Strange noise when working in DMR...
Strange noise when working in DMR...
Hello again.
The first thing I want to say is that Open DM1801 is the best thing that ever happened to Baofeng DM1801. Convenient management, fast operation, very necessary functions.
But unfortunately, when using it, I encountered a problem: a small and interfering noise. I tried to reproduce this noise and record a video on YouTube. There is no noise when you switch on the transmission, but if you make any sound into the DM 1801 microphone, you will hear noise in the receiver of another radio station. The noise is also heard on other radio stations. Is this a common dm1801 problem? Or was I personally unlucky with this particular radio station?
youtu.be/bPvGeMQ5CwI
PS: just in case, I apologize, English is not my native language...
The first thing I want to say is that Open DM1801 is the best thing that ever happened to Baofeng DM1801. Convenient management, fast operation, very necessary functions.
But unfortunately, when using it, I encountered a problem: a small and interfering noise. I tried to reproduce this noise and record a video on YouTube. There is no noise when you switch on the transmission, but if you make any sound into the DM 1801 microphone, you will hear noise in the receiver of another radio station. The noise is also heard on other radio stations. Is this a common dm1801 problem? Or was I personally unlucky with this particular radio station?
youtu.be/bPvGeMQ5CwI
PS: just in case, I apologize, English is not my native language...
Re: Strange noise when working in DMR...
A couple of possibilities. First, it could be how the vocoder handles the noise. This is not like FM if you're on DMR. A chip is analyzing the sounds it hears and doing compression based on voice elements like silibance.
You might also be hearing the feedback of one to the other as it continues to encode for the first silibance it heard, then picked up from the speaker of the other radio.
Does it perform properly when speaking over DMR?
Marc
You might also be hearing the feedback of one to the other as it continues to encode for the first silibance it heard, then picked up from the speaker of the other radio.
Does it perform properly when speaking over DMR?
Marc
Re: Strange noise when working in DMR...
The problem is that when turned on, there is no noise in silence. But if I make any sound (for example, the click of a finger), then a decent noise will start. This noise doesn't stop if I'm talking. This noise is more like the noise of a motorway. My correspondents complain about this noise. There is no such noise in FM mode. If I install the original software, the noise is also present, but less pronounced. The effect is very similar to automatic gain control: with a quiet signal, the gain increases, but with a strong signal, it does not go back.
Re: Strange noise when working in DMR...
Unfortunately, it has been more than a month since the purchase, I will not be able to return it. Is there an electrical (or block) circuit on the dm1801 (or gd77) ? I'll try to fix the problem myself...
Re: Strange noise when working in DMR...
Try contacting Radioddity, they are often will replace faulty radios
Its strange the problem is only audible on DMR. The mic connection to the DMR chip is via a small switch chip which has 6 pins and could be labelled as U12 on some revisions of the PCB. The switch chip connects the audio to pin 5 of the HR-C6000 DMR DSP chip via a capacitor
However the problem may not be the audio connection from the mic, it may be noise on the 3.3V rail, as this could cause noise to the ADC in the C6000
Re: Strange noise when working in DMR...
I didn't buy from an official seller...
Thank you for the hint.VK3KYY wrote: ↑Mon May 25, 2020 6:17 amIts strange the problem is only audible on DMR. The mic connection to the DMR chip is via a small switch chip which has 6 pins and could be labelled as U12 on some revisions of the PCB. The switch chip connects the audio to pin 5 of the HR-C6000 DMR DSP chip via a capacitor
However the problem may not be the audio connection from the mic, it may be noise on the 3.3V rail, as this could cause noise to the ADC in the C6000