OpenGD77

It's probably accurate enough. Power measurements are difficult to do accurately and also not really very important so I wouldn't worry too much about them. It sounds like the minimum your radio can output is 0.28W and the slope is probably not flat below 1W . The firmware power settings below 1W ar...

It may be that your radio cannot go lower than 1W. Individual radios vary greatly so that is a possibility. You can check by going to the 1W Calibration and reducing the adjust level to zero. That is the lowest power that can be achieved. Also to calibrate correctly you should do at least three adja...

Those sort of frequency errors are not unusual and a proper DMR repeater would have no problem with them. Unfortunately most Hotspots use a receiver chip that is not really designed for TDMA and consequently is very critical on frequency. The SDR play doesn't have a very accurate frequency reference...

It may be that your two radios are on very slightly different frequencies. Most hotspots are excessively fussy about frequency. Do you have a means of comparing the transmit frequency of the two radios? A radio or SDR with a spectrum display would show the difference. You could then use the OpenGD77...

I don't think so. The charging voltage is defined internally in the chip.

Colin G4EML

The reason the two handhelds can't hear each other is because they are both set for DCDM TS Split mode. They transmit on the selected timeslot but receive on the other one. Hence when set to transmit on TS2 they are actually receiving on TS1. As the guy says this SFR implementation is specific to An...

Yes, it is called Single Frequency Repeat and is available on high end DMR radios from the likes of Motorola and Hytera. As Daniel says it also needs DCDM support on the handhelds to differentiate the timeslots. It doesn't need a duplexer as it is single frequency. However it does need radio hardwar...

You are correct.

The original firmware does not enumerate as a com port.

OpenGD77 does enumerate as a com port in normal use.

Both radios enumerate as an STM DFU device when set to download firmware. (This is defined in the radios bootloader which remains untouched by OpenGD77. )

Colin G4EML

Yes, as mentioned before we know the the radio can do DCDM but we don't know how to do it! As Roger said, DCDM seems to be a vendor specific feature and as such is not well documented in the ETSI DMR spec. Likewise the limited HRC6000 documentation barely mentions it. It might be possible to generat...

In theory it would be possible to have flat audio option for the radio, at least as far as the actual RF chip is concerned. However there is no control over the additional audio components in the microphone and speaker paths. So the end result may not have a flat response, especially at the low freq...