Duplex mode unreliable

MMDVM_HS Hat hardware
Post Reply
n0xlf
Posts: 11
Joined: Mon Jul 16, 2018 1:03 am

Duplex mode unreliable

Post by n0xlf » Sat Sep 01, 2018 9:19 pm

I'm using a Chinese duplex HAT and have noticed that receiving for duplex mode seems to be hit and miss, depending on the radio used. My CS750 is really bad, with my TYT MD-UV390 being much better but still hit and miss at times. My BER is very low (0-0.3) and offset between RX and TX frequencies is almost 12MHz.

Sometimes I find that I'm talking to myself (ie - the radio keys but the hotspot isn't actually receiving anything). I have played around with the preamble length on both radios thinking that it could be a timing issue but it didn't seem to make a difference.

Is anyone else experiencing something similar?

Running the latest (1.4.7) Duplex HAT firmware.

CA6JAU
Posts: 6
Joined: Thu Aug 30, 2018 8:13 pm

Re: Duplex mode unreliable

Post by CA6JAU » Sun Sep 02, 2018 3:26 pm

Be sure that your TXOffset is correct also, and try to increase your DMR deviation in Pi-Star to 55 % or 60 % and see if you get better results. This at least works with MD380 radios.

n0xlf
Posts: 11
Joined: Mon Jul 16, 2018 1:03 am

Re: Duplex mode unreliable

Post by n0xlf » Tue Sep 04, 2018 6:16 pm

I have the offset dialed in pretty well (hence the low BER), so I'll give the deviation a try..Thanks!

User avatar
W0RMT
Posts: 34
Joined: Wed Apr 11, 2018 12:00 pm
Location: Louisville, CO

Re: Duplex mode unreliable

Post by W0RMT » Sun Oct 14, 2018 4:33 pm

Question: where in pi-star is the setting for DMR Deviation? I do not see it in expert>MMDVMHost
Robert (Bud) M. Talbot III
W0RMT
Colorado Digital system admin
http://coloradodigital.net
DMR: BM 31088
DSTAR: XRF/DCS303D
YSF: 99256
NXDN: 31088
P25: 31088

User avatar
W0RMT
Posts: 34
Joined: Wed Apr 11, 2018 12:00 pm
Location: Louisville, CO

Re: Duplex mode unreliable

Post by W0RMT » Sun Oct 14, 2018 5:07 pm

DIsregard my last- I found it as DMRTXlevel. I've set it to 55 for my duplex board from DB9MAT and DF2ET
Robert (Bud) M. Talbot III
W0RMT
Colorado Digital system admin
http://coloradodigital.net
DMR: BM 31088
DSTAR: XRF/DCS303D
YSF: 99256
NXDN: 31088
P25: 31088

Post Reply