Mobile Antenna

[KyleK911]

I got the antenex ASCANC, when I sit in the car the signal comes in perfect but when I drive the signal seems chopped up. Does anyone know what causes this?

 

[pogbobo]

have you checked all of your connections to make sure they are snug? what kind of mount are you using? have you checked all of the coax to make sure its not pinched or roughed up anywhere? good luck

 

[mjthomas59]

A loose connection is more than likely your issue. Whether it is the antenna not completely tight on the mount, the coax connecting to the mount, the mount not secure to your vehicle, or the coax connecting to your scanner(especially if you have had to install any of your own connectors).

Those are the most likely issues. If its a new install i doubt the shielding around the coax would have rubbed off, but i would definetely check for places that could be getting pinched. Also how new is the coax you have? Its possible the coax is bad, the wiring could be seperating inside causing it to lose contact when being bounced around while driving.

 

[KyleK911]

Thanks guys for the help I will check everything. I am using the trunk mount from the same website. I only made one conection inside the car .

 

[pogbobo]

no prob ... thats a good starting point, just double check the cable and the connections at the scanner and mount ... if that doesn't fix it let us know

 

[KyleK911]

Everything is tight. I still don't know what is causing that.

 

[N1BHH]

When you are mobile, you will experience mobile flutter. Signals don't saturate the ether. You experience multipath and it always happens.

 

[KyleK911]

how do cops ride around and listen without that happening?

 

[pogbobo]

When you are mobile, you will experience mobile flutter. Signals don't saturate the ether. You experience multipath and it always happens.

that has never happened to me lol, guess i'm lucky ...


kyle, does it happen with everything you listen to? or just the far away stuff?

 

[mjthomas59]

When you are mobile, you will experience mobile flutter. Signals don't saturate the ether. You experience multipath and it always happens.

I guess i'm not educated enough to understand that. I've personally never experienced anything like this either.

Lets get a little more detail though. Are you on the fringe of the coverage area for the system you are monitoring. We have all experienced getting out of range of a particular system we wanted to monitor and that would cause static or at the least a loss of signal. However, if it comes in clear while stationary i find it extremely hard to believe that it comes in like garbage while mobile.

What speeds are you going when it starts to lose signal? If you are driving up and down your street and having signal issues, but it comes in clear at your house, i would say there is something else going on. Kind of a long shot but you might check to make sure your scanner is getting the proper amount of power and that the power source is shielded in some way. It could be interference from the alternator/electrical system/engine while you are driving at speed.

Another kind of stupid question, but it does what you are describing, is setting your priority function to "on". This will cause chopping in the signal while it constantly checks the priority frequency while still monitoring a different frequency. This is more common on my uniden scanners(and it is extremely common on motorola radios if a priority channel is selected). Just a thought.

What kind of scanner/radio are you using

 

[KyleK911]

that has never happened to me lol, guess i'm lucky ...


kyle, does it happen with everything you listen to? or just the far away stuff?

It happens with everything.

 

[KyleK911]

I guess i'm not educated enough to understand that. I've personally never experienced anything like this either.

Lets get a little more detail though. Are you on the fringe of the coverage area for the system you are monitoring. We have all experienced getting out of range of a particular system we wanted to monitor and that would cause static or at the least a loss of signal. However, if it comes in clear while stationary i find it extremely hard to believe that it comes in like garbage while mobile.

What speeds are you going when it starts to lose signal? If you are driving up and down your street and having signal issues, but it comes in clear at your house, i would say there is something else going on. Kind of a long shot but you might check to make sure your scanner is getting the proper amount of power and that the power source is shielded in some way. It could be interference from the alternator/electrical system/engine while you are driving at speed.

Another kind of stupid question, but it does what you are describing, is setting your priority function to "on". This will cause chopping in the signal while it constantly checks the priority frequency while still monitoring a different frequency. This is more common on my uniden scanners(and it is extremely common on motorola radios if a priority channel is selected). Just a thought.

What kind of scanner/radio are you using

I can sit in my driveway and it will come in clear, as soon as I go 15-25mph down the road it starts.
I am using a radioshack 2055 maybe there is a bad conection in the scanner is that unheard of?

