Wireless G db antenna question?

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houstonjln

Hi, If I had a wireless g router with a standard 2db antenna , with a laptop with a wireless g adapter, how far away could I go (in feet) staying in the line of sight of the router?

what about a 7db, 14db & 15db antennas?

Please advise, and a have a merry Christmas

Answer
Imagine a light bulb. It radiates light evenly in all directions. That's an isotropic radiator. Antennas are passive devices. They don't amplify the signal. What they do is concentrate the signal power in a smaller volume. Imagine I put a mirror on one side of the light bulb. Now, one side of the mirror is dark and the other side is twice as light. We can say that the mirror is a 3 dBi antenna. 10^(3/10) = 2 Twice as much light on the lit side.

How far your antenna will reach depends on several factors. These include your input power, the cable loss between the source and your antenna, interference in the channel - meaning radio frequency (RF) noise in the atmosphere between your transmitting and receiving antennas, free space loss - which increases by the square of the distance between the transmit antenna and the receive antenna, signal to noise ratio of your source, receiver sensitivity, receive antenna gain, noise temperature of your receive system, and data rate [1]. 802.11g suffers from interference because it operates in the already crowded 2.4 GHz range. Other devices operating in this range include: microwave ovens, Bluetooth devices, baby monitors and (in the USA) digital cordless telephones [2].

For 802.11g, nominal bit speed is 54 Mb/s, but in low signal or noisy environments the transmission speed is slowed to allow more power per bit. For successful reception, the signal power per bit has to exceed the noise power per bit. By slowing the transmission speed, each bit is transmitted longer - giving more signal power per bit. 802.11g specifies DSSS-OFDM modes with payload data rates of 6, 9, 12, 18, 24, 36, 48, and 54 Mb/s as the signal to noise ratio decreases [3]. So, how far your antenna reaches is partly dependent on what data rate you're willing to accept.

Free space loss varies by the square of the range. See equation 5.13 in [1]. Expected range for 802.11g is 38 meters (124') indoors and up to 140 meters (459') outdoors in good RF conditions [4].

A 7 dBi antenna will give 5 dBi more than the standard 2 dBi. The math for the range is sqrt(10^(5/10)) = 1.8. The 7 dBi antenna will give you approximately 1.8 times the range of the 2 dBi.

Likewise for 14 dBi, sqrt(10^(12/10)) = 4. Approximately four times the range.

For 15 dBi, sqrt(10^(13/10)) = 4.5. Approximately four and one-half times the range.

There is a handy Radio Link Budget Calculator available online at [5]. Example numbers for the setup with the wireless router and laptop, use:

Frequency GHz: 2.4
Tx antenna diameter: .06
Tx antenna efficiency: .65 (the default)
Tx power at feed (W): .3
Range (km): .140
Bandwidth: 22000000 (the default)
Rx antenna diameter: .01
Rx antenna efficiency: 0.65 (the default)
Rx system noise temp (degrees K): 440 (the default)
Receiver sensitivity -80 (this is a pretty good wireless card)
You'll get -69 dBm at the receiver - about correct for most wireless cards.

These estimates are consistent with my experience. FWIW, I attached the antenna in [6] to my laptop via a short pigtail. Using this setup, I am able to pick up 802.11b/g access points up to about 1/2 mile away.

Also, you might consider switching to 802.11n. 802.11n uses multi-input, multi-output (MIMO) technology. Basically it shifts phase of several small antennas to digitally "steer" the waveform to improve transmission and receive range [7].

If this doesn't help, e-mail me and I can point you to more info on computing link budgets [8][9].

Do any Christians see visions in relation to the past present or future?

Ten

I will make this long situation as short as possible and easy to understand, I am a baby Christian and it is very hard to find information about these kinds of subjects, so I thought I would ask. My experience is that the closer I get to God and the more times that I am able to push through a temptation, (like cheating on my husband), the more God lets me see and feel. I am not questioning faith; I am just interested in some guidance from someone on the same level as me. I am a little confused as far as someone who has psychic abilities and a gift from God?
Getting right to it, when I am relaxed, my hands will tingle, my body feels very heavy, the feeling I get is in between kind of nervousness and relaxation, in more words I could safely call myself at a standstill and scared to know what I am about to see, but too interested to stop the vision.
I have three types of visions.

1. I see white silhouette on the back of my eyelids, and I am not asleep, I just have my eye closed, I see a lot of angels and sometimes other visions. Example, one time I was told that my son was very sick and I needed to come get him, but in my vision I seen a flash of my son, who looked healthy and was laughing, I got feelings that I was being lied to and it was true, my husband just wanted me home due to separation.


