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O.T. Microwaves
housetrained wrote:
the Roku Box in the kitchen it stops working when the microwave oven is in use. Domestic microwaves (and many other devices) use the same 2.4Ghz frequency as WiFi. WiFi uses about 1/4 of a Watt, a typical microwave about 850 Watts, there will be a a small amount of leakage from the microwave that's not enough to worry about, but which will destroy the WiFi signal, especially as it sounds like your Roku box is closer to the microwave than to the computer (or WiFi access point if you have one). |
O.T. Microwaves
On 16 June, 11:58, Andy Burns wrote:
housetrained wrote: the Roku Box in the kitchen it stops working when the microwave oven is in use. Domestic microwaves (and many other devices) use the same 2.4Ghz frequency as WiFi. WiFi uses about 1/4 of a Watt, a typical microwave about 850 Watts, there will be a a small amount of leakage from the microwave that's not enough to worry about, but which will destroy the WiFi signal, especially as it sounds like your Roku box is closer to the microwave than to the computer (or WiFi access point if you have one). So if you got enough WiFi routers together, could you cook a Chicken? |
O.T. Microwaves
In article , housetrained
scribeth thus This not related to TV's but to sound. Expect some nice person on this NG will know and share the answer. When music is streamed from the computer to the Roku Box in the kitchen it stops working when the microwave oven is in use. Tried moving the Roku etc. but to no avail. S'pose I could try moving the microwave. BUT, should this happen? Is the Microwave 40? Is it dangerous? TIA If your streaming over a wi-fi thats on 2.4 Ghz then it shouldn't be too difficult to conclude what frequency your microwave works at;).. Sometimes some models leak more than others even if they are inside the permitted or considered safe levels. Our streaming radio receives our air point fine located as it is on top of the microwave;!.. -- Tony Sayer |
O.T. Microwaves
In article , Andy
Burns scribeth thus housetrained wrote: the Roku Box in the kitchen it stops working when the microwave oven is in use. Domestic microwaves (and many other devices) use the same 2.4Ghz frequency as WiFi. WiFi uses about 1/4 of a Watt, a typical microwave about 850 Watts, there will be a a small amount of leakage from the microwave that's not enough to worry about, but which will destroy the WiFi signal, especially as it sounds like your Roku box is closer to the microwave than to the computer (or WiFi access point if you have one). You might try a change of channel for your airpoint, might just make enough difference.. -- Tony Sayer |
O.T. Microwaves
"tony sayer" wrote in message ... In article , housetrained scribeth thus This not related to TV's but to sound. Expect some nice person on this NG will know and share the answer. When music is streamed from the computer to the Roku Box in the kitchen it stops working when the microwave oven is in use. Tried moving the Roku etc. but to no avail. S'pose I could try moving the microwave. BUT, should this happen? Is the Microwave 40? Is it dangerous? TIA If your streaming over a wi-fi thats on 2.4 Ghz then it shouldn't be too difficult to conclude what frequency your microwave works at;).. Sometimes some models leak more than others even if they are inside the permitted or considered safe levels. Our streaming radio receives our air point fine located as it is on top of the microwave;!.. -- Tony Sayer My kitchen streaming radio is not one top of the micro, but it's certainly unaffected by the microwave being on. Paul DS |
O.T. Microwaves
On Wed, 16 Jun 2010 04:34:31 -0700 (PDT), Dr Hfuhruhurr
wrote: On 16 June, 11:58, Andy Burns wrote: housetrained wrote: the Roku Box in the kitchen it stops working when the microwave oven is in use. Domestic microwaves (and many other devices) use the same 2.4Ghz frequency as WiFi. WiFi uses about 1/4 of a Watt, a typical microwave about 850 Watts, there will be a a small amount of leakage from the microwave that's not enough to worry about, but which will destroy the WiFi signal, especially as it sounds like your Roku box is closer to the microwave than to the computer (or WiFi access point if you have one). So if you got enough WiFi routers together, could you cook a Chicken? In principle, yes. However, in practice the routers might cook themselves before the chicken was done. -- Peter Duncanson (in uk.tech.digital-tv) |
O.T. Microwaves
On 16/06/2010 13:35, Peter Duncanson wrote:
So if you got enough WiFi routers together, could you cook a Chicken? In principle, yes. However, in practice the routers might cook themselves before the chicken was done. Wouldn't say done, more like "chicken's slowly rotting into something that looks like cheese" ... -- Adrian C |
O.T. Microwaves
