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Old 04-30-2007, 03:26 AM   #1
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Default Spektrum Radio Cross Linking?

Hi all,

New here , and after some help.

I was racing over the weekend and had some bad interference with my Futaba 3PK-S on practice day so a friend told me to try switching from a normal RX to Spektrum. Put the system in the car and had no more problems

Come race day the car was good until racing began, and the car decided to just accelerate at random points around the track when I had already lifted off. Another guy running a 3VC with Spektrum was also having the same trouble, so I switched off and his car went back to normal

Has anybody ever had this or know what could have happened? We both re-paired our cars after the race and the problem didn't come back but really don't want that to come back and mess up a run again!!

We both had the original light grey transmitter modules and the smoked grey RX's if that makes a difference
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Old 04-30-2007, 03:59 AM   #2
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Quote:
Originally Posted by DeLaSoul
Hi all,

New here , and after some help.

I was racing over the weekend and had some bad interference with my Futaba 3PK-S on practice day so a friend told me to try switching from a normal RX to Spektrum. Put the system in the car and had no more problems

Come race day the car was good until racing began, and the car decided to just accelerate at random points around the track when I had already lifted off. Another guy running a 3VC with Spektrum was also having the same trouble, so I switched off and his car went back to normal

Has anybody ever had this or know what could have happened? We both re-paired our cars after the race and the problem didn't come back but really don't want that to come back and mess up a run again!!

We both had the original light grey transmitter modules and the smoked grey RX's if that makes a difference

As far as I know, Spektrum searches for a free channel, negotiate that with the paired receiver and connect. What could had happened is that you both were far away enough when you turned on your radios, so at least the second spektrum connected didn't acknowledged the other first, thus negotiating the same channel with its paired receiver.... when you get close enough, that happened...

I should be solved without further pairing, only turning on a off both radio and receiver....

Please RCGaryK, correct me if I'm wrong...

cheers,
al
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Old 04-30-2007, 02:13 PM   #3
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Quote:
Originally Posted by rampal
As far as I know, Spektrum searches for a free channel, negotiate that with the paired receiver and connect. What could had happened is that you both were far away enough when you turned on your radios, so at least the second spektrum connected didn't acknowledged the other first, thus negotiating the same channel with its paired receiver.... when you get close enough, that happened...

I should be solved without further pairing, only turning on a off both radio and receiver....

Please RCGaryK, correct me if I'm wrong...

cheers,
al
Yeah, not the case. If you didn't have to bind the receivers you would be correct, but the binding process makes the receiver ignore any other signals from any transmitter that does not share that GUID code. Additionally, the collision avoidance software would prevent the two units from being on the same frequency. If they were, then it wouldn't have been an intermittant problem.

DeLaSoul, were these new units that you used or items you borrowed from someone else?
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Old 05-01-2007, 03:01 AM   #4
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Hi RCGaryK,

It was my transmitter module, but i borrowed the RX. I paired them up away from the track and they seemed fine on the Saturday and again in practice on the Sunday.

The guy I borrowed the RX from was also in my race, but he never had any problems (he runs a Helios).

Dave
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Old 05-01-2007, 02:25 PM   #5
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Sounds like both Spektrums ended up on the same frequency. Its not supposed to happen but it can. Once the transmitter has selected a channel it doesn't change unless you power cycle it.
Technically two Spektrum systems should be able to operate on the same channel at the same time - this is one of the great features of "spread spectrum". In this case it sounds like you were basically jamming each others signals similar to what happens on a traditional FM system. The Spektrum receivers would not have responded to packets from the incorrect transmitter but they were probably having problems decoding the packets from the proper transmitter. I have noticed the protocol Spektrum uses is very basic, when you're near the range limit or suffering from interference the receivers can get confused and swap channel data by mistake. The throttle channel may have been seeing the channel 1 or channel 3 position data instead of the proper channel 2 data.
If it ever happens again power cycle one of the transmitters and the problem should go away.
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Old 05-01-2007, 03:31 PM   #6
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Quote:
Originally Posted by DeLaSoul
Hi RCGaryK,

It was my transmitter module, but i borrowed the RX. I paired them up away from the track and they seemed fine on the Saturday and again in practice on the Sunday.

The guy I borrowed the RX from was also in my race, but he never had any problems (he runs a Helios).

Dave
Was the module new?
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Old 05-04-2007, 09:23 AM   #7
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Hi,

No the module is about 18months old (maybe a bit more)

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Old 05-04-2007, 01:12 PM   #8
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OK, might have a solution then, but you will have to send your module in. If your unit is equipped with the shorter coaxial cable from the antenna to the RF board, that may have caused the issue which is totally seperate from the other person there on Spektrum. The shorter lead was actually routed over the RF board which could cause issues in the past. The new antenna remedies this.
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Old 05-05-2007, 12:17 PM   #9
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Okay thanks RCGaryK, I will send the unit back the importer for checking.

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