Wireless links

[Summertown]

I need to build a radio link, High speed is not an issue. I was contemplating the XBee-Pro as distance & terrain are an issue at 150 metres,with some trees, but essentially LOS. A high gain aerial on one end is a possibility.
Question has anyone used them?
Has anyone an idea on range?
Are they available in Oz or is it the buy from the US deal?

 

[gidgee]

have a look at
http://www.microzed.com.au
john

 

 

[xstamp]

You might like to take a look at the following 2.4GHz seven element YAGI from Active Robots

www.active-robots.com/products/radio-solutions/antennae.shtml

 

[manuka]

Aside from tedious technicalities, your wireless choice is a factor of the actual data speed needed, "what's in the way" & of course budget. Considered lower freq. cheap 433 MHZ ISM which readily handles 300- 2400bps?

ZigBee is at 2.4GHZ, so almost any LOS (line of sight)obstruction will be an issue- even your body.I've rustled up several suitable antenna for the 1mW XBee &amp; managed 3km LOS across water however. See =&gt; <A href='http://www.usbwifi.orcon.net.nz/cnr.jpg ' Target=_Blank>External Web Link</a> or <A href='http://www.usbwifi.orcon.net.nz/cardwifi.jpg ' Target=_Blank>External Web Link</a> or <A href='http://www.picaxe.orcon.net.nz/zigscoop.jpg ' Target=_Blank>External Web Link</a> etc . XBee Pro should be good for LOS links only influenced by the earth's curvature!


For easy wireless data however you really can't beat the cheap 433MHz approach, especially since Picaxe serial driving is REALLY easy =&gt; <A href='http://www.picaxe.orcon.net.nz/433rpt.jpg ' Target=_Blank>External Web Link</a>. Refer Australian &quot;Silicon Chip&quot; monthlies ~late 2005/early 2006 for several articles on these.

What's your budget &amp; skill level? Even basic XBees are considerably more costly than classic 433MHz units, &amp; also harder to set up. There are significant interference issues on BOTH bands now with 2.4GHz of course full of WiFi, Video links, DECT phones, Bluetooth, leaky microwave ovens. Down at 433MHz garage door openers, wireless door bells &amp; telemetry units abound too, but at least you can grab a cheap UHF scanner &amp; listen in to perhaps identify the culprit! UHF antenna, perhaps &quot;cotanga&quot; style are a breeze too =&gt; <A href='http://www.picaxe.orcon.net.nz/yagi433.jpg ' Target=_Blank>External Web Link</a>

Although regs. in some countries restrict data use, cheap 470MHz UHF handhelds are quite powerful (~&#189;W ) &amp; imaginative data linking possible. Although these look like toys their performances are astounding. I've sent Hellscrieber, morse &amp; even a simple &quot;Swan Code&quot; over them with ranges (even thru vegetation)of several km. You can pick a pair up new for ~US$30 in many hardware stores. Crazy...

 

[Summertown]

Hi manuka,
Going through your points in order;
300 baud is fine, this devive is part of a logging/control system for an iirgation system &amp; associated bore. 300 baud is a light year faster than water!
Level lof experiance; I have worked as a TV OB engineer for 25 years and during that ttime have come across all manner of RF toys from 170 meg handhelds that bleed across state boundaries in summer, to 13 Ghz link systems in N Queensland in tropical rain. Shall we say; played with RF long enough to have an extremely healthy respect for it. Have a lot of test kit. Budget is just make it work.
I live in a semi Rural environment in the Adelaide Hills, lots of trees so I am concerned about LOS etc.
One question re the XBee series is do they handle reflected signals as does WIFI, and 2.4Ghz TV links, e.g. F1 cars going under bridges without any breakup as the receivers are quite clever. BAck to earth! The 433 approach would be my prefered approach as I well know the lower the Fz. the easier it is to handle, and the house has some wifi. Problem is the only 433 mhz modules I have seen are the Jaycar units that appear to have a range of &lt;50 metres. I need to go at least 250 metres, or 200 metres with trees.

Thoughts.
Thanks

 

[Michael 2727]

Elsema have a range of RX TX gear in all manner of configurations, power, codes, data, etc.
They gear has been used in garage door openers for decades.
You can get them in bare modules or boxed also.

 

[manuka]

Adelaide hills - I know that area pretty well &amp; (in spite of your open foliage eucalypts) would flag away ZigBee as being too obstruction prone unless serious antenna &amp; higher power used ( =$$$).

