DECT phone funny

[Rod Hewitt]

The various mentions of DECT in the last day or so reminded me that I am supposed to be solving a problem.

We have two separate DECT base stations, each with its own handset and each plugged into totally separate phone lines. Perhaps oddly, both handsets are set up to connect to the same base station - let us call that the primary base station. (We can use a menu to choose the other, secondary, base station.) Anywhere between zero and, perhaps, four times a day the handset on the secondary base station makes a noise that says that it has lost contact with the primary base station that it should be using. Changing the handsets round makes no difference.

It seems that something is interrupting the ability of the 'remote' handset to communicate with the primary base station. On the display we can see that the handset loses its signal for a few seconds.

Having a fair amount of electronic kit (computers, wireless network, etc.) we understand if we are to blame for this problem - but it would be really nice to identify what is causing it.

The times at which the problem occurs vary widely - including the early hours when we are asleep and not in person using anything. And it is this that is most annoying as it sometimes wakes us up.

Any ideas or suggestions welcome.

[mrcheerful]

might be passing emergency vehicles, their transmissions can swamp everything, my old answer phone sometimes was set off and recorded their calls!!

mrcheerful

[Mary Fisher]

I was once tape recording a 33 rpm record to use at a funeral.

Good job I tested it - the taped version had a mini-cab message on it ...

Mary

[Nodge]

I don't know the answer I'm afraid but I have the same problem. I have 2 phone lines each with a base station and remote handset. The 2 remotes are not linked to the same base station as in your case though. Either way, I don't think that having 2 base stations is the problem. I can go for weeks with no problem and then I'll get an evening when the remote furthest from the base station will lose contact maybe every half hour or so. At least that is what I assume is happening. It gives a double beep and flashes "Base

1" on it's display. Then about 5 seconds later it gives a deedle deedle sound as it reconnects. I'd probably had the phones about 6 months before this happened for the first time and I assumed there was a fault with one of the phones but perhaps there are other factors involved. The phones are always kept on their stations so it's not a low battery problem. The base station is in my garage at the bottom of the garden about 10 m from the remote station so maybe its affected by the weather or atmospheric conditions although I've not noticed any pattern when the problem occurs. There have been one or two occasions when both remotes have lost contact with their respective base stations at the same time. Could this indicate a problem with the mains supply I wonder?

John

[Rod Hewitt]

"Nodge" wrote in news:OInNd.267$ [e-mail]:

Thank goodness for that! I was beginning to think that I was going nuts. We had just one for years and eventually bought the second. Both Ericssons. It was quite some time after that we started to get this problem.

Agreed - they live on the base stations so definitely not a dead battery.

On the very odd occasion that the main electricity goes, both of them do the same 'we are disconnected' and that is trivial to understand. But even disconnecting the secondary base station from the mains does not cause this problem.

Our base stations are no more than five metres apart (downstairs hall, upstairs bedroom).

mrcheerful's suggestion could have something - but we are not aware of any nearby emrgency vehicles at the times of the problems. In fact, we are aware that with police and ambulance virtually outside it doesn't happen.

[Nodge]

Rod,

Mine lost contact twice this afternoon for no apparent reason. I may try just swopping the base stations over to see if it still happens. Mine are both BT phones by the way.

John

[Rod Hewitt]

"Nodge" wrote in news:soyNd.4180$ [e-mail]:

Hmm, funny, ours did at least twice (so far) this evening - after doing so a few times last night. Definitely more than normal. Perhaps the damp, misty atmosphere is having some effect?

[Holly, in France]

Rod Hewitt wrote in message

No ideas or suggestions at all I'm afraid, just posting to say that we are in exactly the same boat withour DECT phones. Well, not quite since only our base station is connected to the phone line, but the way you have yours set up I think yours is working in the same way as ours, in that it is not using the second phone line anyway. We don't have wireless networks (well, I do have one but I cant get it to work and it isn't installed atm, but that's another story!) or anything else that is likely to interfere with the phone. It behaves exactly as you describe. The second phone is in a upstairs bedroom in the diagonally opposite corner of the house to the first, with two thick stone walls between the base and the handset. Initially I thought it might not work at all in that location, but it does, about 99% of the time. Yesterday it even worked perfectly beyond another partition when I was in the bath! But.....sometimes it loses the signal for no apparent reason, and bleeps as it comes on and off line, just as you say. It always regains the signal in the other corner of the bedroom which is nearer and has a clearer path to the base station. I think it seems to happen more in cold weather, have you found that? It also bleeps on and off when we have a power cut, which is quite useful sometimes, but not after a dozen or so power cuts during the same night! Sorry, not much help, perhaps someone else understands what is going on?

Holly, in France. Holiday home in the Dordogne, website:

[doozer]

I would guess that the device is using the public band which is unlicensed and therefore pretty crowded. All wireless network kit uses it as well as house bound walk around mobile phones (if you see what I mean) and anything else that needs to transmit over short distances.

