nRF Distance Measurement sample

[kenlove]

Hi,

I am testing the performance of NDT.

I have done many tests with the development board, and the results are as follows.

During the 3m and 5m tests, the error jitter is relatively large.

How to make distance measurement more stable?

Is there a reference plan for learning?

My test environment: ncs 2.5.0, nRF Distance Measurement sample, nRF52840DK, Open pavement test

Fullscreen NDT-test-1m.txt Download

[2024-01-22 10:38:14.642]# RECV ASCII>
central data_cb (total: 0)


[2024-01-22 10:38:14.873]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=1.82 phase_slope=3.25 rssi_openspace=31.62 best=1.82


[2024-01-22 10:38:16.652]# RECV ASCII>
central data_cb (total: 1)


[2024-01-22 10:38:16.872]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=1.66 phase_slope=1.70 rssi_openspace=7.94 best=1.66


[2024-01-22 10:38:17.644]# RECV ASCII>
central data_cb (total: 2)


[2024-01-22 10:38:17.893]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=1.29 phase_slope=1.67 rssi_openspace=11.22 best=1.29


[2024-01-22 10:38:18.656]# RECV ASCII>
central data_cb (total: 3)


[2024-01-22 10:38:18.892]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=1.51 phase_slope=1.63 rssi_openspace=10.00 best=1.51


[2024-01-22 10:38:20.657]# RECV ASCII>
central data_cb (total: 4)


[2024-01-22 10:38:21.678]# RECV ASCII>
central data_cb (total: 5)


[2024-01-22 10:38:21.910]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=1.48 phase_slope=1.61 rssi_openspace=8.91 best=1.48


[2024-01-22 10:38:22.669]# RECV ASCII>
central data_cb (total: 6)


[2024-01-22 10:38:22.901]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=1.59 phase_slope=1.67 rssi_openspace=8.91 best=1.59


[2024-01-22 10:38:23.679]# RECV ASCII>
central data_cb (total: 7)


[2024-01-22 10:38:23.928]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=1.76 phase_slope=1.82 rssi_openspace=8.91 best=1.76


[2024-01-22 10:38:24.694]# RECV ASCII>
central data_cb (total: 8)


[2024-01-22 10:38:24.923]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=1.77 phase_slope=1.86 rssi_openspace=8.91 best=1.77


[2024-01-22 10:38:25.683]# RECV ASCII>
central data_cb (total: 9)


[2024-01-22 10:38:25.916]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=1.73 phase_slope=1.81 rssi_openspace=7.94 best=1.73


[2024-01-22 10:38:26.694]# RECV ASCII>
central data_cb (total: 10)


[2024-01-22 10:38:26.926]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=1.70 phase_slope=1.77 rssi_openspace=8.91 best=1.70


[2024-01-22 10:38:27.696]# RECV ASCII>
central data_cb (total: 11)


[2024-01-22 10:38:27.914]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=1.67 phase_slope=1.75 rssi_openspace=10.00 best=1.67


[2024-01-22 10:38:28.691]# RECV ASCII>
central data_cb (total: 12)


[2024-01-22 10:38:28.938]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=1.68 phase_slope=1.83 rssi_openspace=7.94 best=1.68


[2024-01-22 10:38:29.702]# RECV ASCII>
central data_cb (total: 13)


[2024-01-22 10:38:29.934]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=1.74 phase_slope=1.80 rssi_openspace=7.94 best=1.74


[2024-01-22 10:38:30.721]# RECV ASCII>
central data_cb (total: 14)


[2024-01-22 10:38:30.953]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=1.64 phase_slope=1.70 rssi_openspace=8.91 best=1.64


[2024-01-22 10:38:31.728]# RECV ASCII>
central data_cb (total: 15)


[2024-01-22 10:38:31.949]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=1.69 phase_slope=1.76 rssi_openspace=8.91 best=1.69


[2024-01-22 10:38:32.726]# RECV ASCII>
central data_cb (total: 16)


[2024-01-22 10:38:32.971]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=1.73 phase_slope=1.76 rssi_openspace=7.94 best=1.73


[2024-01-22 10:38:33.728]# RECV ASCII>
central data_cb (total: 17)


[2024-01-22 10:38:33.963]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=1.74 phase_slope=1.78 rssi_openspace=8.91 best=1.74


[2024-01-22 10:38:34.724]# RECV ASCII>
central data_cb (total: 18)


