DIY RC radios?

Long ago and not so far away, RC electronic kits and DIY plans etc. were common. Not today. It's still possible, but the imported TX & RX units and price make it not worth the trouble and time, unless you have a very special application in mind.

More or less the same thing has happened to model RC planes. You can build from a kit or plans, or buy an "ARF" plane for less than it might cost to build it from scratch.

I started building a system based on a Freescale 802.15.4 Eval board set, but work got busy and I never finished it.

BobH

and a thought has occured to me.

For what you want visit

This is Gordon Anderson's web site for an advanced programmable encoder, receiver, etc. Also join the YAHOO group group is the online support for the ACE MicroPro 8000 and Gordon's Micro Star. This group has a lot of single stick users and the current membership is over 500 by members world wide.

You will have to get it certified before anyone will let you use it at an AMA sanctioned event or at an AMA club field.

-- Ray

Ray Haddad wrote in news: snipped-for-privacy@4ax.com:

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Did you perhaps miss that line? or do you mean something else?

Brian

Just because the components/subassemblies are certified does not mean the end item is certified. For example, having the transmitter module certified without the pulse circuitry driving the transmitter can be a problem. (At least it has been in the past.) Admittedly, the FCC has relaxed standards here and there. If and how this might come into play with RC transmitters, etc. I don't know.

Obviously, it's possible to design a transmitter module so that the pulse levels fed to it do not have any impact on FCC considerations.

If the modules in question are designed for serial data ("PCM") transmission then the nature of the data going in won't change the certifiability of the module -- basically, the module will take care of that.

"if".

Tim Wescott wrote in news:zLqdnV1m2MtH6U3RnZ2dnUVZ snipped-for-privacy@web-ster.com:

"IF" is correct. The modules have digital, analog, and serial lines. Also, one of the marketed applications right on the document sheets is "remote control". So I would be using the module within it's design and intended application. All it's doing is sending/receiving the data. To the module, what the data is is irrelevant.

The finished product would need certification if I were to market it. That I do know. But I'm not planning on that anyway.

What I was really wondering was if there was some sort of AMA certification. But, that kinda doesn't make sense because then all the radio's we buy (spektrum, futaba, etc...) would be marked as such, would they not? I've never seen or heard of such.

I can certainly understand if there was concern over the reliability of the radio for safety's sake. But that can be demonstrated on the field with tests, which I'd be doing before risking a plane anyway.

Another note, I am currently studying for my ham license. I already know that once I have that I most definately can legally do what I intend. One of the privileges of an amateur radio license is the ability to design, build, and use your own equipment. And that includes telecommand (radio control) and telemetry. Heck, I could even use frequency bands and power levels that are otherwise verboten.

Brian

But you can only bring what you're doing under the banner of amateur radio usage if it's a mode and frequency combination that's approved for your level of license. Even if the 2.4GHz band is approved for amateur use, if you're going to transmit spread spectrum on it it has to be of the sort that the FCC approves -- and the last time I looked, they really only approved of "toy" spread spectrum for amateur use.

I believe that it's possible to use a module's certification in some circumstances, if all the legal and technical i's are dotted and t's are crossed. I'd check with the module manufacturer for clarification, or if you're feeling bold find the appropriate CFRs and see if they make sense to you.

Go ahead and fly without a gold sticker, mate. I didn't miss the fact that the COMPONENTS are certified but you seem to be ignorant of the FACT that the entire UNIT must be certified once complete.

-- Ray

Tim Wescott wrote in news:DNydnQIWcojcCU3RnZ2dnUVZ snipped-for-privacy@web-ster.com:

I will do that. I am open to being in error. I don't claim to "know it all", but there are a couple things in this regard that I do know that I know, and I don't think I'm the only one possibly misunderstanding.

I'll let everyone know what I find.

Brian

OK. I have done my homework and here's what I have found. It took some time to find the appropriate code sections, but I have experience searching through CFR's related to my laser hobby. I didn't mind doing it since, as previously posted, I am working on my amatuer license, so I took this as a learning exercise.

In a nutshell, I can do what I plan to do with this module without the need of any further certifications or licenses beyond that which the module already has. At least as far as the FCC is concerned.

It needs to be noted that the regulations I found are the same regulations that permit us to buy and use existing

2.4 Ghz radios such as those made by Spektrum and Futaba. Only one regulation I mention below is specific to making the radio yourself.

The AMA may have its own requirements, but since I do not currently fly at AMA fields* or AMA sanctioned events, it's a non issue. Should that change and I desire to use a DIY radio I would of course consult the appropriate AMA authorities in advance.

(*)I have access to a large private field with permission to fly there.

DETAILS

The RF module in question operates in the 2.4 Ghz band and is compliant with part 15 of FCC regulations as a class B digital device and has been issued an FCC ID. This ID is issued by the FCC upon verification of the devices compliance with FCC regulations. I verified the the validity of this ID # through the FCC website.

