What are normal values for rssi and remrssi? How do I see if I have a hardware problem? How do I tell if it’s radio interference where I am flying?
I bought a 3DR radio and tried to use it. The connection failed when I was only a few meters away. I lost control almost immediately, so I was glad I had a geo fence and my copter did not just keep going up into the sky. If I go away a little bit the green light starts to blink. I tried both TxPower of 11 and 20.
From the documentation I gathered that there are rssi and remrssi to show the status of the radios signal strength at both ends. And that signal_dBm = (RSSI / 1.9) - 127
So right now I have about 100 for rssi and remrssi (-66dBm) at about 3 m distance and if I go away about 5 to 10 meters it rapidly drops to 70 (-123dBm). Is this normal? Engines off, unarmed.
In Mission Planner I can see a connection signal at the top right of the artificial horizon (packet loss?) and if I look at all the parameters below it I can see rssi and remrssi. Are these the right parameters to look at?
Wouldnt it make sense to show the signal in dBm at both ends, so that you know when you are close to a connection loss? Or make this configurable?
[quote=“TCIII”]@ab0032,
What are the frequencies of the radios that you are using?
Are you sure that you have the correct antennas?
Regards,
TCIII Admin[/quote]
I am using 433Mhz and the antennas that came with it.
But now I managed to screw up things such that I dont get the two to connect any more, I tried speed of 250. Guess I will now have to buy a usb cable with ftdi to get the remote device into a sensible state again.
I also thought that maybe I am sending too much data back and forth, could that be? Maybe I have the wrong settings in Mission Planner, which I uploaded to the APM. And now the APM is overflowing the buffers on the radio. Just wild guesses, what I could be doing wrong.
If I have a baudrate of 56k on the com port and ecc on, what should the speed be for the radio? Twice the baud rate of the serial port? What is the maximum baud rate the APM can handle at the other end? Should both ends use the same baud rate? So many questions and so little knowledge on my side.
@ab0032,
The baud rate for the radios is 57.6K.
Does your PC telemetry radio have a USB connector or is it an aircraft telemetry radio?
If it has a USB connector, then it is not a 3DR telemetry radio as that version had noise issues and was eliminated.
You should be using two aircraft telemetry radios, one on the aircraft and one on the PC.
How are you connecting the PC to the ground telemetry radio? USB or USB to FTDI cable?
Since you say that you will have to buy a USB to FTDI cable then the PC/ground telemetry radio must be the USB only version?
Regards,
TCIII Admin
It looks like the 915MHz version in the 3DR shop. I bought it on ebay in Germany because I didnt want to wait for weeks and get it through customs, which is always a real hassle.
[quote=“TCIII”]
If it has a USB connector, then it is not a 3DR telemetry radio as that version had noise issues and was eliminated.
You should be using two aircraft telemetry radios, one on the aircraft and one on the PC.
How are you connecting the PC to the ground telemetry radio? USB or USB to FTDI cable?
Since you say that you will have to buy a USB to FTDI cable then the PC/ground telemetry radio must be the USB only version?
Regards,
TCIII Admin[/quote]
I thought I bought a 3DR but I now suspect I didnt from what you are saying. It would be good if 3DR had a shop in Europe. I thought it looked just like the one in the 3DR Robotics shop, when did they go away there?
Well what can I do now? Get a new ground station radio and throw the one I have away? Dang.
Is there any way to get it running anyways? At lower speeds maybe?
You are aware that the 915MHz radios are illegal to use in Europe/Germany?
In Europe, 900MHz is used by GSM networks and the operators are not happy about interferences.
Modern cellular networks can triangulate sources of interference and the operators tend to report those to the communications regulation authority which will investigate.
In Germany, possible fines go up to 100’000 Euros and - depending on the case - also incarceration is possible.
You are aware that the 915MHz radios are illegal to use in Europe/Germany?
In Europe, 900MHz is used by GSM networks and the operators are not happy about interferences.
Modern cellular networks can triangulate sources of interference and the operators tend to report those to the communications regulation authority which will investigate.
In Germany, possible fines go up to 100’000 Euros and - depending on the case - also incarceration is possible.[/quote]
Dont worry, mine is 433MHz. When I bought it, I believe the 3DR Robotics 915MHz and the 433MHz had the same asymmetric layout for ground an air module.
Anyways, back to the topic, so the FTDI made interference and noise, so it was removed from the radio chip or the radio chip interfered with the FTDI.
Also I read somewhere that USB could also cause noise and that a USB extension cord should be used.
Could that be true?
@ab0032,
confusing questions !!.
Ok ,you have clone 3DR radio bought from ebay and works on 433Mhz. Correct?
