Ham Radio knocks out Fire Alarm Radio system

[markspoo]

Let me start that I am from Chicago and am both a fire prevention professional and a ham radio operator. I am wondering if anyone in Public Safety Radio, Ham radio or scanning heard the story below. I am attempting to so some FACT finding.
Thanks in advance.

Tucson Fire Department and the surrounding area had an issue with the AES network. The network was basically down and we had little to no communication with over 1,000 Fire Alarm Systems that used RF. This included nearly 100 City of Tucson owned Buildings.

It started on a Saturday Morning and after 6 days of searching the following was found by one of the Central Station Providers:

"We heard a call sign being transmitted intermittently in morse code on 465.9500 along with the interfering transmission. I send an e-mail to the ham radio operator in tucson that the call sign belongs to (he wasn't answering his phone), explained the situation, and asked that he cease any transmissions (if it was him) or help us determine why. At midnight it appears the interference stopped. We just started checking the few that still haven't check in and so far we have been able to communicate with everything just fine."

Tucson Fire Department will be evaluating using RF as a stand alone transmission method for the future. Has anybody else had one Ham operator knock their system out?


Respectfully

Mark Spoo
River Grove Fire Dept
River Grove Illinois
N9VDQ

 

[DougWare]

We heard a call sign being transmitted intermittently in morse code on 465.9500 along with the interfering transmission.

465.9500 is outside the licensed HAM bands.

 

[buddrousa]

What I would like to know is if this system (Fire Alarm Reporting System) is transmitting alarms using commercial 2way radio on a repeater? Was the Ham Radio Operator using 465.9500 or was it a harmonic from 70CM. Years ago we used 2way radio data modems years ago for a local alarm communications.

 

[KevinC]

465.9500 is outside the licensed HAM bands.

I'm going to bet he understands that. They are probably leaning towards intermod.

 

[buddrousa]

Kevin it could have been a trashy UHF amp

 

[DougWare]

I'm no expert in harmonics, but aren't harmonics based on fractions and multiples of frequencies?

It's entirely possible they had something that was malfunctioning and splattering or outright transmitting out of band.

 

[cajunjerry]

Or he is a ham and on a high power linear on the c b channels
Just because he is a ham doesn't mean he is following the rules

 

[KevinC]

Kevin it could have been a trashy UHF amp

It could have been a lot of things. I was just pointing out that 465.950 MHz being outside the amateur radio band doesn't mean the fundamental frequency causing the issue can't be IN the amateur band.

 

[jwt873]

If the interfering signals were Morse code the ham was probably on HF. 465 Mhz is a long way up from there. That's one heck of a harmonic.. (Although CW and SSB is used on 144, 220 and 432 for weak signal work).

Instead of just shutting the guy down they should work with him to see why the problem exists. If I were causing interference, I'd want to know about it and take steps to eliminate it.

 

[KevinC]

If the interfering signals were Morse code the ham was probably on HF. 465 Mhz is a long way up from there. That's one heck of a harmonic.. (Although CW and SSB is used on 144, 220 and 432 for weak signal work).

Instead of just shutting the guy down they should work with him to see why the problem exists. If I were causing interference, I'd want to know about it and take steps to eliminate it.

It was probably the CW ID of a repeater.

 

[markspoo]

Ok folks so we don't get into who has the biggest or whatever I AM LOOKING FOR FACTS!!!!!!

1. Yes I to think it was a harmonic
2. The repeater ID was identified and that ham operator was contacted and the issue went away.
3. I am hypothesizing (yes a big word) that it was either an out of tune repeater/ duplexer or the headend of the alarm equipment was faulty.
4. I am also hypothesizing that maybe the repeater or the fire alarm monitoring equipment was moved recently and there was inadequate due diligence but the alarm company or the ham or the person that allowed both radios to be that close to each other.

AGAIN I AM LOOKING FOR FACTS or first hand knowledge.

Thanks

Mark Spoo

 

[902]

It might have been a spur. Some base stations/repeaters, like the GE MASTR PRO were notorious for breaking into oscillation when the neutralization capacitor needed to be replaced near the tube socket. I had one that I pulled the ICOM (crystal oscillator module, not the radio manufacturer) out and the transmitter kept putting out 60 Watts of broadband noise.

I used to chase a lot of these kinds of things around when I lived in the NYC area, and they NEVER were on the frequencies they were supposed to be on. Yes, they emitted some energy on the frequency they were supposed to be on, but they also threw out "spurs" or that broadband noise (or both at various times).

