Talk:Digital Enhanced Cordless Telecommunications

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There are DECT phones in the US but these operate on 2.4 Ghz. Presumably 1880-1900 Mhz was off limits for the FCC

The cell range of DECT is given here as 25-100 m. It should be known that Midas Communications, India, have a range of DECT based Fixed Wireless Access products that have cell ranges upto 10 km. This is based on clear Line of Sight. --Rupam.das 10:34, 16 November 2005 (UTC) This is based on outdoor, directional antennas on the uplink and less tha 60 degrees antenna segment on the BST. Handset will only be provided coverage in 150m - as for any other. Shyam has deployed DECT links (RLL) for as far as 29km. --KH Flottorp 10:28, 9 July 2006 (UTC)

Contents

[edit] Health effects

I yanked this:

Despite its broad range of technical features, there are considerable health issues with the use of DECT or, in fact, any other wireless devices in that frequency range using pulsed microwave technology. Numerous studies have found effects of these frequencies on body cell communication and the body's hormone levels. While little is known so far on how these low-level effects influence overall health and wellness, longer-term cancer research studies point to an increase of certain types of cancers presumably related to exposure to mobile phone base stations as well as other wireless technology radiation including DECT, wLAN etc. On the basis of these scientific findings, caution should be exercised when switching to a cordless phone using DECT or to any similar wireless technologies. Emmissions to both the user and third parties (neighbours, non-using bystanders) should be avoided. Most DECT base stations do send and, thus, emit radiation around the clock, even when not in use. There are, however, a few selected models available that automatically shut down within 1 or 2 minutes after the end of a call. This will also lower the device's overall energy consumption by a significant amount per year. Strictly limiting exposure (e g by shutting off standby or disconnecting devices from power unless in use) as well as keeping base stations and handsets as far from the body as possible may yield some protection, if avoiding them altogether and repalcing them with an equally feautre-rich corded phone seems unacceptable.

Aside from being generally skeptical about the risk from mobile phones and the like - if there really was a substantial risk, DECT telephones are much lower power than cellphones. this page seems to have a fairly comprehensive analysis of the studies that have been done on cellphone risk; there seems to be very little quantitative evidence to support the case of cellphones as a cancer risk. Any comment on risk from DECT phones should take the vastly lower power levels into account, at the very least. --Robert Merkel 12:56, 12 December 2005 (UTC)

That's not a good reason to remove the paragraph. It could be better written, though, with references to criticism and so on. Btw, you're probably wrong about the comparison with mobile phones. DECT always use the same signal strength, while GSM and other modern standards can use a significantly lower signal strength than DECT when the phone is close to the base station. In addition, I'm told that DECT base stations are always transmitting at full strength, even when there's no call in progress. ABostrom 21:33, 28 September 2007 (UTC)
The following is my updated and corrected version of the above text, which again was deleted by Squiggleslash for some weird reasons. He says, "This is an article about DECT, a heavily biased rant containing dubious health claims does not belong here". If facts and recent findings about health hazards concerning DECT devices do not belong here, then where?
He also says mentioning this topic "makes a mockery of the page in its present form". It makes a mockery of Wikipedia in its present form, if argumentative issues are banned and deleted.
FYI, even a institution of German government warned about DECT phones about 2 years ago. Google translation of http://www.bfs.de/de/bfs/presse/pr06/pr0602 They demanded manufacturers to build low-radiation DECT phones, and guess what the manufacturers did? They build them. They wouldn't have if they were so sure about DECT being absolutely unperilous.
(I added some references and made corrections to the text, which I did copy from a much earlier version of this page.)
Please, someone press the "undo" button. --W-sky (talk) 06:05, 8 January 2008 (UTC)

Health issues

There are considerable health issues with the use of DECT or, in fact, any other wireless devices in that frequency range using pulsed microwave technology. Studies have found effects of these frequencies on body cell communication and the body's hormone levels. [citation needed] While little is known so far on how these low-level effects influence overall health and wellness, point to an increase of certain types of cancers presumably related to exposure to mobile phone base stations as well as other wireless technology radiation including DECT, Wi-Fi etc.[1]