"Andy Burns" wrote in message ... housetrained wrote: the Roku Box in the kitchen it stops working when the microwave oven is in use. Domestic microwaves (and many other devices) use the same 2.4Ghz frequency as WiFi. WiFi uses about 1/4 of a Watt, a typical microwave about 850 Watts, there will be a a small amount of leakage from the microwave that's not enough to worry about, but which will destroy the WiFi signal, especially as it sounds like your Roku box is closer to the microwave than to the computer (or WiFi access point if you have one). From http://www.ofcom.org.uk/static/archi...458/rtl458.pdf "2.0 Summary 2.1 The frequency measured from the domestic microwave cookers varied between approximately 1.87GHz and 2.93GHz (1060MHz). 2.2 Between 2.0GHz and 2.75GHz (750MHz) the RF signal emanating from the cooking chamber was approximately 10dB above the noise with the major signal peaks at between 2.4GHz and 2.5GHz (100MHz). 2.3 The RF power leaking from the all the domestic microwave cookers tested varied between 1549mW and 245mW which is a difference of 8dB. 2.4 Leakage from the doors of domestic microwave cookers is greater from cookers that at have been in constant use over a number of years." Just checking my dodgy maths - is that between 1.59W and 0.245W? If so it is not surprising that there can be interference. More surprising that WiFi works when the microwave is closer than the AP. Although we don't use the microwave as much as the WiFi :-) Cheers Dave R -- No plan survives contact with the enemy. Helmuth von Moltke the Elder |
O.T. Microwaves
Domestic microwaves (and many other devices) use the same 2.4Ghz frequency
as WiFi. WiFi uses about 1/4 of a Watt, a typical microwave about 850 Watts, there will be a a small amount of leakage from the microwave that's not enough to worry about, but which will destroy the WiFi signal, especially as it sounds like your Roku box is closer to the microwave than to the computer (or WiFi access point if you have one). From http://www.ofcom.org.uk/static/archi...rchive/rtl458/ rtl458.pdf "2.0 Summary 2.1 The frequency measured from the domestic microwave cookers varied between approximately 1.87GHz and 2.93GHz (1060MHz). 2.2 Between 2.0GHz and 2.75GHz (750MHz) the RF signal emanating from the cooking chamber was approximately 10dB above the noise with the major signal peaks at between 2.4GHz and 2.5GHz (100MHz). 2.3 The RF power leaking from the all the domestic microwave cookers tested varied between 1549mW and 245mW which is a difference of 8dB. 2.4 Leakage from the doors of domestic microwave cookers is greater from cookers that at have been in constant use over a number of years." Just checking my dodgy maths - is that between 1.59W and 0.245W? Yes as near as makes no difference.. If so it is not surprising that there can be interference. Yes we have seen microwave ovens cause serious to industrial grade microwave links using 2.4, this was a while ago now as these days the spectrum is too polluted in built up areas. One was out in the sticks and used a 3 foot diameter receive parabolic aerial and a microwave oven 400 yards away and in the opposite direction was upsetting that!. Cured it by paying for them to go get a nice new model. Seems older ones do leak quite a bit... More surprising that WiFi works when the microwave is closer than the AP. Although we don't use the microwave as much as the WiFi :-) Depends on how much its leaking.. Cheers Dave R -- Tony Sayer |
O.T. Microwaves
In article , tony sayer
wrote: Domestic microwaves (and many other devices) use the same 2.4Ghz frequency as WiFi. WiFi uses about 1/4 of a Watt, a typical microwave about 850 Watts, there will be a a small amount of leakage from the microwave that's not enough to worry about, but which will destroy the WiFi signal, especially as it sounds like your Roku box is closer to the microwave than to the computer (or WiFi access point if you have one). From http://www.ofcom.org.uk/static/archi...rchive/rtl458/ rtl458.pdf "2.0 Summary 2.1 The frequency measured from the domestic microwave cookers varied between approximately 1.87GHz and 2.93GHz (1060MHz). 2.2 Between 2.0GHz and 2.75GHz (750MHz) the RF signal emanating from the cooking chamber was approximately 10dB above the noise with the major signal peaks at between 2.4GHz and 2.5GHz (100MHz). 2.3 The RF power leaking from the all the domestic microwave cookers tested varied between 1549mW and 245mW which is a difference of 8dB. 2.4 Leakage from the doors of domestic microwave cookers is greater from cookers that at have been in constant use over a number of years." Just checking my dodgy maths - is that between 1.59W and 0.245W? Yes as near as makes no difference.. I am surprised by that as I thought the legal limit for safety reasons was something like 1 or 10 mW per square cm anywhere near the device. Plus I'd expect allowing radiation at the level of 1W would be unacceptable for various interference reasons. Does the original mean 'milliwatts' or might this be a case where 'm' has ended up being used for 'micro'? Above said, whenever I power up my new laptop it tells me wifi is available. Since I don't use wifi I guess it is picking up something from another house. I'll see if our microwave affects that! :-) Slainte, Jim -- Please use the address on the audiomisc page if you wish to email me. Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html Audio Misc http://www.audiomisc.co.uk/index.html |
