New Project involving Xbee modules

lbenson

lbenson

Senior Member
manie--I have a lot of professional MSAccess experience, but I'm opting to go web-based for my own design (which is in the monitoring rather than the controlling vein, but with the options to go the other way). My current favorite programming language--Lua (many C-like features, which is good for me, but with both simplifications and enhancements). My monitoring system controller (which is not yet ready for prime time, but getting close) gets information from 315mHz wireless picaxe modules (6 deployed at present) and runs on an NSLU2 displaying a web page and sending emails regarding events of interest. Very lightweight, but full-featured.
 
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manie

Senior Member
Eclectic: That is the exact one I built, from that site... I went as close to sub-mm perfect as I could, it says 123mm, I have 122.5-123.5 maybe... I am using RG58 (stranded center core) and in-line BNC connectors, I have a good hexagonal crimping tool, I'll probably feed from the bottom unless somebody says no... too much cable losses ! About antenna tuning I know ZERO, but I'll try.... Thanks

Manie
 
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KIGX

Member
manie:

Your 1/4 wave vertical really needs to be mounted on a metal surface, either solid or mesh, preferably something that extends out about the same distance or more as the height of the antenna and having the coax braid grounded to the ground plane either through the connector or some other means. If you can't do that you would likely be better off with a simple dipole.

I can't really see in the picture of your cotanga but keep in mind that the driven element is 2 separate pieces and, if fed by coax, braid to one side center core to the other.

Keep at it, you'll make it all work.
 
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manuka

Senior Member
That 2003 era "cotanga" Yagi of mine (so called since it's made out of coat hanger wire) certainly works OK. However it was intended for educational low budget (or even 0$) insights rather than serious use, & has no impedance matching for starters. I've seen students knock them together on drilled bamboo offcuts in a flash, with feeding via (discarded) TV grade coax. Thus stimulated,some at least will then go on to more professional designs.

Manie- I don't know what your time & $ budget is for this chook house project, but in 2009's harsh economic climate, cost effectiveness rules - at least where I come from! Most exploratory projects suit starting simply, & (when proof of concept is shown) THEN gearing up (if justified) - your approach seems- ahem- just the opposite = "throw a lot of hardware at the problem & hope something sticks". It's all a learning experience of course for you, but I've increasing visions of you at the "can't afford to eat as the housekeeping was blown on telemetry" stage.

In sign off, herewith my message again, & again & ... => START SIMPLY, START SIMPLY, ...
 
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manie

Senior Member
KIGX: The driven elements on the Cotanga Yagi are separate, like a di-pole.

Stan: In the not too distant past, I've blown $$$$'s on rubbish imported so learnt a lesson there which is "go local if you can", one can always talk to them direct. Like now with the blue LCD, I've yet to get an e-mail from Sure to discuss Airmail possibilities !! The always have a system and bugger the paying customer, he is just one of thousands, so why bother... that is why I took the Polygons. Also, in the past, just when you're waiting for the breakthrough, the makeshift pole falls over and breaks the antenna or something on a makeshift connection shorts out and blows your very last chip !! So I tend to TRY and do a bit better job, maybe a little more elaborate but at least I don't have to be cross with myself for being stupid.........

Ah, the economic situation ! The chook-house owner(son-in-law) is funding a lot of this development, he is a lot more "liquid" than I am, and he is really tired of getting up at 3AM in the cold to investigate an alarm. So I speak to him, and him being a "bit" of a perfectionist will always say...."lets do it properly, once only....", so it might look like I throwing money at it but that is not really the case...

Last but maybe not least, this is all very new to me (again) since my last hands-on encounter with electronics was when OC28 Germanium was a miracle of miniturisation.... RF has always been a mystery to me and I follow written work etc. to make sense of it. Stan, please don't dispair ! I'll (we'll) get there, I believe........ your final statement of "START SIMPLY", is this not starting that way ? A step at a time ?

Manie
 
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manuka

Senior Member
LTWBYC = "Learn to walk before you climb" - see 433 RF version below. LTWBFYC also an old army map reading alert to quote horizontal before vertical...
 