Most DECT base stations do send and, thus, emmit radiation around the clock, even when not in use. There are, however, handsets available that reduce signal strength when close to the base station, and base stations that reduce the continuos control signal up to a 100,000th. These are labelled as "ECO DECT" models. However, on the basis of the scientific findings, caution should be exercised when using DECT or similar wireless technologies. Still it is advisable to keep base stations and handsets as far from the body as possible, and especially far away from kids and sleeping places, if avoiding them altogether and replacing them with corded phone seems unacceptable.[2][3]

Scroll down to the bottom of the Talk: page and you'll see my original reasons for yanking this. Your latest edit is no better. Let's pick it apart:
There are considerable health issues with the use of DECT or, in fact, any other wireless devices in that frequency range using pulsed microwave technology."
This is uncited, and not without reason - there is no consensus at all suggesting that any substantial portion of the scientific community believes this to be true. This statement cannot be made in Wikipedia as is. You might have gotten away with "Some concern has been expressed about health issues with...", together with cites of actual concern from reputable organizations, but the statement, as written, is frankly false.
Studies have found effects of these frequencies on body cell communication and the body's hormone levels. [citation needed]"
Not only is this uncited, but it's admitted to that it's uncited. Again, this statement cannot be made in Wikipedia as written.
While little is known so far on how these low-level effects influence overall health and wellness, point to an increase of certain types of cancers presumably related to exposure to mobile phone base stations as well as other wireless technology radiation including DECT, Wi-Fi etc.[1]"
This statement contradicts the first two statements. "Little is known" yet "There are considerable health issues" and "Studies have found.."? Really? I congratulate the writer on actually finding a paper of vague relevance, but the paper is talking about cellphone transmission masts, which generally transmit many thousands of watts of radiation and are incomparable to a fraction-of-a-watt DECT or Wi-fi base-station.
Most DECT base stations do send and, thus, emmit radiation around the clock, even when not in use."
The entire section is a case of "Undue weight", but even within it there are recursive examples. This is one of them. DECT base stations send very brief pulses of information every few seconds when not in use, they're not constantly transmitting, and the power, again, is a fraction of a watt. This is not mentioned, and the over-all tone of the sentence implies that DECT base stations are actually blowing out massive amounts of radiation all the time.
There are, however, handsets available that reduce signal strength when close to the base station, and base stations that reduce the continuos control signal up to a 100,000th. These are labelled as "ECO DECT" models."
There is no continuous control signal, so this sentence is blatantly misleading and the over-all affect is to make the previous sentence look, as I mentioned above, like it's implying something that isn't true.
However, on the basis of the scientific findings, caution should be exercised when using DECT or similar wireless technologies."
This is POV, original research, and apparently untrue on the basis of current scientific knowledge about DECT and other wireless technologies.
Still it is advisable to keep base stations and handsets as far from the body as possible, and especially far away from kids and sleeping places, if avoiding them altogether and replacing them with corded phone seems unacceptable.[2][3]"
This strikes me as alarmist, and not rooted in anything scientific. As for citations, the first source is labeled a "Scientific Study" but appears to be sourced from some kind of non-objective anti-wireless site. Reading the link, the paper contains the same hysterical exaggeration about DECT's "continuous" transmissions when idle, and while not stupid enough to repeat the "OMG, DECT might cause cancer" claim above, repeats dubious claims about DECT possibly being disruptive to sleeping patterns. It's a terrible thing to link to. The second reference is to an appeal for more research based upon apparent circumstantial evidence of a link between DECT and, well, frankly anything that can be described as an illness.
Over-all the section is wrongly located in the DECT section for the following reasons:
1. This is not a DECT specific issue. A more general article that covers health concerns (and covers them properly) might be appropriate to link to, but this is a clear case of placing "undue weight" on a specific issue.
