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1 vote

Ground based GPS?

Look into latest developments on eLoran now under close review as a reliable augmentation to the GPS system. … In contrast to GPS, eLoran is very high power and can penetrate buildings, tunnels and much less susceptible to jamming and spoofing. …
Dan Boschen's user avatar
1 vote

Extracting raw gps messages with GNSS

It's rather straightforward to see the raw data transmitted from any given GPS Satellite, using the details provided in the GPS Signal Specification (for example: see https://www.gps.gov/technical/ps/1995 … specific details would be more than I can explain here in a short post, but I am actively teaching a course that just started where I go through this process in great detail, in Python, using actual GPS
Dan Boschen's user avatar
0 votes

MAX2769 I & Q For Signal Acquisition & Tracking

Yes both I and Q (in-phase and quadrature) data should be used in acquisition, even if the signals themselves are real (for example BPSK such as with GPS). … Below shows an example result with an actual GPS signal using a frequency ramp that sweeps from -5KHz to +5KHz over a time duration of 50 ms. …
Dan Boschen's user avatar
0 votes

CA Code G2 Initial Value vs G2 Delay

The reciprocal of these polynomials (reverse order) is also primitive resulting in 60 total choices (which includes the G1 and G2 polynomials for the GPS C/A Gold Code generator). … Thus you can implement all the GPS C/A codes with a single 20th order LFSR using the convolution of the G1 and G2 polynomials. …
Dan Boschen's user avatar
2 votes
Accepted

Simulation of Doppler shift in C/A code

The GPS is not down-converted to 1.023 MHz, but (if it had no Doppler) it is downconverter to 0 MHz (or DC). That is what baseband is. … The GPS signal goes back and forth between 0° and 180° (BPSK) at a 1.023 MHz rate regardless what frequency it is "carried" at. …
Dan Boschen's user avatar
1 vote
Accepted

Interpretation of a non-canonical Allan Variance plot

computation there-- however I suspect in seeing the time domain data and understanding the application that in the very long term, the ADEV will go down at a $1/\tau$ rate consistent with what we get with GPS
Dan Boschen's user avatar
0 votes
Accepted

Recording L1 and L5 signals in the same Rx channel using USRP N210

Such filtering may already be provide in the LNA-GPS 8-way source and can be measured for verification. …
Dan Boschen's user avatar