BER %

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Rob709
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BER %

Post by Rob709 » Tue Feb 12, 2019 4:55 pm

I recently received a new Openspot2 and have it setup and working on DMR with a TYT MD-UV380 (and DSTAR with a Kenwood TH-D74A). I have made contacts (QSOs) and the signal reports seem to be ok.

However, I'm wondering if anyone can advise why I constantly seem to be showing a BER greater than 0% when I transmit on DMR? While I'm connected to a DMR/BM talkgroup and viewing the OS2 Status page, I notice that almost everyone's transmission displays as B0% L0% (for example: Group DMR voice call from net End: 13:03:39 (00:00.7s B0% L0%) Yet when I transmit, my signal is always reported greater than B0% (Group DMR voice call from modem End: 13:06:00 (00:05.5s B0.8% -23dBm). The lowest I've seen it yet was a BER of 0.3%. The Loss seems to stay at 0%

I also just noticed that everyone's transmission starts with "Group DMR voice call from net" whereas mine starts with "Group DMR voice call from modem" I think that might actually be correct though

I have very fast and stable fiber optic internet connection (1 Gb Up and Down with 1ms ping to local server) and the WIFI signal is excellent (SNR 73dB). Yet the OS2 Network page reports that my Network Connection is Ok (40 ms ping) and the RSSI is -59 dBM.

To test this I've:
I've tried plugging the OS2 into different electrical outlets and moving it to different locations.
Tried different frequencies (433.950 currently)
Tried Autocal and different offsets (300-400 seems to produce best results B0.3%)

Can anyone comment whether this is correct or not? and if not, are there any suggestions?

Thanks in advance,
Rob (VO1RCL)
Rob (VO1RCL)

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HA2NON
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Re: BER %

Post by HA2NON » Tue Feb 12, 2019 5:17 pm

BER below 1% is practically inaudible and is considered very good, so you don't have to worry about it. You can listen back to your transmissions by calling the OS2's built-in local echo on DMR ID 9999, or the network's parrot service which is usually on DMR ID 9990 with a private call.
Norbert "Nonoo" Varga, HA2NON
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Rob709
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Joined: Tue Feb 12, 2019 3:59 am
Location: Canada

Re: BER %

Post by Rob709 » Tue Feb 12, 2019 5:31 pm

Thanks Norbert.

I've tested on both 9999 and 9990 and my transmissions sound fine. I was more just curious about why all the other stations are showing as B0% on the OS2 status page? Surely, not everyone is getting 0% except me? Or perhaps that's just the way the OS2 reports signal received the net versus those received from the modem itself?

I was also going to ask you what server the OS2 Network page pings? I regularly ping my local servers in about 1ms but wherever the OS2 pings takes ~40ms
Rob (VO1RCL)

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HA2NON
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Re: BER %

Post by HA2NON » Tue Feb 12, 2019 6:36 pm

If the network does forward error correction on the received data (BrandMeister does for example) then the received data will be error free in terms of forward error correction, so the BER display will show you 0%.

Currently the OS2 uses netcheck.sharkrf.com but this will be changed soon.
Norbert "Nonoo" Varga, HA2NON
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Rob709
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Re: BER %

Post by Rob709 » Tue Feb 12, 2019 6:46 pm

Understood...thanks for the info.
Rob (VO1RCL)

Bob K
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Re: BER %

Post by Bob K » Wed Feb 20, 2019 1:56 am

Rob,

Having to he same issue here, but with DMR, not DSTAR. My B_% is usually 0.3-0.5 and it get good reports, but most people I copy are B0%.

Did you find a resolution?

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Re: BER %

Post by HA2NON » Wed Feb 20, 2019 8:44 am

The BrandMeister server (I think now DMRplus IPSC servers also do this) recalculates the error correction on incoming packets so it always sends out error-free packets (in terms of forward error correction), so all clients receive packets with 0% BER from the network.

BER below 1% in the received stream from your radio is normal and there will be no noticeable artifacts in your voice.
Norbert "Nonoo" Varga, HA2NON
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Rob709
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Re: BER %

Post by Rob709 » Wed Feb 20, 2019 2:34 pm

Hey Bob K,

The BER% issue for me was never a problem with actual received audio quality or drop-outs at the receiving station end. Everyone has reported that my audio is great. I just happened to notice while watching the SharkRF user interface that everyone else shows as 0% BER while mine shows as 0.3% ish.

As HA2NON posted, the difference seems to be that on my end, I'm seeing BER% reported back from the network rather than locally from my radio to the OS2. Nothing to be concerned about.
Rob (VO1RCL)

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Re: BER %

Post by Bob K » Wed Feb 20, 2019 4:12 pm

Thanks, Rob!

Yes, I think I may be reading too much into it. I'm new to DMR and I'm still getting used to it. However, I have noticed that if I have one of my 380's monitoring WW91 on the openSpot2, and the other monitoring on a local repeater, I OFTEN hear jitter through the OS 2 that is not present on the repeater.

I have also noticed that I occasionally get jitters or garble when calling 9998, 9997 or 9990 - status request replies directly from the openSpot2. I also occasionally get distortion when called the OS2 parrot 9999. Have you experienced this?

Bob

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