The reason for you to mention “it looks like 3DR 915 mhz radio” is so that you can ask for help. Even if it wasn’t you can ask for help or tips. I too have clone and they work well. I am able to prgm them over air.
Tips:
By default they come paired and communicate to each other. Is this your case too?
What were you trying to change/modify when your radiosgot into trouble?
Does your ground radio have USB port?
You don’t have USB-ftdi cable. So I assume your trouble is with air side radio. you need this cable any way if you r in UAV hobby( if not for this case you may need it for other uses). so invest in one.
Read the manual once again and do not change multiple setting at the same time. you will be lost.
Infact you don’t have to change any thing other than port speed/baud rate to match the application. This needs to be done first in com port setting in your computer/laptop to match the radio default rate that come from factory. Once you have communication established with ground radio , switch on air side radio and see the telemetry or any data sent from other radio. make sure you can see it in your telemetry screen/ terminal program. Close this program.
Then if you want to change any setting in telemetry/3DR radio , open the 3DR radio program,
type in the changed setting in both side ( ground side and airside radio screens) and apply it first to Airside radio first and then to ground side. This is important . Once the airside is applied , you may lose the connection to air side, don’t worry, now apply the changes to ground side screen. once this is done, reboot the radios( switch off/on). See if the comms is established.
If you have not done as mentioned above and have applied any changes to ground side radio first then you won’t be able to connect again to airside radio using ground side radio ( on air programming) , your choice is now to reset ground side radio to last working setting or use ftdi cable to program the air side radio with same settings as ground side radio.
Last but most important tip is Patience and persistence. Without which DIY projects will never work. Trouble shooting needs M.meter and patience
Good luck
Good luck.
You are aware that the 915MHz radios are illegal to use in Europe/Germany?
In Europe, 900MHz is used by GSM networks and the operators are not happy about interferences.
Modern cellular networks can triangulate sources of interference and the operators tend to report those to the communications regulation authority which will investigate.
In Germany, possible fines go up to 100’000 Euros and - depending on the case - also incarceration is possible.[/quote]
Dont worry, mine is 433MHz. When I bought it, I believe the 3DR Robotics 915MHz and the 433MHz had the same asymmetric layout for ground an air module.
Anyways, back to the topic, so the FTDI made interference and noise, so it was removed from the radio chip or the radio chip interfered with the FTDI.
Also I read somewhere that USB could also cause noise and that a USB extension cord should be used.
Could that be true?[/quote]
@Morli,
If he has the 433MHz telemetry radios and the PC/ground radio has a USB connector on it, that might explain his signal issue as there was an interference problem on the USB ground radio between the transmitter chip and the USB chip.
I believe that 3DR only sells the 433MHz telemetry radios as aircraft side pairs so a USB to FTDI cable must be used at the PC end. I suspect that the clone 433MHz PC/ground USB radios must have the interference problem that caused 3DR to quit selling them.
Regards,
TCIII Admin
[quote=“morli”]@ab0032,
The reason for you to mention “it looks like 3DR 915 mhz radio” is so that you can ask for help. Even if it wasn’t you can ask for help or tips.
[/quote]
No, I said that because there was a confusion about the version and the layout.
So could I, the problem was that the connection was lost after takeoff a few meters into the air or if I simply walked away a few meters.
Thank you for your long explanation, yes I got that. They were paired and I only started playing with the parameters because I lost the connection at a few meters distance.
I am not quite sure whether I need a 5V or a 3.3V FDTI-USB cable.
I will try a USB extension cord, because I read that sometimes the USB port at the computer causes the interference problem.
I am thinking of cutting the ground module up and inserting a few wires to get the radio away from the FTDI chip if the connection problems remain.
What is the recommended baud rate of the virtual computer port? 115k or 56k?
Does the radio transmission speed need to be higher than the com ports baud rate? (Normally I would assume that RTS and CTS should be used for hardware flow control to prevent buffer overflows, but the hardware just does not use these pins. ftdichip.com/Support/FAQs.htm#HwGen3)
If I use ECC, should I increase the radio transmission speed for the extra bits?
No, the USB-FTDI chip on the board is the problem. It’s creating EMI/RFI around 433MHz. That’s why 3DR doesn’t sell 433MHz modules with USB on board anymore but the air-module with an FTDI-cable.
56k. 115k2 is for direct connection of the APM to the computer.
Additionally, you should get rid of the rubber duck antennas. The China-clone rubber ducks are really bad.
jDrones have some nice 433MHz antennas.
Hi,
I have solved the problem. The antennas were bad. I ordered new antennas and that solved it for me.
Not both usb ports have the same quality, one works better than the other and it is also better with a usb extension cord.
