I need help on buying wireless transmission....

If you could look at this page ---> http://www.futurlec.com.au/RadioModules.jsp I want to buy two of thses units. One will be connected to my computer thje other will be about 15 meters away. They will have to send and also recieve data. I find the number of options confusing . So if you could give me any advice or opinion at all it would help some.

Thank you.

Mike.

I would suggest having a look at the Dorji modules here.

http://www.wiltronics.com.au/catalogue/200791/picaxe-rf-dorji-robots-kits/rf--dorji/dorji-ask-modules/dorji-fsk-rx-modules/dorji-433mhz-107dbm-ask-receiver--dip-package

http://www.wiltronics.com.au/catalogue/200789/picaxe-rf-dorji-robots-kits/rf--dorji/dorji-ask-modules/dorji-fsk-tx-modules/dorji-433mhz-10_17dbm-ask-transmitter--dip-package

Also a little cheaper and have been used a lot on the forum here by many.

Personally i use these.

http://www.wiltronics.com.au/catalogue/200803/picaxe-rf-dorji-robots-kits/rf--dorji/dorji-gfsk-and-fsk-ism-modules/dorji-drf4432d20i-043m1-433mhz-20db-transceiver-module-with-id-ttl-dip

They are a little dearer but when coupled with the USB adapter it makes a neat little dongle that plugs directly into the computer.

http://www.wiltronics.com.au/catalogue/201038/picaxe-rf-dorji-robots-kits/rf--dorji/dorji-rs232-ttl-converter-board/usb-to-ttl--rs232-board-for-dorji-drf4432d20i-043l1

Just what does "connect to your computer" involve ? Serial ports available? What is your budget? How critical is error free data? What's the local 433 MHz environment like ? BEST YOU FIRST DETAIL YOUR INTENTIONS!

I'd fully agree on Dorji ASK offerings for simple 433 MHz needs (& wireless newbies!), but that's subject to further insights on the application & data rates. See HERE for Dorji insights. Those Futurelec modules are pretty old hat now.

Alert: Wiltronic's superior Dorji transceiver modules can take quite a bit of taming, & will probably be an overkill at such short ranges anyway. However they'd certainly suit USB based setups!

THOUGHT: Have you considered Bluetooth ? Many laptops (& all smartphones) have BT inbuilt now anyway.

At 15m you could maybe even use PICAXE IR data ( perhaps with a few focusing lenses) if LOS (line of sight).

They will have to send and also recieve data.

Click to expand...

This means that the best choice will be a pair of Wireless Transceivers and pretty much rules out the cheap ASK/OOK modules. Bluetooth can be a good option but range could be an issue. 15 meters may be a stretch for some Bluetooth modules.

For a range of 15 meters the RF module does not need to have a lot of TX Power. 10dBm is more than enough and will get up to 200 - 300 meters if needed (Assuming something in the 433MHz band.). The other Frequency option is the 2.4GHz ISM band. In this band there is reduced range for the same given TX power output, but 15 meters might be OK with a module that has 5dBm TX output. Most 2.4Ghz modules are front end modules and require complicated code to set up.

RF Modules are generally either front end modules or serial enabled modules. A front end module communicates with the Picaxe via SPI. These modules require that you set up registers and can be quite complicated, requiring quite a bit of code to get working.

Serial enabled modules are front end modules with an embedded microprocessor. This allow a simple RS232 type serial interface Between the module and the Picaxe, and requires a minimal amount of code to get working. The trade off is higher cost.

I would suggest that a 433 MHZ serial enabled RF Transceiver with a TX output of 10 dBm would be a good choice. There are quite a few choices out there including those from Dorji via Wiltronics. (Are you in Australia or NZ?). But these seem a bit overpriced to me, with a pair of 13 dBm modules costing $45. Don't misunderstand, the Dorji module are excellent, just pricy.

My suggestion would be to look into a pair of the relatively new HC-11 or other CC1101 ( Texas Instruments RFIC) based modules. These are serial enabled and have a range of up to 200 meters. Simple to setup. Cost ..... $20 per pair plus Aus Local shipping.

http://www.ebay.com.au/itm/2-X-Wireless-UART-Serial-TTL-RS232-COM-Transparent-Converter-Module-RF-Radio-/190826220938?pt=AU_B_I_Electrical_Test_Equipment&hash=item2c6e210d8a

Goeytex said:

Cost ..... $20 per pair plus Aus Local shipping.

http://www.ebay.com.au/itm/2-X-Wireless-UART-Serial-TTL-RS232-COM-Transparent-Converter-Module-RF-Radio-/190826220938?pt=AU_B_I_Electrical_Test_Equipment&hash=item2c6e210d8a

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I concur with your system analysis, but that's a confusing ebay ad you have linked, says "2x" in many places, but towards the bottom has

"Please note, this price is for single module, to setup the wireless connection, at least 2 pcs of the modules are required!"

