Nextel interference with radio

[ciao99]

Today my radio reception was interrupted by Nextelling while I was driving on Route 9 in Newton. I was listening to the AM band. I know it was Nextel because I heard the chatting and that annoying Nextel ring. I kept hearing the annoying ring and the bantering going over the newscast I was trying to listen to.

I'm not sure if there are tech people in here who can elaborate on what happened. This is the first time I've ever experience this type of interruption.

 

[DanStrassberg]

Today my radio reception was interrupted by Nextelling while I was driving on Route 9 in Newton. I was listening to the AM band. I know it was Nextel because I heard the chatting and that annoying Nextel ring. I kept hearing the annoying ring and the bantering going over the newscast I was trying to listen to.

I'm not sure if there are tech people in here who can elaborate on what happened. This is the first time I've ever experience this type of interruption.

The strongest possibility is that something got messed up at the station you were listening to. The telephone noises and conversations that you heard were most probably mixing with the program at the station's studios or transmitter site and were going out over the air through the station's transmitter. The only place such a problem can be fixed is at the point where the unintended mixing is taking place. Very likely, once the person on duty at the station realized there was a problem, the problem was rectified in relatively short order.

 

[ciao99]

Today my radio reception was interrupted by Nextelling while I was driving on Route 9 in Newton. I was listening to the AM band. I know it was Nextel because I heard the chatting and that annoying Nextel ring. I kept hearing the annoying ring and the bantering going over the newscast I was trying to listen to.

I'm not sure if there are tech people in here who can elaborate on what happened. This is the first time I've ever experience this type of interruption.

The strongest possibility is that something got messed up at the station you were listening to. The telephone noises and conversations that you heard were most probably mixing with the program at the station's studios or transmitter site and were going out over the air through the station's transmitter. The only place such a problem can be fixed is at the point where the unintended mixing is taking place. Very likely, once the person on duty at the station realized there was a problem, the problem was rectified in relatively short order.

I thought that Nextel could interefere with radio signals very much like those satellite radio adaptors or Ipod adaptors work.

 

[NHRadio]

Mr. Strassberg's explanation is (as usual) correct AFAIK. The AM band runs from .530 to 1.7 Mhz or the more commonly written 530-1700 Khz. Nextel uses frequencies in the 800Mhz range and transmits digitally versus AM's analog. There's no way I know of for those services to interfere with each other, however I am not the expert Dan is.

I thought that Nextel could interefere with radio signals very much like those satellite radio adaptors or Ipod adaptors work.

 

[aaronread]

Nextel's iDEN system DOES cause audible interference on powered audio amplifiers...like headphone amplifiers, or small speakers on a computer...it sounds like, as best I can describe it, a "fluttering white noise of static". It's not direct interference with an AM or FM signal, it's purely something happening in the speaker amp itself...but whatever it is, it's from the RF the cellphone itself transmits because it begins the instant the phone call technically starts (as in, before the phone even begins ringing).

The iDEN system is, supposedly, being phased out as Sprint fully absorbs Nextel. iDEN doesn't work terribly well for high-data applications like 3G anyways.

FWIW, the TDMA-based GSM systems (T-Mobile, AT&T Wireless and, previously, Cingular) also cause audible interference from their RF emissions. The difference is that GSM's interference (which sounds vaguely like "dit-dit-dit, dit-dit-dit, dit-duuuuuuuhhhhhh, dit-dit, dit-dit-dit") will actually show up ON TAPE, wherever iDEN only affects the speakers.

That's one big reason why I switched away from Cingular and back to Verizon Wireless a few years back. The CDMA system that Verizon (and Sprint) use doesn't cause any audible interference. Frankly, IMHO it's better at 3G data, too...but I know that's a highly subjective analysis.

Based on the description given, though, I don't think it was iDEN interference you were hearing. Sounds more like someone left a mic on somewhere they shouldn't and it was being added to the final mix. In other words, it seems to me to be more like human error than technical interference.

 

[NHRadio]

I've experienced that "GSM buzz" before...the Shortcut 360 seems to be particularly sensitive to it. Every time I'm in a studio it does that if my phone gets too close...it does it in the last 3 stations I've been in. Anyone know what that is?

FWIW, the TDMA-based GSM systems (T-Mobile, AT&T Wireless and, previously, Cingular) also cause audible interference from their RF emissions. The difference is that GSM's interference (which sounds vaguely like "dit-dit-dit, dit-dit-dit, dit-duuuuuuuhhhhhh, dit-dit, dit-dit-dit") will actually show up ON TAPE, wherever iDEN only affects the speakers.

 

[necrat123]

To build on Aaron was saying (Hi Aaron...), you wouldn't hear the conversation, as all cell phones transmit digitally. If you were hearing the ringing and conversation it was either one of two things...

1) At the radio station (as said before)

or

2) One of those cheap "hands free" phone systems that puts the phone's speaker through your car stereo's tuner.
(It has a small microphone that goes over the handset speaker).
(They used to sell them late at night on TV). You might have been travelling near a car using one.
(Which could explain why you heard the ring too...)

 

[aaronread]

Hi Mike!

I've experienced that "GSM buzz" before...the Shortcut 360 seems to be particularly sensitive to it. Every time I'm in a studio it does that if my phone gets too close...it does it in the last 3 stations I've been in. Anyone know what that is?

I couldn't tell you the actual harmonic interaction of RF interference that GSM or iDEN causes when it interacts with audio amplifiers. I just know that it happens and it's damned annoying. :-\ A bit more seriously though, your cellphone broadcasts at anywhere up to 1 or 2 watts on specific bands of frequencies....in the US it's 850 and 1900 MHz, according to Wikipedia's entry on GSM. So there is most definitely RF energy coming out of your phone, although remember that the higher the frequency, the more watts required to cover the same distance. (i.e. 2 watts at 1900MHz goes a lot less further than 2 watts in the FM band 88-108 MHz)

Something in audio gear, presumably the amplifiers but really it could be anything for all I know, acts as an antenna to this RF (or quite possibly a harmonic of it) and it interprets the interference into audible sounds. Those sounds are, in effect, what happens when you "hear" data bursts.

BTW, the only solution is for you to shut off your cellphone. Not just mute it, turn it completely off. Because it's not audio...it's the RF signal of the phone connecting to the local base stations/towers (even just a "here I am" update). As you can imagine, that's a real pain in the neck...so if it's a real problem for you, you may want to consider switching to Verizon Wireless or Sprint (not Nextel) as both use the CDMA transmission system, which uses different frequencies and does not cause audible interference like AT&T Wireless, T-Mobile or Nextel do.

 

[NHRadio]

The "airplane" mode on my phone works also, probably because it's not putting out any RF.
The Iphone seems to cause more of this interference than my last few GSM phones, why I don't know.

BTW, the only solution is for you to shut off your cellphone. Not just mute it, turn it completely off.