2. The section is one-sided and biased. There is nothing in the article that implies that the general consensus is that there are no serious health issues associated with low power level wireless technologies, indeed dissent is completely ignored.
3. The section contains many statements that are completely counter to the truth.
4. The section is largely uncited, and the cites that are given are unencyclopedic.
5. The section is unencyclopedic and its presence in the article does no credit to Wikipedia.
I don't see how you can't see that. --Squiggleslash (talk) 14:56, 8 January 2008 (UTC)
Hello and thanks a lot for being so elaborate, now I do understand why the section had to be deleted (again). I'm sorry for having persisted to keep the old text. Yet I still want to add something to the discussion (and to the article).
In general: There are two ways of dealing with possible risks of new technology (and DECT, being ~12 years old, still can be considered as 'new technology'). Either you do not acknowledge any risks until there is airtight proof of health danger, or you assume the probability of health danger until it is proven completely harmless.
IMHO, the second way is preferable. The first way is how humans dealt with radioactivity, chemicals, usage of fossile fuel etc., and looking to the past, it shows that this way is not always the best way. So I think: When talking about DECT, you have to mention the possibility or likelihood of health risks. But this way of thinking concerns not only DECT, but all new technology. So there might not be a special reason why this should be mentioned in the article about DECT; it might be just the general way of how to approach new technology, and this everyone has to decide for his own... But there is a special reason. It is exactly because there are so many fears, rumours, scientific and pseudo-scientific essays about the dangers of DECT. Furthermore, especially because of the legitimate criticism of DECT base stations perpetually sending very short but full-power contact signals to their handset(s), and because both base stations and handsets always sending with full signal strength even when very close to each other.
So I think, what must be mentioned in the article is: The signal strength issue and that very new DECT phones ("ECO-DECT") have various ways of reducing emission; that people like medical professionals believe in or at least do not rule out the possibility of health risks from DECT phones; that yet there is no absolute proof of risks or the absence of risks.
What's more: Someone looking for an answer to the whirring question about DECT health risks would possibly look into this Wikipedia article, hoping to find the latest findings and actual state of affairs here.
Though I worry that I could not write this. It might be undue weighted. ;-) --W-sky (talk) 05:06, 21 January 2008 (UTC)
DECT isn't really a new technology. It's a newer standard, but TDM/TDMA/FDMA digital telephones have been used for a lot longer than the life of DECT. DECT is itself a successor to CT2, Japan's PHS is very similar, and, of course, GSM, D-AMPS, and others have been extensively used across the world for a decade and a half. To suggest there are special health issues with DECT would most definitely be placing undue weight on the subject. DECT is considerably lower power than the analog systems it replaces, both during transmissions, and inherently because even when in use the TD nature of the system means the system isn't transmitting continuously.
As I believe I've said before, there is nothing wrong with there being a properly researched article about the health effects of low-power radio technology, and there being a link in the See also: section of this article to it. That article, of course, should look nothing like the section I yanked. There is nothing about DECT however that merits a special section on DECT's dangers, especially when - new technology or otherwise - there is no serious level of concern being expressed by anyone authoritative on this issue. --Squiggleslash (talk) 18:20, 21 January 2008 (UTC)

[edit] DECT in the United States

it would seem that there are now 1.9 ghz DECT devices in use in the US now, including the plantronics CS55 headset - http://www.plantronics.com/north_america/en_US/products/cat29880043/cat29880054/prod5430004 -Joe Zasada, May 29, 2006


It has also appeared in the US consumer market for baby monitors http://www.consumer.philips.com/consumer/catalog/tree/en/us/consumer/personal_care_gr_us_consumer/baby_care_ca_us_consumer/babys_development_su_us_consumer/ce/_productId_SCD590_54_US_CONSUMER/_activeTab_specifications/DECT_baby_monitor+SCD590?proxybuster=JXOW0ZKLBKQE1J0RMRESHQVHKFSEKI5P Ktinga 15:35 21 April 2007 (UTC)