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manie

Senior Member
Stan: Take heart mate ! It worked !!!!!!!!!! All the way from 2003 vintage in modern day materials, it WORKED !!!!

First a confession: maybe I had a bum solder joint or an invissible short on the 1/4 waves (both)..... when I soldered the RG58 co-ax to the boards (reading glasses + 3x magna-viewer, with great care) I first measured R of the 1/4 waves, after new soldering, measured R of Cotanga joints, what a difference !!! Cotanga showed open circuit, 1/4 waves did not.

Anyway, to the test: First test point was my previous 57m best + 3m = 60m. NO PROBLEM! Then +25m = 85m, NO PROBLEM, then boldly went where no Cotanga went before, to 101m, NO PROBLEM, then so full of confidence, right to the end of the field next to the maize (5ft high in pic at distance) = 160m, NO PROBLEM ! All at 9600bd, comms both ways without as much as a hiccup !

Its done guys, THANK YOU ALL !!!

Some pics attached to indicate distance and once again, not really "open" LOS as there are trees/leaves/electric fence etc. in between, but comms was clean and immediate !

Look for the "red dot" (wife's shirt) in pic 1, gives a good idea of distance and conditions...

Manie


PHEW !!! Thanks again.
 

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manie

Senior Member
Stan: DONE !!

I'm still so happy, not a glitch I tell you. Don't shoot that little Cotanga down, it was designed specifically for me and these Polygon units.......
Manie

Edit: At this point a question. Do I carry on with this thread on this project to include all sensors, alarms, motor movements etc, or do i start a new thread ? Temperature is working already.....
 
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manuka

Senior Member
I'm in fact pondering your late season corn- isn't it "knee high by the 4th of July" in your region? Here in NZ it's now well over ones head, with corn flooding the market. Maybe yours is a 2nd crop?
 
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KIGX

Member
Manie:

What the heck are you keeping in, or out, with that electric fence? It looks like a maximum security facility...

And what are the trees with the orange 'flowers'?

After a long winter it is nice to see some green and colour...
 
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manuka

Senior Member
KIGX: You'd have to live in Sth Africa to understand I'm afraid...
Manie: Don't forget to let your wife back inside before dark! Stan.
 
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cvrwy

Member
I would expect Manie has all kinds of 2 and 4 legged critters out there trying to get onto his property when he is not watching.........Right Manie?

We have critters down our way too..........Armadillos, thieves, pit bulls, etc.....
6 acres is too much for a high security fence, I just keep my lever action .44 mag handy........
 
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manie

Senior Member
Well a 44 Automag would be nice but then its all "Royal Game..." can't shoot it if you can't see it in the dark..... JohnM: ever heard on the news in your part of the globe about "Farm Murders" ??? Thought not... the press is very biased towards making the rainbow work at ANY AND ALL costs, including the highest crime figures in the world. At least one place we're beating the USA in being the "biggest in the world..." Thats what we keep out ! Those darn flowers ?? Well they make a mess of your car at least. The "other" trees are Palms LOLOLOLOL !!! Stan: this crop was planted only 4 weeks ago, so very young still, will be above your head in about 2 weeks time, and about the wife.......... had to let her in before the neighbours thought funny of us !

Later today, maybe, I'll try for "LONG" range, see if I can get to the magic 500m mark. Will keep you posted.
Manie
 
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KIGX

Member
OK, didn't realize this was S. Afr. I was thinking giant kangaroos or elephants or something. To me an electric fence is a single wire a few feet above the ground on flimsy stakes to keep the cows from wandering too far. I couldn't figure out why Stan was so concerned about it interfering with the signal...

BTW: Congrats on getting your system running.
 
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manie

Senior Member
The RF/RS232 part is going yes, and also the temperature readings, now comes the humidity/windspeed/wind direction/CO2/CO/NH4/shutter position etc.etc.etc.... will be busy for a while ...
Manie
 
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manuka

Senior Member
NH3/NH4 - there are assorted electronic ammonia/ammonium ion assessment techniques, but AFAIK none are PICAXE friendly. The human nose is of course a very sensitive 20-50 ppm level NH3 detector of course, although it can desensitise rapidly. What had you in mind to measure- NH3 vapour? Doesn't just good old ventilation can work wonders on ammonia levels in chook houses? ("Chook" = colonial slang for "chicken/poultry" by the way).

