Independent tests prove lack of frequency hopping with XPS

[Kiwi]

Step 2,

Because I wanted XPS off Ch1 I setup some noise to force it away from the left side of the graph. To do that I cranked up the wireless video cam.

[Kiwi]

Step 3

Then to be sure I had Ch1 fully loaded up I turned on the signal generator to leave no gaps and be sure to force XPS off that first channel

If you look at the upper graph you will see the yellow line showing the duration and the spread. With the signal gen on it really covers about three channels.

[Kiwi]

Step 4.

Turn the Rx on and lets see what it does to try and find the Transmitter.

In this graph again on the upper panel you can see there six yellow and red dashes followed below by a scattered pattern of dots as the Receiver hunts for an answer. Note that there are no transmits from the Rx in the occupied channels are shown in solid yellow.

[Kiwi]

Step 5.

Turn on the Transmitter and get a link.

Here you can very clearly see the red and yellow signal being recorded in this case on Channel 11.

[Kiwi]

Step 6

Now its time to get things moving or hopping with a little bit of luck. What I done here was place the sig gen in traverse and set it running. As this moves across the channels one at a time in a sequential motion slowly sneaks up on the XPS signal. I really figured if anything was going to make XPS move this would as its a rising noise floor and moving slowly, thus giving XPS lots of time to call for a channel change and out run the danger.

Nothing happened. It rode out the interference and never moved.

[Kiwi]

Step 7.

Try another way. This time I set up the sig gen to pulse on the same frequency as XPS was locked into. I figured seeing as slowly raising the noise floor did not have any impact I would hit the actual channel with pulses. Again these were set to 5 seconds on and 5 seconds off. Here my thoughts were it has to move under this scenario as it has thousands of milliseconds and lots of gaps to escape from that demon interference I was firing at it.

The yellow bands clearly show the whacks of interference I was firing at the XPS.

Again it just stubbornly refused to move to a clean channel. It stayed stuck in the mud so to speak.

[Kiwi]

Step 8.

Well there was only one more way to jolt this thing onto another channel and that was hit it with everything. Full on burst on the same channel, no rising floor. I knew this had not worked for others but if I did not try it then it left a gap and room for debate.

So full strength 2.4 on Ch 11 and still it did not move.

[Kiwi]

Well that about does me on XPS folks. I will not say it does not hop channels as there may be a way that it can. But so far I have:

Raised the noise floor slowly
Pulsed on the same channel
Drowned it with interference

And none of those scenarios causes XPS to swap to a cleaner channel.

SO what's my verdict.

If XPS hops channels then please someone show us on this site and in this thread how, why when and where because I cannot force it to do so, no one else has been successful in doing so. I'm buggered if I know how. I'm out of ideas and scenarios.

I personally would not use this system until its proven.

XPS cannot be made to HOP under reasonable test conditions and circumstances that should force a frequency change.

So after all that I turned off the sig gen and yes sir. XPS was still happily firing away on channel 11.

No thank you.

[aviti]

Thanks Kiwi. I read the post above quoting JD on when the system would hop and either it doesn't make any sense or it's way over my head (quite possible as I'm far from an expert). Does anyone else understand what the heck JD is talking about?

[Kiwi]

Tony,

I'm bilingual and I cant understand it either mate.

Its pure waffle without the cream.

[1bwana1]

Kiwi,
Thanks for your efforts, very interesting. Today, XPS posted a response to the frequency hopping questions. I'm sure you read it. What I would like to see is whether the lack of hopping in the situations you tested in is meaningful to us as fliers. If I read it correctly, XPS implies in their explanation, that the only level of interference that would cause their system to fail, would also cause all of the other 2.4 systems to fail. Does the XPS system see through the interference and continue to offer control, or does it lock out. Since XPS seems to be stuck on one channel, if it fails due to interference then you crash. Spektrum has two channels, so I am assuming that it would continue to work. FUTABA FAAST would probably hop right through it and continue to work. I would really like to see tests on each that would prove, what to an untrained user like me, seems obvious.

Thanks,
STEVE

[cadconversions]

Do you have a futaba / spektrum system to try the similar test on? Also, did the XPS system completely lock out during the test or come through? You never really said one way or the other...