Wireless modules FCC approved

[mackrackit]

I like the LINX products. Buy from Bruce.
http://www.rentron.com/PicBasic/RemoteControl.htm

Generally speaking, the lower the frequency the longer the range given the power is equal at the antenna.

The higher freqs have the advantage of being able to pass through small openings. So it is harder to block the signal. Sometimes increasing the effective range over the lower freqs.

As far as FCC goes, it is a good idea to read and maybe understand Part 15 of 47 CFR.

Some frequencys are legal only at certain powers.

Make sure you use an antenna that is matched to the frequency being used. Dave Houston has good info on his site. Worth a read.
http://davehouston.net/

[Michael]

Thanks.

Some of these (I think) don't require an FCC lab test if put into a product though....I'm interested in something like that because ALL xmtrs (if sold as a product) require FCC approval, right?

I'm not even sure my Xstream are like that.

Just discovered the Xcite -- didn't know about them -- only 40 bucks.

I know there are some modules out there that you can just put in a box that are already FCC approved.

Can't remember where I saw them.

[Michael]

Also -- If you had a choice, everything else being equal....

In a typical modern office building with a lot of steel construction etc would you...

2.4ghz at 50mw

or

900mhz at 100mw

?

What's the general consensus on that?

A real difference or 6 to 1?

[dhouston]

AFAIK, anything sold assembled and ready to use requires FCC testing. The testing is expensive which (in part) explains the high cost of pre-approved modules. Even receivers require testing - it's not only transmitters. You really need to read the Part 15 documentation.

• http://www.fcc.gov/oet/info/rules/

Her's a link with some data on indoor propagation.

• http://sss-mag.com/indoor.html

[Archangel]

Higher the Frequency, the more line of sight the signal becomes, lower the power the shorter the range, that said the higher Frequency units might be a little less affected by noise.

[Bruce]

Even if you toss a pre-certified module into your product, it will most likely still need FCC
cert before you can sell it. Contact one of the certified test labs if you aren't 100% sure.

These guys are one of the best http://www.celectronics.com/

The finished product (even if it uses a pre-certified module), may still need final certification
of the finished product before you can legally sell it.

An FCC certified test facility will tell you straight-up if your product needs further FCC cert.

They will tell you without charging you for the info, and it's worth the effort.

[earltyso]

I have looked into FCC testing myself, only 3-5k if you've got spare change.
Linx Technologies has got some great material on the subject.

After looking through LINX technologies website and making my list of (should have learned this in college EE Communications) questions I called LINX to ask the same kinds of questions you have been asking. Everything posted so far sounds in line with what I was told my the antenna factory/ linx rf modules guys.

One thing to consider is what kind of data are you sending?

Continuous? Intermittent?

900Mhz alows for continuous data but 433-434 Mhz does not. If you are just using rf modules for hobby work or you don't care about FCC rules (you obviously do) you can just send continuous data in a loop at lower freq with lower cost modules from Linx.

Also most of the rf modules require line of sight applications to get the full range advertised by the companies making them.

I admit that I have limited knowledge as I have only been designing with rf for a few years now. So far I have used the LINX KH2-xxx-xx & LR-xxx-xx modules both at 433Mhz. I was cheap and did not buy the prebuilt development boards. So to save my time/money/heartache from a wasted prototype.... I called LINX with LOTS of questions about laying out my ground planes, rp coax connections, etc before having my PCB's made. Taking my time and calling their tech support was worth it. I

totally recommend reading all you can from their FCC dowloads, rf for tech challenged, antenna theory manuals and give em a call. The last guy I spoke with (at linx) was an rf communications vet of 25 years in IRAN, IRAQ, CANADA with military and non military rf design experience. They know their stuff! Hope this helps!

[earltyso]

Just thought I would throw in a plug for Bruce @ Rentron,
I bought my first RF modules in college (4 years ago) from their website and I was very impressed with the service I recieved and variety of low cost rf parts/ examples they offered.
Great job guys!