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Upstream Modulation Changing

avi68
Up to speed

Hi,

I have a Hub 5 in modem mode. Ive noticed that the Upstream modulation has started to fluctuate between 32QAM and 64QAM. This has been happening for over a month now. Initially the modulation would drop to 16QAM and stay between 16 and 32. However, more recently its been sticking at 32QAM, then jumping to 64 and then going back to 32.

Speeds seem to be ok but I have started to notice random packet loss. Last Thursday evening packet loss was very bad but it seems to have stabilised. I have called CS multiple times but the script they follow doesnt seem to have an answer to my issue. Packet loss is still occurring, not as bad, just small amounts randomly. Dont know if anyone can see an issue with my levels?

 

Cable Modem Status

Item

Status

Type

Cable Modem Status

Online

DOCSIS 3.0

Primary downstream channel

Locked

SC-QAM

Channel Overview

Downstream

Upstream

DOCSIS 3.0 channels

31

5

DOCSIS 3.1 channels

1

1

3.0 Downstream channels

Channel

Frequency (Hz)

Power (dBmV)

SNR (dB)

Modulation

Channel ID

1

331000000

6.9

41

QAM 256

25

2

139000000

9.4

40

QAM 256

1

3

147000000

9.3

40

QAM 256

2

4

155000000

9.2

40

QAM 256

3

5

163000000

8.9

40

QAM 256

4

6

171000000

8.8

39

QAM 256

5

7

179000000

8.5

39

QAM 256

6

8

187000000

8.4

39

QAM 256

7

9

195000000

8.3

39

QAM 256

8

10

203000000

8.1

39

QAM 256

9

11

211000000

8.2

39

QAM 256

10

12

219000000

8.1

39

QAM 256

11

13

227000000

7.8

38

QAM 256

12

14

235000000

7.6

38

QAM 256

13

15

243000000

7.3

38

QAM 256

14

16

251000000

7

39

QAM 256

15

17

259000000

6.8

39

QAM 256

16

18

267000000

6.7

39

QAM 256

17

19

275000000

6.6

39

QAM 256

18

20

283000000

6.5

40

QAM 256

19

21

291000000

6.7

40

QAM 256

20

22

299000000

6.7

40

QAM 256

21

23

307000000

7

40

QAM 256

22

24

315000000

7

40

QAM 256

23

25

323000000

7.1

41

QAM 256

24

26

339000000

7

41

QAM 256

26

27

347000000

6.7

41

QAM 256

27

28

355000000

6.7

41

QAM 256

28

29

363000000

6.5

41

QAM 256

29

30

371000000

6.5

41

QAM 256

30

31

379000000

6.5

41

QAM 256

31

3.0 Downstream channels

Channel

Locked Status

RxMER (dB)

Pre RS Errors

Post RS Errors

1

Locked

41

52

0

2

Locked

40

0

0

3

Locked

40

0

0

4

Locked

40

0

0

5

Locked

40

0

0

6

Locked

39

1

0

7

Locked

39

0

0

8

Locked

39

0

0

9

Locked

39

6

0

10

Locked

39

6

0

11

Locked

39

18

0

12

Locked

39

10

0

13

Locked

38

17

0

14

Locked

38

21

0

15

Locked

38

29

0

16

Locked

39

39

0

17

Locked

39

50

0

18

Locked

39

98

0

19

Locked

39

116

0

20

Locked

40

115

0

21

Locked

40

60

0

22

Locked

40

73

0

23

Locked

40

55

0

24

Locked

40

73

0

25

Locked

41

47

0

26

Locked

41

45

0

27

Locked

41

95

0

28

Locked

41

81

0

29

Locked

41

123

0

30

Locked

41

126

0

31

Locked

41

156

0

3.1 Downstream channels

Channel

Channel Width (MHz)

FFT Type

Number of Active Subcarriers

Modulation (Active Profile)

First Active Subcarrier (Hz)

41

94

4K

1840

QAM 4096

1108

3.1 Downstream channels

Channel ID

Locked Status

RxMER Data (dB)

PLC Power (dBmV)

Corrected errors (Active Profile)

Uncorrectable errors (Active Profile)

41

Locked

41

4.9

809061304

65

3.0 Upstream channels

Channel

Frequency (Hz)

Power (dBmV)

Symbol Rate (ksps)

Modulation

Channel ID

0

49600000

44.5

5120

QAM 32

1

1

43100000

44.3

5120

QAM 32

2

2

36600000

44.3

5120

QAM 32

3

3

30100000

44

5120

QAM 32

4

4

23600000

43.8

5120

QAM 32

5

3.0 Upstream channels

Channel

Channel Type

T1 Timeouts

T2 Timeouts

T3 Timeouts

T4 Timeouts

0

ATDMA

0

0

0

0

1

ATDMA

0

0

9

0

2

ATDMA

0

0

0

0

3

ATDMA

0

0

0

0

4

ATDMA

0

0

0

0

3.1 Upstream channels

Channel

Channel Width (MHz)

