Is Wireless Safe?

It's a big question really, isn't it? Is your wireless device going to cause cancer or other health problems? I cannot answer this with certainty, but I can tell you that the best scientific evidence says no. To me, simple logic also strongly suggests no. Most people fear the idea of radiation. Myself included. However, radiation is not one thing.

First, wireless communications (and your microwave oven!) do not use the same type of radiation that is known to be harmful. All emitted energy is radiation, that's why we have radiators for heaters - they emit heat radiation. Only the most energetic electromagnetic radiation - ultraviolet and above - is known to cause cancer. This is known as ionizing radiation, because it has the ability to create ions. Radiation with less energy - visible light, heat/infrared, your microwave oven, your cell phone, and your walkie-talkies - is known as non-ionizing radiation. As far as we know, it does not have any affect on the human body except producing heat. Exposure guidelines are based on heating effects with an enormous margin of safety. Ten times the exposure would likely be perfectly safe.

Second, people worry about things based on their assumptions. Not on reality. To many people a list of power levels would probably look something like:

1. Cell phones
2. Walkie-talkies
3. Wi-Fi
4. Cordless phones

The real order is more likely to be:

1. Walkie-talkies
2. Wi-Fi
3. Cordless phones
4. Cell phones

Yes! It's true! Say what? Cell phones go the furthest - don't they? Yes, they do but not because the signal is stronger. Cell phones go the distance by using extremely efficient coding that allows the signal to be usable at very low received power levels (as low as -113dBm for UMTS) and by having tall towers that help to assure a clear path. Wi-Fi requires a theoretical received signal level of -96dBm - over 50 times stronger than your cell phone requires! Additionally, Wi-Fi in the real world can barely function at that low of a power level, if at all, due to noise in the 2.4 GHz band used and very low speeds possible. Due to this, most of the time, your Wi-Fi devices are transmitting full power or close to it. On the other hand, a UMTS phone will rarely be transmitting at anything close to it's full rated power, usually at a small fraction of it - unless you happen to be a very long distance from a cell site in a poor coverage area. Yes, the NIMBY's blocking of cell towers increases your phone's power output! Cordless phones and walkie talkies both broadcast full power constantly. Walkie-talkies are often 1 watt or more! That's five times the maximum output for a UMTS cell phone. Cordless phones are fairly low, 1/4 of a cell phone's peak output generally - but they're always there, and your cell phone will rarely reach those power levels - only in poor coverage.

So, does this simply mean these people are correct? No way. Even Wi-Fi is running at power levels absolutely minuscule. Logic says if people survived analog cell phones, CB radios, etc for so many years, there is no way modern cell phones, Wi-Fi, etc are going to prove harmful. Maybe they will, but the best studies say no, and logic says no. If they do prove harmful, the risk will be absolutely tiny - since any substantial risk would be well demonstrated by now. We take tiny health risks for convenience all the time. Look at the pollution we tolerate from our vehicles and factories - it's many times more likely to cause us health problems than any wireless technology ever could, even if there did turn out to be a health risk to wireless (which seems very unlikely).

Finally, what about the "just in case" - even I will admit you can't prove a negative? All you can do are bigger, longer studies that continue to demonstrate no risk. We've established that any risk must be infinitesimally small, and that there is no known mechanism for any risk. But we haven't established no risk. But why not buy some protection devices "just in case" "for the children"? Because the people selling these things are con artists. Devices intended to block or re-direct signal are mostly ineffective, and if effective, will only cause your cell phone to ramp up power output - shortening battery life and possibly increasing exposure in areas not blocked by the case/device. But of course, that's if they worked, which the vast majority do not at all. Even worse are devices intended to "neutralize" or "make harmless" radiation. I won't call out a brand name here, but I sure have one in my mind - though I've seen several similar products. These chips of plastic and metal designed to be worn as a bracelet, necklace, or stuck to your phone are claimed to neutralize the radiation and render it harmless. LOL. If I need to explain to you why this is a bad joke, you may as well buy one. It's a really expensive and ugly piece of toy jewelry, that's all. Use your brain for 30 seconds and think, there is no way a small necklace made of plastic or metal will have any effect on radio waves from your cell phone into your brain. The people who sell these devices are often 100% convinced they work, that's one way this scam continues. There's no point in arguing with a person selling them, I tried once. Science, reason, and logic mean nothing to them, and they are completely convinced by their company's pseudo-science and brainwashing.

