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Impedance Measurements of Actual Telephone
Lines
This technical note shows the impedances measured on the
telephone line running from a residence in Mankato, MN on January
7, 1984 to each of several 'quiet termination' lines in the
Mankato area. The results show fairly smooth transitional
impedance change over frequency with all measurements being
predominantly capacitive in their reactance. Other data taken
shows the impedances measured when the same 'quiet termination'
numbers were called through the Wurth Electronics Midcom PBX. Results under this
condition show marked change in impedance with frequency. Wiltron
return loss measurements were also taken and recorded.
Telephone Line Impedances
(7-Jan-1984)
from (507/625-8983), 1780 Lee
Blvd., N. Mankato, MN
Level: 490 mVRMS (-4 dBm)
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|
|
|
507/625-xxxx |
507/257-xxxx |
507/524-xxxx |
|
Freq. |
R
(ohms) |
X
(ohms) |
R
(ohms) |
X
(ohms) |
R
(ohms) |
X
(ohms) |
| 200 |
1.86k |
-920 |
2.04k |
-477 |
1.80k |
-280 |
| 300 |
1.49k |
-910 |
1.60k |
-600 |
1.64k |
-530 |
| 400 |
1.25k |
-900 |
1.40k |
-795 |
1.48k |
-730 |
| 500 |
1.08k |
-880 |
1.20k |
-840 |
1.24k |
-860 |
| 750 |
789 |
-796 |
837 |
-781 |
839 |
-800 |
| 984 |
616 |
-699 |
652 |
-700 |
648 |
-710 |
| 1034 |
597 |
-682 |
631 |
-688 |
627 |
-701 |
| 1200 |
528 |
-624 |
548 |
-634 |
540 |
-640 |
| 1500 |
445 |
-540 |
455 |
-545 |
450 |
-543 |
| 2000 |
371 |
-441 |
377 |
-449 |
375 |
-448 |
| 2500 |
329 |
-377 |
332 |
-379 |
331 |
-380 |
| 3000 |
303 |
-334 |
302 |
-338 |
300 |
-338 |
| 3529 |
282 |
-300 |
282 |
-300 |
282 |
-302 |
| 4000 |
268 |
-278 |
267 |
-281 |
268 |
-280 |
Telephone Line Impedances
(5-Jan-1984)
from extension 331 Midcom, N.
Mankato, MN PABX (507/625-6521)
Level: 490 mVRMS (-4
dBm)
|
|
|
|
507/625-xxxx |
507/257-xxxx |
507/524-xxxx |
|
Freq. |
R
(ohms) |
X
(ohms) |
R
(ohms) |
X
(ohms) |
R
(ohms) |
X
(ohms) |
|
200 |
949 |
356 |
1.12k |
-71.2 |
743 |
269 |
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300 |
1.09k |
-224 |
1.12k |
-78.5 |
1.03k |
-4 |
|
400 |
761 |
-406 |
807 |
-410 |
899 |
-390 |
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500 |
551 |
-354 |
574 |
-372 |
612 |
-385 |
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750 |
364 |
-126 |
363 |
-141 |
353 |
-146 |
|
984 |
350 |
61 |
342 |
69 |
336 |
71.8 |
|
1034 |
358 |
100 |
348 |
96 |
341 |
100 |
|
1200 |
412 |
224 |
403 |
228 |
406 |
233 |
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1500 |
694 |
443 |
686 |
457 |
679 |
465 |
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2000 |
1.1k |
-620 |
1.06k |
-637 |
1.07k |
-629 |
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2500 |
323 |
-300 |
325 |
-293 |
334 |
-303 |
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3000 |
256 |
86 |
252 |
83.4 |
244 |
85 |
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3529 |
1.53k |
1.12k |
1.54k |
1.12k |
1.56k |
1.11k |
|
4000 |
308 |
-695 |
314 |
-745 |
315 |
-745 |
Zo = 600 ohms + 2.15
uF:
|
SRL-lo |
12.0 dB |
11.2 dB |
11.6 dB |
|
ERL |
9.5 dB |
9.2 dB |
9.0 dB |
|
SRL-hi |
7.2 dB |
7.0 dB |
7.0
dB |
Zo = 600
ohms:
|
SRL-lo |
10.5 dB |
10.0 dB |
10.5 dB |
|
ERL |
9.8 dB |
9.5 dB |
9.4 dB |
|
SRL-hi |
7.2 dB |
6.8 dB |
7.0
dB |
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