Doodle Labs Smart Radio Посібник з усунення несправностей - Сторінка 8

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Smart Radio Trouble-Shooting

Guide

"The radios are connected, but the range is poor"

This could be a rather wide topic. The datasheets provide typical performance over distance

assuming a reasonable fade margin (10-15 dB). The fade margin accounts for variations in the

link quality due to things like antenna misalignment or environmental noise. The most common

reasons for poor range are:

1. Not adhering to recommended Fresnel Zone clearance requirements

2. Noise and Interference

3. Power Supply Issues

4. Overheating

5. Poor choice of antennas

6. Antenna cable loss

We will only briefly discuss these topics. Before covering these topics, if your radios are linked,

then you can use the "sysutils checklink" program to perform a quick link check. Setup the two

radios 10m apart from each other and point the antennas straight upwards. Then SSH into one

of the radios and run

root@smartradio:~# sysutils checklink -d 10 -h 10.223.216.116 -g 3

Note that

means 10m distance, and

-d 10

combined antenna gain for both radios, e.g. 2 dBi on radio 1 and 1 dBi on radio 2). The program

takes about 1 minute to run, and will perform link test between each antenna. At the end of the

test, a log file will be saved at

measured RSSI, as well as the link throughtput per antenna. An example is shown below

{

"distance": "10",

"total_antenna_gain": "3",

"frequency_band": "2442",

"expected_RSSI": "-37",

"RSSI1": "-42",

"RSSI2": "-58",

"throughput1": "23987123",

"throughput2": "24518300"

}

The peak single-antenna throughput is approximately 40-45 Mbps per 20-MHz channel

bandwidth per antenna. In the case above, we are getting around 24 Mbps in a 15-MHz

bandwidth due to interference. The expected RSSI was -37 dBm, but the measured RSSI was

significantly lower (-58) on the second antenna because of misalignment.

means 3-dB total antenna gain (this is the

-g 3

. The results report the expected RSSI and

/tmp/results.json

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September 8, 2021