search

globsky / greta-oto

An open source GNSS receiver
49 stars 30 forks source link

the rf frontend #2

Closed iceberg1369 closed 3 years ago

iceberg1369 commented 3 years ago

what is the rf frontend IC you use or recommend?

globsky commented 3 years ago

The baseband design is adaptable to a wide range of RF front-end (some need to do sampling rate adjustment and/or a simple filter) like MAX2769/2771. But for power efficiency, it is better to have a customized RF.

On Sun, Jul 18, 2021 at 12:04 AM fgfgfgfgfg @.***> wrote:

what is the rf frontend IC you use or recommend?

— You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub https://github.com/globsky/greta-oto/issues/2, or unsubscribe https://github.com/notifications/unsubscribe-auth/ANSOZGCFV7PSPNKZRWHTUSTTYJ4I7ANCNFSM5AR3G34A .

iceberg1369 commented 3 years ago

The 2771 is 2bit adc but the code requires 4bit samples. Is 4bit adc even needed. As far as I know 4bit samples has zero impact on snr

globsky commented 3 years ago

2bit is at the over sampling situation (eg. 16MHz) and you will get more sampling bits when you do down sampling. And theoretically, 4bits has more than 1dB SNR gain than 2bits and 12dB better for anti-interference. How ever MAX2771 is just one choice. It is better to have customized RF because commercial GNSS receiver all have RF integrated with baseband.