2. The second vision is almost like a cloud that opens and closed in a flash, it is a tunnel centered and does not take up a lot of space when my eyes are closed, these visions look more like dreams in the sense of animation, but I am not asleep. Example, I seen an upside down embryoâ¦.. and that was it, but a few weeks later in June of 09 I seen a prenatal monitor and these pink sheets that document the contractions, they were going by my vision a million miles a hour, and my eye lids were flickering, like when someone else is trying to put on your mascara. Then when it stopped I got up, I felt scared because this was a very powerful, dramatic and emotional filled vision.
I never told anyone, but a week or so after that vision, my sister in law was 8 months pregnant and the baby was born and passed away.


3. The third visions are kind of large and up close, also in the formation of a dream, they are very open without constrictions like my number two visions. They can go from one end of space to the next kind of like the space of a long flat screen TV. I can have them with my eyes open or closed, but when my eyes are open and God puts something in my spirit, I will look up and away, I noticed, I usually look in a corner of the roof where there is not a lot of eye stimulation. They range from when a person lies to me, to full visions like the following. Example, I was at a salon and the woman I was talking to was telling me that she was getting a divorce and how she moved on, well God had showed me that her husband loved God and was contemplating suicide because he struggled with homosexuality, I seen him as a little boy in a bathroom, with a man who was molesting him, it was so strong that this man did not want to be this way, he just needed help. I got the indication that is was ok to tell her in a gentle way, and she did confirm that she thought he might be âgayâ, and she said that he had expressed suicide and that he was molested as a child, by a man. I told her not to leave him because he might really hurt himself, and that he needed her more now than ever. I told her to tell him that sex is connected to the brain; we just know it feels good regardless of who it comes from or what it comes from, especially as children because our brains are programming themselves at that age. Some of the things I am able to tell people are unexplainable, I just say them. Anyway God is so good, because her boyfriend broke up with her and now she and the hubby are going to counseling.
God bless you all and please be gentle with the comments, I just need honesty and wisdom, I would really like to hear other peoples experienceâ¦thank you!

Answer
I read your experience with great interest. There are many Christians who have visions and dreams, and wonder if it is coming from God or somewhere else. Some say visions from God are good, while ESP is not. But I believe a lot of this is just old verbiage that needs to undergo a paradigm shift. For one thing, I believe satan is defeated, as the Bible tells us that Jesus was to "shortly" crush him under His feet almost 2000 years ago. When people give satan more power than he deserves, there is confusion and fear. The only visions or prophetic dreams I ever get are from God, or my overactive mind. satan has no power over me in this regard.

I think God speaks to us all in the unique ways that we are designed to take in information. Some are too 'logical' to consider a vision or interpret a dream, and others find it fascinating. My guess is that you live more in the "right" side of your brain, which dominates feelings, emotions and intuition.

So the wisdom I could give you would be this: Thank God for all the gifts He's bestowed on you. When you pray, offer these gifts to Him for His glory and the edification of others. Read, praise, worship and meditate on His word. I think you already know all this, but maybe just need the reassurance that others have the same experiences. I have had recurring dreams that were sent to me as a warning (that I only saw after it was too late, but at least it woke me up to pay more attention.) I've also had feelings in my hands like warmth, tingling and swirling, especially when I go to pray for someone, or hear that someone is ill. The most interesting 'supernatural' occurrence I ever had was regarding my young children, who approached me each at separate times over a week, pointing to a verse in the Bible that "Jesus wanted me to read." I think this attests to Jesus' saying that the Kingdom of heaven belongs to 'such as these,' and the need to remain childlike and trusting in order to receive from Him. God bless you on your journey, sister, and may those who you come in contact with - be blessed from His presence in you!

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Best way to track my fitness with iPhone apps?

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philscalis

I have a degree in exercise science and am going to school for physical therapy now and really want to track my fitness now that I have an iPhone and I know the importance of health. However, after researching apps I'm not sure the best app or app combination to use. I want to get a heart rate monitor (wahoo or polar?) and many of the apps will sync with it. I want to track calories, GPS run mapping capabilities, nutritious intake, and I want to track my strength training regimen (sets, reps, etc). The my fitness pal app seems to do some of these things and you can also tie in other apps or sync them with it. However there are so many other ones and I want to know the best way to do this if anyone can help. So far I have downloaded: my fitness pal, endomondo, fitocracy, sportstracker, runkeeper, real intelligence fitness app, and digifit icardio. If someone can help me out it would be much appreciated. I would try them out but don't want to give my info and make an account for all of these apps if they aren't what I want.

