Gateway NRF24L01+ 2.4GHz Wireless Transceiver vs. NRF24L01+PA+LNA Antenna version

[hooraysimpsons]

Is there any reason not to use the NRF24L01+PA+LNA Antenna version radio on the gateway to help increase operational range of the devices? This seems like it would be easier to troubleshoot issues than having repeater-sensor nodes (especially since using sleep options in the repeater nodes may cause issues which would make battery powered ones difficult).

Thanks for the input.

[korttoma]

The challenge with the PA+LNA Antenna version is that it needs quite allot of current to operate properly at full power and the 3,3V output on most arduino boards can not cope with this. Most people have probably solve this by lowering the PA level in the MyConfig.h file like this:

#define RF24_PA_LEVEL_GW   RF24_PA_LOW

Another option is to provide another power source tor the radio.

[Zeph]

Since the network requires bidirectional data transfer, the range limit is defined by the weakest link, which is a node with a standard radio sending to the gateway with the LNA+PA radio. There is nominally a 10 dB gain from the LNA, but see the analysis in this thread: where the effective gain (given noise floor issues) is estimated at 2.6dB. That's not much range improvement. (The antenna may give a little boost too, at least for some directions - tho it could be worse in other directions).

So there's some question of whether using the LNA+PA version for the gateway buys you enough improvement to be worthwhile or not. It may depend on your geometry and just how marginal some of your one-hop-from-gateway linkages are.

As @korttoma says, you may as well reduce the transmit power to reduce power supply needs, since more transmit power (via the PA) doesn't change the weakest link - getting data back from the regular radio on the other end.

(If we were sending data one way from the gateway only, with no need for the nodes to transmit back to the gateway, then the PA would come in handy - but that's not the nature of our network)

[marceltrapman]

@Zeph said:

Since the network requires bidirectional data transfer, the range limit is defined by the weakest link, which is a node with a standard radio sending to the gateway with the LNA+PA radio.

So let's assume that the Gateway and one or two repeaters would have that LNA+PA radio.
Would that not mean that at least between the gateway and repeaters there is maximum range.
And, that the range of the sensor is indeed limited but not an issue when within range of the gateway or a repeater?

[Zeph]

Yes, you will get substantially increased range between units which BOTH have LNA+PA transceivers, primarily because of the more powerful transmitters on both sides.

However the weakest links will still be those with leaf nodes which have basic transceivers, and those links will not be nearly as much improved by the one-end-only LNA+PA enhancement as we might wish, because the msgs and ACK's from the basic transceiver to the enhanced (LNA+PA) will not be much enhanced by the LNA.

One could thus use LNA+PA enhanced units on BOTH sides of the weakest links (including any repeaters where it's helpful). The point is that enhancing just the gateway may not buy one as much as one might hope.

[marceltrapman]

@Zeph Thanks that is what I thought but I wanted to make sure

[marceltrapman]

@Zeph Thanks that is what I thought but I wanted to make sure