So 433MHz looks best. I'd have to dig out my mid 2005 Jaycar ZW-3100/3102 test results, but with a cotanga Yagi we readily managed ~500m with the Jaycar matched pair. The receiver was quite sensitive, but I recall some error in the supplied data meant ranges initially limited however. Mmm-it's coming back to me- Jaycar said 3V on the tx when it fact it needed 5V for any decent range. I note their web site STILL says 3V supply (in spite of my alert) =&gt; <A href='http://www.jaycar.co.nz/productView.asp?ID=ZW3100&amp;CATID=&amp;keywords=433&amp;SPECIAL=&amp;form=KEYWORD&amp;ProdCodeOnly=&amp;Keyword1=&amp;Keyword2=&amp;pageNumber=&amp;priceMin=&amp;priceMax=&amp;SUBCATID= ' Target=_Blank>External Web Link</a>

Check those Silicon Chip &quot;433&quot; articles, as I'd pretty much nailed tweaks etc in them for this Jaycar pair, but also tested out other cheapies. There are several types here in NZ, for as low as ~Aus $3-4 each in fact, that worked really well. The transmitter,shown =&gt; <A href='http://www.picaxe.orcon.net.nz/433rpt.jpg ' Target=_Blank>External Web Link</a>), even had a neat attached micro rubber ducky.

A key aspect of even 300bps wireless data may be error detection- Hippy has explored this in A1 depth &amp; his Picaxe coded CRC approach is viewed as near definitive. You can maybe live with datalogging oddball results, but it's possibly a CRUCIAL feature in your irrigation control scheme given the &quot;Ash Wednesday&quot; SA location.You don't want to have pumped the well/bore/pond dry by mistake when a bush fire alert is on. Come in Hippy ...



Edited by - manuka on 03/09/2006 06:58:22

 

[Summertown]

Hi Again Manuka,
OK I have a set of the Jaycar units here with me in the Middle East, where I am working at the moment so I will l press on with the R&amp;D of the project. Back in Adelaide at Chrissy. I will go &amp; dig up the Silicon Chip article as a starting point. Point taken about the CRC issue, hadn&#8217;t thought of that one. You must know the Hills. We are &lt;3km from Yarabee Rd., the starting point of Ash Wednesday. You can probably look at the log in name &amp; work the rest out!
Thanks again,

 

[manuka]

Middle East! Mmm- try SiChip teasers <A href='http://www.siliconchip.com.au/cms/A_105581/article.html ' Target=_Blank>External Web Link</a> and <A href='http://www.siliconchip.com.au/cms/A_105744/article.html ' Target=_Blank>External Web Link</a>.

Lucky guess on your &quot;Ash Wednesday &quot; <A href='http://www.answers.com/topic/ash-wednesday-fires ' Target=_Blank>External Web Link</a>location, as I don't know the Adelaide Hills THAT well.

Edited by - manuka on 03/09/2006 12:42:11

 

[moxhamj]

Hi Summertown. I have just spent 5 months on a similar project. I can almost see you as well - I'm near the Belair National Park with views of Mt Lofty. Ok, 433's will go about 100 metres. But I needed 500 metres through trees, with interference from nearby 500Kv power lines. Even with a 10 element Quagi at both ends still couldn't quite pull out the data though a signal was just audible. Almost managed it with a modified 27Mhz RC plane Rx/Tx and a 5 metre dipole. 2.4G wasn't even close - lucky to get 100m. I did get it to work with two modified cheap 3w UHF radios but it is illegal to send data so never used this. Tried wires strung between trees but the koalas chewed them (I kid you not!). In the end, solution that worked was to use the wires on the fence (creosote treated pine posts). I never tried parabolic antennas - maybe these are worth a shot.

 

[rolsen]

I had achieved about 5KM with the oatley 433 set with the 4 button encoder using wire coathanger yagi as shown by stan swan.
Trees no problem and receiver worked inside a house. Didn't like hills in the way.

 

[Dippy]

Your max range can also be affected by the method of modulation used. This due to how the data slicing works on many Rx modules.
This is ONE of the reasons for Manchester coding.
You'd have to read articles to get the detail but I think there is a good summary on the RadioMetrix site.

I thought in Oz you could use ~150MHz higher power modules? And have 10km ranges?

At 433 I've achieved 5.2km with yagi.

 

[D n T]

You are in australia, excellent.
Without sounding like an ad for them, have a look at oatley electronics, they have a transciever for 30 dollars, two way comms, lots of fun and easy to use. I have used it instead of the zigbee because of the $$$ situation.
You may have to watch out for the trees. standard 433mhz reception rules apply but they do have a bit of guts.
Just an idea

 

[manuka]

Hippy hasn't yet risen to the bait, so here's his wireless CRC coverage =&gt; <A href='http://www.hippy.freeserve.co.uk/picaxewf.htm ' Target=_Blank>External Web Link</a>.