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Update On Content Filtering

Shalla Secure Services has yet to respond to my email (which also asked for pricing for commercial use), but they did remove the 11 items I submitted to be removed from their porn category (10 LGBT advocacy sites and one dance site) indicating that most likely, a rogue submitter and not Shalla Secure Services added these sites to their porn category and they slipped through a hasty review. This, of course, is pure speculation. I'm hoping they'll return my request for comment. Regardless, the point stands - government mandated content filtering would be prone to these same issues - perhaps even more so since it would be so widely used, many may try to get sites added to the blacklist to promote their agenda.

Thoughts On Content Filtering

I've been working on setting up content filtering of HTTP (web, non-secure) traffic for a client of mine. Today, I was reading the peacefire.org site. This is an anti-filtering site that makes some good points. I'm not a huge fan of the teenage/young adult "us vs. them" mentality. I believe we're all in this life together, and have to work together. I also am on both sides of this fence. I want to make my clients happy who want filtering - and I believe there are some sites, such as the one I'm working at now, where content filtering makes good sense. I am not writing this to argue the merits of content filtering. I can see both sides, and compromises can be made. I'm strongly opposed to content filtering in public libraries however, as they are meant to be public forums devoted to free speech.

Why is that an issue if only porn sites are being blocked? Few would call pornographic material academic speech. It's simple, classification is key. In order to block anything, you must know what it is. Blocks are made using classification services. I've been testing Shalla Secure Services' classification list, a company based out of Germany. All lists are similar, however. I was pretty happy with it - some errors here and there, but nothing that screamed of systematic failure to maintain neutrality. Remember, a list is only a classification, not a block. The user decides what to block, or even what to whitelist (allow only sites in a certain category). The end user determines what categories get blocked (most commonly categories such as pornography and hate sites). I'd like everyone here to go view a couple of these sites currently being classified as porn in Shalla's blacklist:

http://flgc.quaker.org/
http://danceheritage.org/
http://lgbthistorynw.org/
http://glbtadoption.com/
http://www.glbtq.com/
http://lesbiannews.com/

I'm failing to see the porn in these sites. I really don't think the Quakers have much. However, five of these six sites (which are just a sampling) are lesbian/gay/bisexual/transgender rights advocacy sites. I'm not writing this article to get into the morality of gay rights. Heck, I'm not even writing this to argue whether they should or shouldn't be blocked. I'm writing this to demonstrate that they're getting classified very incorrectly by a well-known blacklist provider.

As a private system administrator, one can easily make their own decision about what they'll provide access to for their clients. That's fine. They can whitelist and blacklist things if their classification list provider does a terrible job. Something went wrong here, and either Shalla considers LGBT advocacy a form of porn, or someone compromised their list. This is too many sites, that are too innocent, and too well-known for me to believe this is any form of accident. Shalla is based on public submissions. Perhaps someone with an agenda slipped these in with a larger submission of porn sites that then got accepted in bulk. Who knows? I'm not saying Shalla Secure Services is a bad list provider, not at all. Unless these sites were intentionally added to porn by them, I'm willing to believe a public submission slipped them in to further their agenda.

But that's the point. When it's up to the user, they can control their filtering solutions. In the UK, there is a proposal to require ISPs to block pornography by default. In the Netherlands, ISPs are required to block certain pirate sites. In Australia, Senator Stephen Conroy has long been pushing his far more restrictive view of the Internet where all Internet connections are subject to a blocklist of content he finds objectionable. This is China-style. And, lest you think the US is exempt, we might be the worst of them all. Do you remember SOPA/PIPA? We also require schools and libraries to filter content if they wish to receive discounted Internet service.

Even if you take something essentially everyone in civilized society wants to see blocked, and there is much objectionable content in the world almost every agrees should be blocked, who all can sneak content into the blacklist to further their political goals? Shalla isn't the only blacklist provider who's got GLBT-advocacy sites in their blacklist. Amtrak's even done it. It's called an accident, but these are most probably no accident. They may not be authorized by the provider, but I believe it is almost impossible that someone submitting these sites was not fully aware they were not pornographic, but instead submitted them to further an agenda.

I emailed Shalla Secure Services about their blacklists, and included friendly mention of these errata in their lists. I will be most curious their reply. I also submitted 11 sites that I found incorrectly classified to be removed, it will be most interesting to find if they do so.