 

[fuzzymoto]

Try the stock rubber duckie antenna while you drive as a test to rule out a loose antenna connection. ...or try another radio if you have access to one.

 

[mjthomas59]

It is possible that the bnc mount to the scanner is loose or the wiring inside the scanner could be loose. You might try gently shaking the scanner while sitting in your driveway to see if that causes the signal to fade like you said it would while you are mobile. I'd also check to see if you notice any issues with the connectors on the scanner and coax. If they aren't loose they could still be damaged.

Opening the case on the scanner shouldn't be too difficult, so if you go that route i'd check the connections from the connector built into the 2055 to the computer board. You may have a broken wire there or a cold-solder which could cause intermittent problems.

 

[N1BHH]

I stated before and will state again, when mobile you can experience mobile flutter. I notice it all the time, the signals are constant at the transmitter, but when you are moving away, signals bounce off buildings, are absorbed and attenuated by trees and hills. Tune into a far off signal and this is what happens. Cops get it too, when they are far from where they should be, firefighters, too, everybody gets it.

Try tuning into an FM broadcaster from 50 miles away and drive around and you will experience it. It's variations come from everything around you, and because you are mobile, that just adds to all the variables you have when trying to receive. It happens in big cities. That's why public safety agencies have multiple receiver sites, to hear, and multiple transmitter sites, to cover the gaps. Some agencies can't afford all that, while some do.

 

[rfradioconsult]

You are experiencing "mobile flutter" this is more prelevent at higher frequencies. There are two type of fading; log normal and rayleigh distribution; what you are discribing is the latter. Check Wikipedia for "rayleigh distribution" and "fading.

 

[mjthomas59]

I stated before and will state again, when mobile you can experience mobile flutter. I notice it all the time, the signals are constant at the transmitter, but when you are moving away, signals bounce off buildings, are absorbed and attenuated by trees and hills. Tune into a far off signal and this is what happens. Cops get it too, when they are far from where they should be, firefighters, too, everybody gets it.

Try tuning into an FM broadcaster from 50 miles away and drive around and you will experience it. It's variations come from everything around you, and because you are mobile, that just adds to all the variables you have when trying to receive. It happens in big cities. That's why public safety agencies have multiple receiver sites, to hear, and multiple transmitter sites, to cover the gaps. Some agencies can't afford all that, while some do.

I guess i still don't get it. Atleast not in the way that the OP is describing it. I understand that at long range signals won't come in clear, although that is just as much true for stationary as it is moving.

Regardless you are talking about a person driving on their street doing 15mph equidistant from the transmitter as they would be sitting still in their driveway. I don't personally believe this "mobile flutter" or "fading" can be attributed to that. Going 70mph past a semi on the highway, while at the fringe of the systems coverage area and i understand, coasting down your street with no other obstructions than you have while sitting in your driveway and i think you have to start looking at other possibilities. A system that is crystal clear while stationary shouldn't be so intermittent that you can barely make any words out while mobile.

 

[mjthomas59]

Also, what system are you trying to monitor and where are you in relation to it. I did make mention in my 2ndpost on this thread about being in a fringe area but that was either overlooked by the OP or not an issue.

 

[fuzzymoto]

In my vehicle, as I drive, strong signals remain strong for the most part, but I do hear flutter as I travel and I can certainly hear differences in reception if I'm on a hill, or in a valley. I also encounter interference from wires or other sources (as I drive by) that cause signals to fade or flutter. For me the lower the freq the more things tend to interfere.

I guess the OP could be experiencing any one of these. I've also heard that some vehicles can cause electrical interference too although I have no personally experienced this in mine.

I'd be testing such things as:

Does it happen in the driveway with the engine on or off (or neither)?
Does it happen on a handheld with a rubber duck antenna in the moving car?
Does it happen on all frequencies or just some?
Can you test a different antenna or different scanner in the car?

 

[Ghost4658]

How old is your car?
In my 1975 CJ5 Jeep i had to put a ground wire from the body to the hood to stop that in it.