Background

Enoki did 2.4GHz wireless module nRF24L01+ range test twice in 2020. Enoki reports the retried test result.

Summary

nRF24L01+ was the most excellent in cost performance.

Nominal power and sensitivity

Enoki tried 3 kinds of 2.4GHz wireless module, XBee TWE and nRF24L01+. Table1 shows the nominal power, sensitivity and price.

With Arduino pro mini

nRF24L01+ doesn't work alone like TWE and XBee. Enoki adopted Arduino pro mini to control nRF24L01+.

The next photo is 2 nRF24L01+ which were used for range test. The interface is 6P connector.

Photo1 nRF24L01+

Enoki assembled nRF24L01+ and Arduino pro mini on the universal board that was used for XBees, as shown in Photo2.

Photo2 nRF24L01+ with Arduino pro mini

Range test result

Enoki did simple range test twice. The retried result was drawn in a sheet on 2020-07-15 as shown in Photo3.

Photo3 Test memo

nRF24L01+ range is shorter a little than TWE and XBee,

while it could receive at the corner of north east direction where both of TWE and XBee failed.

Signal decreased because the transmitter was located in the south and west direction, Enoki thinks.

nRF24L01+PA+LNA

AliExpress sells nRF24L01+ with power amplifier and low noise amplifier.^[1][2] Enoki assembled them on the universal boards as shown in Photo4.

Photo4 nRF24L01+PA+LNA

The range test result was not good.

Conclusion

Range ability
As nRF24L01+ transmitter power is little, it is welcome in Japan. Japan's regulation is strict. Wireless LAN power limit is 10dBm (10mW).

Signal processing
Japanese old house wall is covered with metal net to paint cement. Enoki thinks it decreases signal intensity. nRF24L01+ might have good signal processing.

Programming
XBee and TWE open their library to program. But it is difficult for beginners to modify their libraries by Python. While Arduino has a lot of libraries and the language is C.

Cost
TWE is not sold at Amazon US or AliExpress. And the price is very expensive even at Amazon.co.jp. XBee is also expensive.

Performance
Arduino pro mini price is $2.15. Including nRF24L01+, the total cost is less than $3.

Table 1 2.4GHz wireless module

Wireless module	Trans- mitter [dBm]	Receiver [dBm]	Price
nRF24L01+	0	-94	$0.61
TWE	2.5	-95	¥1980
XBee	5	-102	$16.18
nRF24L01+ PA+LNA	20	-104	$1.51

Ref

[1] nRF24L01+PA+LNA Specifications
[2] nRF24L01+PA+LNA Circuit