scanner interfering with 2 way radio transmission?

[chillim]

Hey all,

I have been doing some online research on digital scanners and one of the manuals mentioned something about how scanners emit radio frequency energy and how that can interfere with radio transmissions. Does this mean that the security guard in my apartment complex may possibly have trouble with his 2 way walkie talkies because I am scanning? I thought scanners are supposed to fly under the radar so to speak -- no one knows you are scanning. That's the beauty of the whole activity. Can anyone one of the experts here enlighten us on this subject? How serious is this radio transmission interference? How easy is it for someone with 2 way radios to know that you are scanning? What can I do to minimize the signals my scanner emits? Thanks.

 

[SAR923]

Do you know this is happening or is it just a concern? Assuming the guards are using any kind of quality commercial radios, scanners cannot emit enough RF to interefere with a two way radio. I rode in a patrol car for a lot of years with both scanners and commercial grade radios. I never had a problem with the scanner interfering with the radio but broadcasting when your scanner is on the right frequency brings a whole new meaning to the word "feedback.".

 

[jim202]

To give you a first hand story, I had to track down a source of a scanner causing a problem to
a police radio system back in the mid 80's. Seems like this person obtained a new crystal
controlled scanner to listen to some of the local public safety frequencies. Seems that one
of the crystals was causing enough energy to be radiated and was causing a pulsating
signal to be heard about half a mile away from the scanner.

Took some driving around and some directional finding to narrow it down to a single
house. Had the police go knock on the door and ask if by some chance there was a new
scanner in the house. They said yes. the officer then asked if they could unplug the
scanner to see if it was the source of the interference to the police frequency. When
the scanner was pulled, the signal went away. So it was suggested that the scanner
be taken back to the place it was obtained from and swapped for a different one.

Bottom line is you can have a scanner radiate a signal strong enough to be heard some
distance away. You never know who might com knocking on the door.

Jim

Do you know this is happening or is it just a concern? Assuming the guards are using any kind of quality commercial radios, scanners cannot emit enough RF to interefere with a two way radio. I rode in a patrol car for a lot of years with both scanners and commercial grade radios. I never had a problem with the scanner interfering with the radio but broadcasting when your scanner is on the right frequency brings a whole new meaning to the word "feedback.".

 

[chillim]

thanks for the helpful replies. I wonder how I should test to see if my scanner is emitting. I was thinking about getting Uniden digital mobile/portable. Is there any way I can test this, short of buying 2 way radios myself?

 

[daedalus]

The odds are better for winning the lottery than having a modern scanner causing that kind of interference.

 

[gmclam]

I wonder how I should test to see if my scanner is emitting. ... Is there any way I can test this, short of buying 2 way radios myself?

Does your scanner 'interfere' with other scanners?

 

[Raven95150]

Your scanner should have a label on it that reads, "THIS DEVICE COMPLIES WITH PART 15 OF THE FCC RULES." This means that unless it has been modified and/or is not working properly, it will not cause any harmful interference.

 

[chillim]

Okay, so here is what was written in the Uniden 996 manual. While it complies with FCC 15,

These limits are designed to provide reasonable protection against harmful interference in a residential installation. This scanner generates, uses, and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful interference to radio communications. There is no guarantee that interference will not occur in a particular installation.

What are these radio communications referenced here?

 

[Raven95150]

Okay, so here is what was written in the Uniden 996 manual. While it complies with FCC 15,

These limits are designed to provide reasonable protection against harmful interference in a residential installation. This scanner generates, uses, and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful interference to radio communications. There is no guarantee that interference will not occur in a particular installation.

What are these radio communications referenced here?

Basically it's a disclaimer.

If you are using like the manual tells you to, for example if you have it on a desk in your apartment running off the proper power supply and antenna, it shouldn't cause any problems.

If you work in a 911 dispatch center and hook it up there and run it on some other power supply and antenna, Uniden isn't responsible if it causes interference and the police can't communicate so someone dies, all because you couldn't follow some simple directions.

 

[LEH]

All radios, whether two way or receivers, put out some level of RF energy. In very rare cases, this RF output could cause interference with other radios. Then you need to be fairly close to the other radio for the interference to be noticed (okay, there are those rare occasions like Jim pointed out).

As already stated, the chances of this happening are pretty slim. I would go ahead an use the scanner without worrying about it causing problems. The chances of other RF sources interfering with your scanner are much greater.

Now if you do receive a complaint, you need to stop using it. Don't hold your breath waiting for the knock.