Mode GNSS

GNSS: satellite tracking and position fix.

Group	Satellite & navigation
Default frequency	1575.42 MHz
Default sample rate	4 Msps
In the mode list	GPS, GLONASS, BeiDou

Step-by-step: Tutorial-GNSS

What GNSS is

GNSS satellites (GPS, Galileo, GLONASS, BeiDou) broadcast signals from which a receiver works out position and time.

Frequencies and settings

GPS L1.

Setting	Value
Start frequency	1575.42 MHz
Tuning range of the mode table	1550 to 1610 MHz
Sample rate asked	4 Msps
Lowest working rate	2.046 Msps
Channel width	2.046 MHz

OnAir takes any frequency you type; the numbers above are the mode's starting point and the range its table describes. In the app the shortcut label is GPS, GLONASS, BeiDou.

What OnAir shows

Satellites, position and time; Clock tab: UTC and GPS time, leap seconds (and a pending one), the computer clock offset against the satellites (accuracy limited by USB / SDR latency, 5 - 30 ms), level, C/N0 and offset history, the same Sync computer clock section and optional NTP server as the Time signals mode.

The mode's own tab has these screens: Sky, Map, Channels, Interference, Clock. The other tabs (Overview, Receiver, Scan, History) are described on the Main window page.

Tips and caveats

• Checked with generated signals and impairments; recordings of real signals welcome.
• Which radio: Probably not: an RTL-SDR tunes up to about 1.7 GHz. A HackRF (1 MHz to 6 GHz) or another wideband radio is the usual choice for this frequency range.
• Try it without a radio: most modes include a built-in synthetic test signal, so you can open the screen and try the controls first.
• Receiving and the law: Receiving satellite downlinks is generally legal. Encrypted or spread content is not decoded, and voice codecs that are patented are not shipped with OnAir. See Legal.

Related pages

• Time stations and the clock
• All modes, Satellite & navigation
• Supported radios, Troubleshooting, FAQ
• More in Satellite & navigation: Inmarsat-C, Inmarsat Aero, Iridium, Meteor-M LRPT, GOES HRIT, Elektro-L, Orbcomm, QO-100, CubeSat telemetry, Globalstar