Let's keep filtering where it belongs - in the user's control to determine what the user wants to view and what they want to provide the customers. No matter how well-intentioned, any filter is open to abuse to further an agenda as I believe I have demonstrated. It's much better to not even have the infrastructure in place.

New ATSC/digital antenna muxes in Kalispell

A surprisingly large number of people find my site by looking for digital TV muxes available in Kalispell, MT. After TBN went off-air last year, I contacted the new owner to find her plans for the station, she never responded to my inquiry. It came back on later as TBN (analog) again, and now there is a four channel digital multiplex on that station. Additionally, KSPS PBS Spokane went digital. One 480i channel, no HD, no additional channels. It was cropped to 4:3 but I contacted KSPS asking if they'd go HD. They told me that at some point in the future, hopefully sometime summer 2012. I suggested widescreen SD as an interim solution. Presently, the signal is letterbox widescreen (that I'm watching now as I channel flip, I'm not sure if all content is, I rarely watch PBS). Additionally, some translators have gone digital. Please realize that in an ATSC world, the channel numbers I see do NOT reflect real channel numbers. Unfortunately, my TV is unable to show the real channel numbers, but here's what my TV has available with an indoor directional antenna (Silver Sensor) in the Evergreen area. The picture mode is what I'm currently receiving, not necessarily what they're broadcasting in at prime time:

2.1 KREM - CBS - 480i *EXTREMELY WEAK/NOT WATCHABLE*
4.1 KXLY - ABC - 480i
7.1 KSPS - PBS - 480i
9.1 KCFW-HD - NBC - 1080i
9.2 MeTV - Me TV - 480i
9.3 ThisTV - This TV - 480i
18.1 KAJ-HD - CBS - 1080i
18.2 KAJ-CW - CW - 480i
23.1 KTMF-AB - ABC - 720p
23.2 KTMF-FO - FOX - 720p
26.5 - TBN - 480i
26.6 - The Church Channel - 480i
26.7 - JCTV - 480i
26.8 - Smile Of A Child - 480i
28.1 KAYU - FOX - 480i *EXTREMELY WEAK/NOT WATCHABLE*
29.7 KSPS - PBS - 480i
42.1 KTMFLAB - ABC - 720p
42.2 KTMFLFO - FOX - 720p

With a good outdoor antenna, it is reasonable to expect all of these signals would be available at my home, but there's no reason because the two that aren't watchable are the Spokane SD CBS and FOX. I get the Missoula/Kalispell HD versions of these channels, so unless I really needed another time zone, they're of zero interest. Remember that with digital, there is no better picture to be had from a better signal, as long as it decodes cleanly and is watchable, it's as good as it gets. No analog signals were found, indicating analog broadcasting has completely ceased in Kalispell, MT.

At the end of the day, the broadcast TV *networks* available here are: ABC, FOX, CW, NBC, CBS,  PBS, JCTV, MeTV, ThisTV, TBN, The Church Channel, and Smile of a Child. This is a huge step up from the days of analog when even FOX was not available in Kalispell. All the major networks, plus a handful of TBN channels and some random stuff, are now available.

For every complaint I've heard about the switch to digital broadcasting, which was somewhat delayed in Kalispell since we're a mostly low-power market, I've heard many people impressed by the increased channel selection and picture quality. That's still not you? Contact me - mark@markuhde.com - for a free consultation and we'll see if we can get things fixed for you at your location.

More thoughts on the ENH series.

I thought I'd post a couple more pictures and thoughts on the EnGenius ENH series. These devices work very well, providing several hundred meters or more of coverage (depending on terrain). Here's some pictures to show them off. These are both ENH200's but as I suggested before, if you're buying today, I recommend either the ENH202 (2.4GHz) or the ENH500 (5GHz). For only a few dollars more, the newer ENH202 gets you two-stream MIMO (double speeds with supported clients, and potentially longer range with supported clients). The ENH500 is also MIMO, but runs in the 5GHz band. Higher is not necessarily better in this case. The 5GHz band is relatively unused, and thus has more non-overlapping channels, and use of 40MHz channels is permitted and universally supported (in 2.4GHz it's discouraged and many devices don't support them). 40MHz channels with 2x2 MIMO are required to hit the "300mbps" speed claim of 802.11n (even then, that's the physical layer link rate, not the actual data speed). The ENH200 with a 20MHz channel will only see a real link speed of just 65mbps (single stream MIMO, extended guard interval for compatibility, 20MHz channel). The ENH202 can see 130mbps (two streams, extended guard interval, 20MHz channel), and with the ENH500, that's where you can actually see 300mbps. Sounds great, right? Wrong. The 5GHz band has significantly lower range (as you raise frequency, you decrease range), especially in non-line-of-sight environments (foilage, buildings etc). Additionally, many (possibly even the majority) of deployed Wi-Fi devices do *not* support the 5GHz band, and even within a single manufacturer support varies. For example, the iPhone does not support 5GHz, but the iPad does. Most laptops do not, but more expensive ones - and Macs - usually do. In summary, the ENH202 makes a great outdoor access point and a pair of ENH500's create the fastest possible bridge between two line of sight locations (building to building). Again, all products in this line are a complete pole-mount kit that include the power injector. Just supply a pole mount, cabling, and a network to connect it to.

