Pseudo random noise
Pseudo-random noise ( English P seudo R Andom N oise , PRN ) is a designation for digital signals , the statistical properties of random noise have. Such a sequence is characterized by its AKF ( autocorrelation function ).
Generation, properties
It is generated by a combination of linear feedback shift registers (LFSR), which are switched in such a way that groups of sequences with minimal cross-correlation arise.
The signal can only be filtered out of the background noise by correlation if the generation rule is known .
The longer it takes for a sequence of numbers to repeat itself, the better it fulfills its purpose: the less systematic is recognizable in the signal, the more “random” it is and the more difficult it is to discover and listen to a transmission channel.
application
In data transmission
Originally it was used in the military sector, but for some time it has also been used in WLAN technology or in the oscillator of newer PC motherboards . Here it serves to cause less disruptive signals in the environment. It is also used in the scrambler at 1000BASE-T .
It is typically used in the spread spectrum technique, in which gold sequences are used.
In the GNSS area, due to the GPS signal structure, the designation PRN has also become common for the numbers of the individual satellites.
Each satellite system has its own numbering scheme. In order to summarize different systems, the RTCA Commission has created a common scheme for the additional navigation services ( Satellite-Based Augmentation Systems, SBAS ):
| PRN | system | description |
|---|---|---|
| 1-37 | GPS | 1–32 in use, 33–37 reserved |
| 38-61 | GLONASS | GLONASS 1–24, corresponds to the slot number increased by 37 |
| 62-119 | reserved | |
| 120-138 | GEO | SBAS : WAAS , EGNOS , MSAS , GAGAN |
| 139-210 | reserved | |
| EXX | Galileo | |
| CXX | Beidou |
The assignment of the geostationary satellites can be found under the web links.
See also
Web links
Individual evidence
- ↑ Satellite numbers Galileo and others ( Memento from December 20, 2016 in the Internet Archive ; PDF)