That versatile Oatley transceiver<A href='http://www.oatleyelectronics.com/images/trx433.jpg ' Target=_Blank>External Web Link</a>is in fact based on the well known (&amp; apparently almost obsolete) Nordic wireless product- the <b>nRF401 </b> . See=&gt; <A href='http://www.nvlsi.no/index.cfm?obj=product&amp;act=display&amp;pro=56 ' Target=_Blank>External Web Link</a> Given the Norwegian terrain expect mountain punching performance!

But their specs. aren't THAT superior to $5 garage door cheapies, &amp; the all up cost will be significantly higher. Although field tests show superior performance they're probably an overkill for simple 433 links,although the single package may appeal.

Edited by - manuka on 06/09/2006 22:31:08

 

[Summertown]

Thanks Dippy &amp; Manuka;
Dippy I am familiar with Manchester Code. I work in TV broadcasting &amp; Manchester code is used for TIME CODE on video tape machines in editing etc&#8230;.

I looked at Stan&#8217;s offering and it appears to be a shove it into the transmitter approach, Very good for the original Picaxe education market.

Off the fridge to get a cold beer &amp; plough through the Picaxe search engine.

Dr_Acula yes Cable was an option. Your observations on ferral creatures is accurate. Between Koala&#8217;s, Possums, Wombats &amp; drop bears&#8230;. RF looks like a go.

Guys Thanks.

 

[whizzer]

I&#8217;d heard of Min-Min lights &amp; the Yowie, but Drop Bears were something new to me&#8230;!
This web site on australian legends explains it all <A href='http://members.optusnet.com.au/~blueprnt/myth.html' Target=_Blank>External Web Link</a>

 

[hippy]

Drop-Bears ? Pah, nothing. Now Drop-Cows; be very, very afraid ...

http://www.cis.ysu.edu/~kriss/funstuff/cows.html

 

[moxhamj]

Beware of Drop Bears! Seriously, wildlife is a real problem. No flying cows, but after I build my tank level system, I had problems with both koalas and cows eating the wires. Solution - build an electric fence round the tanks powered by picaxes. Runs off solar power - even got the holy grail of solar working; Max Power Point Tracking. Charges an old 12V car battery using a picaxe step up converter. Energiser runs off an ignition coil bought off ebay for $10. Next project - an electric fence to stop kangaroos stripping the leaves off the apricot trees. I'm really interested in the wireless link - let us know how it goes.

 

[Michael 2727]

Drop Bears only eat little Japanese camera clicking tourists, the clicking annoys them ~ ;o)

 

[D n T]

Summerton, It seems that 433mhz would be a good choice, I got 250+ metres using a 150mm bread board link vertically as my high powered antenna. Using a simple code under 30 lines to flash up Leds to indicate signal or lack of, worked a treat, I just used pre and post amble, had no poblems.

Cautionary note regarding DROP BEARS. If you cover the reciever in VEGEMITE that will keep them away!!!

I'm currently working on a radio link for my moel rocket launcher, means I can get further away for the big ones or the ones my students build&gt;
Time for another coke

R.I.P. Mr Peter Brock

Edited by - D n T on 09/09/2006 13:58:31

 

[hippy]

<i>I'm currently working on a radio link for my moel rocket launcher </i>

Presumably we don't have to mention exactly how safety critical this is, and the absolute necessity for fail-safe; software, electrical and mechanical ?

 

[Summertown]

Hi DNT
What modules did you use?
and what sort of modulation?
Thanks

 

[xstamp]

I mentioned this a while back but for what its worth&#8230; www.sparkfun.com advertise a number of low cost transmitter and receiver modules (315, 418 and 434Mhz) that claim 500ft range at 2.4kbps. They should be directly compatible with the PICAXE serial I/O port and communications software, because they have integral modems. The 4-pin RF-KLP transmitter module is priced at $12. I have not tried these devices but have found it easy to purchase other Spark Fun products using a UK credit card.

 

[D n T]

The units I'm using are run of the mill 433mhz modules available from Jaycar.
trans cat. ZW3100
Rec cat. ZW3102
$20.00 for the pair.
Ther are data sheets and plenty of data on the net, not to mention the mass of discussion on our forum, do a forum search and stand back, the number of times it has been dicussed might need a seperate forum just for wireless.

I just use a preamble to sort out the transmissions ( the rocket launcher is a bit more involved than that though, don't panic)
Example trans:
serout 0, t1200, (&quot;VVVVVVVV&quot;,$99, b0, b1, b2)
example rec:
serin 3, t1200, ($99), b0, b1, b2

I used these as part of my codes to test the range and they work fine.
All the reciever did was varify the values for the variables and flash up an LED code to let me know right or wrong.

Edited by - D n T on 13/09/2006 11:43:59