Hub 4 Gig1 Package Power and Attenuation (15db Forward Path Attenuator in place)

[kevkdg]

I have a Hub 4 (had it for over a year on the M200 package).

Recently I upgraded to the Gig1 package and have been paying attention to settings etc.

I have no apparent connection issues BUT I did wonder whether I should have left the 15db Forward Path Attenuator in place (currently it is in place on the Hub 4) that was there when I switched from Superhub 2ac to Hub 4 over a year ago)

I believe these are the figures of interest (with the 15db attenuator in place).

Any ideas on whether I should remove it completely or swap it for a differently rated attenuator?  If so do VM send these out?

3.0 Downstream channels

Channel Frequency (Hz) Power (dBmV) SNR (dB) Modulation Channel ID

25	330750000	-5.3	39	QAM256	25
6	178750000	-6.8	37.6	QAM256	6
7	186750000	-7	37.4	QAM256	7
8	194750000	-7.3	37.6	QAM256	8
9	202750000	-7.4	37.4	QAM256	9
10	210750000	-7.6	37.6	QAM256	10
11	218750000	-7.7	37.6	QAM256	11
12	226750000	-8.1	37.6	QAM256	12
13	234750000	-8.8	37.4	QAM256	13
14	242750000	-9	36.6	QAM256	14
15	250750000	-8.1	36.6	QAM256	15
16	258750000	-7.4	37.4	QAM256	16
17	266750000	-7.3	37.6	QAM256	17
18	274750000	-7.2	37.6	QAM256	18
19	282750000	-7.1	37.6	QAM256	19
20	290750000	-7	37.6	QAM256	20
21	298750000	-6.7	37.6	QAM256	21
22	306750000	-6.1	37.6	QAM256	22
23	314750000	-5.7	37.6	QAM256	23
24	322750000	-5.3	38.6	QAM256	24
26	338750000	-6.1	38.6	QAM256	26
27	346750000	-6.5	38.6	QAM256	27
28	354750000	-6.7	38.6	QAM256	28
29	362750000	-7.1	37.6	QAM256	29
30	370750000	-7.1	38.6	QAM256	30
31	378750000	-7.3	38.6	QAM256	31
32	386750000	-7.4	38.6	QAM256	32
33	394750000	-7.3	38.6	QAM256	33
34	402750000	-7.4	37.6	QAM256	34
35	410750000	-7.3	38.6	QAM256	35
36	418750000	-7.1	37.6	QAM256	36

[VM-Jon]

Hi,

1gig packages do not use these downstream frequencies however these are out of spec and its likely your OFDM block is too. You should remove the attenuator and repost the readings. Also include the upstream and any information on profiles and OFDM.

Thank you

Jon

[kevkdg]

Thanks @VM-Jon

What is OFDM and how do I check that out.  Same query on profiles?  thanks

Are you saying remove the attenuator completely and get the numbers?  I have a spare 10db one, guess that might be better.

Here is further info (still with 15db attenuator in place)

3.0 Downstream channels

Channel Lock Status RxMER (dB) Pre RS Errors Post RS Errors

25	Locked	38.983261	0	0
6	Locked	37.636276	0	0
7	Locked	37.355988	0	0
8	Locked	37.636276	0	0
9	Locked	37.355988	0	0
10	Locked	37.636276	0	0
11	Locked	37.636276	0	0
12	Locked	37.636276	0	0
13	Locked	37.355988	0	0
14	Locked	36.609653	0	0
15	Locked	36.609653	0	0
16	Locked	37.355988	0	0
17	Locked	37.636276	0	0
18	Locked	37.636276	0	0
19	Locked	37.636276	0	0
20	Locked	37.636276	0	0
21	Locked	37.636276	0	0
22	Locked	37.636276	0	0
23	Locked	37.636276	0	0
24	Locked	38.605377	0	0
26	Locked	38.605377	0	0
27	Locked	38.605377	0	0
28	Locked	38.605377	0	0
29	Locked	37.636276	0	0
30	Locked	38.605377	0	0
31	Locked	38.605377	0	0
32	Locked	38.605377	0	0
33	Locked	38.605377	0	0
34	Locked	37.636276	0	0
35	Locked	38.605377	0	0
36	Locked	37.636276	0	0

