I’m an engineer. When I work I use my dozen years of engineering education and  dozen or so years of engineering experience and creativity to assess a problem, develop strategies for a solution, and then implement that solution.

In assessing a problem, I look at the physical symptoms of a problem, I collect tangible data about whatever I am studying, I push systems to they boundary conditions and examine performance.

When determining one more more possible solutions for a problem I look at what other people have done and specifically what their results were. I may try a few things to see if parts of one solution or another might work.

When I implement a solution I check to see if it worked under normal conditions, I check to see if operating conditions change that my solution is superior to the original implementation, or at least the same.

Then I learn from my mistakes. If I designed something poorly the first time, I want to be sure I understood why it was poor so that I can avoid doing it again.

All of these efforts require strong attention to physical, measurable results. It all requires that I don’t pretend something will just work because I want it to. It requires that I check to see if my assumptions are correct.

Why am I telling you this? Because I am continually amazed when I hear about superstitious engineers, particularly religious ones, and of those, particularly young earth, bible thumping ones.

The other day, I was looking for a simple relay board that would switch 1 amp load when signaled from my tiny digital signals from my microcontroller. Pretty straight forward. I had a bunch of other requirements also. Well I found what I was looking for from Winford Engineering. They make a bunch of boards that are good for prototyping designs, so I got a few of their relay boards.

They work fine.

But I got a little present with my boards.  A little pamphlet, entitled “Facts to Face”. Hmm. I wonder what facts are so important that they would send it along with my order? What am I missing or so unknowledgeable about that someone at Winford felt that they must pass along this vital information. Global Warming? Crime Prevention? Suicide?

Well apparently the first fact is that I need to be saved.  This fact is quoted from some where called Romans. These guys, without knowing one thing about me presume I have sinned by some standard known only to them. Apparently I’m gonna die from this sin disease. Why can’t they just write in readable English?

The second fact is that I can’t save myself! What? I can help myself, and when I can’t I have friends and profressionsals that can… but not from this mysterious sin that they tell me about. Oh Noes!

God’s Son died to save me? Wait, I thought he was resurrected. So he didn’t really die did he? So this dude has been alive floating around for two thousand years and I am supposed to feel bad that he spent a few days strung up. Hey, tell you what, show me modern evidence that I can live forever and I will also happily be strung up to a cross for 3 measly days. Not really much of a sacrifice is it?

The next fact is that God apparently shows me how to be saved. Looks like if I want eternal life, then all I have to do is…you know.. be gods son. I mean really, has anyone actually visited this heaven place? How do we know there isn’t just one person there. Someone send me a photo!

The next fact that I need to hear about is that if I believe in god, he will forgive my nonexistent sins. Whew! that is good to know! But look at that! I can do all things through Christ! That's weird, I don;t even know what that means. Can I do some things through horse? Seems to me that I can do all things through work and learning.

Fact #6 tells me that Christian should be working for God. I would like to know how much God pays per hour. I mean with no actual guarantee that he is there, seems to me that I’d like something tangible now. Good thing I am not a Christian, I guess I am free form this work paid by IOUs.

I got a giggle that they sent this to me. I was at a loss to understand why they would send this out. So I asked.

Is it a company policy to send along religious paraphernalia with
shipments or is someone in your shipping department doing this for you?

I got a response pretty quickly

Yes, this is our company policy. The three owners of the company
(myself being one) all believe the Bible is true, and God's Word, and we
hope our customers will take a minute to evaluate the claims of the
Bible. So, it is our policy to include this in the first order we send
to each of our customers.

I will never order from them again.

Its not that they are religious. I don’t care what they do on their own time. Who am I to comment on their shared delusion? No, I won’t order from them for two reasons: I find it insulting for them to tell me, by way of a dumb pamphlet, that they think I am one way or another without knowing me. The presumption!  But more importantly, I won’t order from them because they have clearly demonstrated that they are willing to make extremely important decisions about themselves, about their lives and about other people based on nothing other than some dumb book and the cultish blathering of those who follow it. If I need to return something will they tell me that God told them not to take it? If I need them to fix something will they pray for it to get better?

I don’t really care that they sent this pamphlet. I just think its a dumb business practice. It won’t convert anyone, and people who already believe that nonsense already have a bible. They are just wasting money, and doing nothing. Its not like relay boards are that hard to find (or make).

