Independent tests prove lack of frequency hopping with XPS

[brn2fly]

	Quote: Originally Posted by exeter_acres
	Do they hop if you use a123 batteries?

ROTFLMAO nice touch

[exeter_acres]

[brn2fly]

	Quote: Originally Posted by ben_beyer
	I lost a new plane (7th flight I beleive) to an XPS lockout. I just had to watch it's last few seconds before it hit the ground and I was still holding the stick in the proper directions to correct it. If I ever do 2.4 again (I've since gone back to 72), it will be Futaba or JR/Spektrum. Does anyone know if when the primary channel on JR/Spektrum will change to an open frequency once it finds one open? I've heard that the system picks two channels and doesn't move but others have said that when the primary gets knocked out, it goes to the secondary until a new primary is established. Just looking for clarification.

Currently the JR/Spektrum picks two open channels and stays on them. It does not change channels after being turning on. Futaba frequency hops(among the channels). I think it changes frequency 500 times a second.

[Pale Rider]

	Quote: Originally Posted by exeter_acres
	Do they hop if you use a123 batteries?

Nope--they would long-jump

Now with Li-ion--yes they would just hop.

[brn2fly]

	Quote: Originally Posted by Pale Rider
	Nope--they would long-jump Now with Li-ion--yes they would just hop.

But Li-Ions have endurance!

[Pale Rider]

	Quote: Originally Posted by brn2fly
	But Li-Ions have endurance!

nothing that some performance-enhancing substances can't cure--oh wait thats baseball

[brn2fly]

	Quote: Originally Posted by Pale Rider
	nothing that some performance-enhancing substances can't cure--oh wait thats baseball

LOL

[dick hanson]

try Bonerall

[martin18152]

Beware of military radar, frequencies are classified; however fall with in the GHz range. They are very powerful and their scatter frequencies might be a problem. If you are near a military base, I would watch using a non frequency hopping system.

[RH1N0]

XJet,

I believe the XBee-PRO OEM module uses direct sequence spread spectrum and that it defaults to 3 retries before a packet is dropped. So would channel hopping need to be implemented on the XPS carrier board? How long does the module take to change to a different channel? And can it test a new channel for interference while still transmitting on the current channel?

As a general observation, I think it's great when a product is user upgradeable via firmware revisions but the buyer should know, at the time of purchase, if they will be required to regularly update or modify their product. Some people like to tinker and others just want to "fit and forget".

[XJet]

	Quote: Originally Posted by RH1N0
	XJet, I believe the XBee-PRO OEM module uses direct sequence spread spectrum and that it defaults to 3 retries before a packet is dropped. So would channel hopping need to be implemented on the XPS carrier board? How long does the module take to change to a different channel? And can it test a new channel for interference while still transmitting on the current channel?

Yes, the XBee/Pro systems are DSSS and do not have any intrinsic frequency-hopping capabilities.

No, they can't perform a channel-scan while receiving data -- incoming data will be lost during the channel-scan operation.

I don't recall the exact channel-change time off the top of my head but JD has said that MaxStream are modifying the firmware for him so that it can change channels more rapidly.

That would mean existing users would have to return their transmitter modules and receivers for two sets of firmware updates -- one involving new code for the XPS firmware and one for the XBee/Pro firmware.

Given the delays involved in just getting "in stock" items shipped, this could be a logistical nighmare. I hope he gets things sorted before spring so we don't see thousands of XPS users all waiting for their systems to be updated and returned.

I also expect the cost (to XPS) could be significant if everyone decides to get their systems updated -- let's hope they have sufficient financial resources to cover that cost.

However, bearing these issues in mind, I suspect XPS will strongly downplay the importance of such an upgrade -- but I wouldn't wish to risk an expensive model to a system with no frequency agility so I'd certainly recommend that people *do* get their systems upgraded when/if that option becomes available.

[sweetpea]

Could those upgrades be made from the optical firmware device that is being finalized now that several people are testing with?