| To: | k3mm@comcast.net, "'Jim Jarvis'" <jimjarvis@comcast.net>,<towertalk@contesting.com> |
|---|---|
| Subject: | RE: [TowerTalk] BPL.... very important point missed |
| From: | Jim Lux <jimlux@earthlink.net> |
| Date: | Fri, 09 Jan 2004 17:08:03 -0800 |
| List-post: | <mailto:towertalk@contesting.com> |
At 06:24 PM 1/9/2004 -0600, Tyler Stewart wrote:
There are already better ways to do that... Low power RF Part 15? radios in the 900 mhz band. True enough, but, nobody ever said that the technically best approach gets chosen. They may have other factors that figure into the decision (cross subsidization may be only one, a variety of regulatory incentives/disincentives may be another...) Think also of the management mindset in a power distribution utility. These are people who live, breathe, and think "WIRES", not RF. Sure, someone down in operations and planning knows they use microwave links for control, but at a fundamental level, they think in terms of stringing wires on poles and keeping the wires connected. They still use carrier current comm links too. BPL is a natural to them. RF and wireless is not. And, deregulation notwithstanding, a vast number of people in a utility are there from the regulated days (and significant parts of most utilities are still regulated, even in deregulation-happy California). That means long time horizons (they think in terms of 50 year amortizations, not 120 day IPOs) and "keeping the lights on" mindsets. If a high level manager (who IS thinking 120 day IPOs) asks their technical staff for recommendations on how to do communications, that regulated mentality will come through in the recommendations. The guy who's been managing the distribution network is going to think "wired connection" for data, not, gosh I could use this nifty private 2.5GHz multihop wireless network. He knows (instinctively, and with years of data to back it up) how reliable a wire is, how much it will cost to install and maintain, how many employees he'll need to maintain it, how long it will take to recover from an outage, and on and on, because they've been doing it for literally a century. If the senior manager asks the line manager for cost estimates for the approaches, he'll get a report that looks like this: Approach Estimated Cost BPL wired - $X million to install 5% uncertainty; Y million/yr to maintain 5% uncertainty Wireless - $0.5X million install 100% uncertainty; $Y to Z/yr to maintain 500% uncertainty* *we're depending on forecasts from the wireless vendors for these estimates, and they only have 1 year experience. The senior manager is going to go... Whoa.. I'm going to go with what we know how to do. Not only can they do meterreading but they automatically report power outages, which wont happen when the power lines are damaged with BPL. These utility applications dont need BPL bandwidth, and the RF stuff is already out there and has become fairly cheap to deploy. BPL bandwidth isn't all that great, particularly in the upstream direction. One can make some quick estimates though, of the data rate requirements: Say you want to uplink, from each customer, their usage at 1 minutes intervals. That's 1440 measurements per day, probably 8 bits per measurement, but subject to significant compression, so figure on the order of 500 bits/customer/day. In Thousand Oaks, CA, where I live, there are about 100,000 people, and about 50,000 electric meters. So that's 25000 kbits/day, or, about 300 bits/second. You'd want significant margin in something like this, and you probably want redundancy and two way protocols, with time tags, and so forth. BPL is very well suited to these sorts of data rates. Say the utility wanted to add, as a value added, unregulated, feature, something like alarm monitoring or remote home control (something currently provided by very effective data rate communications over phone lines). They could easily run, say, 10 bits/second/household (or, half a megabit/sec). This could be very attractive, because the incremental cost to the utility to provide the service would be very small, and the original "metering" application might be covered under their regulated operations, so they are in the nifty situation of having the hardware and installation (the expensive part) covered under their regulated side and the data communications service (the cheap part) able to support the unregulated side. Businesses might find this sort of service very attractive, compared to conventional alarm companies, especially if it's a 24/7 100 percent availability continous thing that could receive UL alarm certification. Right now, they have to use leased lines. Home alarms can use autodialers, but, because they don't provide continuous monitoring of the link (i.e. they only dial when someone triggers the alarm), they can't be used for sensitive (i.e. significant insurance loss exposure) type applications. Again, this kind of thing would be great for the unregulated side of the utility. No infrastructure costs (because those are borne by the regulated side as part of the metering/billing function) and low incremental cost to provide the service. IMHO BPL will never be economically viable. It doesn't have to be economically viable, in and of itself, to be deployed and cause problems. Economic viability only determines what happens in the long run, and there are plenty of examples of companies, or even entire industries, doing downright stupid things for perceived short term benefit of one sort or another. That's why we can't wait for economics to passively kill BPL by itself (which I think it inevitably will). We don't want to endure the pain while it lives. We must also pursue regulatory aspects (which ARRL is reasonably on top of). On the other hand, economic forces could help kill it quicker, and market perceptions of uncertainty can probably kill it quickest, because "the market" hates uncertainty. You can make money both going up and going down, but it's hard to make money on totally random coin flips. Sure, you can get paid for flipping the coin, but nobody's going to pay anyone to do that very long. I think that a lot of the folks advocating BPL are in the "being paid to flip the coin" category, claiming that it's not as uncertain as all that. The sooner that the folks doing the paying realize that's what's going on, the better, and that's where education in the appropriate media is important. Someone else who is knowledgeable about this technology informs me that all that power line interference that you suffer with now will no doubt destroy BPL as well. So if you do get BPL in your area, they will have to fix all your power line noises (not to mention some consumer electronics noises)! _______________________________________________ See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions and ask for Sherman, W2FLA. _______________________________________________ TowerTalk mailing list TowerTalk@contesting.com http://lists.contesting.com/mailman/listinfo/towertalk |
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