O.T. Microwaves
In article , David WE Roberts
wrote: From http://www.ofcom.org.uk/static/archi...458/rtl458.pdf I've now had a look at the above and am underwhelmed by the level of detail, etc. My initial reaction was that if an undergrad had given me this as a report I would have discussed it with them and sent them back to the lab to do it properly! :-) I've looked a few times at the report, and I may have missed something, but at present my comments are... Distance between source and measurement antenna not specified. (Yes this matters unless we know the distance was great enough to put the source antenna in each case and the measurement antenna into their respective 'far fields' - which could be some distance for the microwave oven as an antenna.) Which antenna was used for measurements and which as the "substitution antenna"? Can't see this in the report. (Yes it matters for the above reason. A 20dB horn will have a longer far field than a lower gain antenna.) Measured power was in peak direction. Not an integrated result. No indication of the integrated values for the actual microwave ovens. Antenna patterns of antennas not given. This matters as a result of the other points I make since the measurements seem to compare a peak directed coupling (with unknown patterns) with the assumed behaviour of another "substitution antenna" of unknown pattern and with values where it isn't clear if they are either 'ERP' or real power totals or directed couplings. Table at top of page 8 (section 5.3) has two columns for powers which I will refer to as A and B via. A = "Measured Peak erp (dBm)" and B = "Max Radiated power (mW)" but the use of neither of these terms is defined in the report so far as I saw. A is in dBm and the largest value is 0.0 (dBm) - i.e. 1 mW Yet B for the same cooker is listed as 1549 mW - i.e. 31.9 dBm The ratio between A and B seems to vary from one cooker to another, but does tend to be of the order of 30dB. Now if A *were* an ERP then it is hard to know what B means unless we assume something like the "substitution antenna" had an apallingly low radiation efficiency and had to driven by around 1 Watt in order to radiate a total of 1mW! An alternative possibility is that the report's author does not know the meaning of ERP. :-) I have a feeling that A was actually the nominal recieved levels at the measurement instruments and B was the power poked into the "substitution antenna" to get the same measured levels. But without knowing the patterns distances, etc, this result is virtually meaningless if this is the case since we are comparing two different radiated powers and couplings using a rx level in one case and a tx level in the other - without even knowing if the results *are* under mututal far field conditions. OTOH we could imagine all kinds of alternative meanings for the powers listed in the table. We aren't told any of the settings on the measurement kit, either. This also matters. Conclusion: I have no idea if these results mean much. The A values may seem consistent with powers/cmsquared of the order of less than a mW/sqcm. But given the absence of any real explanations in the report even this is guesswork. Hence I have no idea if any of the ovens radiated powers above a 1mW let alone a watt. The results don't really give enough info to tell. Anyone have any *reliable* measurements on this? Slainte, Jim -- Please use the address on the audiomisc page if you wish to email me. Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html Audio Misc http://www.audiomisc.co.uk/index.html |
O.T. Microwaves
An alternative possibility is that the report's author does not know the
