Date:2010-09-10 01:38:50 (9 years 3 months ago)
Author:Werner Almesberger
Commit:0a0a50d73d36afb6c40a6d17c2df7a6f9a0fa57a
Message:Performance comparison of atusb vs. atusd.

- atusd/tests/send-20100909: conducted performance comparison of atusb vs.
atusd
- atusd/ERRATA: changed also first board to capacitative divider
Files: atusd/ERRATA (1 diff)
atusd/tests/send-20100909 (1 diff)

Change Details

atusd/ERRATA
2525  R3 -> 33 pF
2626  R4 -> 220 pF
2727
28  Applied work-around also to first 20100908 board after confirming dismal
29  performance caused by clock instability.
30
2831- considering that the clock input has a Vpp of only 400-500 mV, we should
2932  have a ground plane also under as much of the the clock circuit as
3033  possible.
atusd/tests/send-20100909
1Signal strength tests. "Local" devices are on lab bench, about 5 cm apart.
2"Distant" device is in the adjacent room, separated by one thin brick wall
3and 4 m of air.
4
5TX is requested 0 dBm (effectively -0.2 dBm). Transmission is without
6CSMA-CA and ARQ. Results are LQI and ED (dBm). "garbled" is a bad CRC and
7corrupted frame content. "-" is no reception.
8
9Distant Local
10--------------- --------------- ---------------
11100903-red 100903-orange 100908-B
12
13TX 255, -90 255, -90
14TX 255, -90 garbled
15TX 255, -90 255, -90
16TX 255, -90 255, -90
17TX 255, -90 255, -90
18
19- TX garbled
20garbled TX 255, -52
21255, -89 TX 255, -52
22255, -89 TX 255, -53
23- TX 255, -53
24
25255, -88 255, -48 TX
26255, -86 255, -46 TX
27255, -86 255, -49 TX
28255, -86 255, -49 TX
29255, -87 255, -49 TX
30
31100903-red 100903-orange 100908-A
32
33TX 255, -90 garbled
34TX 255, -89 180, -89
35TX 255, -87 196, -89
36TX 255, -87 148, -89
37TX 255, -87 -
38
39255, -86 TX garbled
40255, -87 TX 255, -49
41255, -86 TX 255, -49
42255, -87 TX 255, -49
43255, -86 TX 255, -49
44
45- garbled (-44) TX
46- - TX
47- - TX
48- - TX
49- - TX
50
51100903-red 100903-orange 100908-A (reworked)
52
53TX 255, -87 255, -87
54TX 255, -87 255, -88
55TX 255, -87 255, -87
56TX 255, -87 255, -88
57TX 255, -87 255, -88
58
59255, -86 TX 255, -56
60255, -86 TX 255, -57
61255, -86 TX 255, -58
62255, -86 TX 255, -58
63255, -86 TX 255, -58
64
65255, -85 255, -52 TX
66255, -85 255, -52 TX
67255, -85 255, -52 TX
68255, -86 255, -52 TX
69255, -86 255, -52 TX
70
71
72Conclusions
73-----------
74
75- 20100902 (atusb) and 20100908 (atusd) board show similar performance when
76  at least one station is an atusb
77
78- resistive divider doesn't work
79
80- no clear indication of whether capacitative divider causes interferences.
81  Marked difference in one series of tests but the others look the same.
82
83- reception level is about 4 dB above workable minimum. (Specified receiver
84  sensitivity is -101 dBm, but things start to deteriorate around -90 dBm.)
85  We have a reserve of 3.2 dB for transmission (used -0.2 dBm, maximum is
86  +3.0 dBm).

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