPGA Spartan3e500.
Tracking of one satellite is realized now. On the figure below outputs from 6 correlators during 1 second (after acquisition is done) is shown.

correlator outputs during tracking

It can be seen that satellite signal is stably tracking. But the result is not ideal. Delay locked loop is working not good (There should be one maximum-level signal I_prompt output from correlator and two weaker signals of approximately the same level I_late and I_early correlator outputs).
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Comments

Posted by peter on May 05, 2013  •  15:11:15

what is the front-end that you use to digitize the input? It seems that it contains 4 antenna connectors. Can you connect 4 different antennas at the same time to this front-end?

Posted by admin on May 18, 2013  •  01:03:11

It's my front-end that I've described here: http://gnss-sdr.ru/index.ph...

2 connectors for 2 max2769 LNAs (1 for active antenna and 1 for passive antenna). The 3rd connector is for external reference clock input and the 4th is for reference clock output.

So you can not connect 4 different antennas.

Posted by lyf8118 on July 14, 2014  •  13:00:57

You mean you used tracking modules to perform signal acquisition?

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