pi-star duplex hotspot

[W8LDO]

does anyone have settings for the pi-star duplex modem. I can get my hotspots to work simplex but having problems with missing transmit and receive about every hour or so. My Anytone D-578 funchtions just fine with all modems in duplex mode. Something with the timing on all 4 radioddity gd-77 handhelds and my two TYT md-9600's. Been working for months on the hotspots to hand shake properly with the units by changing various settings in the pi-star with no luck. All work fine in simplex mode on the hotspots.

[VK3KYY]

does anyone have settings for the pi-star duplex modem. I can get my hotspots to work simplex but having problems with missing transmit and receive about every hour or so. My Anytone D-578 funchtions just fine with all modems in duplex mode. Something with the timing on all 4 radioddity gd-77 handhelds and my two TYT md-9600's. Been working for months on the hotspots to hand shake properly with the units by changing various settings in the pi-star with no luck. All work fine in simplex mode on the hotspots.

Duplex modems are highly sensitive to the transcriver frequency.

I presume you adjusted the hotspot to originally work with your Anytone, rather than the other radios

Have you compared the frequency of the GD77 etc with the tx and rx freq of your Anytone. If the frequency difference is more than a few hundred Hz the hotspot is likely to have problems.

I used the CPS to calibrate the frequency of all my radios to be the same, using a SDR dongle, as my frequeny counter only resolves to 1kHz accuracy, which is not good enough in this case.

Unfortunately at the moment, we do no have a calibration system for the MD9600 or UV380, because the calibration table in the radio has a completely different data structure.

On the MD9600 although the calibration can be changed my reloading the official firmware and using the official CPS, it can also be manually adjusted using a trim pot on the PCB. But I don't know where that trim pot is.

[ve2ugo]

I used the CPS to calibrate the frequency of all my radios to be the same, using a SDR dongle, as my frequeny counter only resolves to 1kHz accuracy, which is not good enough in this case.

Roger,

what software did you use to calibrate your radio with your SDR dongle?

What procedure did you use?

73!

[VK3KYY]

I used the CPS to calibrate the frequency of all my radios to be the same, using a SDR dongle, as my frequeny counter only resolves to 1kHz accuracy, which is not good enough in this case.

Roger,

what software did you use to calibrate your radio with your SDR dongle?

What procedure did you use?

73!

I think I used SDR#
I just use the spectrum plot to compare various radios, while transmitting on FM with no modulation, and adjusted the transmit frequencies to be the same on all radios.

I can't calibrate to absolute frequencies, becasue I don't have an accurate reference frequency.

I just needed to make sure all radios transmitted on exactly the same frequency, as the duplex hotspots do not tollerate radios which are off frequency by more than a few hundred Hz