While I have for the most part sworn off reading Discovery News because of its tendency, like New Scientist, to hype and misreport, I did see this.

A new Pew Research Center poll indicates that 27 percent of Americans say the nation's greatest achievements are in science, medicine and technology, more than any category other than don't know.

But that's down from 47 percent in a similar study a decade ago, the center reported Thursday.

How depressing. The Europeans publish more science than we do, and continue to excel in a number of areas over the US (except military size which is what we have excelled in for decades).

But you know what? Considering that

87 percent of AAAS scientists believed that humans and other living things evolved naturally, compared with 32 percent of the general public

I’ll take this as a win:

And 69 percent of Americans say all parents should be required to vaccinate their children, compared with 82 percent of scientists.

Note, that says required. That is different than what we have now, where parents are just encouraged.

Today at work I was looking for electrochemical methods to move specific ions. Turns out that there are both electrochemical methods to do it and electrodialysis methods (I'd call electrodialisys a subset of electrochemistry). But this is not a post on that.

This is a post on an amazing product called the Hardness Master. Look at the amazing things this thing can do!

▪ Provides an effective and healthy alternative to Water Softeners and De-scalers
▪ Utilizes latest MaxConditioning™ technology to effectively address a broader range of scale and hard water problems
▪ Handles up to 50 grains per gallon (or 50 gpg or 855 mg/L or 855 ppm) of water hardness
Note: The Total # of grains per gallon (gpg) is equal to the Total # of mg/L value ÷ 17.1 (i.e., Total gpg = Total mg/L ÷ 17.1)
▪ Easy to install (do-it-yourself installation requires no plumber and no cutting of pipes)
▪ Accommodates up to 1 1/2" plumbing, or even greater (call for details)
▪ NO salt or chemicals needed (healthier & wiser choice)
▪ "Green" and eco-friendly technology
▪ No Maintenance (just "set it and forget it" operation)
▪ Extends the life of your water heater and plumbing fixtures
▪ Works with Copper, PVC and Steel pipes
▪ Soap and shampoo lather much better
▪ Changes the Hard Water Molecules to Soft Crystals
▪ Treated Water Feels Silky Smooth
▪ Prevents new Scale forming
▪ Removes old Scale layers

It's that MaxConditioning Technology that I am admiring so much! Really, who knew that running current in a coil could provide me with such an amazing list of properties as mentioned above! I mean really it changes Hard Water Molecules to Soft Crystals! Is that a molecule of hard water, or a water molecule that is hard? Calcium carbonate is a rock, a crystal of it is soft? Oh look! Customer testimonials!

Clearly this product has all the markings of being woo. But is it?

OK, lets discuss the core technology here. There are so many things wrong with the description it is hard to know where to start. So, I'll go in bits and pieces and I hope you'll bear with me. Lets start with the field it creates . Electric fields and magnetic fields are in fact related but to simplify, an electric field is defined by the voltage potential between two objects (think Van Der Graf generator, or lightning) while an magnetic field is defined by the current traveling through a conductor (think electromagnet). MaxConditioning Technology is the latter, current runs through a wire, it is not an "electric field" as claimed. So which is it? Does an electric field make this process work? That would mean that this device doesn't do what it says because it created a magnetic field, not an electric one. So what about this magnetic field?

The HardnessMaster™ advanced MaxConditioning™ technology produces an oscillating electric field in the water pipe (refer to pictures above and below) which changes continuously in frequency and amplitude. This changes the property of the hardness minerals so they stay in solution and not form scale in pipes, water heater, on fixtures and bath walls, etc.

What exactly is a "hardness mineral"? Shall we presume that they meant a magnetic field and that this performs the magic for them? OK, fine, but by what mechanism? Magnets mostly affect metals, in particular ferrous metals. If used in MRI strengths and frequencies, can be used to energize water. But there really isn't much of a case to be made that calcium carbonate is affects by magnets in any way. OK, so they oscillate the magnetic field at varying frequencies, but how does that change the solubility of the calcium?

Here is an article that studied the solubility of calcium carbonate in water in a magnetic field (a static, unchanging one). The result?

It was found that magnetic treatment increases the total amount of precipitate...

