glitching/cogging on new 4.5

[BrianG]

Originally Posted by JThiessen

Well we tried a few things tonight:
I replaced and relocated the the traxxas reciever with another traxxas reciever and the result was the same.
I then put three ferrite rings on several different wires (ESC-Reciever wire, motor wires, and sensor wire). Same result.
I then put my 2.4 Spektrum on it, and that ran good.

So this brings up serveral questions:
1) Is this an expected upgrade for people when they purchase one of these? Most of us (the sick ones on the dark side) already have them, but there is a large population of RC'ers who save avery penny just to get this $300 piece of speed and justifiably cant afford to drop another 300 on a 2.4G radio system. I've run all of mine with the stock TQ-3 system, with no issues - is it a random thing?
2) I found one solution to the issue (2.4). I didnt find the actual problem. Does anyone have any experince with 75Mhz FM? I'd like him to be able to try that before looking at the 2.4G stuff. I know just the difference in AM to FM radio (yeah, the one in your car!) is huge. Maybe this is a better/cheaper solution.

NovakTwo, I know question 1 is kinda putting you on the spot (if you choose to respond). My intent is to get a feel from the members here on this, but would also value your feedback.

It does seem hit-or-miss with the stock TQ system (probably mostly miss), but doesn't surprise me that it didn't work.

With the tests you did, you eliminated noise being induced on the throttle/BEC lines. Putting ferrite rings on the motor wires is pretty much useless.

The only other things you could try is 1) use a capacitor (1000uf+ 10v+) in an unused receiver slot, and 2) use a receiver pack to eliminate the BEC causing problems. But to me, it sounds like the noise is coming in through the antenna.

BL motors/wires are producing lots of noise because of the current they are pulling. Not only is it producing the noise at whatever frequency it is running at, but also harmonics (mutiples). So, there is all kinds of noise.

If you look up AM, you'll see that the signal rides on the top and bottom (amplitude) of the carrier radio frequency. Upon reception, the radio simply filters out the RF portion leaving the control signal. Unfortunately, noise affects the tops and bottoms and washes out the good signal. The reason why some TQ systems work ok and some don't could simply be the crystals being used. If the harmonics of the BL noise is close to the crystal frequency, it will be affected more. The filters in a radio are pretty narrow banded, so the further away the frequency (and the harmonics) are, the better. This assumes it's not just an issue with RF washout.

FM varies the frequency of the RF in proportion to the embedded signal. Upon reception, the radio chops the tops and bottoms of the RF signal (where the vast majority of the noise is), and decodes the shift in frequency to get the control signals. However, even though FM is much better at rejecting noise, it can still have issues if the noise is bad enough. 75MHz FM is further away from BL system noise, so it should work better.

2.4GHz systems are all together different. They are packet-based and use pretty complex dsp to verify and error-correct. Not only that, but the ferequency is wayy higher than the noise from the BL system, even with the harmonics. These systems may be more expensive, but you could get one that will control several different vehicles with just the addition of another receiver. Totally worth it IMO, and that's not even counting all the extra bells and whistles of a good system.