Choppy transmissions while scanning and driving

[Gsquared]

So I just got a Nagoya UT-72 Super Loading Coil 19-Inch Magnetic Mount VHF/UHF (144/430Mhz) Antenna for a Baofeng uv-5r. I have a Chevy Tahoe and put the antenna as far back as possible right in the middle of the roof. In the past, I've had the same issue with Uniden scanners and other mobile mount antennas so it may just be a normal thing while driving. I'm monitoring local 151-156 fire/rescue channels and as soon as I start driving, the transmission gets very choppy. I know that's a common issue to have inside a vehicle with radios that have a rubber ducky but I was hoping for solid feeds while driving.

I read on older Radio Reference posts that it could be an RF issue with things like the radio, black boxes, alternators, spark plug wires, etc. I've tried to move the antenna as far away from the front of the SUV as possible and even tried hand holding the radio in different spots as a know a few inches or feet can make a difference. If it matters, I have the radio velcroed to the dash right next to the radio/LCD screen. How do police and rescue vehicles combat interference? Are their radios more powerful in receiving than consumer scanners or radios?

 

[ofd8001]

The question on your vehicle is "what happens if you pull off the road somewhere and shut everything off in your car?" If your reception improves, slowly add things like starting the engine, revving it a little, driving at low speeds, then high speeds, etc.

There is a world of difference in your setup versus a "regular" public safety vehicle. With the average scanner user, cost is a consideration. With public safety, not so much. Where budgets are tight and they do opt for economy, there is a noticeable difference in quality of radios. In other words, "You get what you pay for" is alive and well - an extra zero or two is added to the public safety radio compared to the consumer radio. (That said, I do have and use a Baofeng uv-5r for doing some things at my church.)

The actual installation is much different too. Unless the system is designed to be portable only, such as in a large metropolitan city, mobile radios have multiple chassis grounds, the antennas are permanent mount so they have a good chassis ground and the cables are not moved around much. You may also have some adapters in your antenna cables which degrade signal a tad.

Lastly, the vehicles themselves are built with radios in mind. There will be additional bonding straps as part of the police/special service package along with some other things that are intended to suppress interference from things like alternators that generate RF.

There are those that would suggest you get an NMO antenna and drill a hole on the roof for best reception, which is true. I cringe at that for a new vehicle, plus I have a garage door clearance issue. So I use a vehicle specific bracket for my scanner antenna with good results.

 

[wtp]

the term is fence posting, usually people notice it with FM radio.
think metal signs, metal poles, wires, buildings.
and when they are bounced and out of phase the RF waves cancel each other.

 

[Gsquared]

The question on your vehicle is "what happens if you pull off the road somewhere and shut everything off in your car?" If your reception improves, slowly add things like starting the engine, revving it a little, driving at low speeds, then high speeds, etc.

There is a world of difference in your setup versus a "regular" public safety vehicle. With the average scanner user, cost is a consideration. With public safety, not so much. Where budgets are tight and they do opt for economy, there is a noticeable difference in quality of radios. In other words, "You get what you pay for" is alive and well - an extra zero or two is added to the public safety radio compared to the consumer radio. (That said, I do have and use a Baofeng uv-5r for doing some things at my church.)

The actual installation is much different too. Unless the system is designed to be portable only, such as in a large metropolitan city, mobile radios have multiple chassis grounds, the antennas are permanent mount so they have a good chassis ground and the cables are not moved around much. You may also have some adapters in your antenna cables which degrade signal a tad.

Lastly, the vehicles themselves are built with radios in mind. There will be additional bonding straps as part of the police/special service package along with some other things that are intended to suppress interference from things like alternators that generate RF.

There are those that would suggest you get an NMO antenna and drill a hole on the roof for best reception, which is true. I cringe at that for a new vehicle, plus I have a garage door clearance issue. So I use a vehicle specific bracket for my scanner antenna with good results.

Great info even though depressing for me. I've never heard of a vehicle-specific antenna bracket. Can you explain this a bit? Also, the clearance in my garage is exactly why I went with the mobile mount. I have to get out and lay it down every time I come home. Too bad these freqs aren't in the 800Mhz or I would do a NMO.

 

[hill]

I don't think the term is fence posting, but it should be picket fencing.

 

[Gsquared]

I don't think the term is fence posting, but it should be picket fencing.