3.1 Downstream channels

Channel Channel Width (MHz) FFT Type Number of Active Subcarriers Modulation (Active Profile) First Active Subcarrier (Hz)

159

94

4K

1840

QAM4096

424

3.1 Downstream channels

Channel ID Lock Status RxMER Data (dB) PLC Power (dBmV) Correcteds (Active Profile) Uncorrectables (Active Profile)

159

Locked

41

-5.6

4075275249

0

3.0 Upstream channels

Channel Frequency (Hz) Power (dBmV) Symbol Rate (ksps) Modulation Channel ID

1	60300000	41.3	5120 KSym/sec	64QAM	1
2	39400000	40.8	5120 KSym/sec	64QAM	4
3	46200000	40.8	5120 KSym/sec	64QAM	3
4	53700000	41.3	5120 KSym/sec	64QAM	2

3.0 Upstream channels

Channel Channel Type T1 Timeouts T2 Timeouts T3 Timeouts T4 Timeouts

1	US_TYPE_STDMA	0	0	0	0
2	US_TYPE_STDMA	0	0	1	0
3	US_TYPE_STDMA	0	0	0	0
4	US_TYPE_STDMA	0	0	0	0

[kevkdg]

Figures now WITHOUT any attenuator fitted:

3.0 Downstream channels

Channel Frequency (Hz) Power (dBmV) SNR (dB) Modulation Channel ID

25	330750000	9.9	39	QAM256	25
6	178750000	8.1	38.6	QAM256	6
7	186750000	7.8	38.6	QAM256	7
8	194750000	7.6	38.6	QAM256	8
9	202750000	7.7	38.6	QAM256	9
10	210750000	7.5	38.6	QAM256	10
11	218750000	7.2	38.6	QAM256	11
12	226750000	6.8	38.6	QAM256	12
13	234750000	6.3	38.6	QAM256	13
14	242750000	6.1	37.6	QAM256	14
15	250750000	6.9	38.6	QAM256	15
16	258750000	7.7	38.6	QAM256	16
17	266750000	7.9	39	QAM256	17
18	274750000	8.1	38.6	QAM256	18
19	282750000	8.1	38.6	QAM256	19
20	290750000	8.1	38.6	QAM256	20
21	298750000	8.7	39	QAM256	21
22	306750000	9.4	39	QAM256	22
23	314750000	9.7	39	QAM256	23
24	322750000	9.8	39	QAM256	24
26	338750000	9.5	39	QAM256	26
27	346750000	9.1	39	QAM256	27
28	354750000	8.6	39	QAM256	28
29	362750000	8	39	QAM256	29
30	370750000	8.1	39	QAM256	30
31	378750000	8.3	39	QAM256	31
32	386750000	8	39	QAM256	32
33	394750000	7.7	40.4	QAM256	33
34	402750000	7.5	39	QAM256	34
35	410750000	7.9	39	QAM256	35
36	418750000	8.3	38.6	QAM256	36

3.0 Downstream channels

Channel Lock Status RxMER (dB) Pre RS Errors Post RS Errors

25	Locked	38.983261	0	0
6	Locked	38.605377	0	0
7	Locked	38.605377	0	0
8	Locked	38.605377	0	0
9	Locked	38.605377	0	0
10	Locked	38.605377	0	0
11	Locked	38.605377	6	0
12	Locked	38.605377	0	0
13	Locked	38.605377	0	0
14	Locked	37.636276	0	0
15	Locked	38.605377	0	0
16	Locked	38.605377	0	0
17	Locked	38.983261	0	0
18	Locked	38.605377	0	0
19	Locked	38.605377	0	0
20	Locked	38.605377	0	0
21	Locked	38.983261	0	0
22	Locked	38.983261	0	0
23	Locked	38.983261	0	0
24	Locked	38.983261	0	0
26	Locked	38.983261	0	0
27	Locked	38.983261	0	0
28	Locked	38.983261	0	0
29	Locked	38.983261	0	0
30	Locked	38.983261	0	0
31	Locked	38.983261	0	0
32	Locked	38.983261	0	0
33	Locked	40.366287	0	0
34	Locked	38.983261	0	0
35	Locked	38.983261	0	0
36	Locked	38.605377	0	0

