# Questions tagged [gps]

Questions regarding the Global Positioning System's satellites and uses.

66 questions
Filter by
Sorted by
Tagged with
58 views

### How to estimate that receiving GNSS signals Earth while orbiting the Moon will still provide locations to about 200 meters of uncertainty?

IEEE Spectrum's Can Astronauts Use GPS to Navigate on the Moon? NASA Scientists Say Yes says: Kar-Ming Cheung and Charles Lee of NASA’s Jet Propulsion Laboratory in California did the math, and ...
89 views

### Interpolating precise ephemerides of GPS satellites

My objective is to obtain at least a sub-meter position accuracy by interpolation of the GPS ephemerides. There is conflicting research outside, where some authors state that a simple Lagrange or ...
63 views

### Two line element set

I was wondering where I could find the TLE of a satellite ( I am looking for CASSIOPE). I went into this link - https://www.n2yo.com/satellite/?s=39265 but it has only got the most recent updated TLE. ...
139 views

### What will the US government start to label its GPS spacecraft after SVN 99

GPS spacecraft are currently identified by their “Space Vehicle Number” (SVN) which now number 01 through 75. What will happen after 99 GPS satellites are launched? Is there any plan currently in ...
4k views

### Could a Falcon Heavy really put six GPS Block III satellites in orbit at the same time?

This answer says: GPS Block III satellites are being launched to replace failed or aging Block II satellites, which doesn't require launching more than one at a time. A Falcon Heavy could fill up ...
462 views

### Why multiple GPS satellites are never launched on the same rocket?

From what I've read, GPS satellites have been always put in orbit one at a time. In contrast, Galileo (aboard Ariane or Soyuz) and GLONASS (aboard Proton) sometimes are launched at the same time. Is ...
167 views

### When going to Mars, how do you measure exact distances to determine course corrections?

When probes fly to Mars, they must adjust their trajectories multiple times during transit to ensure correct orbit insertion. They fire their small onboard rockets a little bit to do this. But how do ...
186 views

### Delay-Doppler maps in space science

Maybe this question might be more physics related, but I've read about mostly in context of space science: What is a delay-doppler map (DDM)? I can find it in exploration of asteroids (e.g. (...
9k views

### What is GPS' 19 year rollover and does it present a cybersecurity issue?

The NPR new item and audio podcast The Global Positioning System Resets talks about a 19 year cycling of something in the GPS system, but it's not clear what it is. Every 19 years, the Global ...
720 views

### Does GPS spoofing ever come from space? How are spoofings usually detected?

The BBC News article Study maps 'extensive Russian GPS spoofing' says: (GPS spoofing) involves the state using strong radio signals to drown out reliable navigation data, says non-profit C4ADS. ...
5k views

### What is required to make GPS signals available indoors?

GPS satellites don't transmit strong enough to reach indoors, through the roofs and walls of buildings, like cell phones do. GPS signals that enter buildings through windows are unreliable since they ...
57 views

### GPS PPS stable signal [closed]

My question concerns the GPS NMEA reading data about PPS signal. Is there any way to know via software using NMEA that the GPS PPS signal provided by its outport is already synchronized with the one ...
651 views

### Do GPS satellites use the earth's magnetic field in any way?

There's a lot of speculation about how changes or flips in the Earth's magnetic field would affect us, our machines, and sea turtles. I'm curious about the GPS satellites themselves. In one way they ...
61 views

### Examples of both hardware and software GNSS recievers

I am writing an essay titled: Critically evaluate the positional fixing capabilities of current smartphone technologies for real world GIS data collection I am wanting examples of both hardware and ...
261 views

### Displaying NMEA data in text console [closed]

I'm using an ublox EVK M8T and I'm trying to make a script that displays in text console in real time the data from NMEA and also the time marker from when an event happens. Is there a possibility to ...
30 views

### What is the Cheapest way to track my balloon (only altitude or gps coordinates)? [closed]

I want to build extreme cheap high altitude stuff - balloon, paper plane :) anything. Its cold outside now, and i dont want to track, and collect the my landed "spacecraft". So, i need a very cheap ...
179 views