EnGenius ENH200

So, I promised more reviews and information on here for dealing with your Wi-Fi woes. Here's one product that I use in my installations that may interest you. It's the Engenius ENH200 Business Class Long Range Wireless N Outdoor Client Bridge/Access Point. This product is an all-in-one outdoor Wi-Fi radio and antenna designed for maximum coverage. The built-in 10dBi gain sector antenna provides excellent long-range outdoor coverage, and the WDS modes allow even longer range bridges between two of these units to be made. The newer ENH202 costs only slightly more, and provides you with dual-stream 802.11n (double the maximum theoretical data rate). I have yet to install the ENH202, but assuming performance is otherwise equal to the ENH200 (and I have no reason to believe it won't be), it would be almost silly not to spend a few dollars extra for the MIMO 2x2 spatial stream support.

What's really nice is this unit includes everything you need except the cable (and the network you're adding it to). The Power over Ethernet injector is in the box, and all you need is to provide a pole to mount it on (same size as a satellite dish) and an Ethernet cable from your switch to the access point (shielded strongly recommended for ESD protection, make sure to ground the injector for the shield to be useful though). It supports 4 SSIDs, with VLAN tagging to isolate them, and many enterprise-class functions. EnGenius's free EZ Controller (EnGenius Zone Controller) allows simplified management from a Windows desktop. All in all, a very nice product.

In my "real-world" experience, I can easily count on range with good signal strength and performance to any client of at least 100 meters even through thick trees, assuming the AP is mounted several meters off the ground. 100 meters would also be a reasonable limit for covering a detached warehouse-style building, etc. For in-building coverage a field test is essential as every building is constructed differently, but I have managed to cover large empty buildings by using an ENH200 over 50 meters from the building (100 meters total to the back of the building, and I still had good - though not excellent - performance). Outdoors, with line of sight and a clear path (adequate height to maintain a clear fresnel zone), 500+ meters is easily accomplished. The largest limiting factor is the height the antenna needs to be at, the furthest I've reached is 500 meters and still been able to barely hang on with my iPhone, but the unit was only mounted approximately 2 meters off the ground - the "fresnel zone" (outside the scope of this blog post, but a complicating factor for any long range radio and one of the reasons radio towers are so tall) was not clear at that distance, despite having visual line of sight. I haven't tested the limits of what range can be accomplished with these but mounted on tall buildings or towers, 1km to mobile stations - and much further for bridges between two of these units - would be an easy goal. For most outdoor Wi-Fi applications, 200 meters of open area or 100 meters in the trees is still excellent coverage, and more likely to be what you're planning.

Coverage pattern and waterproofing depends on these units being mounted right-side up, at an adequate height, with drip loops in the cabling to prevent water entry. They are directional sectors covering "slice of pie" shape with the best signal being directly in front of the unit. Pay very careful attention to channel planning with these units, and if being used solely as a bridge - and the terrain makes it possible - consider using the 5GHz ENH500 units. These are the 5GHz band version of the ENH202 and have the benefit of far less traffic in that band, but the disadvantage of reduced coverage combined with many client devices being unable to use the 5GHz band. They're excellent for bridges though, or in open-air outdoor situations where all attached devices can use the 5GHz band (which is hit-or-miss. iPads can use it, iPhones cannot for example). 5GHz does not have the in-building or foliage penetration that 2.4GHz has, so choose carefully and base on link budget calculations and a site survey if in doubt.

For professional network design services in Montana, please feel free to email me at mark@markuhde.com for a complimentary initial consultation. Have a great day!