[kevkdg]

Figures now WITHOUT any attenuator fitted:

3.1 Downstream channels

Channel Channel Width (MHz) FFT Type Number of Active Subcarriers Modulation (Active Profile) First Active Subcarrier (Hz)

159

94

4K

1840

QAM4096

424

3.1 Downstream channels

Channel ID Lock Status RxMER Data (dB) PLC Power (dBmV) Correcteds (Active Profile) Uncorrectables (Active Profile)

159

Locked

42

9.5

3590287

0

3.0 Upstream channels

Channel Frequency (Hz) Power (dBmV) Symbol Rate (ksps) Modulation Channel ID

1	25800000	39.8	5120 KSym/sec	64QAM	6
2	32600000	40.3	5120 KSym/sec	64QAM	5
3	39400000	40.3	5120 KSym/sec	64QAM	4
4	46200000	40.3	5120 KSym/sec	64QAM	3

3.0 Upstream channels

Channel Channel Type T1 Timeouts T2 Timeouts T3 Timeouts T4 Timeouts

1	US_TYPE_STDMA	0	0	0	0
2	US_TYPE_STDMA	0	0	0	0
3	US_TYPE_STDMA	0	0	0	0
4	US_TYPE_STDMA	0	0	0	0

[kevkdg]

Figures with a 10db Attenuator Fitted:

3.0 Downstream channels

Channel Frequency (Hz) Power (dBmV) SNR (dB) Modulation Channel ID

25	330750000	-0.3	39	QAM256	25
6	178750000	-1.7	38.6	QAM256	6
7	186750000	-1.9	38.6	QAM256	7
8	194750000	-2.1	37.9	QAM256	8
9	202750000	-2.3	37.6	QAM256	9
10	210750000	-2.3	39	QAM256	10
11	218750000	-2.5	39	QAM256	11
12	226750000	-2.8	37.6	QAM256	12
13	234750000	-3.7	37.6	QAM256	13
14	242750000	-3.9	37.6	QAM256	14
15	250750000	-2.9	37.6	QAM256	15
16	258750000	-2.2	38.6	QAM256	16
17	266750000	-2.1	38.6	QAM256	17
18	274750000	-2	38.6	QAM256	18
19	282750000	-1.9	39	QAM256	19
20	290750000	-1.8	39	QAM256	20
21	298750000	-1.5	38.6	QAM256	21
22	306750000	-0.9	39	QAM256	22
23	314750000	-0.5	39	QAM256	23
24	322750000	-0.2	38.6	QAM256	24
26	338750000	-1	38.6	QAM256	26
27	346750000	-1.3	39	QAM256	27
28	354750000	-1.5	38.6	QAM256	28
29	362750000	-2	39	QAM256	29
30	370750000	-2	39	QAM256	30
31	378750000	-2.1	38.6	QAM256	31
32	386750000	-2.3	39	QAM256	32
33	394750000	-2.2	39	QAM256	33
34	402750000	-2.3	38.6	QAM256	34
35	410750000	-2.2	39	QAM256	35
36	418750000	-1.9	38.6	QAM256	36