These were mostly killed off from LMR service by narrowbanding, but I suppose some ham repeaters are still using things like this.

I should note that they are tanks when they are working properly. But when they're not, watch out.

 

[buddrousa]

Markspoo I was just getting the picture. It makes sense that a 70CM ham repeater with a trashy amp could do what you are talking about also the owner of the ALARM REPEATER may need to look into his receiver as if it may being starting to have a open frontend. The other possible cause is the ham repeater is mixing with a new signal causing the result.

 

[rfradioconsult]

This sounds like a classic Intermod problem, you have 2 transmitters that are mixing and generating a 3rd frequency on the alarm receive frequency. A 2A-B = alarm receiver input. I would contact the ham in question and determine his transmit frequency, then you would know 2 of the frequencies involved and should solve for the 3rd. This would give you a place to start.

There are several sites that you can plug in the values on the Internet to solve the problem. You can carry the exercise even further. Good luck Sherlock Holmes, been there done that.

 

[ecps92]

Lots of Questions to be asked and get answers.

a. Since the Morse was in (likely) FM, it is assumed it was likely a Repeater or link
Does this amateur have a Repeater and what are it's frequencies. ??
It could be 2m, 220, 440, 900, 6m etc

b. Is the Repeater linked ? And what are those Frequencies.

c. Is the Repeater at the same Radio RX Site ?

d. Could it be a bad RX site (don't just blame the Ham)



So many others, but likely we won't know unless one of the Techs posts back here after the investigation is completed.

This sounds like a classic Intermod problem, you have 2 transmitters that are mixing and generating a 3rd frequency on the alarm receive frequency. A 2A-B = alarm receiver input. I would contact the ham in question and determine his transmit frequency, then you would know 2 of the frequencies involved and should solve for the 3rd. This would give you a place to start.

There are several sites that you can plug in the values on the Internet to solve the problem. You can carry the exercise even further. Good luck Sherlock Holmes, been there done that.

 

[Rred]

Mark-
I would think there is great reason to mistrust the FD system, regardless of why the problem happened. Whatever went wrong, it sounds like the system is terribly "frail" if a simple accident or solo piece of equipment can take it down that way. The vendor should probably also be involved in finding the real problem and a real solution for it, if that's even possible.

 

[marcotor]

Ok folks so we don't get into who has the biggest or whatever I AM LOOKING FOR FACTS!!!!!!

AGAIN I AM LOOKING FOR FACTS or first hand knowledge.

You're in the wrong place.

 

[mikepdx]

I'd strongly suggest you contact an experienced LMR professional to solve the problem.

 

[ecps92]

Going back and Re-Reading your Original Post.

Contact the Agency involved for the facts vs a hobby message board :roll:

Let me start that I am from Chicago and am both a fire prevention professional and a ham radio operator. I am wondering if anyone in Public Safety Radio, Ham radio or scanning heard the story below. I am attempting to so some FACT finding.
Thanks in advance.

Tucson Fire Department and the surrounding area had an issue with the AES network. The network was basically down and we had little to no communication with over 1,000 Fire Alarm Systems that used RF. This included nearly 100 City of Tucson owned Buildings.

It started on a Saturday Morning and after 6 days of searching the following was found by one of the Central Station Providers:

"We heard a call sign being transmitted intermittently in morse code on 465.9500 along with the interfering transmission. I send an e-mail to the ham radio operator in tucson that the call sign belongs to (he wasn't answering his phone), explained the situation, and asked that he cease any transmissions (if it was him) or help us determine why. At midnight it appears the interference stopped. We just started checking the few that still haven't check in and so far we have been able to communicate with everything just fine."

Tucson Fire Department will be evaluating using RF as a stand alone transmission method for the future. Has anybody else had one Ham operator knock their system out?


Respectfully

Mark Spoo
River Grove Fire Dept
River Grove Illinois
N9VDQ

 

[krokus]

AGAIN I AM LOOKING FOR FACTS or first hand knowledge.

The facts are that none of us were there, so we can only go by what we read in your anecdote. There are a lot of experienced people here, but we can only give you ideas and guesses, without being able to assess the evidence directly.

I notice that you are in Illinois, and referencing an event in Arizona. Are you involved in the Arizona event, or monitoring the results, as part of an evaluation of prospects for your alarm system?

Sent via Tapatalk