GPS/GNSS Blog RSS Feed

The Increasing Influence of GPS Timing
The old saying "time is money" has never been more true than today, with almost every aspect of modern living governed to some extent by precision timing.... read more
5/16/2012 9:03:31 AM - Andy Walker
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What is Carrier Phase Tracking?
Carrier phase tracking is a highly accurate means of positioning used in GNSS surveying applications. The product of the period of the carrier frequency... read more
5/7/2012 8:26:19 AM - Andy Walker
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Why Test GNSS Receivers for EMC?
Although there is no specific product standard for EMC in GNSS receivers, testing for immunity to electromagnetic interference has to be an essential part... read more
5/7/2012 8:24:09 AM - Andy Walker
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What is the Land Mobile Multipath Model?
Developed specifically to meet the demands of the mobile phone industry, the Land Mobile Multipath (LMM) model provides a pragmatic approach to assessing... read more
5/7/2012 8:19:59 AM - Andy Walker
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Will Your GNSS System Manage the Upcoming Leap Seconds Insertion?
This free of charge Spirent... read more
2/1/2012 9:15:52 AM - Stuart Smith
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Automate Your GNSS Receiver Testing
"We are in Testing Times", a phrase being used more and more these days in relation to many things. However, 'Testing Times' is also a concern to anyone... read more
12/15/2011 1:42:08 PM - Stuart Smith
Tags: GNSS Receivers

A Review of the Possible Sources of Common GPS Errors
Today, GPS applications and services are everywhere, and accessible to almost everyone. In the UK you can now purchase a portable "SatNav" system,... read more
10/25/2011 9:58:12 AM -
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Simulating Roadside Buildings with SimGen Vertical Planes Feature
One of the major considerations in designing a GNSS receiver for automotive applications is to ensure that the performance is not unduly affected by... read more
10/25/2011 9:49:04 AM - Andy Walker
Tags: GNSS Receivers

High-Precision GNSS Market Set For Growth
With the latest report from market research guru ABI Research predicting that the high-precision GNSS sector is set to double in size between 2011 and... read more
10/21/2011 9:39:34 AM - Andy Walker
Tags: GNSS Receivers

What is PRN Code?
Pseudorandom noise (PRN) codes are an important element of code division multiple access (CDMA) based satellite navigation systems. Each satellite within... read more
10/19/2011 3:14:04 PM - Andy Walker
Tags: GNSS Receivers

Why Test GNSS Receivers for EMC?
Although there is no specific product standard for EMC in GNSS receivers, testing for immunity to electromagnetic interference has to be an essential part... read more
10/19/2011 2:54:27 PM - Andy Walker
Tags: GNSS Receivers

COMPASS on Track for Global Coverage
While the Russian GLONASS constellation is slowly approaching full operational status, developers of future multi-GNSS systems also need to focus on the... read more
10/19/2011 2:39:30 PM - Andy Walker
Tags: GNSS Receivers

What is CNAV?
CNAV is the name for the civilian navigation message that will be carried by the modernized GPS system. And while the CNAV message will carry similar data... read more
10/10/2011 10:13:33 AM - Andy Walker
Tags: GLONASS, Multi-GNSS

GNSS Chipset Expansion Must be Underpinned by Quality
With a recent report predicting that consumer and precision GNSS receiver IC shipments will reach two billion units by 2016, it is important to remember... read more
7/2/2011 9:09:57 AM - Andy Walker
Tags: Inertial Sensors

How will GPS/GLONASS Chipset Integration Help the Consumer?
The integration of GPS and GLONASS systems within the same receiver offers many advantages to both the manufacturer and the end user. And now that this... read more
6/16/2011 3:52:00 PM - Andy Walker
Tags: GNSS Receivers, GLONASS

Do You Need a Screened Enclosure to Test a GNSS Receiver?
The traditional logic that all RF testing should be carried out in a screened enclosure has much to recommend it. But do you always need to go to this... read more
6/15/2011 7:47:41 AM - Andy Walker
Tags: GNSS Receivers

GNSS Record & Playback Complements Testing with Simulators
All Global Navigation Satellite Systems (GNSS) work by measuring the transmission-time delay from a satellite to the receiver. With a clear view of the... read more
6/10/2011 3:25:38 PM - Andy Walker
Tags: Record & Playback

What is Wi-Fi Positioning?
Although satellite-based navigation systems are the preferred means for establishing location in "open" terrain, they do suffer shortcomings in areas... read more
6/1/2011 4:40:57 PM - Andy Walker
Tags: Multi-GNSS

What is Binary Offset Carrier Modulation?
Binary offset carrier modulation (or BOCM) is a split-spectrum modulation scheme used by the Galileo navigation satellite system. BOCM is a square... read more
5/31/2011 11:15:29 AM - Andy Walker
Tags: Galileo

What is GAGAN?
The GPS Aided Geo Augmented Navigation or GPS and Geo Augmented Navigation system (GAGAN) is a space-based augmentation system (SBAS) funded by the Indian... read more
5/23/2011 7:16:40 PM - Andy Walker
Tags: GPS Augmentation

LightSquared GPS Testing: Spirent's Perspective
The FCC, LightSquared and GPS industry have all agreed that the many questions around the potential for LightSquared's proposed L-Band... read more
5/18/2011 10:03:38 PM - Andy Walker
Tags: GPS Simulation

What is CNSS?
CNSS is the Compass Navigation Satellite System, which will eventually comprise up to 30 medium-earth-orbit satellites and five geosynchronous satellites... read more
5/18/2011 9:49:23 PM - Andy Walker
Tags: Galileo, Beidou, Compass

