What causes "motorboating"?

[sfreiman]

I recently returned to scanning, so am not fully up to speed on today's technology. Now and then, I hear transmissions that sound garbled, I believe this is called "motorboating"? I have a BC796D with the APCO Card. It only seems to happen on some transmissions on certail frequencies, not all. I believe some frequencies in Tucson, AZ have both regular and digital transmissions. Is there a way to solve this?

 

[hoser147]

Usually it is caused by the scanner not being able to decode the signal..

 

[davidmc36]

I recently returned to scanning, so am not fully up to speed on today's technology. Now and then, I hear transmissions that sound garbled, I believe this is called "motorboating"? I have a BC796D with the APCO Card. It only seems to happen on some transmissions on certail frequencies, not all. I believe some frequencies in Tucson, AZ have both regular and digital transmissions. Is there a way to solve this?

Are you hearing the "motorboating" of the digital signal that is not getting decoded, or the garbled (more like R2-D2) sound of an Encrypted communication? If it is the latter, you may have talk-groups that are strictly Encrypted that you may want ot lock out, or they may just on occasion encrypt on a normally digital talkgroup. I see the latter situation where I am if they are heading to do a bust or something.

 

[sfreiman]

It sounds more like the digital signal that is not getting decoded, not the latter, garbled sound. It sounds like a regular transmission (can kind of hear them talking) with a loud motorboat-like sound covering it up.

 

[davidmc36]

It sounds more like the digital signal that is not getting decoded, not the latter, garbled sound. It sounds like a regular transmission (can kind of hear them talking) with a loud motorboat-like sound covering it up.

Maybe it is strong interference or something that you hear over the weaker voice comm. Maybe a better antenna to get what you want to come in better. Or try moving the scanner to see if it is something nearby that you can hear when the other signal is a bit weak. Do you have an outside antenna or the one attached right to the scanner?

 

[Skypilot007]

This is the same thing that seems to plauge all uniden digital scanners on most P25 trunked systems. On a lot of transmissions not all, there will be the motorboating sound for 1/2 a second to several seconds in lenth then the audio transmission comes thru. Alway at the begining of the transmission. If you're getting the motorboating sound for an entire transmission then its probably a weak signal on that particular voice channel that your scanner is not decoding.

 

[slicerwizard]

On a lot of transmissions not all, there will be the motorboating sound for 1/2 a second to several seconds in lenth then the audio transmission comes thru. Alway at the begining of the transmission.

You are describing the period while the audio channel is keyed up, but idling, and the P25 audio hasn't started yet. The P25 decoder chip doesn't detect any P25 voice, so it passes the idling noise to the scanner's speaker.

Uniden could've handled this analog/digital strapping flags for each talkgroup or (even better) a smarter P25 chip. Instead, they did neither. An incredibly stupid decision on Uniden's part.

 

[UPMan]

The latest firmware (v3.01.00) improves performance in this regard.

 

[jerk]

The latest firmware (v3.01.00) improves performance in this regard.

Yes it does, however, you will still get it sometimes, but now it's more related to a weak signal or reception.

Try moving the scanner to a different location or using a better (higher) antenna.

 

[wvscanner]

I still get quite abit of the noise on a conv. vhf freq. that is in the federal ranges and the signal comes in great. At times I only get the last word of what they are saying.

 

[sfreiman]

...If you're getting the motorboating sound for an entire transmission then its probably a weak signal on that particular voice channel that your scanner is not decoding.

This sounds like what is most likely happening.

 

[kenisned]

The latest firmware (v3.01.00) improves performance in this regard.

His scanner was a 785D, is there an update for that?

 

[UPMan]

The 785D cannot be updated.

 

[kenisned]

The 785D cannot be updated.

Okay, that's what I thought.

I will say this, i use that scanner for our P25 UHF TRS here in Morris County, NJ. IMO, it performs better than the 996.

Not a slam on the 996, just an interesting observation.

 

[davidmc36]

Okay, that's what I thought.

I will say this, i use that scanner for our P25 UHF TRS here in Morris County, NJ. IMO, it performs better than the 996.

Not a slam on the 996, just an interesting observation.

I find my 996 a little on the deaf side too, but it is THE ONLY scanner for permanent install in my car with GPS ability.

 

[Have_Teeth]

The latest firmware (v3.01.00) improves performance in this regard.

Really? I performed the 3.01.00 upgrade two days ago. The first thing I noticed was the motorboating was still there!

800 MHz, 3600bps trunk. The "quality" settings are adjusted properly and my received signal stregth is full bars.

As for the actual system, the quantars are operating within spec in terms of deviation/balance and warp adjustment.

No simulcasting.

It also motorboats for a conventional UHF Quantar which has a two second hangtime. The UHF Quantar is also adjusted within spec.

 

[W6KRU]

I don't have any motorboating at all. The only way I hear it is when I push my "Hold" button. I listen to a couple of different large P25 systems and quite a few conventional systems using my 396T w/3.01.00.

 

[slicerwizard]

I don't have any motorboating at all. The only way I hear it is when I push my "Hold" button. I listen to a couple of different large P25 systems and quite a few conventional systems using my 396T w/3.01.00.

You won't hear motorboating on a P25 system because the scanner knows there is no analog audio in use.

 

[W6KRU]

You won't hear motorboating on a P25 system because the scanner knows there is no analog audio in use.

Huh? I thought that was what we were discussing? I was presenting a counterpoint to the following post.

This is the same thing that seems to plauge all uniden digital scanners on most P25 trunked systems. On a lot of transmissions not all, there will be the motorboating sound for 1/2 a second to several seconds in lenth then the audio transmission comes thru. Alway at the begining of the transmission. If you're getting the motorboating sound for an entire transmission then its probably a weak signal on that particular voice channel that your scanner is not decoding.

 

[K8TEK]

A P25 system uses exclusively IMBE. A way for Uniden to fix the motorboating problem would be to be able to tell the scanner that certain talkgroups on a Smartzone system are exclusively digital. Uniden ignored these requests on their previous models and finally decided to implement it on the "new" BCD396XT. Unfortunately, us customers that already purchased their inferior 396T were left in the dark. I really wonder what the people at Uniden are thinking. I was a loyal customer for years, but they really dropped the ball with all of their digital products.