Power (dBmV)

FFT Type

Modulation

6

11

40.0

2K

QAM 256

3.1 Upstream channels

Channel

Channel Type

Number of Active Subcarriers

First Active Subcarrier (Hz)

T3 Timeouts

T4 Timeouts

6

OFDMA

220

74000000

0

0

 

31 REPLIES 31

Viper-t
Fibre optic

So engineer said there is packet loss when he did a traceroute reported to networks and was very thorough while at my parents place and spoke freely of the problems which also effects a few of us I'm monitoring. I've noticed they have changed there ip address to wa7 area near the Midlands (monitoring?) we are all in Bristol. Hasn't rang back as of yet he rang last week and said to give him some time a day or 2 which I gave a week, specs below problems persist. He didn't sound optimistic saying that all of Bristol was ****** and wouldn't have any sort of time on a fix, can I get a ticket number? He put a double forward path as 3.1 was 11dbmv that's nearly centered the 3.0 and 3.1 is now at 5.2 even though -9 total was put on. 

hannel Frequency (Hz) Power (dBmV) SNR (dB) Modulation Channel ID
1331000000441QAM 25625
21470000000.941QAM 2562
31550000000.941QAM 2563
4163000000141QAM 2564
51710000001.341QAM 2565
61790000001.541QAM 2566
71870000001.641QAM 2567
8195000000241QAM 2568
92030000002.141QAM 2569
102110000002.541QAM 25610
112190000002.541QAM 25611
122270000002.741QAM 25612
132350000002.941QAM 25613
142430000002.941QAM 25614
152510000002.841QAM 25615
162590000002.942QAM 25616
172670000002.941QAM 25617
182750000003.142QAM 25618
192830000003.342QAM 25619
202910000003.442QAM 25620
212990000003.442QAM 25621
223070000003.642QAM 25622
233150000003.842QAM 25623
24323000000442QAM 25624
253390000004.141QAM 25626
263470000004.141QAM 25627
273550000004.141QAM 25628
283630000004.241QAM 25629
293710000004.141QAM 25630
30379000000441QAM 25631
313870000003.841QAM 25632

3.0 Downstream channels

Channel Locked Status RxMER (dB) Pre RS Errors Post RS Errors
1Locked4100
2Locked4100
3Locked4100
4Locked4110
5Locked4100
6Locked4100
7Locked4100
8Locked4100
9Locked4100
10Locked4100
11Locked4100
12Locked4100
13Locked4100
14Locked4100
15Locked4100
16Locked4200
17Locked4100
18Locked4200
19Locked4200
20Locked4200
21Locked4200
22Locked4200
23Locked4200
24Locked4210
25Locked4100
26Locked4100
27Locked4100
28Locked4110
29Locked4100
30Locked4100
31Locked4100

3.1 Downstream channels

Channel Channel Width (MHz) FFT Type Number of Active Subcarriers Modulation (Active Profile) First Active Subcarrier (Hz)
33944K1840QAM 40961108

3.1 Downstream channels

Channel ID Locked Status RxMER Data (dB) PLC Power (dBmV) Corrected errors (Active Profile) Uncorrectable errors (Active Profile)
33Locked415.22700563850

 

Channel Frequency (Hz) Power (dBmV) Symbol Rate (ksps) Modulation Channel ID
04960000043.55120QAM 641
14310000043.55120QAM 642
23660000043.55120QAM 643
33010000043.55120QAM 644
42360000043.55120QAM 645

3.0 Upstream channels

Channel Channel Type T1 Timeouts T2 Timeouts T3 Timeouts T4 Timeouts
0ATDMA0000
1ATDMA0000
2ATDMA0000
3ATDMA0000
4ATDMA0010

3.1 Upstream channels

Channel Channel Width (MHz) Power (dBmV) FFT Type Modulation
61139.52KQAM 256

3.1 Upstream channels

Channel Channel Type Number of Active Subcarriers First Active Subcarrier (Hz) T3 Timeouts T4 Timeouts
6OFDMA2207400000000

Im no expert, but that those stats look ok to me. Ignore the Pre RS errors and corrected errors (3.1 channel). Its the post RS and uncorrected errors you need to be worried about. If they start to rise quickly then theres a fault. 

Regarding packet loss, how are you measuring this? I have a few BQM's on a few houses down my street and compare packet loss and issues with their graphs. If  we all have blips at the same time then I know its an area issue if its just me or them then its something local to our setup. My firewall also shows me if there is packet loss on my WAN connection, thats the way I know if there are problems.