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Decrease BER %
Posted: Fri Mar 29, 2019 2:41 pm
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
Re: Decrease BER %
Posted: Fri Mar 29, 2019 5:31 pm
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.
Andrew M1DNS, (Mod)
Re: Decrease BER %
Posted: Thu Apr 04, 2019 9:27 pm
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
dh3ybe
Re: Decrease BER %
Posted: Thu May 02, 2019 1:27 pm
by RC3C
Hi
I have during 0,2% to 0,4% in BER (green color) with RXOffset/TXOffset -300. Try to use this value.
Re: Decrease BER %
Posted: Thu May 02, 2019 3:42 pm
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:
- Set up Pi-Star with the MMDVMHost Configuration Mode you want to use. Be sure to apply changes.
- The best way to work on this is to have Pi-Star open in two browsers:
- Set up the first to view the Expert Editor, where you'll do the adjustments:
- Enter Expert Editor: pi-star.local/admin/expert.
- Click MMDVMHost.
- Scroll down to the Modem section and find the RXOffset setting.
- Set up the second to view the dashboard so you can view the resulting BER readings.
- The easiest thing to do is to make calls lasting a few seconds to a Parrot talkgroup or reflector.
- 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%.
- Begin with +/-100 offsets, and see how that affects the BER.
- 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.
- 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
Re: Decrease BER %
Posted: Thu May 02, 2019 4:59 pm
by M1DNS
admin/expert/edit_mmdvmhost.php
Andrew M1DNS, (Mod)
Re: Decrease BER %
Posted: Sat May 04, 2019 9:43 am
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 (20.06 KiB) Viewed 17797 times
in minimum
- rxtxoffset-300 min.PNG (13.09 KiB) Viewed 17796 times
Re: Decrease BER %
Posted: Sun Jun 13, 2021 6:26 pm
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.