The manufacturer specifications state that the device works on 2.400 to 2.4835* Ghz at 100 mW of power, using frequency hopping spread spectrum across 16 discrete channels.

47CFR2.106 allocates this frequency band for amateur use under the rules of part 97.

47CFR97.215 allows the use of amateur frequencies for the control of model craft limited to 1 watt of power.

47CFR18.301 defines this frequency band for ISM use (industrial, scientific, medical).

47CFR18.203 describes the requirements necessary for a device to be granted this designation by the FCC.

47CFR part 15 governs devices which may be operated without a license.

47CFR15.247 permits and describes the use of spread spectrum frequency hopping on these frequencies.

47CFR15.23 states that authorization is not required for home built devices for personal use that are not marketed or made from a kit, although they are still subject to the rules under 47CFR15.5 dealing with interference.

(*) The online documentation actually states 2.400-2.485. I have informed the manufacturer of their typographical error. I verified the frequency range with 47CFR2.106 and checked the FCC statement in the manual of my existing

2.4 Ghz radio which states 2.400-2.4835.

Brian

Nobody mentioned the FCC. I just said it had to be certified before you could use it at an AMA field. You exploded and did the rest all by yourself. But you did learn a lot. Good on ya!

-- Ray

Certified by who? To what criteria? For that matter, to what end?

The AMA? They're in the business of certifying radios? That's news to me!!

The FCC? That's exactly the 'homework' he did!

So what governmental or non-governmental authority were _you_ citing when you made your -- unproven -- claim that his radio had to be certified before he could fly it at an AMA field?

First, under the aegis of Amateur Radio, you are permitted to do things a bit differently than everyone else. Next, as long as you can satisfy the current FCC requirements, you should be good to go. Just a few years back, Mfrs had to have transmitter modules approved for use on specific transmitter models.

Evidently that changed somewhat as part of the 2.4Ghz authorization.

I also don't see where Skywise exploded. He didn't get into calling anybody names or anything. He just did research on the subject and reported what he found.

Chuck wrote in news:KBmAo.5971$ snipped-for-privacy@newsfe13.iad:

I didn't research for when things changed, but I thought I saw something about 2.4 going back to the early 80's.

But basically, 2.4Ghz is one of those bands set aside for folks to use for limited purposes and limited power without a license.

Marketing a device of course still requires FCC certifications. But we're talking strictly the home hobbyist doing something on their own.

In fact, let me quote 47CFR15.23 in it's entirety since it includes justification language.

§ 15.23 Home-built devices. (a) Equipment authorization is not required for devices that are not marketed, are not constructed from a kit, and are built in quantities of five or less for personal use. (b) It is recognized that the individual builder of home-built equipment may not possess the means to perform the measurements for determining compliance with the regulations. In this case, the builder is expected to employ good engineering practices to meet the specified technical standards to the greatest extent practicable. The provisions of § 15.5 apply to this equipment.

Section 15.5 refers to interference issues, which anyone who has read the FCC label on a product may find familiar - that a device must not cause interference and must accept interference from other devices.

This has been an enjoyable exercise for me, especially since, as I posted previously, I am working on getting my amateur radio license. As I progress I am going to become quite familiar with these regulations.

OH!!! I almost forgot. I had also contacted the manufacturer about this as well. Since the module is already compliant, I would not be required to perform additional tests on the entire unit in order to obtain certification. But again, that would only be necessary should I market the device. But it would make it much easier for me to do so!

Brian

Skywise (Brian)

Thanks for doing the research. You are entirely correct, as long as the RF deck has been certified by itself to the FCC, it is legal to use anyway you see fit. I fly my own homemade transmitters on the ham bands and on the 2.4 GHz band. The transmitter band is what ever module I plug into it at the time.

Further, If you research for example the Futaba 9C transmitter, it says that the 72 MHz modules can only be used in the Futaba transmitter and not in other transmitters. The only place it says this, is in their operators manual which was included as part of the certification.

However, if you research the Hitec Spectra (50 channel 72 MHz RF deck), it was certified by its self. At one time they even advertised it for other transmitters and then backed down on that. But the certification was not changed. You decide why they changed their mind.

All of the removable 2.4 GHz decks I know of are certified by themselves for any transmitter that they will plug into.

I don't know where Mr. Haddad is coming from as far as AMA etc is concerned. I CD AMA sanction fly in's and your transmitter would not be a problem.

I have held a ham ticket and a commerical FCC ticket for more than 40 years and have been tracking this very subject for tha amout of time.

If you did decide to market a transmitter you would need to certify to part 15 about the encoder/transmitter only since any RF module you would use would already be certified. But, as you found, if you make 5 or less for your own use, that step is not necessary.

Good luck on your venture.

Dan

You really don't know or are you just trying this on, Tim?

-- Ray