[time-nuts] L1 and L2 frequencies
jimlux at earthlink.net
Fri Jan 16 09:39:07 EST 2015
On 1/16/15 4:58 AM, Li Ang wrote:
> I have a question about the GPS antenna. Since the GPS signal strength on
> the ground is about 20db lower than the thermal noise, does the gain of
> antenna matter?
Not a whole lot.. Obviously, you don't want something -10dBi, and there
is a direct effect of SNR and timing uncertainty (which turns into
position uncertainty). If the SNR is too bad, you won't be able to
acquire the signal.
The PN code runs at 1 Mchip/sec, so you can look at the SNR in 1 Hz
bandwidth as being 60dB higher than the received SNR.
Typically with GPS you worry more about side/back lobe performance so
that you don't pick up multipath reflections.
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