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Phones, Microwaves and WiFi

November 14th, 2007 · No Comments

Warning, engineers, scientist and those who like to argue should skip this article.
All information given here is “baby steps” and not meant to be the science of what I am covering.

If you would like to argue about the exact specifications of this weeks topics please join the U.N., W.T.O. or some other useless group of arguers.

Cordless phones are a blessing. I can check out e-mail, go to the kitchen, walk next door to get one of the kids and even sit on my backyard swing and enjoy the freedom of America, all while still talking or listening on the phone. Cordless phones use radio frequency just like the radio you use to listen to music or your favorite local talk show. Instead of being in a low range and with high output, phones use a higher range and lower output. This prevents you from going to the store using your home phone.

Common frequencies for cordless phones are 900MHz, 2.4 GHz (2400MHz), and 5GHz. These are simply the “radio stations” being used. Inside of each frequency are several channels. Think of them like 900, 905, 910 MHz. This helps keep you neighbor’s phone from picking up your conversations.

Microwaves have gone from devices to warm up leftovers to providing complete meals in an instance. The 1 minute hot dog has turned into the 20 second hot dog. All the warming and cooking is done not by direct heat but by very intense radio frequencies. By using the 2.4GHz bandwidth, locking into a small box (the inside of the microwave) and pushing it quickly and repeatedly food is heated “evenly” because the radio wave goes all the way through the food.

Wireless networks are also a blessing. You can check e-mail from the couch without your daughter tripping over a network cable. You can be surfing for articles on the famous purple hippos of Indonesia from the comfort of your bed or listening to streaming downloads of your favorite music while sunning by the pool. While the speed of the wireless connections and distance between your access point and your wireless device (laptop, Pocket PC) has grown dramatically over the last two years the frequencies have changed little. Wireless “B”, “G and now Pre “N” standards use the 2.4GHz frequency and the “A” standard used 5GHz.

Without going into the blah blah blah of wireless you will notice something in common, cordless phones, microwaves and wireless networks all use the same frequency. This can and does result in strange issues when using any combination of these. Let me give you a few examples. At Diversified Plastics we had a rather large warehouse (larger than a two football fields side by side) with several access points in the ceiling (over 25 foot high if I remember correctly). When items were being inventoried or picked out for shipping a wireless scanner was used to scan the barcodes. The forklift driver carried a cordless phone on his hip and the scanner on the other side. After a while the phone died. When we replaced it we purchased a 2.4GHz phone. If the scanner was on (not necessarily scanning) and the phone would ring it would break the connection and require the scanner to be rebooted. If the phone rang while an item was being scanned the scanner and server that the files went to would have to be rebooted. This even occurred if the phone was on the desk and the shipper was on the far side of the building. The answer of course was to go back to a 900MHz phone.

Though that may not seem to affect you, let’s move to Mr. Self Employed. Mr. Employed works from home as an architect. He just had to have a wireless network, even though there was no need to share information between his home computers he just wanted the kids to be able to access the internet from upstairs and some sales slime at Best Buy told him that wireless was the “only way to go”. The problem is that upstairs is the kid’s game room with a small refrigerator and a microwave and of course a phone with their own private line. To make matters worse, between his office where the internet connection and thus his wireless access point was and the upstairs game room was the kitchen. In his office was his business line on a cordless phone and in the kitchen was the home phone number, once again on a cordless phone. When I received the call as a recommendation from a mutual friend Mr. Employed was fit to be tied. He had exchanged multiple pieces of equipment (Access point, wireless cards) and spent countless hours on the phone with the manufacturers of the products, Best Buy, his internet cable provider and on his own trying to figure why over the last month his internet kept dropping out and having “short term outages”. I tried to explaining the issues of the microwaves and phones and their connections and being a part time teacher to computer newbies, I feel that I can do a pretty good job of explaining such things.

Well Mr. Employed just didn’t get it. I tried a few tricks such as permanently setting the channels on the access point but cordless phones float between channels. After an hour Mr. Employed refused to pay me because I did not “fix” the problem. Gritting my teeth I stated again that the only way to solve this issue was to buy either new networking equipment that operated in the 5GHz band and replace his new phone that operated n the 5Ghz band with one that operated in the 2.4GHz or 900MHz spectrum or to change all phones to 900MHz or 5GHz and remove the microwave from the game room and then “hope” the kitchen microwave wouldn’t interfere with the upstairs computers internet connection. I also reminded him of another option that was to simply run a wired cable from the access point up the stairs to the room. This could be run hidden through the walls and ceiling.

I have not heard back from Mr. Employed and I am quite sure that he is still fighting his network or has thrown it all in the face of the people he bought the equipment from. The moral of our lessons, there is more to technology than meets the eye. If you have or want a wireless network, a little planning and information seeking will go a long way.

Well thats all for now, stay tuned to this same bat channel and this same bat time when next week we will see how well the Astros are doing at bat.

Well, maybe not but I hope you have a virus free week.

Tags: Hardware · Networking · Wireless

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