?

The same seller sells a single unit for 11.90 (Aus). ------> http://www.ebay.com.au/itm/200906060741

I think its a safe bet that the previous listing is for 2 modules.

My guess is that the person in charge of posting the ads was sloppy and failed to remove the line from the ad for the single module. With a feedback rating of 99.8%, it does not seem that this seller is out to scam anyone.

Agreed, I'm used to seeing them around $10.

rigidigital said:

One will be connected to my computer thje other will be about 15 meters away. They will have to send and also recieve data

Click to expand...

More information on what you mean by 'data' would help.

'Data' could be 1 or 2 bytes for controlling something or many Megabytes of data for logging or file transfer purposes.

I havent thought out all the details or even how it will work, but im making a start. I will be using smart cards from parrallax to log in/out employees. I imagined the card reader connected to a transceiver so the transceiver on the pc could then use that data to record in a spreadsheet or AccessDB . Im going to make mistakes for sure but that never has botherred me, sorry its 2:20 am. I am not thinking ,time for the blanket show in a few minutes.

And, thx so much everyone for the links for the wifi modules, i have bought two already.

Paired modules such as the ERF and URF are easy to use with the PICAXE, provide a wire-free serial link between the PC and PICAXE and a ready to use solution -

www.picaxestore.com/rfa030

I'd like to buy 2 transceivers as shown on this thread, but I can't find how to ask whether their $20 price is for 1 or for 2 transceivers.
I'm not a member of e-bay yet, so my questioning is restricted (meaning non-existent).
If the price is only for one of them then it is too dear for me just to play about with.
Does anyone actually know whether the $20 is for 1 or two transceivers?

has anyone actually paid $20 and received 2 transceivers?

I have sent a message to the seller to explain / correct the listing. To me it is clearly for 2 modules with a error as previously noted. However, I will post again when and if the seller replies. Here is a copy of the message that I sent.

Dear top_electronics_au,

There are several people in NZ and AU that are interested in these modules. However there is concern because the listing title says 2X, while another line in the listing contradicts that. saying the listing is for only 1 module. Can you please clear this up and correct the listing so that is it not contradictory?

Refer to the discussion in the Picaxe Forum where your listing has been referred to hundreds of potential customers.

http://www.picaxeforum.co.uk/showthread.php?25826-I-need-help-on-buying-wireless-transmission&p=262916&viewfull=1#post262916

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you have a keen eye Goeytex , that seller seems to be confusing. as you said you'd be bidding on two units but you can make an offer as i did, he accepted my offer but complained he wasnt making more than two dollars out of the deal, Here is another link http://www.ebay.com.au/itm/200906060741 Goeytex saw. Again, id just make him an offer.

Hi,

Amy at top_electronics_au quickly replied to my inquiry and confirmed that the listing for $19.90 was indeed for 2 modules.

They also have a listing for a single module for AU $11.90.

Considering the fast reply to my inquiry I would feel comfortable ordering from this seller if I were in AU or NZ.

Here is the reply I received from Amy

Dear Goeytex,

Hey! How are you doing?

Thank you very much for your information

For the Wireless module, we have 2 different listings currently:

the single piece for $11.9/pcs:

http://www.ebay.com.au/itm/200906060741

The 2-pcs listing for 19.9/each 2-pcs with discount:
http://www.ebay.com.au/itm/190826220938

The 1 pcs listing is specially designed for the customers who already purchased before, and want to buy more. Because the module can only work via 2-pcs together

Again, thank you so much for your information Just feel free to come back if you need anything in the future
Have a nice ANZAC day^_^

Amy

Click to expand...

if your soldering skills are not too bad then these modules are worth a look, they cost me $10 for a pair and they are pretty simple to use in "one wire mode", pump it in one end and see it on the other.

http://www.inhaos.com/product_info.php?products_id=60

i had a brief play with mine when they came a while ago and overall i like them.
the seller also sells them via ebay just type in LC1000R in the search box, it should find it.

goeytex also did a writeup for them here:

http://www.picaxeforum.co.uk/showthread.php?24970-Using-an-INHAOS-LC-1000-with-the-Picaxe



tony

There are also those xbee things such as parallax sells. Some have an incredible range if you ever needed it. But you do pay.