Uh, that's the opposite of what you want! They claimed the magnetic field decreased solubility, not precipitation! However, it appears that even with precipitation, there is a little more to the story. If you have precipitation of CaCO3 (calcium carbonate), you want it to come out in the water and not on the surfaces of things. So even with precipitation, if it only comes out in the flowing water, a case could be made that it is better than scaling up on and in small orifices.

I think we can say that this is probably the definitive summary report on using magnetic fields to clean up water. They looked at 108 articles on magnetic water treatment and took the 34 best, based on procedural quality, measurement quality, hypothesis testing and other merits. While this great summary mostly concerns itself with permanent magnets without changing fields, there is one paper in there by Fan and Cho that seems to be the one that this particular device is based off of. Its a 1997 paper called, "Microscopic Observation of Calcium Carbonate Particles:Validation of an electronic Anti-Fouling Technology". There were three other papers by this group in 1998 and 1999 all using the same "anti-fouling technology" with small, but measurable differences in scale buildup between the AFT use and nonuse.

However these results are not replicated by anyone, and the WQA discusses these papers in the following way:

The report doesn't set out to make any definitive statement statement that magnetic water treatments works (nor did the even define what "working" means). In fact, they summarize the findings of these 34 papers as follows:

One thing to note from the summary. None of the papers were able to verify any of the proposed hypotheses of why magnetic water treatment should work . Most of the papers didn't even show much, if any, improvement.

With no verified mechanism by which scaling would be prevented, sporadic and limited evidence that magnetic therapy has any effect at all on water quality, no reason that a magnetic field should have any effect on a non-ferrous particle, in particular calcium carbonate, and no verification that pulsing a magnetic field through which water with high calcium concentrations flow does anything, I think we can safely say that, until there is more evidence, this is not effective.

Forgetting for the moment that the core technology is unlikely to work, lets take a look at some of the other claims...

It will also gradually dissolve away any preexisting scale that may exist in your pipes and water appliances

Oh goody another claim for which a possible mechanism is completely absent. The coil only wraps around one little spot, why would scale that is located in the faucet get removed? I believe that the possibility they are going for is that if the calcium particles have agglomerated, then the water surrounding the crystals will have a low concentration of calcium in it, therefore the scale has a chance to dissolve in it. Or at least, thats how I would defend this claim if this were my product.

"Green" and eco-friendly technology

This would only be true if the device worked! Otherwise its a power consuming chink of plastic and metal.

The funniest part, with respect to the rest of the product description is the animation, which completely counters the claims made on the first page and all of the supporting data from journal papers as presented above. In that animation they do claim that the solubility rises. They show larger particles entering the coil area, and no particles leaving implying that they get dissolved. This is completely in opposition to the idea of "hard water molecules" being changed into "soft crystals". It also goes completely against the results from Cho in their anti-fouling papers.

So we have:

• Extraordinary claims that defy current understanding of a process
• User testimonials
• Flashy animations that describe processes that don't happen
• Appeals to being green, cheap, easy

I say don't buy this product. What do you say?

P.S. If anyone at Vitasalus (feel free to browse their selection of other woo-ish products), who makes this product, wants an independent test of it, I will happily do a professional job of it. But I am not going to spend 300 bucks just to find out that I was right on the off chance that I might be wrong.

As you may have seen, the next Skeptic’s circle has arrived at Homologous Legs. He gives us a nice journey through the wide and varied circle of skeptics who bring you great posts every couple of weeks!

As you will know by going there,  completely to my wife’s disdain and exasperation, I signed up for the next circle, #115. Her furious flustering is completely warranted, since she is so pregnant I have seen small objects orbit around her. Yes, we are about to have a baby, and of course the due date is within days of the next circle.

I really have been wanting to do this for a while and in my excitement I didn't attach the offered date to the birthday of my new son, because, as he will soon know, his dad is an absent minded dork.

I don’t want to limit the entries, I hate when people do that. I want everyone to have exposure of their best and brightest posts. But please take it easy on me, please just send me your single best post from the next two weeks. If you don’t have something “Circle Quality” please send nothing, we all have dry patches. At worst, flag it as “2nd tier” and I will look at it in a second round for entry (in case everyone gets scared off by my request here and sends nothing). I don’t want to discourage people from putting stuff in the circle, but I want to provide a quality one even with my scheduling conflicts. Please be my proof reader.

All entries can be sent to techskeptic@gmail.com

Do good work! Send em in!

