Here’s a presumably ‘good’ picture, no hollow curve. Modem 4.
If I draw a diagonal straight line from (x=40, y=12) -> (x=85, y=10), and then I inspect the (x=60, y), you see that I’m in danger of hitting that small dip down to y=10 at (x=~58?, y=10) approx. with the diagonal.
Both fortunately and unfortunately, depending on how you look at it, I don’t have any hollow curve data. If I do see an iffy picture, I can immediately save the bitloading numbers by fetching the file : http://modem:8000/data/Bits.
xdslctl: ADSL driver and PHY status
Status: Showtime
Last Retrain Reason: 8000
Last initialization procedure status: 0
Max: Upstream rate = 321 Kbps, Downstream rate = 3304 Kbps
Bearer: 0, Upstream rate = 396 Kbps, Downstream rate = 3154 Kbps
Tone number Bit Allocation
0 0
1 0
2 0
3 0
4 0
5 0
6 0
7 8
8 9
9 9
10 10
11 9
12 9
13 9
14 8
15 7
16 7
17 7
18 6
19 6
20 5
21 5
22 5
23 4
24 4
25 4
26 4
27 4
28 3
29 3
30 3
31 3
32 0
33 8
34 9
35 10
36 11
37 11
38 11
39 12
40 12
41 12
42 12
43 12
44 12
45 12
46 7
47 12
48 2
49 12
50 12
51 11
52 11
53 11
54 11
55 11
56 11
57 11
58 10
59 10
60 11
61 11
62 12
63 12
64 12
65 12
66 12
67 11
68 12
69 11
70 11
71 11
72 11
73 11
74 11
75 11
76 11
77 11
78 11
79 10
80 10
81 10
82 10
83 10
84 10
85 10
86 10
87 9
88 9
89 9
90 9
91 9
92 9
93 9
94 9
95 9
96 8
97 8
98 8
99 8
100 8
101 8
102 8
103 7
104 7
105 7
106 7
107 7
108 7
109 7
110 7
111 7
112 6
113 6
114 6
115 6
116 6
117 6
118 6
119 5
120 4
121 3
122 2
123 4
124 4
125 3
126 4
127 3
128 4
129 3
130 3
131 4
132 4
133 3
134 3
135 3
136 2
137 3
138 3
139 3
140 3
141 3
142 2
143 3
144 3
145 3
146 2
147 2
148 0
149 1
150 0
151 1
152 0
153 1
154 1
155 0
156 0
157 0
158 0
159 0
160 0
161 0
162 0
163 0
164 0
165 0
166 0
167 0
168 0
169 0
170 0
171 0
172 0
173 0
174 0
175 0
176 0
177 0
178 0
179 0
180 0
181 0
182 0
183 0
184 0
185 0
186 0
187 0
188 0
189 0
190 0
From x-46 to x=58 the y-quantisation says to me that y is firmly down at 11, or even less than half a bit lower, say 10.8 in places because there is presumably one point where y dips under y<=10.49. Does this departure from y=12 down to y=11 or even slightly less count as the merest hint of incipient hollow curve?
We can’t draw any conclusions based on ‘curves’ of depth y+/- 0.5 as we’re right in the noise. And what are we to make of the solid y=12 region 62 <= x <= 66 ?