Friday, February 10, 2012

There's more to the NBN than fast Internet

People keep on framing debate about Australia's NBN (National Broadband Network) as if it's all about building a new service for faster Internet and that keeping the existing copper POTS infrastructure is a viable option.

Cost of services to end users as compared to POTS introduction

Look at the history of telephone rollouts. Initially they were unaffordable for many and there was a great deal of doubt about their utility - after all, you could usually just go to the local post office if you wanted to make a call, so what was the big deal?

Things are a bit different now.

On the other hand, unlike telephone rollouts (and their later enabling of MODEMs and dial-up banks) the NBN replaces an existing service. In that regard it's quite different, so we can't draw a direct comparison with the infrastructure rollout for phones. One could argue that the NBN is improving an existing service, rather than creating a new service, and at its cost is economically unjustifiable.

The POTS network is ailing

There's a reason why copper is being decomissioned where the NBN is being rolled out, and it's not just to provide economic incentive to push people onto the NBN and help fund it.

The copper phone network is ailing. There aren't enough physical lines to service increasing population densities as discrete houses are replaced with flats, high density developments, etc. High-frequency cross-talk from multiple ADSL services on long parallel copper lines is degrading service and causing poorer results for all users. Junctions and pits are needing more and more maintenance as they age and corrode. Installing new copper is more and more expensive as the price for copper goes through the roof.

Money spent on the copper network is being sunk into a network that's going to have to be dropped or massively rebuilt at some point. There's going to be a point where it's better to stop spending on it and replace it instead.

Given that, the NBN rollout is the replacement of infrastructure that'll otherwise become more and more overloaded, ineffective, and expensive to operate. I increasingly see its actual performance benefits as secondary. It's more like replacing that falling-down school with a fancy new building that happens to have air-conditioning and pretty skylights, but has to be built anyway because the old one has to be knocked down and rebuilt soon one way or another.

Tuesday, January 31, 2012

SoWACS: The soil water moisture content measurement systems and sensors mailing list

If you've been following the soil moisture stuff I've been playing with you will have seen me referencing many others' work, both hobbyists and pros. This isn't new stuff, though it's poorly documented on the 'net and hard to find.

It turns out there's a mailing list dedicated to the topic - but you'd be really, really lucky to find it. Check the archives out here, they're seriously informative:

http://groups.google.com/group/sowacs?pli=1

The group moved from its old hosting to Google Groups a while ago, but the best stuff is in the old archive on sowacs.com. It's a bit patchy, frustratingly, and there don't seem to be mbox files of the archives to download, but it's still very informative.

Monday, January 23, 2012

I've had it with HTC - thanks for the rescue, CyanogenMod + AAHK

HTC pushed an Android 2.3.5 update to my Vodafone Australia-branded HTC Desire HD. There was no changelog, and along with the Android update it turns out I get a new version of HTC Sense (yay?) with all sorts of animations I can't turn off and extra bloat.

Great work HTC, you made the phone faster, then ruined it with more pointless animation. At least the "no window animations" setting used to work in the old version...

Friday, January 20, 2012

Atmel Microcontroller (non-ATmega/ATtiny compatible) with built-in 433MHz (US: 310MHz) transmitter!

While researching parts for my soil moisture sensors I stumbled across these awesome Atmel microcontrollers:

I was so excited I had to share. At about AU$8 each, these little beasties might make building wireless soil moisture sensors so much easier it's just not funny. The main problem is going to be ordering them, since Jaycar and Element14 don't carry them, and DigiKey has them as non-stock components with 4000 unit minimum volumes. They're 4-bit 8051-architecture micros so they're not going to be compatible with the ATmega or ATtiny range, so I lose the advantage of having the same arch on sensor and control system. For something as relatively simple as sampling an analog temperature and humidity sensor that may not be a big problem.

It may still land up being easier to use an ATtiny for the analog sensor controller and digital sensor data transmitter, so I can use (mostly) the same software tools as for the ATmega on the control board. I could then hook the sensor's ATtiny up to either some wiring for wired service, or to an RF transmitter IC for wireless operation without much if any change to the sensor codebase.

Atmel also have a family of RF receiver ICs (with matching tx modules or transceivers available) so I might be able to avoid the need for a breakout board / shield for the RF receiver support and just make it an optional component in the base design. Things like the ATA5723 /ATA5724/ATA5728 and the ATA5745 /ATA5746 RF receiver ICs could be awfully handy at about AU$4 each ... if I can find someone who'll sell them to me in less than 1,500 unit quantities. If not, there are lots of other highly integrated 433MHz RF receivers and transmitter ICs out there.

The ATA8204P3-TKQY looks particularly suitable; it's a slower and cheaper unit without UHF, but that shouldn't be a biggie for my use. It's cheaper than any of the other units except the ATA8202-PXQW 19 on digi-key, and should do the job fine. It's surface mount so it won't be assembly-friendly, though. An alternative might be the ALPHA-RX433S from RF-Solutions as that's packaged as a little module that'd be a bit saner to solder up.

Tuesday, January 17, 2012

DIY DC soil moisture sensor - early test successful

Laptop connected to Arduino connected to flowerpot

On the the progressive difficulty scale of home built soil moisture sensors the bottom of the ladder is a DC soil conductivity sensor that uses simple resistivity measurement.

It took a couple of hours build one of those last night, most of which was spent incompetently attempting to produce a decent solder joint on steel wire and on the cleaned heads of galvanized nails. Anyone who can use a soldering iron without being a hazard to themselves and those around them should be able to whip something like this up in a few minutes.

Monday, January 16, 2012

Interested in soil moisture sensors and irrigation control? Start with the UF/IFAS virual extension series

I've been having ... "fun" ... trying to find a way to build an affordable network of soil moisture sensors that don't require too much looking after.

It's harder than you'd think, but this UF/IFAS Virtual Extension series on soil moisture and irrigation has made it a lot easier to understand the different approaches and sensor types. It'll help you understand the differences between resistive and capacitive soil moisture measurement, introduce alternatives like tensiometers, etc. This is important whether you plan to DIY your sensors or buy off the shelf.

Saturday, January 14, 2012

Using a RHT03 (aliases: RHT-22, DHT22, AM2302) temperature/humidity sensor from Arduino

I picked up a nice compact little temperature and relative humidity sensor called the RHT03 for a project from Little Bird Electronics. It and very similar parts appear to go by the names RHT-22, DHT-22 and AM2302. You can find the part at SparkFun, Adafruit, etc too.

It took a lot more work to get it working than I expected, so I thought I'd write it up here for anyone else who is looking into it. There's sample code at the end of this post, but you should probably read the details because this is a quirky beast.

UPDATE: I since found a library on GitHub: nethoncho/Arduino-DHT22 that does a better job more simply and compactly. It works fine with my sensor. It needed some changes for Arduino 1.0 and some further tweaks to work how I wanted, so I've uploaded a fork here: https://github.com/ringerc/Arduino-DHT22.