Frequency Bands and Signal De-/Activation
When testing GNSS receivers, it is oftentimes required to test for multi-frequency, multi-constellation performance. All of the four major GNSS systems, i.e. GPS, Glonass, Galileo, and BeiDou, transmit numerous signals across several frequencies, but through international cooperation, these frequency bands have been coordinated:
The RF signals transmitted from satellites of different constellation systems…
- … are transmitted on frequencies close to each other, yet they do not interfere with each other
- … can be decoded by one receiver (if supported by the receiver manufacturer)
- … can be grouped into four main bands.
These four frequency bands are:
For multi-frequency, multi-constellation testing it is suggested to test any of the constellations, frequency bands, or any combination together.
The following frequency bands can be generated (GSG-configuration dependent):
- P(Y): Pseudo encryption
Frequency bands can be turned ON/OFF separately, so as to configure which types of RF signals specific to each supported satellite system shall be active/inactive when a scenario is running.
Depending on the configuration of your GSG unit, all of the frequency bands listed above can be turned ON/OFF.
To turn ON/OFF a signal band, navigate to: Select > [Select Scenario] > Configure Scenario: View 3/3 > [Satellite System]: Enter a number of satellites > 1 (see Number of Satellites).
The satellite constellation (see Satellite Constellations) must be configured accordingly, in order to allow for, e.g., the L2C band to be simulated. In other words, if you chose to disable satellites that can generate this signal, it will not be generated, even if you activate the signal. Hence, it is recommended to leave all signal types ON (default), thereby letting the configured satellite type determine which RF signals are active.
Use cases for turning OFF the transmission of individual frequency bands are:
- simulating a one-band antenna
- reserving the maximum number of channels for other requirements (e.g., L1-only transmission)
Altering active RF signals will not alter the navigation message. Hence from a receiver point of view, choosing to de-active L2 and L5 will mimic the situation of using a single band (L1) antenna.
Settings are GNSS-specific, not satellite-specific.
For GLONASS, C/A code is always used.