Answer
I track some of the same stuff you do, but not everything and I've tried some of the products you have, but not all. However, here's my take:

1. I use Runkeeper as my basic app. I'm primarily a runner and so are most of my friends. It links easily to facebook if you are interested in that. For me, this is how I communicate with my running community. It has some other basic cardio functions in it as well (elliptical, etc)
2. Runkeeper has a GPS function to be used with the iphone, it's generally accurate within 0.1-0.3 mile. However, when I want to be really accurate, I still default to my garmin which I can still link to my Runkeeper account. (ie, when I'm racing or want to track elevation)
3. Realize also that when you use GPS function on your phone, it will wear down the battery very quickly. I'll use the Runkeeper GPS function if I'm running or cycling an hour or less, but it's not ideal for long distances.
4. Runkeeper and probably most fitness apps will link to a heart rate monitor. However, I'd first ask why you intend to use one? As a PT, myself, I've come to the realization that unless you have a medical condition that warrants it, tracking heart rate is overly burdensome for little pay off. Just used your rate of Rate of Perceived Exertion. Whether you are doing intervals or tempo workouts, it's your exertional effort that's the real issue. Most of the established "guidelines" for heart rate during exercise were established for patients recovering from cardiac events, not necessarily for healthy adult fitness. So, unless you want to get into research about cardiac effort, I'd say don't bother. I suppose you can use it if you want to get a MORE accurate idea of your caloric burn, but I have better options for that (more later). I DIDN"T use one for years, mostly because I take a beta blocker which throws the whole target heart rate out the window anyway. I'm using one now (more on that in a minute) only because I'm pregnant and NEED to make sure my heart rate doesn't go over a certain amount (and I have arguements about that anyway). I use the iphone app with it, but haven't linked it to my RK. It does record it on the wahoo site, but I never go back and look at it. The wahoo site also does GPS and if you get the hardware, you can link it with your bike or a foot pod.
5. If you do want to use a HR monitor, I use the wahoo. My husband and I both have Garmin 910XT's and even though he got the heart rate monitor for it, he's happier with the wahoo. Again, he's not even using it anymore and I am. However, I don't even bother logging my heart rate...I use it only as a warning system. I do think I can link it with RK, but haven't bothered. Once I have the baby, I'll stop using it. Not sure why hubby doesn't like the garmin monitor...I just took his word for it.
6. Now, onto strength. RK doesn't really have a place to log this. I used MapMyRun for awhile which at least gave me an idea of how long I was weight lifting and an approximation of calories. In my opinion, if you are looking for an app that does everything, I'd say be prepared for a really complicated app. I found that the more features it has, the less user friendly it becomes. This is how I felt about MMR. For strength training, I'd consider a separate app. Same thing goes for nutrition. There are probably apps out there designed just for that which are much more user friendly.
7. Back to calorie counting. All the apps give you a basic ESTIMATION of your calories burned based on your weight and work out parameters. Even if you are using a heart rate monitor, again, this is only an ESTIMATE. Unless you are in a lab, all these tools provide estimates only. However, if you really want to know what your body is using and burning, I'd recommend the Body Media System. It's about as accurate as you can get with calorie count without having to be in a lab. The web app also has a nutritional log.


So here's my take in a nutshell:
1. Use a basic app for your cardio. Runkeeper is my personal favorite. Only use the GPS for shorter workouts
2. Use a separate GPS (I've only used garmins) if you want to be really accurate with your distance or if you are doing a long work out and simply sync it to your cardio app (like RK) from the garmin site.
3. Don't bother with a HR monitor unless you have a medical reason to do so
4. Use a separate app for your weight lifting and nutrition.
5. Consider a body media system if you REALLY want an accurate calorie count. It's expensive new, but I got a Core basic system used on ebay for $32. (myself, I'm content using the basic estimates from my cardio app).

Maybe there's an app that does everything, but I find that it gets too complicated....I don't want to spend 30 minutes logging my info.

What is "NT Kernal & System" in my resource monitor?

perryinjax

Windows 7 resource monitor shows something running called this.. it is not using much resource or cpu and everything seems to be fine. I am just curious as to what it does and what is it for?

Answer
In 'baby talk'... it handles all of the communications between the software and hardware in your system.
You'll find it runs high at startup and should reduce once everything is 'talking' to each other.

If you find it's using a lot of resources all the time, you may have a problem. Other than that, it's vital to your system âº

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