3.0 Downstream channels

Channel Lock Status RxMER (dB) Pre RS Errors Post RS Errors

25	Locked	38.983261	0	0
6	Locked	38.605377	0	0
7	Locked	38.605377	0	0
8	Locked	37.935909	0	0
9	Locked	37.636276	0	0
10	Locked	38.983261	0	0
11	Locked	38.983261	8	0
12	Locked	37.636276	6	0
13	Locked	37.636276	2	0
14	Locked	37.636276	0	0
15	Locked	37.636276	10	0
16	Locked	38.605377	9	0
17	Locked	38.605377	0	0
18	Locked	38.605377	0	0
19	Locked	38.983261	0	0
20	Locked	38.983261	0	0
21	Locked	38.605377	0	0
22	Locked	38.983261	0	0
23	Locked	38.983261	0	0
24	Locked	38.605377	1	0
26	Locked	38.605377	0	0
27	Locked	38.983261	0	0
28	Locked	38.605377	0	0
29	Locked	38.983261	0	0
30	Locked	38.983261	2	0
31	Locked	38.605377	2	0
32	Locked	38.983261	4	0
33	Locked	38.983261	4	0
34	Locked	38.605377	4	0
35	Locked	38.983261	0	0
36	Locked	38.605377	1	0

[kevkdg]

Figures with a 10db Attenuator Fitted:

3.1 Downstream channels

Channel Channel Width (MHz) FFT Type Number of Active Subcarriers Modulation (Active Profile) First Active Subcarrier (Hz)

159

94

4K

1840

QAM4096

424

3.1 Downstream channels

Channel ID Lock Status RxMER Data (dB) PLC Power (dBmV) Correcteds (Active Profile) Uncorrectables (Active Profile)

159

Locked

42

-0.4

2368867

0

3.0 Upstream channels

Channel Frequency (Hz) Power (dBmV) Symbol Rate (ksps) Modulation Channel ID

1	25800000	40.3	5120 KSym/sec	64QAM	6
2	32600000	40.3	5120 KSym/sec	64QAM	5
3	39400000	40.3	5120 KSym/sec	64QAM	4
4	46200000	40.3	5120 KSym/sec	64QAM	3

3.0 Upstream channels

Channel Channel Type T1 Timeouts T2 Timeouts T3 Timeouts T4 Timeouts

1	US_TYPE_STDMA	0	0	0	0
2	US_TYPE_STDMA	0	0	0	0
3	US_TYPE_STDMA	0	0	0	0
4	US_TYPE_STDMA	0	0	0	0

[Tudor]

The 10dB stats look fairly good, but I think you probably only need a 6dB forward path attenuator. This would probably put you in the optimum power range.

[kevkdg]

Thanks.

As I'm using DOCSIS 3.1, should I ignore the 3.0 figures?

Is the number I'm interested in the one relating to "PLC Power (dBmV)" in the 3.1 download section?

If so, does the same range principle apply of -6 to +10 (or ideally -3 to +8 to allows for seasonal temp variations in resistance)?

I still don't know what OFDM Block is and how to find the readings?  Also, the same for the requested "Profile" info?

Do VM post out 6bd attenuators?

[kevkdg]

The reason I ask is that my DOCSIS 3.1 stats are:

- 15db attenuator:

Channel ID Lock Status RxMER Data (dB) PLC Power (dBmV) Correcteds (Active Profile) Uncorrectables (Active Profile)

159

Locked

41

-5.6

4075275249

0

 

- 10db attenuator:

Channel ID Lock Status RxMER Data (dB) PLC Power (dBmV) Correcteds (Active Profile) Uncorrectables (Active Profile)

159

Locked

42

-0.4

46824194

0

No Attenuator:

Channel ID Lock Status RxMER Data (dB) PLC Power (dBmV) Correcteds (Active Profile) Uncorrectables (Active Profile)

159

Locked

42

9.5

3590287

0

So if the objective is to get the DOCSIS 3.1 PLC Power (dBmV) to as near to zero as possible, then for DOCSIS 3.1 the 10dB attenuator does this.  However, for DOCSIS 3.0 channels (which I don't think I'm using) then I can see a 6dB would be better.

Do attenuators also impact upstream levels?