Here is an ebay sale for 10 rf units super supper cheap. http://www.ebay.com.au/itm/221409383133?ssPageName=STRK:MESINDXX:IT&_trksid=p3984.m1436.l2649

You get what you pay for.

The modules above are bottom of the barrel, dumb modules with no error checking, no encryption, & no packet handling. The same modules are < 50c each in lots of 20 from AliExpress. Might get 100ft range if you are lucky.

yeah, Goeytex, that's what i guessed and i wasn't tempted !

I hope I'm not hijacking the thread, but I am also looking for some rf modules. I'm trying to put together a long range (upto 5km) mobile data network (with error checking). Stations will be moving, so beam aerials are not an option and data rates are low, typically position and status selected from a limited list of options. Licensing is not a problem for the eventual application, so I can consider any frequency. Output power upto 0.5W would be ideal. I've done some Googling, but not found much which meets this requirement. Radiometrix have one module, http://www.radiometrix.com/content/bim3h. Does anyone have any information or suppliers for such equipment?

Thanks in advance,

Graham

PS Forgot to mention that all stations are transmit and receive.

0.5W might well be ideal, but would it be legal ?

A geniune question, what are the rules for getting such stuff licensed ?

Even 10mw is enough to get you 10-20km, with well matched omni antennas, with good line of sight between TX and RX.

The distance you get is massively dependent on the environment and terrain, whilst 10mw might well be good for 20km with LOS, that distance might drop to 200m or less in an urban environment.

Licensing is not a problem for the eventual application, so I can consider any frequency

Click to expand...

I find that very hard to believe! Are you up with radio regs ? These can levy serious fines on offenders...

Mobile = vehicle ? VHF/UHF sigs. will be blocked by hills, so just what terrain? Those 860 MHz units would especially be troubled if almost ANYTHING was in the signal path. Repeaters maybe? Cellular coverage available? BUDGET ? Are you up with ham radio, which can be used for APRS ( GPS linked packet radio)? Stan.

10mW will go a long way with a truly clear line of sight, but at ground level it is much more limited and we have to consider someone lying on the ground in a sub optimal orientation, i.e. horizontally polarised aerial, so 20dB loss for a vertically polarised receiver. In the UK if you want to use 0.5W, just apply to Ofcom and pay a nominal sum for a licence.
Mobile = man portable. No repeaters, no cell coverage. Budget? Don't know specifically, but upto £150 per station.
I knew someone would question "no problem licensing", but these may well be used unlicensed as there is zero chance of anyone else hearing them, i.e. extreme remote locations. That doesn't mean I am not aware of licensing conditions, but costs are modest even in Europe.
APRS is an option I'm looking at.

Graham O said:

In the UK if you want to use 0.5W, just apply to Ofcom and pay a nominal sum for a licence.

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Dont you also have to meet a pile of certification, testing and build regulations ?

I can think of a device, cheap too, that will do it (0.5W) , but as your planning to use and illegal transmitter .........

At UHF height & a clear signal path is ESSENTIAL. Even the best 10mW units at horizontal ground level (perhaps with blocking vegetation) would be pushed to get 100 metres-even hand held UHF CB sets struggle!

I'm in NZ, but have a healthy respect for a countries radio regs,& can relate all many of strife resulting if even minor aspects are "overlooked"...

Before this goes off on a tangent perhaps specify FULLY just what the application is. There are diverse low frequency systems that just may be an answer.

This is hard work!
In the UK and I would imagine throughout Europe, (I have been through the process in Sweden -£57 for a repeater licence) if you get a licence from Ofcom, for commercial use, then it needs to be for equipment complying with harmonised legislation, hence my wish to buy a module, such as the Radiometrix ones which meet the spec. Build regulations - sorted.
I say again, licensing is not a problem. It can be paid for where appropriate, but in many parts of the world, radios used for safety purposes are license exempt or tolerated. I'm talking to Ofcom about this and they do not see a problem. Licensing - sorted.

manuka said:

Even the best 10mW units at horizontal ground level (perhaps with blocking vegetation) would be pushed to get 100 metres-even hand held UHF CB sets struggle!

Click to expand...

With 1/4 wave antennas, around 1.5M off the ground, the LOS across flat ground, no obstructions, of the RFM22 is 300M or so.

