Decoding an unidentified GNSS pseudorandom noise (PRN) code could be quite easily done with a high-gain steerable dish antenna as was utilized, by way of instance, in determine the BeiDou-M1 broadcast codes until they had been publicly announced signal decoder. The ratio inside one chip of this code is enough to ascertain its signal. This report describes a way of getting this info utilizing receiver and a GNSS antenna using firmware. The method has been verified using the signs from the Galileo In-Orbit Validation (IOV) satellites. Regardless of the fact that pilot signal partitioning that was just appears to be possible at first glance, it’s revealed that signals may be deciphered.
The concept is to perform accumulation of every chip of an unknown sign through a period interval that is long. The period might be provided that a satellite pass that is complete . Among the channels of the receiver is configured in exactly the identical manner as for signal monitoring. The I and Q signal elements are gathered during a chip period from the digital signal processor, and such values have been added to a variety mobile. A limited quantity of information ought to be known about its own RF frequency the sign; the chip speed; the total code length; and the approach.
The decoding of binary-phase-shift-keying (BPSK) signals (as most frequently used) is the topic of the report. It looks like complex signals’ decoding is possible but this ought to be proved. A limitation of the method (generally with this dish system ) is the maximum overall code length which may be managed: for spans greater than a second and bitrates greater than 10,000 kilobits per minute, the recipient’s sources might not be enough to take care of the signal.
Reconstructing the Stage of the Signal
This technique necessitates. Throughout the accumulation period that is entire, the phase difference between the phase of the signal created by the channel of the receiver and the signal period ought to be a lot less than 1 cycle of the carrier frequency. Based upon the accessible signs of the GNSS, different approaches might be used. The instance is reconstruction of a sign while two signals on frequencies are of construction that is known and could be monitored.