-Tech

P.S. For fun, tell me what the name of the planet you would be from is (if you were not from this one), it doesn’t have to be real. Tell me what the name of your species would be if you were from that planet. Oh, and I’d really like to know what you would be doing in your life, as a member of that species on that planet. Or heck, keep this information to yourself, if you think its so secret.

P.S.S. Yeah, I’m a 41 year old little boy. :P

Well I’m going to give this a shot. I am very aware of my limitations. I wish I had time to  be expert on a great many things, but we must pick and choose. I have an idea that I think will enhance many skeptical debates, but I need help. If you answer yes to all of the following questions, maybe you can send me an email?

Can you program websites? I don't mean modify templates, I can do that. I mean could you, with time, create a website like reddit or recovery.org? Can you create code that would be generated for people to place on their websites that would direct people to particular links on this website? Similar to digg buttons.

Are you truly skeptical? Would you really change your mind about something given a standard of evidence that you use for other things you agree with? If it could be shown the gun ownership reduces crime without increasing accidental death, would you change your gun control stance? Is there ever enough evidence that could be assembled that would lead you to believe in a designer?

Do you have time to make a website? I have no idea how long this would take, there may be tools available around to make implementation faster. I’m not looking for a lot of graphics or flash. Just functionality. I don’t think its pure html, i suspect there is java involved. But I am not sure. These is not a static site and will require a database and account creation.

Would you want to work with an anonymous skeptic?

Well those are my big questions. I’m sure more may crop up.

I really think this idea could attract a lot of traffic and I really think it would help a lot in skeptical debates and getting information out there. I can’t offer money, who has any? I can offer some part of any sort of google ad revenue, but some of that money would have to go towards maintaining the site.

Any takers?

Hi all.

Just a quick note here. A blogger who I have been reading for a while is in need of some help. She recently had some gall bladder problems and she had it removed in the emergency room. She is in pain and needs a couple of bucks to get a bed. She recently moved and has been sleeping on the couch.

I "met" Amanda through her blog as she was writing her thoughts as she deconverted from a pretty strong fundamentalist faith into agnosticism. It was a very hard journey for her (as I understand it is for many who go through similar trials). In the process she lost some friends and most of her readership. As I said, its a tough road. One I never had to go through.

I can already imagine the fundies reacting with some heartwarming responses such as "You deserve it for turning your back on god". I don't know if anyone said that, I can just imagine it. Throw a couple of bucks her way, she doesnt need much, show her how helpful the atheist community can be.

I've mentioned the perpetual motion machine company Steorn before. But it unlike other companies sellng nonsense, they never tried to justify their claims by warping science or actually, you know, selling a device. So I have kept quiet on it. The last I had heard was that they were going to get a jury of scientists to evaluate their claims. I knew that if it was a real panel, they would sort out where the extra energy was coming from.

I knew that there was a problem just from their description of their "technology" they made the claim that magnets somehow allowed them to gain energy "just like when you walk up and down a hill, you have gained energy". I knew that they would either find the error (this was being very optimistic on my part), or they were simply trying to pull a fast one (the realist in me).

Today from Ben Goldacre, I learned that the panel has spoken. Guess what. Nada. Funny part is that the company claims that the jury only looked at the technology while it suffered from a problem that has been corrected after the jury was complete. Pretty funny.

Implementing Orbo in a reliable and consistent manner had remained a challenge for the organization, one that we had made no secret of. Due to these difficulties we had focused on providing the Jury with test data relating to the underlying magnetic effect behind Orbo. This work concluded at the end of 2008.”
McCarthy concluded by stating that “during 2009 the company had resolved the key technical problems related to the implementation of Orbo and is now focused on commercial launch towards the end of this year, at which time academic and engineering validation would be released concurrent with public demonstrations”.

Typical woo.

That said, I am pretty pleased how this has all turned out. I even commend Steorn for going through with the jury. They must have themselves pretty deluded to think that they would get past an honest panel of skeptics. Regardless, they honestly went about the testing and let the jury publish their findings ( sans the details unfortunately).

This sort of reminds me of my position about NCCAM. Orac and PZ have been railing against NCCAM for years. We have found out that they spent 2.5 billion dollars finding out that virtually nothing of the CAM industry works.