But as we know obstructions, hills and the like degrade range.

Hi,

rigidigital said:

One will be connected to my computer thje other will be about 15 meters away.

Click to expand...

Graham O said:

I hope I'm not hijacking the thread, ....Output power upto 0.5W would be ideal.....

Click to expand...

IMHO it was a serious mistake to hijack an active thread from a (probably) relatively inexperienced OP in a license-exempt band.

Graham O said:

This is hard work!

Click to expand...

So you really can't complain if you get some flack when you are apparently proposing illegal (or at least anti-social) use of the RF spectrum. Like many others, you seem to be asking for a "solution" without specifying what you are actually trying to achieve.

Cheers, Alan.

I was going to write a response, but can't be bothered. I'll get the information elsewhere.

The application is neither illegal transmissions nor anti-social. You have assumed that.

I apologise for hijacking the thread.

Graham O said:

The application is neither illegal transmissions nor anti-social. You have assumed that.

Click to expand...

To be fair, you did say, "these may well be used unlicensed as there is zero chance of anyone else hearing them, i.e. extreme remote locations".

Though it may not be what you meant; it is quite easy to read that as equipment requiring a license being used without one with the excuse that it would not matter. And that would prima facie be illegal.

Hi,

Graham O said:

I'll get the information elsewhere.

Click to expand...

That is of course your choice. But you have had some serious radio "experts" (I am NOT including myself in that description) offering advice here. Personally, I would ask a moderator to move this "hijack" section to a dedicated thread for further discussion. But if you're not going to reveal what you actually are trying to do, then there may be no point.

AllyCat said:

you are apparently proposing illegal (or at least anti-social) use of the RF spectrum.

Click to expand...

Cheers, Alan.

Sigh- I'd posted the response below, but then deleted it as the saga developed.
However herewith, it may save someones life -
-----------------------------------------------------------------------------------------
Graham O: Of course it's hard work! Given the MH370 mystery- especially this tragic ongoing mystery - it's a miracle that well planned low power radio links work at all. I wouldn't be cavalier about "no one will hear my signals". Some radio hams take great delight in "foxhunting" (illegal) transmitters,especially in remote regions. The 1971 Baker Street bank job springs to mind too!

I repeat - best you specify fully the application, terrain, environment, weather, power supplies, needed IP rating etc etc.

FWIW (& quite aside from remote wireless links even being possible!)- here in great outdoors NZ it's long been found that "weak hearted" electronic devices promptly fail after even a minor downpour, river dunking,fumble fingers drop or rough terrain scramble. Human safety in such circumstances requires bullet proof design,testing & certification- legal implications may otherwise arise.

The WandaTrack is well considered here,being especially useful for older types who can't face up to smartphones. Publicity arose recently from the failure of such a tracking device that'd been fitted to a very active wearer with a medical condition. He tragically scampered and searchers only finally located him deceased...

Two devices come to mind. The Hope RFM22BP(Ebay) and the Dorji DRF4431F27/DRF4432F27 (Ebay). These are both based upon a Silicon Labs Si4432 or SI4431 RFIC and can use the same code. These are front end modules so there is no RS232 type serial interface. The interface between the module and the Picaxe is is 3 wire SPI.

I have tested the Dorji module @ 433MHz and the LOS Range with the TX elevated 25ft above ground level was > 8 Km with cheap duck antennas. I did not test beyond 8km. A directional antenna on the RX side should improve range significantly while allowing the TX power to be reduced. A directional antenna on the TX side might get you arrested.

At 500mw TX power these are very likely not "legal" in many areas, so use at your own risk.

Well, it may interest others to fully appreciate the difference in range between an Urban environment and real good line of sight, for UHF reception.

$50SAT uses a RFM22B, 100mW at 437.505Mhz. You can hear the Morse beacon tones from that on a Baofeng handheld when the satellite is 700-800km away.

When I put the same transmitter (literally) on a chair in my garden, the tone went in-audible about 1km away.

So a 800:1 difference, good line of sight to Urban.

Well shown there sir! Antenna elevation for a clear LOS signal path is essential for UHF comms. But at least you had a half metre high chair-at grass roots level performance may have been seriously "half cut". Stan.

I found out more about RF and the different modules than i could ever have on my own. Personally, i didnt consider anyone a hijacker and it even seemed a little silly to accuse people of it or even for some to have apologised !

So I just need to say thank you all for taking part and opening my eyes to so much, thanks every single one of you. Mike.