Editorial Advisory Board Q&A: Should all GNSS follow NavIC?

Would it be beneficial for GNSS constellations to transmit signals at higher frequencies, such as in the S-band or the C-band, following the example of the Indian NavIC?

Jean-Marie Sleewaegen

“The S- and C-bands refer to frequency bands centered around 2492 MHz and 5020 MHz. The main advantage compared to L-band is the reduced effect of the ionosphere. However, this comes at the expense of higher propagation losses, increased phase jitter due to the lower wavelength, and extra cost in the receiver and antenna when combined with L-band. The added value for existing GNSS systems already transmitting multiple signals in L-band is probably low. However, because they are less congested than L-band, those bands could be attractive to new space-based PNT services.”
— Jean-Marie Sleewaegen, Septentrio

Alison Brown

“The main challenge with adding additional bands to GNSS constellations (other than getting frequency allocations) is that these will not be compatible with any existing GNSS chip sets or fielded antennas. The cost/benefit analysis is unlikely to be attractive for most GNSS chip vendors to develop products with this capability.”
— Alison Brown, NAVSYS Corporation

Ellen Hall

“There are benefits that the higher bands can offer in GNSS, however the constellation and system must be designed to take advantage of them, which makes it very difficult for the legacy systems that were designed around L-band only to tap into any of these benefits. Higher bands have lower ionospheric distortion, which enables better single-frequency accuracy and unlocks some interesting multi-frequency capability, while shorter wavelengths can allow for smaller antennas in user equipment. However, the tropo/atmospheric distortion gets worse as well as the spreading losses. Another consideration for the higher bands is spectrum interference, as the S-band area especially is extremely busy.”

— Ellen Hall, Spirent Federal Systems