The reason that portion of the spectrum is public is not because the powers that be wanted to leave us some free but because it's a pretty useless bit of bandwidth for long range transmission. It is the same area that water absorbs in therefore the attenuation is very high. In winter the relative humidity is higher therefore your phone might have more trouble getting a signal through.

As for the original problem with loosing signal it could be any number of devices causing the problem. The biggest offender is normally a microwave oven but some devices (wireless hubs in particular) will scan the available bandwidth to select the quietest frequency and interrupt other devices in the process.

[doozer]

Yes it would probably use the same bit of the spectrum. It costs quite a bit to rent / buy a frequency - way more than a company producing most any consumer kit could afford. I believe it should say somewhere on it (or in the accompanying documentation) what frequency it uses. As you suggest though it probably isn't that. These sorts of problems are notoriously difficult to figure out even when the interference is there almost all the time.

I don't know about wireless phones but mobile phones and I believe wireless lans will lower the transmission power to the minimum necessary to provide service. Perhaps the level is dropping low enough at times that a moments interference is enough for it to lose the base station.

Having

[Holly, in France]

describe.

perhaps

Thanks. Don't think this is the problem in our case, since the nearest neighbours are well outside the range of the phone. We do have a wireless weather station gadget, would that use the same system? Having said that, the phone was the same before I bought the weather station and the problem hasn't got any worse.

Yes, that is a possibility. Although on the whole when it is very cold here (and it seems to me to be the cold which affects it, but I might have that wrong, haven't made any notes etc) the RH is quite low. I am measuring the RH inside and out atm because I am drying timber in the gite and I try to work out what is the best temperature/RH combination on any given day, whether I should leave the doors open etc. I have no idea whether it is doing any good as far as drying the wood goes, but it's quite interesting. Also if the RH was the cause I would have thought that the phone wouldn't work well in the bath :-)

-- Holly, in France. Holiday home in the Dordogne, website:

[Mike]

DECT has it's own dedicated band Europe-wide and should be clear of all other interferers.

[Rod Hewitt]

"Mike" wrote in news:d0kjj6$fn5$ [e-mail]:

That rather stomps on some of the theories!

Still looking. Replaced both batteries recently on an 'in case' basis - maybe marginally better but really not sure. (Both about 5 years old and saw the product description suggested changing annually.) We too have a weather station thingy (el cheapo) - but I can't believe that a single AA cell would be enough to disrupt the DECT. Also, why at certain times more often? Typically late evening after a whole day (and sometimes the preceding night) without a hitch?

[Mike]

One it doesn't is somebody is using a high power DECT link (only supposed to be used in South America) as a private data link. Are you near any companies, possibly ones with two buildings on opposite sides of the road ?

[Capitol]

That's a bit like believing that car drivers don't use mobile phones! As has been said, microwaves are very bad for 2.4 GHz Dect frequencies, also, zenon headlamps and some car ignition( electronic?) systems on modern cars. Slab sided vehicles seem able to produce out of phase reflections which can lower signal levels also. I suspect that HF switching interference(arcing) can also transmit from power lines and temporarily knock out the AGC. I find that any brush motor device has a chance of causing enough interference to knock out a 2.4GHz link, even though it is nominally suppressed. Possibly because when tested, the required standard did not go much beyond 1GHz.

Range etc can sometimes be helped by adding passive yagi array reflectors/radiators in gaps between rooms or the receive aerial performance can be improved.

Regards Capitol

[Mike]

DECT is at around 1900 MHz so shouldn't be affected by a microwave which is at 2.4 GHz together with most wireless LANs.

More likely though these are supposed to be tested to 2GHz now. Older (or US) systems may not comply though.

[tony sayer]

In article , Capitol writes

Are you certain that your phone/s use the 2.4 Ghz band AFAIR these were around 1.9 ish Ghz?.....

[Mike]

Is this when it's cooling down ? Or perhaps heating up when the heating comes on ?

[Holly, in France]

Specs of mine are as follows. I'm copying anything relevant looking, translating from French as nec, don't know what it all means....

GAP (Generic Access Profile) Frequencies 1880 - 1900 MHz

120 channels duplex Modulation GFSK 32kbit/s Power of (signal?) emission 10mW average by channel range 300m open 50m in building rest of it not relevant.

Ours has the problem when I am certain that none of the suggested sources of possible interference are present. Only fridge and freezer are on all the time, other stuff is left plugged in and on standby. No mobile phone signals here atm, we are in a valley, hoping for improvement later in the year when new mast is due. Whatever causes the phone problem, I think it must be either a variable component/fault in the phone or something to do with the weather conditions?? Either that or something secret and military that we don't know about, but I'm not that paranoid :-) My mum is good in cases like this, she can diagnose the problem immediately "it's just one of those things". I think she might be right! It isn't much of a problem here, but since it was mentioned I thought it worth looking into it. Any more thoughts anyone?

-- Holly, in France. Holiday home in the Dordogne, website:

[Holly, in France]

Perhaps if we make an effort to see when it happens, possible sources of interference, weather conditions etc, we (or someone) might be able to work out what is going on. Or not :-)

-- Holly, in France. Holiday home in the Dordogne, website: