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#Post#: 156--------------------------------------------------
MMDVM CALIBRATION ON PI-STAR
DIR By: robertbretzman
Date: December 28, 2018, 6:52 pm
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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.
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