Jump to content

"Trainer signal lost/recovered" with wireless buddy box


Allan Bennett
 Share

Recommended Posts

I've created a wireless buddy system using an X4 receiver in the module bay of my Taranis X9D Plus from this how-to.  It's working fine except for the fact that it keeps losing its link, with "Trainer signal lost" message, for a split-second several times during a flight.  It's not an issue with the fixed-wing trainer model I'm using because when it happens it just means the model is under the instructor's control for that time, and all the student sees is a slight delay in response to whatever control input he was giving.

 

But I now want to use it with a racing quad, where such a momentary unintentional loss of student control is more likely to lead to a crash.  Any idea what might be causing the loss of signal -- the student and I stand a couple of metres apart, so I don't expect it to be swamping, but maybe the single antenna on the X4 is the problem?  Any known history of this kind of issue?

Link to comment
Share on other sites

I was going to suggest swamping but as you say the Tx's are 2 meters apart so that seems unlikely.

 

I have done similar with my Jumper T16 Pro using a Delta (Futaba / Frsky) and a Orange (Spektrum) receiver (in swappable module cases) both of which have 2 antennae and do not seem to suffer from this issue so I would question the orientation of the trainer Tx antenna and the receiver antenna.

 

Does this happen particularly when the student rotates to view the aircraft, that may give a clue to the blanking of the signal?

Link to comment
Share on other sites

Both trannies have good power Denis.  I'll check the XM receiver power connection though.

 

Since the XM receiver only has a single antenna I did wonder if putting my student's antenna pointing up (to match the receiver antenna) would help, but in the workshop it made no difference.  It happened in the workshop today while I was setting another model up to work with the buddy box.  As someone at the field pointed out today, at that kind of range (say 2 - 5 metres), antenna orientation and bodies in the way of the signal really shouldn't make a difference.

Link to comment
Share on other sites

To put it into perspective the Multiplex wireless system is either a small din plug unit that plugs into the tx or a very small brick that fixes inside the transmitter, neither of which has any aerials on them and they just work, so i don't think it's the single aerial on the receiver.

 

As Denis says, I would look at the XM receiver power supply and work from there, can you log the power supply to this receiver on the student transmitter?

Link to comment
Share on other sites

That's a good point Frank.  I hadn't thought about logging the XM on the student Tx -- I'll have to make sure signal strength and battery votage are 'discovered' before I use it next.

 

Oops, seems I can't do that.  There's no RSSI indication received from the XM.  

Edited by Allan Bennett
Link to comment
Share on other sites

Could it be the master transmitter swamping the RX inside it? When my Dad made a wireless trainer setup for his X9D he used a longer wire from the module bay so he could mount the RX and a separate (small) power supply in a box clipped to his belt to avoid this type of issue. I would start there with your troubleshooting.

Link to comment
Share on other sites

I flew again this morning with my grandson on the buddy box, having first checked the connection of the XM module to the pins in the module bay, and the alerts continued at maybe 30-60 second intervals.  I've been checking this out again this afternoon, and following are my observations:-

  1. Voltage at the pin in the module bay is 7.65, which is well within the quoted acceptable range for the XM receiver (3.5 to 10.0v)
  2. When I get the "Trainer signal lost" alert, I can now see that the XM receiver loses its bind with the 'slave' transmitter -- the green light goes out for a split second, and sometimes the red light comes on for a split second
  3. Even with the XM receiver out of the transmitter, and powered by a separate 4-cell NiMh pack, it still lost bind, though not as frequently as when it was installed in the trannie
  4. Using the SBUS output from an X4R receiver instead of the XM resulted in zero "Trainer signal lost" events over a 15-minute test period.

In light of MattyB's comment above, I'm going to re-check with the X4R receiver fully inside the module bay, rather than half in/half out that I had in today's test.  If swamping is the problem, would lining the module bay with conductive material (foil?) not alleviate the problem? 

Link to comment
Share on other sites

The X4R has passed my tests -- 15 minutes without any "Trainer signal lost", including taking the master transmitter round the back of the house with the slave still in the garage.  So I've now made it permanent.

 

It's the pinless version, without its cardboard casing, and is attached by a narrow strip of sticky foam tape at either end, leaving the main processor uncovered.  After taking the picture two bits of tape were added to make sure the antennae are away from the exposed electronics, and don't move.  I've used a 5-pin plug to reduce the risk of me mis-placing it when plugging in.

20210810_152332.jpg

Link to comment
Share on other sites

  • 2 weeks later...

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...