BPI-R4 WiFi range

Banana Pi Router design BPI-R4(MT7988)
145

Yes I might be wrong, it’s only a theory and since I don’t have an R4 I can’t test it myself.

That said, -81dBm is a lot better than some other people seem to get. Example from openwrt forum:

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Unknown if they have SFP modules or not, but a user in the same thread that is using at least one SFP is getting numbers similar to you

146

Finally guys some good news

1 Like
147

Yeah the channel selection matters too, have to find the channel with the least noise

148

Also, as mentioned in openwrt-forum, the value reported in LUCI/webgui might not be the correct noise value (all 3 bands always report the exact same noise level…), I now measure noise using the cli:

iw phy-2g  survey dump | grep -B 1 noise

(replace phy-2g with the name of your device) - strangely (and probably the cause for the luci error), even if I only specify 2g-device, it reports noise for all wireless-channels:

root@OpenWrt:~# iw phy-2g  survey dump | grep -B 1 noise
	frequency:			2412 MHz [in use]
	noise:				-78 dBm
--
	frequency:			5180 MHz [in use]
	noise:				-63 dBm
--
	frequency:			5955 MHz
	noise:				-84 dBm
--
	frequency:			5975 MHz
	noise:				-84 dBm
--
	frequency:			5995 MHz
	noise:				-84 dBm
--
	frequency:			6015 MHz
	noise:				-84 dBm
--
	frequency:			6035 MHz
	noise:				-85 dBm
--
	frequency:			6055 MHz
	noise:				-85 dBm
--
	frequency:			6075 MHz
	noise:				-85 dBm
--
	frequency:			6095 MHz
	noise:				-84 dBm
--
	frequency:			6115 MHz
	noise:				-85 dBm
--
	frequency:			6135 MHz
	noise:				-85 dBm
--
	frequency:			6155 MHz
	noise:				-85 dBm
--
	frequency:			6175 MHz
	noise:				-85 dBm
--
	frequency:			6195 MHz
	noise:				-86 dBm
--
	frequency:			6215 MHz
	noise:				-86 dBm
--
	frequency:			6235 MHz
	noise:				-87 dBm
--
	frequency:			6255 MHz
	noise:				-88 dBm
--
	frequency:			6275 MHz
	noise:				-87 dBm
--
	frequency:			6295 MHz
	noise:				-88 dBm
--
	frequency:			6315 MHz
	noise:				-89 dBm
--
	frequency:			6335 MHz
	noise:				-90 dBm
--
	frequency:			6355 MHz [in use]
	noise:				-81 dBm
--
	frequency:			6375 MHz
	noise:				-91 dBm
--
	frequency:			6395 MHz
	noise:				-91 dBm
--
	frequency:			6415 MHz
	noise:				-91 dBm
149

Yeah I saw that, I just report LUCI values so everyones on the same ball

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150

BPI-R4 seems to report the noise value for the last AP on the list. So, it’s important to turn off the 6 GHz band when, e.g., trying to find the best channel for 5 GHz.

151

Thank you for your input. Do you think it’s possible for the noise to leak through the 12V power circuit, too? The filtering on the BPI-R4 looks rather bare-bones to me. I could take a look at the ripple with an oscilloscope, but I’m not sure what PtP range would be considered normal for this application.

152

Would probably have to compare it to another 6ghz WiFi router to get some baseline

153

Yes it’s certainly possible for this to be the case. For telecom power supplies about 100mVpp would be typical. That said, it also depends a lot on what frequencies are present. Any harmonics through the 5GHz band will have a big impact