I recall assorted issues from my time living near a NZ poultry farm as a kid in fact, & some of these were NOT pretty... Stan
 
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manie

Senior Member
Stan:

The idea behind checking gas levels is to ensure the chook-house (yes, picked that "slang" up in one of your earlier posts...) gets ventilated despite "low" temperature being sensed. The area can get very cold in winter and then the gas build-up can occur when the curtains remain shut to preserve heat. Know of some farmers who lost whole runs of 20,000 plus chicks because ventilation was not done properly, quite a monetary loss !! Also, humidty can cause moisture dripping on chicks during colder spells and then the "air must be cleared" so to speak, even if it means a short period of low temperatures..

Also:
Magical 300m achieved ! 9600bd, NO PRE-AMBLE in code, just the data byte sent and received to put "most stress" on transmission/reception... NO need to send temp. setpoint twice for instance.... NICE !
Click to expand...
Manie
 
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manie

Senior Member
New range test done, and WOW ! Driving there is almost 1kM, cutting out rectangle, I estimate LOS distance as 800 meter ! In the two pics, note the 11 KV power lines directly in the LOS path. The yellow rectangle marks the remote transmitter (controller) spot. The second pic shows the "base" antenna, tucked up against the wall and with Palmtree fronds waving over it. Still at 9600bd, still no pre-amble, just raw data immediate transmission. I'm very happy !

These 433MHz units from Polygon certainly seem to live up to their claim of "easy" 300m range which I've now almost trippled ! I will use thier units again !
 

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manuka

Senior Member
Mani: Good stuff- but although 433 MHz signals will "punch" thru' vegetation, that range boost arises from the Yagi you're seemingly using at one end of course. Across water (I live harbourside here in Wellington, NZ) LOS links of several km are feasible.
 
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manie

Senior Member
Stan: I use the Yagi at both ends. Does that mean then that I should cover greater range even at LOS ? I can still drop baud rate down and use software data checking etc when it gets marginal. This then suggests quite a bit of range possible, maybe in Km's range ?
 
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manuka

Senior Member
Sure- give it a try. Wireless data can be a little miracle, but so many local issues (usually interference at 433MHz) arise to throw a spanner in the works. I even recall an Australian elevated WiFi outdoor AP (access point) that stopped working due to an invasion of ANTS (& their "house keeping")! Guess they twigged the AP used an ANTtenna of course...
 
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manie

Senior Member
The nmemonics are sometimes staggering. I know Nordic also uses some ANT protocol in one of their devices....?? It seems though that S.A. is still a bit "quiet" on the 433 front, I'm just extremely pleased with the performance of these locally produced Polygon units. Especially after you guys said that the receiver seems a bit "deaf" !! I have to get back to Polygon and report that I'm happy so far, I promissed to do so, and now I can say its OK. Will more elements in the Yagi have a beneficial effect or not ? Maybe something to look at for future reference....
 
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manie

Senior Member
Manuka: I think this can close the thread now that I'm really happy. Tested range out "on the road", ran out of LOS (hilly country here) at 1.5Km, stiil no pre-amble, just straight data bytes sent/received. NO LOSS at 1.5Km ! I think I can deploy this now !
 
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manuka

Senior Member
OK- there'd been little recent XBee content anyway! Suggest you use RSA in future postings by the way, as SA alone is readily confused with the state of South Australia. Stan
 
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manuka

Senior Member
~900 MHz SURE- I know them at lower freq 433 MHz OK, & they're similar to Yishi, HopeRF et.al. You're moving into the 2nd generation wireless data stuff with these superior units of course, as their unified design offers fast RX/TX switch over for error checking/correction etc. I personally favour this type, but they're not so easy to use. Check the extensive Forum thread => http://www.picaxeforum.co.uk/showthread.php?t=10511&highlight=hoperf
 
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