• This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn more.

RCTimer and HobbyKing 433MHz Radio Telemetry Range

#1
I have the RCTimer telemetry unit on my jDrones ArduCopter running firmware 2.9.1.b. I'm getting a measly range like barely 50 metres. Mostly less. What could be causing this? And what is the range of this unit? How different is it from the HK unit? And is there any option where I can build an antenna for this, and would it improve anything?
 
#3
I have seen that kit. It's been on my wishlist. Can't quite afford it right now :) And how exactly does one go about increasing range with the programming interface? Any other antennae that might be of help?
Thank you so much!
 

tramsgar

Senior Member
#4
Some say that the USB-FTDI module thingy on the transmitter end of that kit interferes a lot with the rx/tx part of the board. If you're skilled at soldering you could try to break out that module to get some distance and/or add filters. If that's the problem, using two air modules (one with tx sw) would work. What does the RSSI say? Seems like dipolar antennas are popular among those who build them, haven't tried that tough.
 

tramsgar

Senior Member
#8
Well USB2 has a data rate at 480 Mbit/s so that's close enough to interfere. At least one clock on that board could cause the interference. Some says they get no interference at all. It may be through the power line if the power part of the USB module is badly designed. Or via EMI. A low pass filter on gnd & acc? I haven't investigated the range on my own kit yet as I just got it. If I had the equipment, like a digital oscilloscope... It's hard to find good sources on this, but I read one recommending just breaking the USB module out with a ribbon cable. Or solder a bypass FTDI connection.

50 m sounds very little even if the problem was the USB module. I'd check for antenna problems, like bad or broken soldering.
 
#9
Let me know how yours turns out. I was looking at thread on the DIYDrones forums http://diydrones.com/forum/topics/r...radio?id=705844:Topic:1007879&page=2#comments
Apparently they could be using 2.4GHz antennae. Soldering seems fine though. No signs of cold solders.
How do I force change the USB speed if I can at all?
I'm studying electronics engg right now, so hopefully in another couple of years I can maybe understand these better :)
And if I were to build a dipole or a monopole antenna, what would be the way to go about it?
 

tramsgar

Senior Member
#12
Put something in the chain that's slow. USB falls back to the slowest common standard. Maybe an old mouse or keyboard? Inferior USB stick or hub? Some versions of Windows can report if your chain is slowed down by a device (as an advice to connect it to its own port). I don't really know of a way to force lower speed in software. Perhaps in BIOS? Or maybe that resets once the OS driver takes over the hardware... Sry, no definite answer.
 
#13
Let me know how yours turns out. I was looking at thread on the DIYDrones forums http://diydrones.com/forum/topics/r...radio?id=705844:Topic:1007879&page=2#comments
Apparently they could be using 2.4GHz antennae. Soldering seems fine though. No signs of cold solders.
How do I force change the USB speed if I can at all?
I'm studying electronics engg right now, so hopefully in another couple of years I can maybe understand these better :)
And if I were to build a dipole or a monopole antenna, what would be the way to go about it?
I tried the one meter range test. I've gotten hold of the HK Telemetry kit 915MHz. At one meter you're supposed to get an rssi and rerssi value of around 200. With the RCTimer unit I'm getting around 117ish and with the HK unit I'm getting 196. So I think it's safe to say that the RCTimer unit has bad/wrong antennae.

Now, the other problem is, my FPV is on 900. Now I'm wondering what to do since I've been wanting to start out with fpv for quite a while now.
 

tramsgar

Senior Member
#14
Telemetry on 915 and FPV on ~900 MHz is of course a bad bet =). But also 433 equipment could cause harmonics in the 900 band so if you use those together you'd probably want to use filters on either or both. David and Chad had a quick tip about that a while ago, I believe.
 
#15
I have the RCTimer telemetry unit on my jDrones ArduCopter running firmware 2.9.1.b. I'm getting a measly range like barely 50 metres. Mostly less. What could be causing this? And what is the range of this unit? How different is it from the HK unit? And is there any option where I can build an antenna for this, and would it improve anything?
Hi!
I had the same issue at the beginning. It was a faulty antenna. Best solution to solve it is to purchase new 433MHz antenna on ebay. No more problem for me anymore!