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--- searchwing-pi-datarate [2021/11/17 22:51]
wf68spef [Pi4/CM4 data transfer rate test]
+++ searchwing-pi-datarate [2021/11/18 15:08] (current)
wf68spef [pi4 config]
@@ Line 524: / Line 524: @@
   * CM4 5Ghz Wifi
   * Laptop T14 via Gigabit Ethernet
+==== pi4 theoretical speed ====
+from https://forums.raspberrypi.com/viewtopic.php?t=291824&start=25#p1768600
+//Fri Nov 27, 2020 2:03 pm
+The WiFi chip is connected via a 4-bit SDIO link that typically runs at 41.7MHz giving an upper **limit on throughput of ~160Mbs**. In practise you won't get close to that because it is a simplex link (only one direction at a time) and there is overhead in each of the protocol and transport layers. Given that, 112Mbps sounds pretty good. Even though the throughput hasn't increased, being able to properly use the wide channels means that the channel (which is a shared medium) is occupied for a shorter time, leaving more time for other devices.
+//
 ==== pi4 config ====
@@ Line 545: / Line 556: @@
 		channel 64 (5320 MHz), width: 80 MHz, center1: 5290 MHz
 		txpower 31.00 dBm
+pi@testi:~ $ iwconfig wlan0
+wlan0     IEEE 802.11  ESSID:"XXXXXXXXXXXX"
+          Mode:Managed  Frequency:5.32 GHz  Access Point: 3C:A6:2F:CB:E0:7E
+          Bit Rate=433.3 Mb/s   Tx-Power=31 dBm
+          Retry short limit:7   RTS thr:off   Fragment thr:off
+          Power Management:on
+          Link Quality=70/70  Signal level=-29 dBm
+          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
+          Tx excessive retries:1  Invalid misc:0   Missed beacon:0
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