NRF24L01+PA+LNA with AT2401C - Power Output ?

Projects Networking, Protocols, and Devices
1

I have some NRF24L01+PA+LNA fitted with the AT2401C PA\LNA IC.

Does anyone know the power gain of the AT2401C, I cannot find a datasheet ?

The RFX2401C is similar and tha datasheet for that says the power gain is 25dB, saturation level of 22dBm. Thus if the power level of the NRF24L01 is set to -18dBm (setPALevel(0):wink: you would expect the module to output -18dBm + 25dB = 7dBm.

So does anyone know for sure the power gain of the AT2401C ?

2

srnet:
I have some NRF24L01+PA+LNA fitted with the AT2401C PA\LNA IC.

Does anyone know the power gain of the AT2401C, I cannot find a datasheet ?

The RFX2401C is similar and tha datasheet for that says the power gain is 25dB, saturation level of 22dBm. Thus if the power level of the NRF24L01 is set to -18dBm (setPALevel(0):wink: you would expect the module to output -18dBm + 25dB = 7dBm.

So does anyone know for sure the power gain of the AT2401C ?

Are you mixing the power gain of the receiver with the output setting of the transmitter, which is limited to 1 milliwatt.
Paul

3

No, I realise that the output of the NRF24L01 itself is set to 0dBm/1mW when you use setPALevel(RF24_PA_MAX).

setPALevel(0) should be the same as setPALevel(RF24_PA_MIN), i.e. -18dBm.

Whats more confusing is what the RF24.h file says;

/**
     * Set Power Amplifier (PA) level to one of four levels:
     * RF24_PA_MIN, RF24_PA_LOW, RF24_PA_HIGH and RF24_PA_MAX
     *
     * The power levels correspond to the following output levels respectively:
     * NRF24L01: -18dBm, -12dBm,-6dBM, and 0dBm, lnaEnable affects modules with LNA
     *
     * SI24R1: -6dBm, 0dBm, 3dBm and 7dBm with lnaEnable = 1 
     *        -12dBm,-4dBm, 1dBm and 4dBm with lnaEnable = 0
     *
     * @param level Desired PA level.
     * @param lnaEnable En/Disable LNA Gain
     */

But then my +PA+LNA devices dont use the SI24R1 but the AT2401C.

I would measure it, but I dont have a Spectrum anlyser or Power meter that is fast enough to pick up even the longest NRF24L01 packet.

4

Perhaps the board manufacturer discovered they could not sell the board because of the potential of a user making the output more than 1milliwatt. So they changed IC to one that could not go that high.
Paul

5

Yes, its entirely possible that this AT2401C is not like an RFX2401C at all, has less than 25dB gain, so is not putting out the 7dBm expected.

The AT2401C is fitted to all my NRF24L01+PA+LNA.

I found this article;

https://www.programmersought.com/article/16374679647/

Which suggests different levels for gain and power.

6

I was comparing the NRF24L01+PA+LNA with an SX1280 LoRa device, when both are on the approx same data rate, 250kbps for the NRF24L01 and 200kbps for the LoRa, and with the NRF24L01+PA+LNA on maximum power and the LoRa device on 10mW, the LoRa device goes 10.5 times the distance.

However its not clear wha the power output of the NRF24L01+PA+LNA actually is, so you dont know if your using it legally.

7

The distance has much more to do with the antenna and the receiver noise figure than the transmitter power.

Paul

8

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