Feeling As If I Have Been Cheated...

[Zhongjie]

Recently I have purchased a contract with vodafone for mobile broadband, the usb modem lite.

I live in South London (Tooting specifically) and because of the giant mast in Crystal Palace I would have thought that reception for 3G services would be at least half decent where I am.

Instead all I can connect to is GPRS and the only 3G network available to me is "roaming"??? Why do I have that option even though I live in the UK?

GPRS connection is horribly slow, connection manager shows something between 10-45 kbps maximum. When the advertised speed is 7.2mbps i wasn't naive to think "yes that is what I'd be getting" but was hoping to have at least a stable 1mbps connection, guess I had my head up in the stars even then.

Now onto my specific problems:

I have changed the usb modem to only detect 3G networks only, I can detect it but the signal is VERY POOR and it has a "r" in a square next to it showing that it is roaming. When I try and connect I get RAS error code 678, from a little research this means that the server I am trying to connect to is not responding or does not exist.

I have tried to connect using the windows network manager instead of the mobile connect software. Same error code.

Only other thing I can think of is that my machine is under a desk, but I severely doubt that makes such a huge impact on reception.

Are there any hints or tips to improve my situation or am I just going to have to return it and try something else?

[Neil_Brown]

Moving to a window may indeed help - it's certainly worth a try.

If the above doesnt solve that then Neil will be the man to listen to,as always.

Kind words - thank you, richie - although, I must admit that I'm in the dark on this one too - my main interest lies in the Linux side of things

[heady]

You never know,It could make all the diference get some bluetack and stick the dongle to the window...

This is true. With RF signal strength there are a few main issues: attenuation, interference & multi-path loss.
These issues effectively move the signal receiving point further from the mobile phone tower.*

What you want to improve the situation is to move the signal receiving point closer to the mobile phone tower.

Radio waves are attenuated as they travel out from the mobile phone tower. Every different substance they travel through may attenuate more or less than air - usually more. e.g. Walls, glass, tables, PC cases etc...

Therefore, one way to improve the attenuation situation is to move the signal receiving point closer to the mobile phone tower and as close to a direct-line-of-sight as possible. This may not always be possible - but every obstacle removed from the path will help.

If your modem supports an external antenna - then this would be the idea situation as the external antenna will virtually move the reception point closer to the mobile phone tower maybe without having to physically moving anything.

A phone may work were a Mobile Broadband modem will not because the system is designed so that a voice call using much less bandwidth can operate at lower signal levels.

The other issue is interference. Computers generate interference across the frequency band including in the same frequency band used by the Mobile Broadband. Interference effectively moves the signal receiving point further from the mobile phone tower. Therefore, moving the modem away from the interference will move the signal receiving point closer.

The last issue is multi-path loss. Everytime a signal hits an obstacle the signal bounces in a different direction - eventually arriving at the modem. As there are multiple signals arriving at the signal receiving point these either add together or sometimes subtract. If they subtract then the signal receiving point is moved further from the mobile phone tower. As the wavelength is about approx. 15cm - moving the signal receiving point within this bounded box - may change the subtraction to addition. Therefore, moving the signal receiving point closer to the mobile phone tower.


*This is somewhat simplified and not entirely correct.

[Zhongjie]

This is true. With RF signal strength there are a few main issues: attenuation, interference & multi-path loss.
These issues effectively move the signal receiving point further from the mobile phone tower.*

What you want to improve the situation is to move the signal receiving point closer to the mobile phone tower.

Radio waves are attenuated as they travel out from the mobile phone tower. Every different substance they travel through may attenuate more or less than air - usually more. e.g. Walls, glass, tables, PC cases etc...

Therefore, one way to improve the attenuation situation is to move the signal receiving point closer to the mobile phone tower and as close to a direct-line-of-sight as possible. This may not always be possible - but every obstacle removed from the path will help.

If your modem supports an external antenna - then this would be the idea situation as the external antenna will virtually move the reception point closer to the mobile phone tower maybe without having to physically moving anything.

A phone may work were a Mobile Broadband modem will not because the system is designed so that a voice call using much less bandwidth can operate at lower signal levels.

The other issue is interference. Computers generate interference across the frequency band including in the same frequency band used by the Mobile Broadband. Interference effectively moves the signal receiving point further from the mobile phone tower. Therefore, moving the modem away from the interference will move the signal receiving point closer.

