ATmega256RFR2 and WiFi booster?

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This wouldn't be the first thing I've built with the ATmega128RFA1 or ATmega256RFR2, but now I really want to connect it to a 2W or 3W off-the-shelf WiFi booster. These boosters are bidirectional but rely on detecting the RF power in order to determine direction and operate the RF switches inside.

 

The preamble of all packets is 4 bytes long and cannot be changed. I do plan on using 250 kb/s. Datasheets says the preamble is going to take around 128 microseconds.

 

Is this enough preamble time to activate a typical $50 WiFi booster?

 

Thanks

Last Edited: Thu. Oct 15, 2015 - 09:54 PM
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Wi-Fi preambles are even shorter, so it should work. But since some of the preamble may not be received, you should expect higher than normal frame loss.

 

But you will be potentially violating FCC rules with 3W transmitter.

NOTE: I no longer actively read this forum. Please ask your question on www.eevblog.com/forum if you want my answer.

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How much preamble is required to trigger another RFA1 or RFR2 chip to receive? Or is this unknown? Is it related to how stable the power is?

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It is not a binary thing. Even 1 byte (or even 4 bits) will be enough in most cases. But with shortened preamble you are lowering probability of receiving the frame under noisy conditions.

NOTE: I no longer actively read this forum. Please ask your question on www.eevblog.com/forum if you want my answer.

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yea I think I understand, thank you.

 

correct me if I am wrong, the RX is set to a certain frequency and the first couple of waves simply "zeros" the phase detection, so the PSK has a phase reference?

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It is more complex than this, but yes, that's the basic idea. So if your signal is noisy, you need more of it for PLL to settle.

NOTE: I no longer actively read this forum. Please ask your question on www.eevblog.com/forum if you want my answer.