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Download speed > sync speed?!

iangoldby
Grafter
Posts: 27
Registered: 10-05-2008

Download speed > sync speed?!

My modem is currently synced at 256 kbps. Yet with the Plusnet speed tester I just got a download rate of 322 kbps! Is this even vaguely plausible? How can the actual data throughput possibly be higher than the modem sync speed? Just to confirm it, I tried again and got 310 kbps.
I tried the thinkbroadband speed tester too - that gave me 208 kbps.
Perhaps the Plusnet speed tester is being a tad 'optimistic'?
5 REPLIES
Community Veteran
Posts: 14,469
Registered: 30-07-2007

Re: Download speed > sync speed?!

256Kbs is very low for a broadband connection... are you sure you are looking at the right value?
What are the full line stats from your modem/router - i.e. line attenuation, SNR etc for both upstream and downstream.
iangoldby
Grafter
Posts: 27
Registered: 10-05-2008

Re: Download speed > sync speed?!

I have a ticket open at the moment for changing from the MAX product to a fixed rate product. That change-over hasn't gone correctly, so it is possible this is an artefact of that.
Right now, my stats are:
Bandwidth (Up/Down) [kbps/kbps]: 448 / 864
Line Attenuation (Up/Down) [dB]: 31,5 / 57,0
SN Margin (Up/Down) [dB]: 14,0 / 11,5
somewhat better than the 256 kbps I had earlier this evening.
However, I reckon it's more likely that it is due to some external interference - either electrical or weather. I lost my connection very abruptly on Saturday. When the modem resynced it was at a much slower speed than usual, and that has persisted right to the present. My line attenuation is 57 dB, so I should be getting at least 1500kbps - in the recent past I've had as high as 3550kbps. (Basically, my line is very unstable, which is why I'm moving back to the fixed rate product.)
My complete guess at the moment is that on Saturday someone at National Grid moved a switch and the electrical transmission lines across the river from my house are now operating badly out of balance. But that is just a guess. Usually when I get this sort of interference it just lasts an hour or so.
I tried tuning a MW radio to 612 kHz and all I can hear is a loud 50Hz buzzing. But I don't know what it sounds like when the connection is working properly, so that could be a complete red-herring.
Anyway, what this thread is really about is whether the PN speed tester is over-estimating the speed, perhaps especially for very slow connections?
Community Veteran
Posts: 14,469
Registered: 30-07-2007

Re: Download speed > sync speed?!

Are you sure your DS sync rate was 256Kbs when you ran the test?
What speedtest resulk do you get now with the current sync rates?
It looks like your min DS SNR has increased to 12dB which will result in a lower sync rate. As you are on a long line you may well get unpredicable speeds, especially if you do have outside influences. As you are going for a fixed rate there is probably little point in offering advice on getting your current connection any faster.
Note: With that DS line attenutation you will only get a 1Mbs fixed rate speed
iangoldby
Grafter
Posts: 27
Registered: 10-05-2008

Re: Download speed > sync speed?!

I have absolutely no doubt that my downstream sync rate was 256 kbps when I ran the first two speed tests. The more realistic result from the thinkbroadband speed tester would seem to corroborate that. That's why I think the PN speed tester is being a bit of an over-estimate.
(As for improving my current connection, I've been trying since April. I had a support ticket open for two months that never resulted in a satisfactory conclusion. I've ruled out my internal wiring and/or modem as a cause, but other than that it could be anything. Going back to a fixed rate connection is really a last resort.)
Community Veteran
Posts: 19,100
Thanks: 437
Fixes: 21
Registered: 31-08-2007

Re: Download speed > sync speed?!

If you haven't got severe local EMI or REIN, which may be above lawful limits (and can therefore force whoever is responsible to fix it) or internal wiring problems causing or picking up interference, then you definitely have a line fault which needs fixing and changing products will not "fix" it.
I would start by making sure your internal wiring is up to spec. then have a listen to your phone line to see if you can hear any crackling or similar noises.
Edit: If it's easy to borrow another router from a friend, check that the stats are consistent.