meaning of ERP. :-) I have a feeling that A was actually the nominal recieved levels at the measurement instruments and B was the power poked into the "substitution antenna" to get the same measured levels. But without knowing the patterns distances, etc, this result is virtually meaningless if this is the case since we are comparing two different radiated powers and couplings using a rx level in one case and a tx level in the other - without even knowing if the results *are* under mututal far field conditions. OTOH we could imagine all kinds of alternative meanings for the powers listed in the table. We aren't told any of the settings on the measurement kit, either. This also matters. Conclusion: I have no idea if these results mean much. The A values may seem consistent with powers/cmsquared of the order of less than a mW/sqcm. But given the absence of any real explanations in the report even this is guesswork. Hence I have no idea if any of the ovens radiated powers above a 1mW let alone a watt. The results don't really give enough info to tell. Anyone have any *reliable* measurements on this? Slainte, Jim Why don't you take it up with Ofcom Jim?. And see what they have to say about their measurements?.... -- Tony Sayer |
O.T. Microwaves
tried several channels yesterday - ch8 seems slightly better but still had
trouble cutting out etc. Maybe it's time to persuade the wife to buy a new MW. Thanks to all who helped. -- John the West Ham fan "housetrained" wrote in message ... This not related to TV's but to sound. Expect some nice person on this NG will know and share the answer. When music is streamed from the computer to the Roku Box in the kitchen it stops working when the microwave oven is in use. Tried moving the Roku etc. but to no avail. S'pose I could try moving the microwave. BUT, should this happen? Is the Microwave 40? Is it dangerous? TIA -- John the West Ham fan |
O.T. Microwaves
In article , tony sayer
wrote: An alternative possibility is that the report's author does not know the meaning of ERP. :-) [snip] Anyone have any *reliable* measurements on this? Why don't you take it up with Ofcom Jim?. Ars Long Vita Brevis. :-) ....or as I translate that, Life is too short to worry about past politefoul/polite-ups. ;- Enough for now to caution that the 'results' presented in the reference may not mean what they seem to say. I'll now go and find my 'Nice' albums to check the spelling... Slainte, Jim -- Please use the address on the audiomisc page if you wish to email me. Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html Audio Misc http://www.audiomisc.co.uk/index.html |
O.T. Microwaves
The message
from Jim Lesurf contains these words: In article , tony sayer wrote: An alternative possibility is that the report's author does not know the meaning of ERP. :-) [snip] Anyone have any *reliable* measurements on this? Why don't you take it up with Ofcom Jim?. Ars Long Vita Brevis. :-) ....or as I translate that, Life is too short to worry about past politefoul/polite-ups. ;- Enough for now to caution that the 'results' presented in the reference may not mean what they seem to say. I'll now go and find my 'Nice' albums to check the spelling... "Ars Longa Vita Brevis" afaicr. ;-) |
O.T. Microwaves
Persuaded her - it's on it's way:-)
-- John the West Ham fan "housetrained" wrote in message ... tried several channels yesterday - ch8 seems slightly better but still had trouble cutting out etc. Maybe it's time to persuade the wife to buy a new MW. Thanks to all who helped. -- John the West Ham fan "housetrained" wrote in message ... This not related to TV's but to sound. Expect some nice person on this NG will know and share the answer. When music is streamed from the computer to the Roku Box in the kitchen it stops working when the microwave oven is in use. Tried moving the Roku etc. but to no avail. S'pose I could try moving the microwave. BUT, should this happen? Is the Microwave 40? Is it dangerous? TIA -- John the West Ham fan |
O.T. Microwaves
In article , Jim Lesurf
writes In article , David WE Roberts wrote: From http://www.ofcom.org.uk/static/archi.../topics/archiv e/rtl458/rtl458.pdf I've now had a look at the above and am underwhelmed by the level of detail, etc. Bugger the detail Jim! How long will a 5-lb chicken take on an N+ router? There's a war on, and every saving helps! ;-) -- Kennedy Yes, Socrates himself is particularly missed; A lovely little thinker, but a bugger when he's ****ed. Python Philosophers (replace 'nospam' with 'kennedym' when replying) |
O.T. Microwaves
Used it, on ch8 sub 13 all ok- yipeeeeeeeeeeeeeeeeeeeeeeeee
-- John the West Ham fan "housetrained" wrote in message ... Persuaded her - it's on it's way:-) -- John the West Ham fan "housetrained" wrote in message ... tried several channels yesterday - ch8 seems slightly better but still had trouble cutting out etc. Maybe it's time to persuade the wife to buy a new MW. Thanks to all who helped. -- John the West Ham fan "housetrained" wrote in message ... This not related to TV's but to sound. Expect some nice person on this NG will know and share the answer. When music is streamed from the computer to the Roku Box in the kitchen it stops working when the microwave oven is in use. Tried moving the Roku etc. but to no avail. S'pose I could try moving the microwave. BUT, should this happen? Is the Microwave 40? Is it dangerous? TIA -- John the West Ham fan |
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