MMDVM HS Dual Hat JumboSpot

MMDVM_HS Hat hardware
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Joined: Sun Dec 30, 2018 9:18 pm

MMDVM HS Dual Hat JumboSpot

Post by on7ma »

Hi Everyone
having bought a MMDVM Dual Hat from Ali (14 Mhz) and upgraded to 1.4.14 on RPI 3B+

Everything works fine on Ysf, but I can NOT get it to work with Anytone D868 or D878
"Repeater Fail" Message

Anyone had this problem.. problem to Anytone ? Found Solution ?
I could not test with other DMR Portables

Tnx 4 hlp Jempi, ON7MA
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Posts: 36
Joined: Wed Apr 11, 2018 12:00 pm
Location: Louisville, CO

Re: MMDVM HS Dual Hat JumboSpot

Post by W0RMT »

This is a known issue with DMR and the duplex MMDVM boards, and is especially problematic with the Anytone radios. It has to do with the timing differences, or lack of timing synchronization between radio and board. See Andy CA6JAU's github page- scroll down to "Known Issues"

Here is what you can do:
1. Adjust DMRTXlevel to 55 or 60 in Expert>MMDVMHost under the Modem section
2. Use mmdvmcal to find the best RXOffset to start with for your board on DMR, then set RXOffset in Expert>MMDVMHost under the Modem section (*Note that this offset will be different from what you have set for YSF- it is mode and radio<>board specific). I'll paste the mmdvmcal procedure below.

There are a couple of other things you can do to try and help, but there should get you to the key up stage at least. Of course, check frequency, color code, etc in your radio settings and on the board too.

Good luck and let us know how it goes.

mmdvmcal procedure:

To use pistar-mmdvmcal to calculate TXoffset
A. Preliminaries:- Set DMR rig to desired hotspot frequency, CC1 Slot1 TG9. Call it Fd (in Hz) In Pistar set TXoffset and RXoffset to zero, otherwise they'll screw up the calculation.

B. connect to your pi-star setup with ssh.

C. Type:- sudo pistar-mmdvmcal" <enter>

D. Tap E key & enter TX frequency of your hotspot in Hz

F. Tap <M> key. Hotspot generates a dmr tone.

G. Tap <Space> Hotspot transmits tone. You should hear tone on rig.

H. Repeat presses on f key until tone disappears. Note this frequency as f.

I. Repeat presses on F key until tone reappears, keep going until it disappears again. Note this frequency as F.

J. Q to quit.

The calculation:
You have 3 frequencies, Fd, f and F to play with. f is the lower edge of the hotspot transmission and F is the upper edge of the hotspot transmission. Assuming the transmission is symmetrical around its peak value, the average of f & F gives the peak frequency of the hotspot transmission ie where it is transmitting.

So the hotspot is TXing at freq. {(F+f)/2} Hz
TXoffset is the difference between rig and hotspot TX frequencies.

TXoffset = Fd - {(F+f)/2}

TXOffset & RXoffset don't have to be the same, but for starters set both to the calculated value. If ber isn't good, vary RXoffset only until it is.
Robert (Bud) M. Talbot III
Colorado Digital system admin
DMR: BM 31088
YSF: 99256
NXDN: 31088
P25: 31088
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