But isn't that good? Isn't that exactly what we want some organization to do? Check if something works and publish the results? I'd love for CAM to work. I'd love for all that nice comforting woo to work. But I want an organization to check for efficacy with rigorous studies. Considering the scope of studies, finding out that only one worked (ginseng for chemotherapy nausea), to me was worth it. This is enough for me, you, and the government to point to and say "nonsense!". I'm pretty happy wth both the Steorn outcome and the NCCAM outcome.

I realize that Steorn has spun the result already, and most woos will simply ignore the NCCAM results. But we now have a big thing to point at. And I like that.

For my current work I have to be aware of and understand a lot of the goings-on in the heat treating world. One avenue for pursuing this are trade journals. Like virtually every field there is a trade journal for it, and the one I am going to be talking about in Industrial Heating.

Reed Miller (pictured) puts out a rant pretty much every month about how bad the Obama administration is (or how bad it was going to be). Its pretty funny, as the economy is falling apart all around him, he was decrying how bad the next administration was going to be.

Anyway, this month was their energy savings edition. In it we get treated to not one but two rants by Miller, the editor and also Barry Ashby the Washington editor. First lets look at Millers contribution.

He starts out with the same canard you hear from every denialist: Implementing actions designed to curb climate change will ruin the economy.

As our nation became engaged in a protracted recession, no one believed “climate taxes” would happen here because it would be pure foolishness. Nobody is foolish enough to tax the engine of our economy in the midst of a recession, right?

When our president was elected, how-ever, it became clear that he wasn’t going to let a little thing like a recession prevent him from going down that road. Since President Obama seems to take his cues from Europe, I began to watch what was happening there to get a sense of where we would likely go in the U.S. In January, we began to document the news reported by our friends in Europe as well as what was happening right here in a bulletin-board thread on our website.

Let’s look at an important part there. He says that he has been looking at what is going on with other countries that have in fact implemented cap and trade schemes.

It’s hard to even mention this topic without discussing the basic reason for a carbon tax. The overhyped global-warming issue is the reason/excuse that is used. Because there has been no documented warming in the past 11 years, however, global warming is now referred to as climate change, but by any name the remedy is apparently the same – taxing consumers.

Sigh. I sigh every time I read that sort of nonsense. There is plenty of warming that has occurred, it is masked by the extremely high maximum that occurred in 1998 and the recent solar minimum. You only think that global warming has stopped if you choose a small data set and try to fit a straight line to it. You have to completely ignore the physics. You have to ignore the fact that temperature has not dropped off when solar irradiance has.

The sun only recently has reversed course to start shining more and more light on the Earth. We can expect this “global Warming has stopped” trend to be at an end now. So once you have put yourself into the global warming denial camp, is there any reason to expect endorsement of policies that go towards countering these issues? I think not.

Obama’s goal from the beginning has been to enact a European-style cap-and-trade system as a tax. If you don’t think this type of system is taxation, here’s what Obama had to say: “Under my cap-and-trade plan, electricity prices would necessarily skyrocket.” Testifying before Congress, Obama’s budget director said, “Firms would not ultimately bear most of the costs of the (cap-and-trade) allowances but instead would pass them along to their customers in the form of higher prices … price increases would be essential to the success of a cap-and-trade program.”

uh oh… an ellipsis. Now I have to go look this up. Well first off, I find out that the first quote was not in regard to the current energy plan. Obama said this over a year and a half ago with respect to a different plan altogether. The second quote is not related to the first.

Now I am not going to pretend that I understand the intricacies of a Cap and Trade program and its effects on the economy. Seems to me, since industry is unwilling to cut carbon emissions voluntarily, some form of regulation needs to be put in place. Cap and trade is not only being used in Europe (remember Mr. Miller said he has been watching the results over there), but we use cap and trade for emissions already!

What? You didn’t know that? Yeah, we implemented a successful cap and trade program for sulfur dioxide, the main cause of acid rain. Since then acid rain and its effects have improved.

As it became obvious Congress was not going to enact cap and trade quickly enough for Mr. Obama, he decided to force their hand through the regulatory process. On April 17, the EPA declared that CO2 and five other greenhouse gases “endanger public health and welfare.” Obama is clearly trying to skirt the legislative process by not allowing the necessary discussion to take place. About cap and trade, lawmakers have stated, “Legislation so far-reaching should be fully vetted and given appropriate time for debate.” Unfortunately, if legislators take the proper amount of time, Obama seems ready to use the EPA ruling under the Clean Air Act to short-circuit the process and accomplish the same objective.