[2024-01-22 10:38:34.879]# RECV ASCII>
W: malformed advertising data 26 / 17


[2024-01-22 10:38:34.970]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=1.70 phase_slope=1.73 rssi_openspace=7.94 best=1.70


[2024-01-22 10:38:35.742]# RECV ASCII>
central data_cb (total: 19)


[2024-01-22 10:38:35.972]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=1.78 phase_slope=1.80 rssi_openspace=8.91 best=1.78


[2024-01-22 10:38:36.746]# RECV ASCII>
central data_cb (total: 20)


[2024-01-22 10:38:36.978]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=1.55 phase_slope=1.73 rssi_openspace=8.91 best=1.55


[2024-01-22 10:38:38.745]# RECV ASCII>
central data_cb (total: 21)


[2024-01-22 10:38:38.980]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=1.88 phase_slope=1.89 rssi_openspace=7.08 best=1.88


[2024-01-22 10:38:39.759]# RECV ASCII>
central data_cb (total: 22)


[2024-01-22 10:38:39.976]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=1.69 phase_slope=1.66 rssi_openspace=8.91 best=1.69


[2024-01-22 10:38:40.752]# RECV ASCII>
central data_cb (total: 23)


[2024-01-22 10:38:41.000]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=1.32 phase_slope=1.44 rssi_openspace=11.22 best=1.32


[2024-01-22 10:38:41.763]# RECV ASCII>
central data_cb (total: 24)


[2024-01-22 10:38:41.993]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=1.67 phase_slope=1.79 rssi_openspace=7.94 best=1.67

Fullscreen NDT-test-3m.txt Download

[2024-01-22 10:41:49.236]# RECV ASCII>
central data_cb (total: 65)


[2024-01-22 10:41:49.469]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: crc fail
	Distance estimates: mcpd: ifft=2.05 phase_slope=0.00 rssi_openspace=44.67 best=2.05


[2024-01-22 10:41:51.243]# RECV ASCII>
central data_cb (total: 66)


[2024-01-22 10:41:51.478]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=3.52 phase_slope=7.97 rssi_openspace=44.67 best=3.52


[2024-01-22 10:41:52.259]# RECV ASCII>
central data_cb (total: 67)


[2024-01-22 10:41:53.271]# RECV ASCII>
central data_cb (total: 68)


[2024-01-22 10:41:54.264]# RECV ASCII>
central data_cb (total: 69)


[2024-01-22 10:41:59.282]# RECV ASCII>
central data_cb (total: 70)


[2024-01-22 10:41:59.516]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=3.02 phase_slope=14.92 rssi_openspace=89.13 best=3.02


[2024-01-22 10:42:05.312]# RECV ASCII>
central data_cb (total: 71)


[2024-01-22 10:42:06.312]# RECV ASCII>
central data_cb (total: 72)


[2024-01-22 10:42:19.411]# RECV ASCII>
central data_cb (total: 73)


[2024-01-22 10:42:21.424]# RECV ASCII>
central data_cb (total: 74)


[2024-01-22 10:42:21.659]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=1.51 phase_slope=14.28 rssi_openspace=89.13 best=1.51


[2024-01-22 10:42:22.425]# RECV ASCII>
central data_cb (total: 75)


[2024-01-22 10:42:23.433]# RECV ASCII>
central data_cb (total: 76)


[2024-01-22 10:42:26.442]# RECV ASCII>
central data_cb (total: 77)


[2024-01-22 10:42:26.675]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=1.92 phase_slope=23.82 rssi_openspace=141.25 best=1.92


[2024-01-22 10:42:27.449]# RECV ASCII>
central data_cb (total: 78)


[2024-01-22 10:42:27.681]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=3.18 phase_slope=14.79 rssi_openspace=89.13 best=3.18


[2024-01-22 10:42:33.489]# RECV ASCII>
central data_cb (total: 79)


[2024-01-22 10:42:37.508]# RECV ASCII>
central data_cb (total: 80)


[2024-01-22 10:42:37.726]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=4.23 phase_slope=7.56 rssi_openspace=35.48 best=4.23


[2024-01-22 10:42:38.518]# RECV ASCII>
central data_cb (total: 81)


[2024-01-22 10:42:41.522]# RECV ASCII>
central data_cb (total: 82)


[2024-01-22 10:42:41.756]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=3.61 phase_slope=11.66 rssi_openspace=50.12 best=3.61


[2024-01-22 10:42:42.529]# RECV ASCII>
central data_cb (total: 83)


[2024-01-22 10:42:42.759]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=3.64 phase_slope=12.84 rssi_openspace=100.00 best=3.64