[edit] Spam / commercial links

I have removed a spam / commercial link to a UK handset retailer cordless-phones.uk.com . I suspect this to be an attempt at increasing search engine ranking. Andrew Oakley 09:30, 18 September 2006 (UTC)

Searching through the history, the spam link appeared to have been added by 62.219.183.196 . Andrew Oakley 09:34, 18 September 2006 (UTC)

[edit] More than one external call at a time

It is not possible to have more than one external telephone call in operation on a typical domestic DECT system. Attempts to make an external call from one handset, whilst an external call is already being taken on another handset, generally give an error or warning, such as an engaged tone. However, this is possible with a business DECT system attached to a PABX.

Here in Germany, consumer DECT systems with an ISDN connection are popular. Siemens and other companies are selling these (f.e. the "Siemens Gigaset CX450 isdn" sells for around 75 Euros). With these devices it's possible to have several internal and external calls simultaneously (using multiple handsets but only one base station). --213.39.129.112 10:38, 25 September 2006 (UTC)

[edit] Multipath Interference

I have recently been trying to work out DECT isnt working well in a large ~ 80m x 20m metal clad (Walls floors ceiling) building which is mainly space with a few odds and sods of metal structures. The structure has the added feature of round (focussing) end walls.

My only possible explanation was multipath interference. At a bit rate of a shade over 1.1 Mbit / sec (I dont know where the bitrate on the main page comes from) a 90ns time difference (30m length)in paths causes a 10% encroachment between adjacent bits, according to [1] this is enough to cause problems.

Any similar experience / comments?

Glass90land 13:51, 17 October 2007 (UTC)

[edit] Multipath Interference - a response

Your problem is indeed multipath, but not between the bit symbols: the DECT GMSK modulation will work at signal/interference ratios down to about 12db, and even metal walls will struggle to produce such levels with only 10% encroachment. Instead the problem is phase interference between cycles of the carrier, which at 1.89GHz have a wavelength of about 15cm. This is normal in most environments, and leads to a phenomenon called Rayleigh fading, since the depth and distribution of the fades normally follows Rayleigh statistics. In a clad, curved metal box the fades will be much more frequent and deeper, causing a reception environment resembling nothing so much as a Swiss cheese. The normal DECT solution to fading is called antenna diversity - to have two antennae (usually but not always at the base station) about half a wavelength apart, and the signals are switched to whichever has a decent signal. Thus if one antenna is in a fade, the other is probably getting a good signal. This method was employed in DECT PABXs and DECT wireless LANs, but consumer cordless phones tend not to have two antennae.

--Andrew Bud 01:14, 30 October 2007 (UTC)

[edit] DECT with Bluetooth in the US

Is it just me or is a DECT cordless phone with Bluetooth impossible to get in the US? Would one be able to buy the Siemens SL565 (available in the UK) and use it in the US? 74.68.112.149 (talk) 10:28, 24 December 2007 (UTC)

Alas, no. DECT in the US uses a different set of frequencies to DECT in Europe. Sorry. FWIW, the Wikipedia talk: pages are primarily for discussions of the pages associated with them, not the topics. Just a friendly warning, because some people get annoyed about that kind of thing. --Squiggleslash (talk) 11:33, 24 December 2007 (UTC)

[edit] "Health issues"

Please do not re-add this.

The section that was added to this article was:

  • POV
  • Places "undue weight" on the subject. There is no mainstream concern about the health affects of DECT
  • At odds with the apparent truth, claiming that DECT is thought to cause health issues when the reverse appears to be true from the vast bulk of literature I've seen
  • Is not specific to DECT so doesn't belong here in the first place.

The section is as relevant here as a section about whether porn leads to violence would be in the MPEG article. It shouldn't be put here. It clearly violates WP:NPOV and is off-topic. --Squiggleslash (talk) 02:27, 4 January 2008 (UTC)