Re:Homemade GPS Receiver
by zb on Monday October 03, 2011 @04:55PM
(#3068013)
The L1 carrier is spread over a 2 MHz bandwidth and its strength at the Earth's surface is -130 dBm. Thermal noise power in the same bandwidth is -111 dBm, so a GPS signal at the receiving antenna is ~ 20 dB below the noise floor.
This is slightly misleading; the bandwidth of the entire signal is 2MHz (it's a 1MHz chip). The bandwidth of the carrier is much narrower - it is above the noise floor typically by somewhere between about 15 and 50dBHz (you can see this quite easily on a spectrum analyser). The spread-spectrum part of the signal is indeed well below the noise floor.
That minor quibble aside, this is a pretty awesome effort for one guy to do end-to-end.
This is slightly misleading; the bandwidth of the entire signal is 2MHz (it's a 1MHz chip). The bandwidth of the carrier is much narrower - it is above the noise floor typically by somewhere between about 15 and 50dBHz (you can see this quite easily on a spectrum analyser). The spread-spectrum part of the signal is indeed well below the noise floor.
That minor quibble aside, this is a pretty awesome effort for one guy to do end-to-end.