[2024-01-22 10:42:43.539]# RECV ASCII>
central data_cb (total: 84)


[2024-01-22 10:42:44.535]# RECV ASCII>
central data_cb (total: 85)


[2024-01-22 10:43:09.301]# RECV ASCII>
central data_cb (total: 86)


[2024-01-22 10:43:09.534]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=3.87 phase_slope=4.69 rssi_openspace=35.48 best=3.87


[2024-01-22 10:43:10.309]# RECV ASCII>
central data_cb (total: 87)


[2024-01-22 10:43:10.527]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=3.89 phase_slope=5.72 rssi_openspace=31.62 best=3.89


[2024-01-22 10:43:16.337]# RECV ASCII>
central data_cb (total: 88)


[2024-01-22 10:43:17.345]# RECV ASCII>
central data_cb (total: 89)


[2024-01-22 10:43:17.578]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=4.23 phase_slope=6.89 rssi_openspace=39.81 best=4.23


[2024-01-22 10:43:18.355]# RECV ASCII>
central data_cb (total: 90)


[2024-01-22 10:43:18.574]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=3.81 phase_slope=7.09 rssi_openspace=35.48 best=3.81


[2024-01-22 10:43:19.362]# RECV ASCII>
central data_cb (total: 91)


[2024-01-22 10:43:26.385]# RECV ASCII>
central data_cb (total: 92)


[2024-01-22 10:43:28.400]# RECV ASCII>
central data_cb (total: 93)


[2024-01-22 10:43:28.633]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=3.53 phase_slope=8.52 rssi_openspace=50.12 best=3.53


[2024-01-22 10:43:29.409]# RECV ASCII>
central data_cb (total: 94)


[2024-01-22 10:43:29.643]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=3.81 phase_slope=7.13 rssi_openspace=35.48 best=3.81


[2024-01-22 10:43:30.403]# RECV ASCII>
central data_cb (total: 95)


[2024-01-22 10:43:30.640]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=4.14 phase_slope=8.13 rssi_openspace=44.67 best=4.14

Fullscreen NDT-test-5m.txt Download

[2024-01-22 10:46:21.398]# RECV ASCII>
central data_cb (total: 125)


[2024-01-22 10:46:21.475]# RECV ASCII>
W: malformed advertising data 90 / 8


[2024-01-22 10:46:21.630]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=5.86 phase_slope=9.82 rssi_openspace=70.79 best=5.86


[2024-01-22 10:46:23.411]# RECV ASCII>
central data_cb (total: 126)


[2024-01-22 10:46:23.488]# RECV ASCII>
W: malformed advertising data 90 / 8


[2024-01-22 10:46:23.643]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=4.90 phase_slope=18.47 rssi_openspace=177.83 best=4.90


[2024-01-22 10:46:25.415]# RECV ASCII>
central data_cb (total: 127)


[2024-01-22 10:46:27.887]# RECV ASCII>
W: malformed advertising data 90 / 8


[2024-01-22 10:46:30.440]# RECV ASCII>
central data_cb (total: 128)


[2024-01-22 10:46:35.678]# RECV ASCII>
W: malformed advertising data 26 / 17


[2024-01-22 10:46:35.881]# RECV ASCII>
W: malformed advertising data 90 / 8


[2024-01-22 10:46:46.140]# RECV ASCII>
central data_cb (total: 129)


[2024-01-22 10:46:46.374]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=6.28 phase_slope=11.82 rssi_openspace=63.10 best=6.28


[2024-01-22 10:46:55.174]# RECV ASCII>
central data_cb (total: 130)


[2024-01-22 10:47:00.202]# RECV ASCII>
central data_cb (total: 131)


[2024-01-22 10:47:10.248]# RECV ASCII>
central data_cb (total: 132)


[2024-01-22 10:47:30.889]# RECV ASCII>
W: malformed advertising data 26 / 17


[2024-01-22 10:47:37.073]# RECV ASCII>
W: malformed advertising data 90 / 8


[2024-01-22 10:47:40.358]# RECV ASCII>
central data_cb (total: 133)


[2024-01-22 10:47:40.884]# RECV ASCII>
W: malformed advertising data 26 / 17


[2024-01-22 10:47:41.364]# RECV ASCII>
central data_cb (total: 134)


[2024-01-22 10:47:41.598]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=1.70 phase_slope=23.35 rssi_openspace=141.25 best=1.70


