GNSS Record and Playback System

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"We used the LabVIEW graphical programming environment with the LabVIEW FPGA Module to significantly ease implementation and make it possible for us to initially consider this solution."

- Davit Zargaryan, 10X Engineering LLC

The Challenge:
Designing and deploying GPS, GLONASS, and other navigation signals and developing a system to record and playback signals for GPS\GLONASS tracker signal reception quality testing.

The Solution:
Combining the benefits of LabVIEW software and FlexRIO adapter modules to develop an easy and maintainable record and playback system with a user friendly interface.

Davit Zargaryan - 10X Engineering LLC
Vachagan Petrosyan - 10X Engineering LLC

About 10X Engineering

10X Engineering LLC, founded in 2013, is an NI Alliance Partner with the knowledge and experience to deliver innovative engineering solutions for RF product (units, devices, components) quality and line testing, custom-designed automated test equipment system assembly, verification, and development. Our solutions cover a variety of industrial sectors such as RF software defined radio, radiolocation, spectrum monitoring, and more. For every request we receive, we follow procedures for technical and software functional requirements clarification, RF measurement methodology selection, and hardware configurations. If needed, we take responsibility to prove a concept and demonstrate the flexibility and reliability of our solution.

Problem Background and Solution

Our customer develops portable GPS\GLONASS GPRS trackers and needed to generate real navigation signals for device under test signal reception quality testing. Our first and most important challenge was to develop a portable system for outside use, implementing records of GNSS signals and long-term carrier trajectory. The system needed to playback recorded data in other sites such as laboratories and buildings.

The GNSS Record and Playback System (Figure 1) features hardware that includes the active antenna’s power supply, RF signal preamplifing and splitting box, transceivers, and more. For user comfort, we included a touch (antivandal SAW sensor) panel to avoid using a keyboard and mouse.

We used a FlexRIO FPGA board and NI 5791 modules to address the challenge of recording three parallel GNSS bands. We used an NI 8260 HDD module (SSD RAID) for storage capacity and the desired record and playback speeds. We used the LabVIEW graphical programming environment with the LabVIEW FPGA Module to significantly ease implementation and make it possible for us to initially consider this solution.

To meet our requirements, we used the following NI hardware:

System Specification

Number of TX channels

Number of RX channels



Input impedance 50 ohms
Frequency range 200 MHz–4.4 GHz

Supported GNSS standards and bands


GPS: L1, L2, L5

Galileo: E1, E5a, E5b


BeiDou: B1, B2

QZSS: L1, L2

SBAS (OmniSTAR and StarFire)

Real-time bandwidth

1 channel–50 MHz

2 channel–15 MHz

3 channel–11 Mhz


14-bit A/D converter (RX channel)

16-bit D/A converter (TX channel)

Output max power 0 dB m (max)
Phase noise (10 kHz on 2.4 GHz) -100 dB c\Hz
Sensitivity of RX channel -135 dB m
Internal data storage (SSD) 1.2 TB
Record Duration (3-channel parallel–BW each 10MHz) 7500 s
Active GNSS antenna Trimble Zephyr Geodetic Model 2


The GNSS Record and Playback System software includes the following modes:

Record—continuous record data to TDMS file in the RAID, three channels parallel (one file for each channel)

Measure—measuring input signal of system (output power, spectrum, IQ, and more)

Read from file—acquisition and analysis of recorded signal

Playback—continuous playback of recorded signals from file


We created our current solution with a FlexRIO 5791 adapter module and used LabVIEW to program our user interface, which helped us achieve more flexibility and functionality than in the customer requirements within a 3.8 month time period.

Author Information:
Davit Zargaryan
10X Engineering LLC
Hovsep Emin 123
Tel: Yerevan

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