Whipping noise when driving while listening?

[ryangassxx]

Ok, I know I'm going to have to be very clear about what I mean about this. Do you know how when say for instance you try to use a transistor radio inside of your car while you're driving this signal will sometimes make sort of an intermittent whip sound because of the movement of the car? Ok this is what I mean by the whipping noise.

Here's my dilemma. For a while I used to use a handheld scanner while listening inside of my car. When doing this i would always have the issue of the whipping noise. I assumed it was because I had the antenna (which is connected to the top of the scanner) inside of the car with me, and that it just wasn't the ideal place for an antenna to receive a signal. A few days ago I purchased a window mount external car scanner antenna. After rigging the whole thing up, I was disappointed to find that I am still having the whipping sound issue.. I thought that by having the antenna on the outside of my car, it would completely resolve this issue..

How is it that car radios do not suffer from this problem? I always assumed it was just because of the external antenna, but I see now that this is not true..



Just for informational purposes for any radio guys who might want to help attack this problem, I am using a Pro 97, and the Radio Shack Model: 20-011 antenna which can be found here http://www.radioshack.com/product/i...052.2032075.2032078.2032098&parentPage=family

I mounted the antenna on the back window of my Ford Explorer, almost at the very top of the glass. The antenna sticks up pretty far in the air as a result and clears the rest of the vehicle in all directions for the most part.

If anyone has any solution at all to the whipping sound problem, please let me know..
Thanks in advance.

 

[jim202]

Have no idea what your calling a whipping noise.

Been in the radio field for better than 40 years now and have never heard
anyone call any noise a whipping noise.

By any chance are you trying to explain the fast in and out signal strength
changes of signals that are not very strong. These signals go up and
down in signal strength as the vehicle is moving. The faster you move,
the faster these up and down signal strengths occur.

If this is what your trying to describe, it is caused by multi path signals.
This is the arrival of the same signal from multiple directions. These
signals can be in phase, or out of phase, or any place in between.
Under the right conditions, the signal could be cancelled out all
together. So this is why the signals seem to go up and down in
signal strength. It is like you looking at a picket fence that is
representing the signal strength. That is where the term "PICKET
FENCE" comes from.

If this isn't what your hearing, then you will need to explain it better
to us that can't seem to understand what a whipping sound is. Maybe
you are talking about riding on a horse drawn cart and the driver is
snapping his whip over the horse's back. That has always made a
sharp snap or crack sound when I have heard it.

Jim

 

[SLWilson]

Noise

Not sure either what you're describing, but, if it IS some type of interference noise, I'd try to start with the vehicles onboard computer. I've had trouble with a couple of those creating "noise" in my radio stuff on GM vehicles....Had to actually ground everything a little better to get rid of it....It doesn't really sound like what you've bought for an antenna is grounded!!!

Steve/KB8FAR

 

[mancow]

Are you monitoring a simulcast system? I know that the KC, MO system sounds like that if you get on the outlying edges and are moving. It will do it even if you are stationary if you are far enough away. It's the effect of multipath and the signals from different sites arriving at different times.

 

[ind224]

Watch the whip itself. My RS magnetic (the one with the two coils and base) is now bolted to the side rail of the bed. That puts in the in airstream and it makes (vibrates) to the shape of a Coke bottle at speeds if that makes sense. I plan on a PVC sleeve to hold the whip still.

I agree with Mancow on the multipath. And it can come from buildings, airplanes, birds or anything that blocks/bounces/reroutes the signal even for a fraction of a second.

 

[fineshot1]

Yes - I think ryangassxx is refering to "mobile flutter" (thats what i call it) on a weak received signal. I think jim202's explanation is the best to explain it.

 

[iMONITOR]

Possibly this is what you're hearing:

picket fencing - (Repeater Term) A condition experienced on VHF and above where a signal rapidly fluctuates in amplitude causing a sound akin to rubbing a stick on a picket fence. If a repeater user's signal isn't strong enough to maintain solid access to the machine's input (such as when operating from a vehicle passing beneath underpasses or through hilly terrain), the signal would be hard to copy because of a pronounced, rapid fluttery or choppy characteristic.

 

[ryangassxx]

Find a portable am fm radio, tune into a station, take it into the car with you and drive around.. You'll hear the whipping noise.. This is something I've been aware of since I was a small child..

 

[OpSec]

Find a portable am fm radio, tune into a station, take it into the car with you and drive around.. You'll hear the whipping noise.. This is something I've been aware of since I was a small child..

Um, no...? Just for S&G's, I whipped out my Sony Walkman and listened to a fairly distant FM station in the car while I ran errands this morning, and I never heard the sound you are describing.

 

[mancow]

The only way I can describe the sound that I'm thinkink of is that it's kind of like a turntable that's being used as an instrument. You know, how they use their hand to move it back and forth. Or... maybe like rubbing something over some guitar strings or a cable. That screetchy sound that warbles back and forth. It's terrible but it's definitely not the picket fence effect. That's a single signal that's bouncing around and hitting the antenna at odd angles and is fluctuating in signal level. The simulcast problem is caused by mutiple signals all on the same frequency modulated exactly the same but they are arriving at the antenna at different times. It really freaks out the receiver.

 

[com501]

Might be a static discharge issue. This happens where the humidity is low and the tires of the vehicle tend to insulate the static buildup from discharging. Do you get zapped ever when you step out of the car or walk up to it and touch it?

Just a thought...

 

[korman]

After reading these replies on the subject of whipping noise, I would like to share my bit of info in relation with the multipath FM interference. I am now driving a Silverado 2011 since December and I noticed all kinds of noises or interferences that I did not have on the radio of my 2006 grand Caravan. One of the interference is a clear intermittent scratching noise just like if there would be a skinned wire intermittently rubbing on the frame causing harmonics to be picked up by the radio receiver. Another type of interference or what I call an objection of hearing clearly the voice of the radio commentator without short portions of distorted voice. I think that might be due to Multi Path FM Interference but I also have some doubts about this when I read about listening to a portable radio set within the car and I think that it is possible that the portable set might not be a set capable of picking up simulcast which is a station broadcasting both an analog and a digital signal on the same frequency i.e. 90.7 FM.

Could it be that the manufacturers of the radios in the General Motors vehicules in the recent years are actually having a glitch within the receiver that would cause these interferences? I would like comments on this subject of interferences on GM radios within the FM band.
Regards,
Korman

 

[kb2vxa]

Like the director said "can the dialog and cut to the chase". The "whipping noise" as you call it is signal flutter or "picket fencing" caused by multipath reception. Without getting overly technical you're hearing intermittent drop-outs from reflections.

That dialog having been canned here's the chase.
"How is it that car radios do not suffer from this problem?"
Because they use through metal 1/4 wave solid rod antennas and FM broadcast signals are bone crushing strong compared to two-way communications. Add to this the fact that no professional two-way installer in his right mind would use a POS through glass window mount antenna and give users whiplash of the ears you have your answer... you need a GOOD antenna.

 

[NCFire11]

you arent talking about alternator whine are you? just making sure

 

[korman]

Not at all Jtsou!

 

[rfradioconsult]

The correct term is "Rayleigh Fading"

 

[W8RMH]

I had this same problem on a Pro-93 and a Pro-95. It cleared up when I switched to Uniden.