Decrease BER %

MMDVM_HS Hat hardware
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kc7wsu
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Decrease BER %

Post by kc7wsu »

I have an MMDVM_HS and am getting a 1.0-1.5% BER with a -475 offset. This is a JumboSPOT that I purchased to play with. I already have 2x DVMega.

Has anybody tried swapping the TXCO for a higher quality one to remove the offset and decrease the BER?

Regards,

Chris Andrist, KC7WSU
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Re: Decrease BER %

Post by M1DNS »

What you have is a relatively good BER already. I wouldn't bother.
Try a little fine tuning, changes in steps of 2 or 5 might bring it down a little more. Anything 1.0 or below is fine for home use.



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dh3ybe
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Re: Decrease BER %

Post by dh3ybe »

Hi Chris,

or the tx power could be high, if your work with the hotspot in the same room. HF is disturbing eletronic devices a little bit.

Best regards
Kai
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Re: Decrease BER %

Post by RC3C »

Hi

I have during 0,2% to 0,4% in BER (green color) with RXOffset/TXOffset -300. Try to use this value.
73! Anton aka Tony
EL #2102, EL #53698, DMR #2503041, XLX937-B
Clubs: RC5C, RY3AAL, NMDXC

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Re: Decrease BER %

Post by KE0FHS »

Each individual hotspot can require a different offset. If you're experiencing high (greater than 1%) Bit Error Rate (BER) with your radio, you can try reducing it by adjusting the RX Offset:
  1. Set up Pi-Star with the MMDVMHost Configuration Mode you want to use. Be sure to apply changes.
  2. The best way to work on this is to have Pi-Star open in two browsers:
    1. Set up the first to view the Expert Editor, where you'll do the adjustments:
      1. Enter Expert Editor: pi-star.local/admin/expert.
      2. Click MMDVMHost.
      3. Scroll down to the Modem section and find the RXOffset setting.
    2. Set up the second to view the dashboard so you can view the resulting BER readings.
  3. The easiest thing to do is to make calls lasting a few seconds to a Parrot talkgroup or reflector.
  4. In the Expert Editor, adjust the RXOffset setting, make a parrot call, and observe the readings. You're aiming for a BER of less than 1%, preferably less the 0.5%.
    1. Begin with +/-100 offsets, and see how that affects the BER.
    2. Once you find the lowest BER with the +/-100-step offsets, repeat the process with +/-50-step offsets, and finally +/-10-step offsets until you find the lowest BER.
  5. Repeat this process in each MMDVMHost Configuration Mode in which you're experiencing high BER, until you achieve the optimal BER in each one. If you can't find a good balance for the BER between the different modes, it may be better to use different hotspots for each different mode.
Alternative and more exact method to calculate offsets: Daniel, K9NPX, has a good article on using MMDVMCAL to get more exact RXOffset (and TXOffset) settings for a DMR radio: Hotspot Offset Calibration: http://www.k9npx.com/2019/02/hotspot-of ... n.html?m=1
73, Toshen, KE0FHS
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Re: Decrease BER %

Post by M1DNS »

admin/expert/edit_mmdvmhost.php



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Re: Decrease BER %

Post by RC3C »

KE0FHS wrote: Thu May 02, 2019 3:42 pm Each individual hotspot can require a different offset.
Yes, it does. I have TYT MD380UV at home with nano hotspot MMDVM_HS_hat. It has (as I wrote b4) in max 0,4% BER

in maximum
rxtxoffset-300.PNG
rxtxoffset-300.PNG (20.06 KiB) Viewed 17551 times
in minimum
rxtxoffset-300 min.PNG
rxtxoffset-300 min.PNG (13.09 KiB) Viewed 17550 times
73! Anton aka Tony
EL #2102, EL #53698, DMR #2503041, XLX937-B
Clubs: RC5C, RY3AAL, NMDXC

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K5NES
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Re: Decrease BER %

Post by K5NES »

Newbie here. If my BER% is 0.7, should I just leave it alone? Kinda like if it ain't broke, don't fix it. I've amde a few contacts now on the AmericaNet, and everyone says that I sound good. Just don't want to be a LID.
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