Choosing between having more signals or more satellites has become a classic dilemma for the users of GNSS applications. But before we deal with that, let’s clear the difference between the two choices. The term “more signals” refers to navigation signals transmitted through three or more frequencies. On the other hand, “more satellites” means an additional GNSS system—such as GPS, GLONASS, and Galileo—to the one that is being used.
There is no one-size-fits-all answer to the question, “Would you rather have more signals or more satellites?” Primarily, it depends on the operating environment, the desired positioning accuracy, and other critical factors. But, there are certain benefits of having more signals compared to having more satellites, and vice versa.
The key advantage of using multiple signals is having improved accuracy. With more frequencies, the ionospheric effects or errors can be mitigated. Ionized by solar and cosmic radiation, the ionosphere causes low-frequency radio waves to bend and refract as they pass through the Earth’s atmosphere, which leads to an apparent delay in the signal transit from the satellite to the receiver.
The apparent time delay for a higher frequency wave is less than it is for a lower frequency wave. So, when using a multiple-frequency receiver, there is a higher chance to mitigate the significant portion of ionospheric bias, hence, the improved accuracy of signal transmission.
Having more satellites is most beneficial when there’s reduced or compromised satellite visibility. Multiple GNSS systems yield lower dilution of precision values or better measurement geometry, which is a vital factor in getting more precise position estimates.
At the end, it’s a question of which one is more important to you: more accurate signal transmission or more precise position estimates. T then again, there are other important factors you should consider. Thus, it is essential to have GNSS signal simulation before using the receiver. With simulation, you can test the limits of your receiver and see whether you need multiple signals or multiple satellites.
To learn more about signal simulation and GNSS systems, don’t hesitate to give us a call.