[2024-01-22 10:47:49.484]# RECV ASCII>
W: malformed advertising data 90 / 8


[2024-01-22 10:47:51.408]# RECV ASCII>
central data_cb (total: 135)


[2024-01-22 10:47:52.404]# RECV ASCII>
central data_cb (total: 136)


[2024-01-22 10:47:53.408]# RECV ASCII>
central data_cb (total: 137)


[2024-01-22 10:47:54.416]# RECV ASCII>
central data_cb (total: 138)


[2024-01-22 10:47:54.650]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=6.13 phase_slope=10.41 rssi_openspace=56.23 best=6.13


[2024-01-22 10:48:17.849]# RECV ASCII>
central data_cb (total: 139)


[2024-01-22 10:48:22.877]# RECV ASCII>
central data_cb (total: 140)


[2024-01-22 10:48:30.937]# RECV ASCII>
central data_cb (total: 141)


[2024-01-22 10:48:46.674]# RECV ASCII>
central data_cb (total: 142)


[2024-01-22 10:48:53.071]# RECV ASCII>
W: malformed advertising data 90 / 8


[2024-01-22 10:48:53.726]# RECV ASCII>
central data_cb (total: 143)


[2024-01-22 10:48:53.959]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=5.57 phase_slope=19.17 rssi_openspace=89.13 best=5.57


[2024-01-22 10:48:58.743]# RECV ASCII>
central data_cb (total: 144)


[2024-01-22 10:49:03.767]# RECV ASCII>
central data_cb (total: 145)


[2024-01-22 10:49:06.773]# RECV ASCII>
central data_cb (total: 146)


[2024-01-22 10:49:07.021]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=7.07 phase_slope=12.64 rssi_openspace=56.23 best=7.07


[2024-01-22 10:49:08.295]# RECV ASCII>
W: malformed advertising data 90 / 8


[2024-01-22 10:49:10.813]# RECV ASCII>
central data_cb (total: 147)


[2024-01-22 10:49:11.811]# RECV ASCII>
central data_cb (total: 148)


[2024-01-22 10:49:38.037]# RECV ASCII>
central data_cb (total: 149)


[2024-01-22 10:49:38.270]# RECV ASCII>

Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: crc fail
	Distance estimates: mcpd: ifft=6.45 phase_slope=26.22 rssi_openspace=112.20 best=6.45


[2024-01-22 10:49:42.044]# RECV ASCII>
central data_cb (total: 150)


[2024-01-22 10:49:44.058]# RECV ASCII>
central data_cb (total: 151)


[2024-01-22 10:49:46.281]# RECV ASCII>
W: malformed advertising data 90 / 8


[2024-01-22 10:49:48.078]# RECV ASCII>
central data_cb (total: 152)


[2024-01-22 10:49:54.116]# RECV ASCII>
central data_cb (total: 153)


[2024-01-22 10:49:59.147]# RECV ASCII>
central data_cb (total: 154)


[2024-01-22 10:50:19.900]# RECV ASCII>
central data_cb (total: 155)


[2024-01-22 10:50:27.930]# RECV ASCII>
central data_cb (total: 156)


[2024-01-22 10:50:31.933]# RECV ASCII>
central data_cb (total: 157)


[2024-01-22 10:50:32.932]# RECV ASCII>
central data_cb (total: 158)


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Measurement result:
	Addr: C2:9A:D5:34:D1:CA (random)
	Quality: ok
	Distance estimates: mcpd: ifft=3.52 phase_slope=14.46 rssi_openspace=112.20 best=3.52


[2024-01-22 10:50:34.682]# RECV ASCII>
W: malformed advertising data 90 / 8


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central data_cb (total: 159)


[2024-01-22 10:50:41.989]# RECV ASCII>
central data_cb (total: 160)

[Simonr]

Hi

Are you using an nRF52840 DK on both sides of the test? If not, what are you using on the other side for testing?

In order to get better and more stable results, you could enable the High-precision calculation, that does a more compute-intensive high-precision distance calculation by setting the CONFIG_DM_HIGH_PRECISION_CALC Kconfig option. High-precision calculation has an impact on MCPD ranging mode only. It also seems like you could do with the calibration explained in the section below the high-precision, as there is an ~70 cm offset in most of your measurements.

Best regards,

Simon

[kenlove]

Hi Simon

According to your suggestion, I will re-test and use DK at both ends.

If you have the test data, you can also provide it to me.

Best regards,

Kenlove

[PaKa]

We highly recommend to use some kind of low pass filtering as well. A 3 stage median filter removes most outliers with minimum latency impact.