We are testing and evaluating a DRONE system using ZUBAX’s GNSS2 (VER2.3).
During an outdoor flight test, a drop in the number of satellite positionings due to strong interference from outside the GNSS band, which has been a topic on this site before, resulted in a drop in the number of satellite positionings and the resulting flight stoppage (hovering) of the DRONE.
We believe that this event was caused by a 1.5GHz band cellular base station near our test site as an interfering wave, and the out-of-band interference wave suppressed the sensitivity of the GNSS receiving module, leading to positioning loss.
The specifications of the interference waves that we estimated are as follows.
(1)1.5GHz band cellular base station ; Transmission frequency 1495-1515MHz OFDM EIRP+63dBm
(2)Separation distance between drone and cellular base station: 700m
(3)Reception level of cellular base station transmission waves on drone: -27dBm
In order to perform accurate positioning with GNSS2 under the above conditions, we believe that the current receiving system post filter (BPF after the LNA) is not sufficient to suppress interference waves, and it is necessary to add a SAW BPF to the front stage.
Are there any improvements in the latest models of GNSS2 to deal with these nearby interference ?
The latest revision of Zubax GNSS 2 does not incorporate any changes to the RF front-end. You may be interested in the following alternatives:
Thank you for the information on the current hardware status of GNSS2 and the introduction of new models.
With the current GNSS2, it is not possible to operate a drone near a cellular base station in the 1.5GHz band, so we plan to modify it by adding a saw filter to the patch antenna output.