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Author Topic: Downstream line attenuation difference on modem routers  (Read 1117 times)

adslmax

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Downstream line attenuation difference on modem routers
« on: November 12, 2020, 02:31:37 AM »

Why is downstream line attenuation are different varies in modem routers with the same short dsl cable (unchanged):

Zyxel xmg3927-b50a Modem Router: 12.0dB
Billion 8800NL Modem Router: 11.7dB
Openreach Modem HG612: 11.6dB
TP Link VR2600 Modem Router: 11.4dB
Plusnet Hub One Modem Router: 10.9dB

« Last Edit: November 12, 2020, 02:34:50 AM by adslmax »
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Alex Atkin UK

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Re: Downstream line attenuation difference on modem routers
« Reply #1 on: November 12, 2020, 04:25:52 AM »

Its a guesstimate based on line conditions, I'd considering one or two dB to be within margin of error.
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re0

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Re: Downstream line attenuation difference on modem routers
« Reply #2 on: November 12, 2020, 04:36:25 AM »

Plus these devices are using different chipsets, so I wouldn't be surprised if that was a factor. Along with differences in manufacturing.

To get a better idea, and I am not recommending this because of DLM (please, don't do this if you don't want to mess things up), run the same test mutliple times - you could then average out the values for each device and they may sit closer together (except for the Plusnet Hub One, I'd imagine, since it is Lantiq).

All the modems are within about 1 dB of each other, so nothing to worry about here.
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adslmax

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Re: Downstream line attenuation difference on modem routers
« Reply #3 on: November 12, 2020, 11:29:03 AM »

TP Link VR2600 Modem Router are the highest maximum data rate with 86-87Mbps with higher SNR at 6.8dB with line attenuation at 11.4dB. The worst lowest maximum data rate with 77Mbps with lower SNR at 4.0dB with good shorter line attenuation at 10.9dB are Plusnet Hub One which it seem so strange.

I thought Broadcom chipset are much better than Lantiq chipset for huawei cabinet
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re0

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Re: Downstream line attenuation difference on modem routers
« Reply #4 on: November 12, 2020, 01:05:15 PM »

The physical line characteristics haven't changed - it's still the same length. Just that the Hub One is generally not a good modem (from experience). Attenuation readings can be ignored for the most part, as long as the line is performing as it should. Only worry would be if one modem was showing a very high reading, or if all were. But nothing to see here. Just put one of the modems on and leave it alone.
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meritez

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Re: Downstream line attenuation difference on modem routers
« Reply #5 on: November 12, 2020, 01:12:13 PM »

Isnt the Plusnet Hub One a Lantiq chipset? https://openwrt.org/toh/bt/homehub_v5a

Quote
Information on this page also applies to the 'Plusnet Hub One' and 'BT Business Hub 5'
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re0

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Re: Downstream line attenuation difference on modem routers
« Reply #6 on: November 12, 2020, 01:18:43 PM »

It is.
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adslmax

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Re: Downstream line attenuation difference on modem routers
« Reply #7 on: November 12, 2020, 01:21:59 PM »

Can see BTW updated for g fast estimated changes from 198/12 to 244/36 because of plusnet hub one with shorter line attenuation or was it nothing to do with this?
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re0

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Re: Downstream line attenuation difference on modem routers
« Reply #8 on: November 12, 2020, 01:23:25 PM »

Can see BTW updated for g fast estimated changes from 198/12 to 244/16 because of plusnet hub one with shorter line attenuation or was it nothing to do with this?
No. Nothing at all.
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adslmax

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Re: Downstream line attenuation difference on modem routers
« Reply #9 on: November 12, 2020, 01:28:22 PM »

Last few weeks opposite side of my house all houses are estimated at 80/77 20/19 with g fast at 330/50 but it now changed to 279/40. All houses are now varies 220/279 on G fast but just one house still on 330/50 and one house was removed g fast.

Why it unreliable checker by BTW who can't put it right figure
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re0

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Re: Downstream line attenuation difference on modem routers
« Reply #10 on: November 12, 2020, 02:05:06 PM »

Normal. Mine changed a bit over the last year or so. At one point, it was giving me estimates for 330 for both clean and impacted on both high and low. It's been 330/50 on high for both clean and impacted since, that I know.
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meritez

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Re: Downstream line attenuation difference on modem routers
« Reply #11 on: November 12, 2020, 03:17:49 PM »

Last few weeks opposite side of my house all houses are estimated at 80/77 20/19 with g fast at 330/50 but it now changed to 279/40. All houses are now varies 220/279 on G fast but just one house still on 330/50 and one house was removed g fast.

Why it unreliable checker by BTW who can't put it right figure

Because the poor quality lines are bringing the figure down...
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adslmax

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Re: Downstream line attenuation difference on modem routers
« Reply #12 on: November 12, 2020, 03:46:46 PM »

DSL Checker has changed again but on waiting list for VDSL only

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adslmax

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Re: Downstream line attenuation difference on modem routers
« Reply #13 on: November 12, 2020, 03:49:29 PM »

Just that the Hub One is generally not a good modem (from experience).

Thanks I have swapped back to Billion and leave it alone

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re0

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Re: Downstream line attenuation difference on modem routers
« Reply #14 on: November 13, 2020, 08:19:51 AM »

DSL Checker has changed again but on waiting list for VDSL only

Looks like a full cabinet then.
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