S500 and radio interference causes random keys or reboots


(Chad Taylor) #1

I have an S500 that I use at a desk used for dispatching. Now and then if the phone is positioned just right it will randomly reboot the phone, access the call log, dial a number or even change menu screens when the two-way radio is keyed up. This gets worse if I set a handheld in proximity to it. The system we are on is a UHF using frequencies from 450.1000mhz to 468.9750mhz. I have found a way to mitigate the problem for the most part by not setting the handheld near it and rerouting the antenna coax for the two-way in a direction away from the phone but it still happens from time to time.

The phone is my only phone so I don’t have another to try it out with. The two way radio system is on a Kenwood Nexedge Digital Trunking system so it checks in with the control channel from time to time on its own.

Are there any other two-way radio users or Amateur Radio operators that have experienced the same thing?


(Tony Lewis - https://bit.ly/2SbDAyc) #2

Wow that is pretty amazing since we have no wireless anything in the phone that would cause that kind of issues. Seems like your radio is doing a massive emissions leak to me.


#3

(Tony Lewis - https://bit.ly/2SbDAyc) #4

Of course we do and we have part 15 certification. But this just seems weird and something bigger is going on with a emissions leak from your radio


(Tony Lewis - https://bit.ly/2SbDAyc) #5

But then again my GSM phone to choose to our Polycom conf phone makes it do weird things to do who knows. Interference is a bitch when it happens.


(Dave Burgess) #6

When I was working in FM, we had a situation where we had two pieces of equipment that were wired “funny”, specifically in the floating ground that wasn’t supposed to float. Not going to get into a lot of detail, but the monitor amp in the live studio was wired such that if you touched the console and brushed your lips against the metal mesh on the mic with the monitor “turned well up” (as in “Dude Looked Like A Lady” was Introing in), you’d get 110v into your mouth.

Double check your grounds.


(Chad Taylor) #7

I agree with the “interference is a bitch” statement as a Ham operator for the past 10 years I have seen a lot of that!!

I have tried to track down all the usual suspects with the two-way and phone: grounding, cabling, rerouting the coax for the two-way etc. That would not explain the handheld issue though. These radios are not your average run of the mill $100 Chinese specials, these radios are Kenwood NX-320 and NX-820 radios that are far superior to what is normally used by Hams and they are on the top end of the quality spectrum for commercial two-ways. So with that in mind I decided to check a few other things out. My cheap FRS radios do the same thing as well as a decent FT-60 dual band radio. When transmitting near the phone it changes menu screens and dials from the recent call list.

I have resolved myself to that fact so I am not upset I was merely just putting it out there as an FYI and not a rant or bitching. lol I will keep the dispatch desk laid out the way I have it and not put the handheld near the phone, problem solved for the most part.


(Dave Burgess) #8

I’m glad all that’s happening is a random “butt dial”. My station manager came in and asked me why I’d just sworn on the air and what was I doing sitting under the rear console holding my face.


#9

I actually had this very issue on a job where we took two S700 to a remote job site. Anytime someone was sitting at my or my co-workers desk and keyed the PTT on radio our phones would either reboot or trigger a BFL some of which are intercom keys. It took about two days to realize that this is why our phones were randomly calling our coworkers across the country.


(ElectsysTech) #10

We have a customer using S505 Sangoma phones. They were reporting a problem with phones going hook and off-hook at random. We finally figured out today that the problem is caused by their Motorola RMU2040 UHF business band radios. If someone presses the PTT button to transmit on their radio and is holding it within <3’ from the phone, the phone will go hook and off hook each time they key up. They can actually answer and hang up calls using their business band radios – cool and not cool.
Sangoma needs to take this to engineering to modify the design of these phones to be more resistant to RF interference. A little shielding around the right component would probably solve the problem.
Antony
ElectSys Tech Sangoma dealer


(Dave Burgess) #11

This is not a new topic. A couple of years ago we (this community) identified this problem and offered several solutions.

Part of the problem is the FCC declaration on who is responsible for preventing Radio Interference. The transmitter is solely responsible for remediation on this topic, so, even though we pressed Sangoma to step up, there (clearly) has not been much movement on this.

The simplest effective solution we found was a metallic spray paint that could be applied to the inside of the phone body. This reduced the interference considerably (down from 1 meter to less than a foot). Other solutions include other Faraday Cage solutions, including metal window screen and aluminum foil.