Any method mapping origin firmware calibration data to opengd77

[BG6VNE]

Hey guys,

Just get an DM1701 and flashed it to OpenGD77 latest version, works about BER 5% with my MMDVM Hotspot. Then I try to use MMDVMCal to find out the Tx/Rx offset which should be -500, but still get BER 3% with range -200 to -500 set to the hotspot.

After digging about the OpenGD77 manual, I realize that the firmware already include the Calibration Funciton in the options, which require a dummy load and a frequency & power meter to do so, which I don't have.

Then I remember that In the installation instructions, it says we should backup the calibration data with the original CPS "Ctrl + T" menu, and I have done that, then I try to use original CPS to read the calibration data but only get all empty result and sometimes error.

I'm wondering if there is any method can mapping the original calibration data to the opengd77 format, and then setup manually to the radio, it should be able to skip the dummy load and power meter to get the correct Tx/Rx frequency and power setting ?

Don't know if this can happen

[G4EML]

The original calibration data is already used by OpenGD77 so what you suggest has already been done automatically.

[VK3KYY]

The reason we added the calibration functionality to the firmware is because the power and frequency calibration done at the factory is not very accurate.

The power levels are very inaccurate, and its likely that they don't bother calibrating the power at all. The frequency accuracy is not always adequate when using a hotspot.

If you only have 1 radio, you can adjust the hotspot frequency, but if you have multiple radios, you have to calibrate the frequencies of all radios so that they are within +/- 200Hz of each other.

[BG6VNE]

The original calibration data is already used by OpenGD77 so what you suggest has already been done automatically.

emmmm.... I see... So it's just the original CPS can't get the caliberation data zone correctly (since the port and driver swift)

[BG6VNE]

The reason we added the calibration functionality to the firmware is because the power and frequency calibration done at the factory is not very accurate.

The power levels are very inaccurate, and its likely that they don't bother calibrating the power at all. The frequency accuracy is not always adequate when using a hotspot.

If you only have 1 radio, you can adjust the hotspot frequency, but if you have multiple radios, you have to calibrate the frequencies of all radios so that they are within +/- 200Hz of each other.

Got it. For now I just have 1 DMR radio, I will try to use the MMDVMCal again to find out the proper hotspot frequency offset.

Many thanks!

[VK3KYY]

The reason we added the calibration functionality to the firmware is because the power and frequency calibration done at the factory is not very accurate.

The power levels are very inaccurate, and its likely that they don't bother calibrating the power at all. The frequency accuracy is not always adequate when using a hotspot.

If you only have 1 radio, you can adjust the hotspot frequency, but if you have multiple radios, you have to calibrate the frequencies of all radios so that they are within +/- 200Hz of each other.

Got it. For now I just have 1 DMR radio, I will try to use the MMDVMCal again to find out the proper hotspot frequency offset.

Many thanks!

I don't know what hardware you are using, but normally people use PiStar and just go into the configuation and change the Tx and Rx offset in increments of 100Hz, until the lowest BER is achieved.
Note. Sometimes very large offerts e.g. > +/- 1000Hz are needed to achieve good BER values.

[SA0BUX]

The reason we added the calibration functionality to the firmware is because the power and frequency calibration done at the factory is not very accurate.

The power levels are very inaccurate, and its likely that they don't bother calibrating the power at all. The frequency accuracy is not always adequate when using a hotspot.

If you only have 1 radio, you can adjust the hotspot frequency, but if you have multiple radios, you have to calibrate the frequencies of all radios so that they are within +/- 200Hz of each other.

Got it. For now I just have 1 DMR radio, I will try to use the MMDVMCal again to find out the proper hotspot frequency offset.

Many thanks!

I don't know what hardware you are using, but normally people use PiStar and just go into the configuation and change the Tx and Rx offset in increments of 100Hz, until the lowest BER is achieved.
Note. Sometimes very large offerts e.g. > +/- 1000Hz are needed to achieve good BER values.

Before I had a decent counter that was useable on VHF/UHF I used a RTL-SDR V3 to check frequencies and deviation settings , this USB stick
has decent accuracy as it has a TCXO.
SDR sticks can also be calibrated with kalibrate-rtl towards 2G/3G base stations or other known good transmitters.

[BG6VNE]

The reason we added the calibration functionality to the firmware is because the power and frequency calibration done at the factory is not very accurate.

The power levels are very inaccurate, and its likely that they don't bother calibrating the power at all. The frequency accuracy is not always adequate when using a hotspot.

If you only have 1 radio, you can adjust the hotspot frequency, but if you have multiple radios, you have to calibrate the frequencies of all radios so that they are within +/- 200Hz of each other.

Got it. For now I just have 1 DMR radio, I will try to use the MMDVMCal again to find out the proper hotspot frequency offset.

Many thanks!

I don't know what hardware you are using, but normally people use PiStar and just go into the configuation and change the Tx and Rx offset in increments of 100Hz, until the lowest BER is achieved.
Note. Sometimes very large offerts e.g. > +/- 1000Hz are needed to achieve good BER values.

I'm using a duplex MMDVM plate with bare MMDVMHost software running my NAS.

And yeah, the same method to adjust offset by 100HZ/step, in the range about -200 to -400 the best BER I can get is 1-3% on transmit voice about 10 sec. Out the range get higher BER.

I will try to some other method to get better result.

Thanks for your help and the development of OpenGD77 firmware!

[VK3KYY]

Change your settings to Simplex and set the offset to get minimum BER, then change back to Duplex

MMDVM HS Duplex hotspots work in Simplex mode