I’m sorry, where have you been for the last 30 year that this has been discussed? Obama is not short circuiting the process. The bill still has to go through congress. No congress, no debate. 30 years is plenty of time. Never mind the fact that this quote is also out of context. It was by Mike Johanns, a nebraska republican, who was not complaining that the Cap and Trade system was being skirted by congress, he was taking issue with the method by which it was being introduced in congress (through a budget reconciliation process rather than a stand alone bill). I agree it shoudl be a stand alone bill, but Mr. Reed, by taking his quote out of context had implied that Obama was trying to skirt Congress altogether, which is simply not true.

Cap-and-trade legislation is intended to apply to power plants, steel mills or other large emitters of CO2. If taxation occurs through regulation with the EPA invoking the Clean Air Act, however, smaller businesses could also be affected.

And out comes the slippery slope argument.

Under this type of heavy-handed rule making, I wonder what will happen when all of the Wal-Mart haters of the world get their hands on this?

And the fear mongering.

Assuming cap-and-trade legislation is the likely result, what will it cost the consumer? An MIT study looked at the scheme proposed by the president, who projects revenue of $366 billion in a single year. Quoting the study, John Ensign, a U.S. Senator from Nevada, estimated the tax burden on each family would be $3,000 per year. Using an alternative household number given in the MIT study, the annual impact could be as high as $4,560 per year. It is promised that some of the taxed money will be rebated back to consumers, but some of it will also be used for other purposes. Most of us know how effective government rebates are. Once they get the money, they are unable to let it go. So, it’s anyone’s guess as to what our net tax liability will be. Needless to say, it will be painful.

Any chance that this is the study that you are misusing? Republicans in congress were specifically corrected by the author who specified the additional cost may be 340 dollars. Mr. Miller is over stating this cost by ten times. Then we are supposed to trust him that the $3000/year is definitely right, but the rest of the program will never come through. Mr. Reed is cherry picking.

Can we afford another tax? Will manufacturers remain in the U.S., or will they find a less-taxed place in which to do business?

More fear mongering.

But wait! I thought he said he has been examining the effects of cap and trade in Europe. Well? What happened with that riveting analysis?

I’m am not making any claims that Cap and Trade is the right thing to do, I’d support a straight out tax on carbon that many republicans are calling for. The fact is that it is high time to get some action going and I am glad to see our president finally breaking the shackles of mediocrity and getting something in motion. Articles like Mr. Reeds provide absolutely nothing but a one sided masturbatory exercise in denialism.

Short post here. I'm not going to do a detailed critique.

woot.com had a sale on a Roomba. I got one. Its awesome. Even my generally technophobic wife likes it. We have a pretty big place so we keep it confined to our bedroom where the two dogs sleep at night. Our room is about 25x25, I leave the door open to the bathroom and it finds our way into the walk in closet. Its really great. Neither of us like to vacuum (who does?), so now you hit a button in the morning, go to work, dump the dirt when you get home. Really, not a lot of work there.

There are two drawbacks using it. The first is that you have to roomba-size the room. That means taping down throw rugs with strong double sided rug tape (you get it at home depot), getting rid of clutter, push stray wires against the wall, and things like that. The second is that it is not methodical. For the most part it moves around the room in a random pattern. That means you can't expect it to do that same sort of job you would do with a vacuum. That is why you bend over and press the button every day. Yeesh, so much work! Its not really a drawback, its more of a shift in the way you have to think about vacuuming your room.

Our room looks very clean all the time now, but I am still amazed that it still manages to find dog hair and such (honestly, its a little gross that the dirt cartridge is transparent, you can see how much skin and dander it sucks up).

Every week it need minimal maintenance. You need to pop out the brushes (no tools needed) and pull out the long hair (not mine!) and threads that have rolled up into the brushes. Its a 5 minute job.

Anyway, even my mom wants one now. I think these are great and I want more for the rest of our house.

Now, Dear iRobot, could you please make the following:

Lawn mower that nibbles at the grass (i.e. no large lawnmower blades, something closer to small hedge clippers. Solar powered in a way it just charges batteries during the day and nibbles at night. GPS guided in a way that I can just walk around with the GPS module to create waypoints that define the mowing area. Provide a differential transmitter so that the accuracy can be good.

For 500 bucks, I'd buy this in 2 seconds.