Record and playback systems in multi-GNSS receiver testing
Record and playback systems (RPSs) such as the new read more
5/18/2011 9:39:34 PM - Andy Walker
Tags: GNSS Simulation

What is a GPS almanac?
In the wider world, an almanac is an annual publication dedicated to information such as weather forecasts, tide tables, lunar cycles etc. A typical... read more
5/18/2011 9:09:24 PM - Andy Walker
Tags: GNSS Receivers

GPS Modernization: What is M-Code?
An important part of the current GPS modernization program, M-code is the name given to a new signal that is designed to improve both the security and... read more
5/18/2011 9:04:07 PM - Andy Walker
Tags: GPS Modernization

What is Dilution of Precision in GNSS Receivers?
Although a GNSS receiver requires only four satellite signals to provide a complete positional fix in three dimensions, the accuracy of this fix depends... read more
4/30/2011 9:20:01 AM - Andy Walker
Tags: GNSS Receivers

What is RAIM?
RAIM stands for receiver autonomous integrity monitoring, a technology used in GNSS receivers to assess the integrity of the GNSS signals that are being... read more
4/29/2011 5:27:29 PM - Andy Walker
Tags: GNSS Receivers

Using Inertial Sensors to Improve GPS Performance
GPS and inertial sensors complement each other extremely well. GPS works best with a good view of the sky. When the sky view gets obstructed, for example... read more
4/29/2011 5:19:54 PM - John Pottle
Tags: GPS, Inertial Sensors

What is WGS-84?
The World Geodetic System provides a standard co-ordinate frame for the Earth, a standard spheroidal reference surface (or ellipsoid) for raw altitude... read more
4/29/2011 5:16:37 PM - Andy Walker
Tags: GPS

What is a Terrain Obscuration Model?
Particularly relevant for ground-vehicle-based GNSS receivers, terrain obscuration is the phenomenon of temporary and intermittent masking of GNSS signals... read more
4/20/2011 11:35:53 AM - Andy Walker
Tags: GNSS Receivers

Time Discrepancies in Multi-GNSS Receivers
One of the major issues in testing GNSS receivers designed for use with multiple satellite systems is that the different systems do not necessarily share... read more
4/20/2011 11:25:42 AM - Andy Walker
Tags: Multi-GNSS

GPS Modernization and the L2C Signal
L2C is the name given to one of the new signals to be broadcast from the satellites in the modernized GPS constellation. This new signal is intended for... read more
4/15/2011 11:19:21 AM - Andy Walker
Tags: GNSS Simulation, GPS Modernization

Japanese Earthquake Highlights Importance of GNSS Timing
One of the more surprising consequences from the March 2011 earthquake in Japan was that the forces unleashed shifted the earth's mass sufficiently to... read more
4/11/2011 10:14:07 AM - Andy Walker
Tags: GNSS Simulators

GPS Modernization With Improved Civilian Signals
In addition to the new signals to be broadcast under the GPS... read more
4/4/2011 8:06:45 PM - Andy Walker
Tags: GPS Modernization

When Will Galileo be Ready?
The official opening on 20th December 2010 of the Fucino Galileo Control Centre, 130km east of Rome, has brought the Galileo global navigation satellite... read more
4/4/2011 6:49:34 PM - Andy Walker
Tags: Galileo

Motion Simulation with GNSS Scenario Software
For most GNSS receivers, static navigation accuracy is only part of the story. The ubiquitous automotive satnav system is the most common case where... read more
4/4/2011 4:50:58 PM - Andy Walker
Tags: GNSS Testing

Sampling Quantisation for GPS or GNSS RPS Systems
When talking about Record and Playback Systems (RPS), more bits mean more resolution which has got to be better right? Indeed if familiar with the classic... read more
3/21/2011 5:49:06 PM - Steve Hickling
Tags: GNSS Simulation

EGNOS:Fit to FLy
The recent certification of the European Geostationary Navigation Overlay Service (EGNOS) for safety of life applications now means that its performance... read more
3/21/2011 5:25:41 PM - Andy Walker
Tags: GNSS Simulation

What's the deal with using GPS in trains?
There's a simple, compelling, theory around using GPS in trains: by using GPS for position information, coupled with train communication systems, the need... read more
2/17/2011 6:41:33 PM - Andy Walker
Tags: Railway

How do you test an IVNS?
The integrated in-vehicle navigation system (IVNS) is becoming an increasingly popular feature in many automotive applications, ranging from relatively... read more
2/17/2011 6:35:57 PM - Andy Walker
Tags: IVNS

Improving railway navigation
The use of GNSS in navigation, timing and related systems for transportation is ever increasing. The railways are no exception. There are various... read more
2/17/2011 6:24:59 PM - Stuart Smith
Tags: Railway

What is QZSS?
The Quasi-Zenith Satellite System (QZSS) is a GPS augmentation... read more
2/9/2011 10:33:30 AM - Andy Walker
Tags: QZSS, GPS, GNSS

What is a Pseudolite?
A pseudolite (or pseudo-satellite) is any device that performs a specific task that would otherwise require a satellite. So, for example, a dedicated... read more
2/9/2011 10:15:06 AM - Andy Walker
Tags: Pseudolites, GNSS, Single Generator

What is Record & Playback
All Global Navigation Satellite Systems (GNSS) work by measuring the transmission-time delay from a satellite to the receiver. With a clear view of the... read more
2/8/2011 8:39:02 PM - Andy Walker
Tags: GNSS, GSS6400

The Importance of Static Navigation Accuracy in a GNSS Receiver
Of all the performance metrics for a GNSS receiver, navigation accuracy is probably the most important. More to the point, pinpoint static navigation... read more
2/8/2011 8:06:01 PM - Andy Walker
Tags: GNSS, Static Navigation