The last issue is multi-path loss. Everytime a signal hits an obstacle the signal bounces in a different direction - eventually arriving at the modem. As there are multiple signals arriving at the signal receiving point these either add together or sometimes subtract. If they subtract then the signal receiving point is moved further from the mobile phone tower. As the wavelength is about approx. 15cm - moving the signal receiving point within this bounded box - may change the subtraction to addition. Therefore, moving the signal receiving point closer to the mobile phone tower.


*This is somewhat simplified and not entirely correct.

its weird, I tried connecting just past midnight this morning and although I had a very weak signal, I had a 3G connection and could get about 300-400 kbps speed.

Now im on this morning, im back to 3G (roaming) and RAS error code 678 cannot connect.

[LeeJS]

Hi Zhongjie and welcome that our great eForum community,

As you can see there are lots of people on here as well as the Admin Team who're always eager to help and it's great to see that some of others members have been on hand here.

I've tried to check the coverage where you are but our coverage viewer isn't accepting the post code in your profile. Could you post the full post code of where you're having these problems so that we can take another look at this for you.

Many thanks,

Lee

eForum Team

[heady]

its weird, I tried connecting just past midnight this morning and although I had a very weak signal, I had a 3G connection and could get about 300-400 kbps speed.

Now im on this morning, im back to 3G (roaming) and RAS error code 678 cannot connect.

This sounds like "cell breathing" to me.

The nature of the 3G radio footprint is that the cell will change size slightly depending on load. The more subscribers using the cell the smaller the footprint - less number of subscribers using the cell the bigger the footprint. This is just how the system works.

Therefore, if this pattern is repeatable over the next few days - I'd be looking at the steps listed above to try to get the signal receiving point closer to the mobile phone tower.

[Zhongjie]

Hi Zhongjie and welcome that our great eForum community,

As you can see there are lots of people on here as well as the Admin Team who're always eager to help and it's great to see that some of others members have been on hand here.

I've tried to check the coverage where you are but our coverage viewer isn't accepting the post code in your profile. Could you post the full post code of where you're having these problems so that we can take another look at this for you.

Many thanks,

Lee

eForum Team

Update on how it is going:

I can connect to the 3G service, but at best I get a poor signal. I have tried moving it around the room several times to no avail.

My full post code is: SW17 0(ZERO)PD

[peterpp_bg]

A pack of 3 USB cables, each 2m long, purchased from a nearby "Comet" stores, did cost me a little less than 20 pounds (was on discount).
You won't believe how much difference it makes to stick your modem to the window.
Also try different corners of the window, there is a difference too.
Give the modem some time before placing it in a new spot and trying to connect. It needs it. Believe me, I went from 0 to 2 ticks on the signal strength, by just playing the "move me around like aerial" game.

[Zhongjie]

A pack of 3 USB cables, each 2m long, purchased from a nearby "Comet" stores, did cost me a little less than 20 pounds (was on discount).
You won't believe how much difference it makes to stick your modem to the window.
Also try different corners of the window, there is a difference too.
Give the modem some time before placing it in a new spot and trying to connect. It needs it. Believe me, I went from 0 to 2 ticks on the signal strength, by just playing the "move me around like aerial" game.

I just moved it to the window and got even worse results =/

The odd thing is, crystal palace is in the direction of my window and im getting no 3G signal.

I do however get VERY good GPRS signal, does this even make any sense?

[richie1913]

Hi again,sounds like you could do with a external antenna,most usb dongles have a input connector for one,even though some are not visible like the k3565,you have to put a hole in the plastic case,there is a walkthrough online,dont know why they hid the very thing that could stop a lot of people having problems though,does sound like this would be your only option to get a decent 3g signal.

[Zhongjie]

Hi again,sounds like you could do with a external antenna,most usb dongles have a input connector for one,even though some are not visible like the k3565,you have to put a hole in the plastic case,there is a walkthrough online,dont know why they hid the very thing that could stop a lot of people having problems though,does sound like this would be your only option to get a decent 3g signal.

I think they hid it because this kind of modification makes your warranty void and if you break it then you are screwed.

Is there any specific walkthrough for my dongle? I did a search and I got a LOT of results for different types.