Yep. I found some posts with the term picket fencing. Maybe my best bet is to get my kid to "loan" me a radio from the firehouse. KIDDING. I'm just kidding. It is interesting though that they use an app on their cell phones to receive calls from dispatch. I guess that's just another way to make sure they get their calls. I'm assuming radios are still more dependable than phones because they don't lose signal like a cell phone does. They're just the modern day beeper.

 

[wtp]

it has been decades since i used the term.
it was for some kids and CB radio with very short antennas.
at least i was in the ballpark. (i hope i get that one right)

 

[ofd8001]

https://www.theantennafarm.com/catalog/mobile-antenna-mounts-264/fender-bracket-mounts-268/nmo-vehicle-specific-mounts-297/

NMO is a type of antenna mount (literally meaning New MOtorola), it is not necessarily specific to 800 range frequencies.

They might be using a service such as "I am Responding". It is a supplemental way of tone and voice paging, but isn't perfect. A lot of things can go wrong given the number of moving parts between the dispatch center and the responder.

If you or someone you know is relatively tech savvy, you might check eBay for a higher end radio and program it. I'd caution against programming transmit frequencies to avoid legal and practical problems.

And you could always persuade the local fire department to be a Broadcastify feed provider. My former department did that as is the current department and it works well.

 

[Gsquared]

I'd caution against programming transmit frequencies to avoid legal and practical problems.

In Chirp, I turned duplex off for those frequencies. I don't want to butt dial the fire department.

 

[Ubbe]

You will always get that swooshing sound with analog transmissions while driving if the signal isn't strong enough. In digital it might not even give a steady signal long enough to start to decode after it have synced. When I got my Icom R2500 scanner with dual diversity and used one antenna at the back and one at the front of the car roof it totally removed all swooshing phenmomens and gave a steady signal. It's was almost like magic what a difference a diversity system could make.

/Ubbe

 

[ko6jw_2]

One of the worst things about Baofeng radios is the receiver. They have no selectivity and they can desense and overload easily. This can be caused by any signal - not just ones on nearby frequencies. The issues of digital vs analog are not relevant since the Baofeng cannot receive any digital mode. You cannot expect a radio that sells for less than $30 to perform well. They are miserable as scanners.

 

[iMONITOR]

I don't think the term is fence posting, but it should be picket fencing.

it has been decades since i used the term.
it was for some kids and CB radio with very short antennas.
at least i was in the ballpark. (i hope i get that one right)

You're forgiven, not too many people have "picket" fencing these days anyway!

 

[SteveSimpkin]

One of the worst things about Baofeng radios is the receiver. They have no selectivity and they can desense and overload easily. This can be caused by any signal - not just ones on nearby frequencies. The issues of digital vs analog are not relevant since the Baofeng cannot receive any digital mode. You cannot expect a radio that sells for less than $30 to perform well. They are miserable as scanners.

Agreed. You may want to consider trying a scanner instead of a Baofeng UV-5R. Baofeng radios are well know as being marginal radios. Even an inexpensive analog scanner like the Uniden BC125AT will outperform a UV-5R.

 

[mmckenna]

Great info even though depressing for me. I've never heard of a vehicle-specific antenna bracket. Can you explain this a bit? Also, the clearance in my garage is exactly why I went with the mobile mount. I have to get out and lay it down every time I come home. Too bad these freqs aren't in the 800Mhz or I would do a NMO.

You'd have to decide what is more important, you vehicle in the garage, or a well performing antenna.

Putting the antenna down on the fender may be a good solution, but it probably won't be without some issues. Mobile antennas like to have a nice even ground plane around them. Setting the antenna off to one side of the vehicle results in a lopsided ground plane and will make the performance slightly directional, as in it'll work better in some directions as compared to others.

The other issue is that it puts the antenna down below the roof line. That will result in some shadowing towards the rear of the vehicle. The reception won't be as good when the transmitting site is behind you.

An ideal solution is to have a permanent mount NMO in the center of the vehicle roof. That gives it an ideal ground plane.
Not sure how much that antenna moves around while at highway speeds, but if it is, that can create changes in reception and can mimic picket fencing.

As others suggested, try parking somewhere in the open with the engine shut off and ALL USB cigarette lighter plugs pulled. See if performance improves.

If you have a bit of garage clearance to work with, there are some very flexible VHF antennas that would work on your roof. If it's a close fit, then you'll have to decide what's more important.