### Why the PRN obtained from Android is different from calculated by TLE

I want to use TLE data to calculate the azimuth and elevation of every GPS satellites at user's location. In order to verify the correctness of TLE calculation, I wrote an Android app that can be ...
2k views

### What is this gap in the GNSS satellite trajectories?

I've recently bought a USB-connected multi-constellation GNSS-receiver with a U-blox 8 chip in it. I've downloaded the U-center software that can display a lot of details about the received signals. ...
13k views

### How can a Mars helicopter be autonomous if there isn't a Martian GPS?

For a drone to be autonomous, it needs something like a GPS to be able to navigate. If it doesn't have GPS, you'd have to manually control it. Do the orbiters provide something like GPS then? I ...
174 views

### Does the Soyuz spacecraft really try to achieve attitude accuracy of 0.5° from GLONASS and GPS signals?

This answer mentions that the Wikipedia article Soyuz MS (Союз МС, the latest revision of the Soyuz spacecraft, evolution of the Soyuz TMA-M) says: Instead of relying on ground stations for orbital ...
109 views

### Current status of the use of GPS mutli-antenna time differentials for satellite attitude determination?

I am certain that I read a year or three ago about an unmanned satellite that was going to be testing a method of attitude determination that relied upon two (or more) separate antennas on one ...
555 views

### Do operating GPS satellites ever make orbital maneuvers for station-keeping?

Since GPS satellites need to face the Earth, they might execute momentum-unloading from time to time using pairs thrusters so as to produce torque but minimal change in the orbit, but I am guessing ...
529 views

### Why do GPS satellites have increasing eccentricity over time?

When comparing GPS, Beidou, Galileo, GLONASS, and potentially other GNSS, we can see that the eccentricities of GPS spacecraft are increasing with time (i.e. apogees increasing and perigees decreasing)...
82 views

### What are RAIM Service Outage, RNP and EnRoute on GPS DOP maps? What does the red line mean?

Reading @Antzi's question about GLONASS and GALILEO led me to the NTSB's Current GPS SPS Navigation Service Display or SPS PDOP (dilution of precision) map for GPS. Each time the map updates (every ...
312 views

### What do these GPS-related emblems represent? Does one of them show “Marvin the Martian”?

The Wikipedia page linked in @OrganicMarble's answer about the Air Force Space and Missile Museum contains the image below, of a (now retired) GPS monitoring station. To the right of the station ...
463 views

### Does the “17” really mean anything with respect to GNSS orbits being rational factions of a sidereal day?

This answer suggests that the orbital periods of the four large GNSSS contstellations are linked to the sidereal rotation period of the earth by rational numbers with 17 or 34 as the denominator in ...
251 views

### Why are orbital periods different for different GNSS positioning system constellations?

My question is restricted to global positioning systems (Regional ones have geosynchronous constraints, which limits drastically the orbit choice) The diagram in this question highlights different ...
1k views

3k views

### Ground longitude/latitude under a satellite (cartesian coordinates) at a specfic epoch

The script I'm wanting to develop uses the cartesian coordinates (XYZ) from a satellite, and in conjunction with the range, elevation and azimuth from a location, I then take a satellite’s orbital ...
1k views

### Did the NASA PhoneSat actually try to use the GPS from the phone itself?

I was reading this article about NASA's PhoneSat Flight Demonstrations and came across this sentence. "To achieve this, NASA's PhoneSat design makes extensive use of commercial-off-the-shelf ...
618 views

### Will Glonass, Galileo, or BeiDou-2 satellites provide better cis-lunar navigation than GPS?

My question is: Has there been any effort to improve or optimize the radiation patterns on the subsequent satellite navigation constellations (e.g. Glonass, Galileo, BeiDou-2) to facilitate trans-GEO ...
90 views

### Has GPS been used beyond GEO? [duplicate]

When researching this question I came upon a presentation entitled Enabling a Fully Interoperable GNSS Space Service Volume; slides 12, 24, 25, 26 are also shown below. The idea is that while GPS ...
5k views

### Current situation with CoCom regulations and GPS receivers for balloons and cubesats

I wanted to ask this at aviation SE because they are quite rules-and-regulations oriented there, but this question is not (really) about aviation. I'm trying to understand the current situation for ...