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M: 01:22:37.939 Debug: DMRIdleRX: data sync found centre/threshold 10 441 M: 01:22:32.678 DMR, Logged into the master successfully M: 01:22:31.446 Debug: DMRIdleRX: data sync found centre/threshold -20 498 M: 01:22:31.442 Debug: DMRIdleRX: data sync found centre/threshold 0 473 Here is what I am getting on the MMDVMHost terminal screen when I key the MD-380: Since I am not familiar with DMR, it might be a MD380 radio setup problem or maybe an MMDVM.ini setting. My unit now works on all modes except DMR. Thank you for the excellent guide for tuning up the MMDVM board. The DMR signals evolve at about +/- 400mV We can clearly seen that the DMR is a digital mode with “switched frames”, with “no transmission” periods (largest amplitudes), where the noise signals evolve at a maximum of +/- 1 V. This is an example of signals you have on analog input A0 when a DMR signal is received by the receiver. If signal saturation exceeds 3V peak-to-peak, decrease the amplitude by turning potentiometer R99. You can take mass on JP5 or JP6 for example.Įven in the absence of an RF signal by the receiver, the filter amplifies the signals. ![]() #AUDIO TUNER CALIBRATION VERIFICATION#Verification consists in checking the oscilloscope signal A0 which is sent to the arduino. If you can, configure your radio to send RX audio even if the squelch (COR) is not active. The GM360 signal sent to the accessory jack is “Audio RX Flat”. We will use an oscilloscope for this operation.įirst of all, I specify that your receiving station must output a low frequency signal without preemphasis or de-emphasis. Indeed, the goal is simply that the audio levels are not too strong and do not saturate the analog input of the arduino Due. Setting DMR using a simple SDR RTL key Tuning DMR reception Since the LF level is zero, you should only read the fundamental frequency on your analyzer (Bessel function J 0). Check that the multi-turn TX potentiometer ( R98 on my shield) is close to the middle of its range, and in any case, not at the end of the range. To do this, press the “t” key (lower key t) several times. ![]() We will start by reducing the LF signal level generated by the MMDVM board, reducing the gain to 0%. Set your analyzer to see the transmit signal. Be sure to set up a sufficiently powerful attenuator to protect your analyzer. Your spectrum analyzer must now be connected to the RF output of the transmitter. You can optionally listen the signal with an analog receiver set on the output frequency of your (future) relay. #AUDIO TUNER CALIBRATION SOFTWARE#At this time, the MMDVMCal software sends a low-frequency signal of 1200 Hz to your transmitter. The PTT light on the MMDVM board must light up. To switch to transmission, press the space bar. Place the “D” command (shift key D) to enter the DMR mode setting. The commands are:ĭ DMR Deviation Mode (Adjust for 2.75Khz Deviation) Usually, the USB port is created under /dev/ttyACM0 sudo /opt/MMDVMCal/MMDVMCal /dev/ttyACM0 #AUDIO TUNER CALIBRATION SERIAL#Start the tuning software, specifying the serial port on which the arduino is connected to the Raspberry Pi. MMDVM, filter shield with PS2 connectors for transceivers ![]() The Squelch (COR) signal level must be checked (active = high level), and if necessary be reversed by programming the GM360. They are connected to the filter shield with PS2 (6-pin) connectors, and on the GM360 accessory socket (Supplier eg Aliexpress). In my case, I use two Motorola GM360 sets. Take a moment to check your wire-to-wire connections before you start the settings (Rx Audio, Squelch, Tx Audio, PTT and Ground). To make our adjustments, your transceivers must be connected to the MMDVM filter shield. We will launch the compilation of the software. #AUDIO TUNER CALIBRATION CODE#We change now to the /opt/MMDVMCal directory that contains the source code previously downloaded. Sudo git clone Compile the MMDVMCal software We are now downloading Jonathan’s MMDVMCal project and made available on, with this command: cd /opt/ ![]() #AUDIO TUNER CALIBRATION SOFTWARE DOWNLOAD#Installing the Calibration Software Download MMDVMCal For this, we will use the calibration software MMDVMCal.
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