Flyojumper

Does anyone know the average range of the 3 types of radio? Does it also vary a lot between models or do all AM radio pretty much have the same range, all FM the same range, etc...
Some manufacturers reported range would be nice (or even better if it was an independant review source)
Thanks.

Nomadio_Sales

Nomadio is getting 1/2 mile now @ 100mW output power
Spek is 10mW output

Flyojumper

Thanks but is the range directly proportional to the output power in mW? If so, I doubt it would be a linear relation, would it? (that would mean the spektrum only has 1/20th of a mile range...)

bentgear

Not sure of the range, but I do know a good quality unit of any type will exceed your ability to view a 1/10 scale RC vehicle and have visual control.

Ed M.

Infinite Gundam

At 200m and at level ground, it would be difficult to make head or tails of the R/C, so I think range isn't really an issue with ground R/Cs. No point having 1/2 mile range when you couldn't even see the R/C but sure makes you feel more secure.

Flyojumper

Yeah, I agree with you guys on that but I do see posts once in a while of people using FM and getting range issues past only 50m, so I'm starting to think that even FM doesn't really have great range... (or at least some FM systems?)
I'd be way satsisfied to have 150m ish range max (500ft) but it seems like not all systems are capable of even that so I thought I would try to gather up as much info as I can on the subject.

bentgear

I would say many or most systems are capable, but sometimes due to installation problems or prior crash damage or "man this thing is dirty it sure does need to put under the water hose" the end result leaves a lot to be desired.

Ed M.

Nomadio_Sales

Not all radios are the same. Most 75MHz or 27Mhz in the USA do not even come close to MAX allowed potput by the FCC because there is no need to have that much power.
However, on 2.4 Ghz it is a BIG issue to put out max allowed power because 2.4 GHz is an open band with loads of traffic using the bandwidth. Thus the louder you are the better.
Not so much of an issue so far because the entry level 2.4 GHz systems on the market are DSSS not FHDSSS (aka hoppers) once more hoppers are in the field you will notice your DSSS radios range will drop and the response time will slow due to the receiver having to take time to filter out the noise from the Hoppers. You may already see this if you have a wireless network a blue tooth and some other 2.4 GHz traffice near your DSSS radios.

Flyojumper

lol @water hose comment

However, the higher the basic "average" range is, the higher the range on even a crappy setup should be, so aiming high at first can only be beneficial since it would allow you to still achieve good range under less than optimal conditions.
BTW, is the range/power of the signal also somehow proportional to how glitch resistant the system is? (BL systems, metal to metal contacts from aluminium parts, etc...)

mattnin

The lower the frequency, the higher the range. Also the higher the power output, the higher the range.

Typically, AM radios have a lower frequency than FM, so they can have a higher range. However, AM radios do not have the clarity of an FM radio. Spektrum is a form of FM radio but usually in a much higher band, 2.4GHz.

So a radio with 2.4GHz transmitting frequency requires more power to achieve the same range as a 75MHz radio, and a 75MHz radio requires more power to achieve the same range as a 27MHz radio.

Nomadio_Sales

Great explanation!

Flyojumper

Thanks, great explanation indeed!
Do you know by any chance the reason why the lower frequency result in longer range?
So basically, the best chance for a high range and low glitching radio would be a FM radio at 27Mhz right? (low frequency and high signal resolution due to FM). (given that the power output doesn't vary too much from a radio to the next)
From people's experience, does glitching still occur with FM or is it a rare occurence? (from what I've read it seems there are 3 forms of electromagnetic interference that cause glitching: motor/ESC, metal to metal contact and outside causes like powerpoles, etc... which of those 3 are best prevented by FM?)

mattnin

Without getting too much into the math, here is how it works.

Every radio wave is affected by Earths surface impedance and its attenuation in free space, among other things such as reflection, refraction, and diffraction. Most importantly, impedance and attenuation are directly proportional to frequency. The total impedance and attenuation of the radio wave increase per distance. All these factors combine to reduce the signal strength.

Flyojumper

Alright, thanks.
Do you know what's the advantage of higher frequency versus lower then? (there must be one or else why would the new systems be on 2.4Ghz, right?)
Also, most FM radios are on 75Mhz, do they only pick that over 27Mhz for the larger channel choice? (for someone who is not concerned with channel choice, it makes the most sense to use 27mhz then?)

YakPak

Guys,
Could someone explain the difference between FM and PCM. I am thinking about a Futaba 9 channel super and not sure what advantges PCM has over FM.
Thanks for your help
YakPak

Infinite Gundam

PCM is supposedly more resistant to interference than PPM (aka normal FM). Also I read that most PCM systems come with built-in failsafe (my 3PK does), which is not normally available in PPM systems. Do a search on PCM in the general radio forum, should answer your questions.

SManMTB

[link=http://www.aerodesign.de/peter/2000/PCM/PCM_PPM_eng.html]PPM vs. PCM - All you need to know.[/link]