OPENGD77 selective receive( frequency drifting by 2.5 khz)

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4I8GL
Posts: 6
Joined: Thu Dec 12, 2019 3:13 am

OPENGD77 selective receive( frequency drifting by 2.5 khz)

Post by 4I8GL » Sat Apr 09, 2022 3:26 am

I recently updated mg gd77. I used to have the stable firmware on january 2020. No problems at all.

I recently updated to 0228 stable release.

I followed in details the update procedure.

I am experiencing some bugs. Sometimes my opengdd77 radio won't recsive some callers. But on my dashboard it was registered and on the other radio its receiving well(dm1701)


I already set the filter to none.

What seems to be the problem or is there any solution
Last edited by 4I8GL on Sun Apr 10, 2022 2:33 am, edited 1 time in total.

VK3KYY
Posts: 7473
Joined: Sat Nov 16, 2019 3:25 am
Location: Melbourne, Australia

Re: OPENGD77 selective receive

Post by VK3KYY » Sat Apr 09, 2022 5:55 am

No one else reported this problem, and with over 1000 downloads of the firmware, I think you probably have a configuation problem with your radio or codeplug.

4I8GL
Posts: 6
Joined: Thu Dec 12, 2019 3:13 am

Re: OPENGD77 selective receive

Post by 4I8GL » Sat Apr 09, 2022 7:54 am

I tried in my other hotspot with different frequency. I works well. I will check again. I will update you

4I8GL
Posts: 6
Joined: Thu Dec 12, 2019 3:13 am

Re: OPENGD77 selective receive

Post by 4I8GL » Sun Apr 10, 2022 2:29 am

I found out the problem. The frequency of the radio drifting a bit. By 2.5khz. 438.200 set on my frequency. But upon checking on vfo its has no problem on 438.19750 sometimes on 438.200 is ok. Can i calibrate this. On dm1701 it has no problem receiving.

4I8GL
Posts: 6
Joined: Thu Dec 12, 2019 3:13 am

Re: OPENGD77 selective receive

Post by 4I8GL » Sun Apr 10, 2022 2:32 am

Sometimes its on 438.20250

VK3KYY
Posts: 7473
Joined: Sat Nov 16, 2019 3:25 am
Location: Melbourne, Australia

Re: OPENGD77 selective receive( frequency drifting by 2.5 khz)

Post by VK3KYY » Sun Apr 10, 2022 4:29 am

Your radio must have a hardware fault.

G4EML
Posts: 919
Joined: Sat Nov 16, 2019 10:01 am

Re: OPENGD77 selective receive( frequency drifting by 2.5 khz)

Post by G4EML » Sun Apr 10, 2022 7:21 am

As Roger says, either your radio has a fault or, more likely, the problem is with your hotspot. They are well known for having very poor signals.

If you have a second DMR radio you can test by setting them both to the same frequency simplex. If the two radios communicate OK then the problem lies with your hotspot.

Colin.

VK3KYY
Posts: 7473
Joined: Sat Nov 16, 2019 3:25 am
Location: Melbourne, Australia

Re: OPENGD77 selective receive( frequency drifting by 2.5 khz)

Post by VK3KYY » Sun Apr 10, 2022 7:45 am

Also. If you have 2 radios and one hotspot, you need to calibrate the master reference oscillator in both radios to be on exactly the same frequency, within a few hundred Hz, otherwise the hotspot won't work with both radios... Because the hotspots do not have as much frequency tollerance as the radios, because the RF chip used in the hotspots ADF7021 is not designed to handle this sort of 4FSK traffic, the ADF7021 is designed as for short range short burst telemetry.

4I8GL
Posts: 6
Joined: Thu Dec 12, 2019 3:13 am

Re: OPENGD77 selective receive( frequency drifting by 2.5 khz)

Post by 4I8GL » Sun Apr 10, 2022 9:50 am

I use Motorola SM120 for tx/rx of my hotspot. Connected to mmdvm and rpi3.

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