DM-1701 TX CC issues

[K7TLU]

Full transparency I am a complete OpenGD77 noob, a bit of a DMR noob, an IT Manager/Programmer, General overall nerd, and I have been known to miss that single key bullet point in a manual on occasion.

Hardware: Baofeng DM-1701
Firmware: OpenGD77 Built20230809207900 [3cf6fd3 D]

Okay to my issue: My DM-1701 that I loaded OpenGD77 onto does not seem to be transmitting color codes properly.

When I first flashed the firmware and loaded a code plug, I noticed right away that I could not 'hit' my hotspot even when I was in the same room. I went and pulled up the hotspot (W0CHP-PiStar) dashboard and attempted to transmit again this time watching the RF activity on the dashboard, and again no activity registered. Oh I should mention that the radio swiftly timed out (repeater channel config) when the PTT was depressed.

Next I break out my other DMR radio, an Anytone and test the hot spot, no problems. Okay so can the 1701 receive? Hit the hotspot into parrot TG with the Anytone, and monitor on the 1701... 1701 receives no problems, with the color code set no less.

So now I setup the VFO's on both radios to the same frequency and color code, just trying to get a simplex contact... No dice. Again the Anytone can transmit and be received by the 1701 however the 1701 cannot transmit and be received by the Anytone. If I place the Anytone into digital monitor mode (no filter on CC) I can then transmit from the 1701 and be received by Anytone.

I can also say that the wave form on that I can capture on my little TinySA looks different between the Anytone and the 1701

Thats about all the troubleshooting I have done. Thank you in advance for any assistance, it would be greatly appreciated.
73

[K7TLU]

I forgot to mention that the 1701 can transmit FM with CTCSS into a local repeater without issue.

[SA0BUX]

Are your hotspot a duplex hotspot ?

Maybe you can check your radios and hotspot with a frequency counter ( in FM mode and carrier only on the hotspot ) to see how much the
frequencies differ on them.

[VK3KYY]

Its not normally possible to use 2 radios on the same hotspot unless you calibrate the Tx frequencies of each radio to within approx 100Hz

The best method is usually receive on a SDR at the maximum resolution / zoom, and compare the FM signal (with no audio e g, connect the USB cable to the radio but not the PC)

Then change the Tx freq of one radio e.g. the DM1701 so that its the same as the Anytone

The problem is that the hotspot Rx frequency tollerance is very very narrow, only perhasp +/- 200Hz or even +/- 100Hz

[SA0BUX]

Yes , you can use the TinySA and compare the frequencies with it.

I guess that W0CHP-Pistar also have mmdvmcal (pistar-mmdvmcal) , useful for frequency calibration.

Code: Select all

Starting Calibration...
Version: 1, description: MMDVM_HS_Hat-v1.5.2 20201108 14.7456MHz ADF7021 FW by CA6JAU GitID #89daa20
The commands are:
    H/h      Display help
    Q/q      Quit
    W/w      Enable/disable modem debug messages
    E/e      Enter frequency (current: 433000000 Hz)
    F        Increase frequency
    f        Decrease frequency
    Z/z      Enter frequency step
    T        Increase deviation
    t        Decrease deviation
    P        Increase RF power
    p        Decrease RF power
    C/c      Carrier Only Mode
    D/d      DMR Deviation Mode (Adjust for 2.75Khz Deviation)
    M/m      DMR Simplex 1031 Hz Test Pattern (CC1 ID1 TG9)
    K/k      BER Test Mode (FEC) for D-Star
    b        BER Test Mode (FEC) for DMR Simplex (CC1)
    B        BER Test Mode (1031 Hz Test Pattern) for DMR Simplex (CC1 ID1 TG9)
    J        BER Test Mode (FEC) for YSF
    j        BER Test Mode (FEC) for P25
    n        BER Test Mode (FEC) for NXDN
    g        POCSAG 600Hz Test Pattern
    S/s      RSSI Mode
    I/i      Interrupt Counter Mode
    V/v      Display version of MMDVMCal
    <space>  Toggle transmit

[OK2MOP]

Probably not relevant, but on my Simplex MMDVM hotspot, I had to set the DM-1701 to TS2 to send/receive the calls via hotspot (TS1 did not work) - July 2023 versions, even when actually in simplex the TS setting should probably not matter.

[VK3KYY]

Probably not relevant, but on my Simplex MMDVM hotspot, I had to set the DM-1701 to TS2 to send/receive the calls via hotspot (TS1 did not work) - July 2023 versions, even when actually in simplex the TS setting should probably not matter.

FYI.

In Simplexthe timeslots are not numbered.

See the ETSI standard.

The radio sends forf 30mS then waits 30mS and then transmits again. There is no synchonisation signal or data in the Tx indicating the TS number.

FYI.
Simplex hotspots are easier to setup becuase the hotspot has longer for its internal bitstream PLL to lock onto the signal, becuase the radio is transmitting data every 30mS

In Duplex Tx, if the hotspot is not active, then the HT sends a special DMR frame to wake the repeater / hotspot, then waits several hundred milliseconds before sending another wakeup frame.
Becuase each wakeup frame is only 30mS or less Duplex hotspots require more accurate frequency calibration, so that the hotspot can imm ediatly read the frame correctly

[G4EML]

The previous comments regarding frequency adjustment are valid when using a hotspot. However you say that you also could not be heard on a simplex call between two radios. That is probably a different issue. Frequency accuracy is still important but is much less critical than with a hotspot.

You say you could only hear the signal if you put the Anytone into monitor mode. In that mode the Anytone will display the received colour code and talkgroup. What did that indicate? Was it the colour code you were expecting?

Colin G4EML

[VK3KYY]

The previous comments regarding frequency adjustment are valid when using a hotspot. However you say that you also could not be heard on a simplex call between two radios. That is probably a different issue. Frequency accuracy is still important but is much less critical than with a hotspot.

You say you could only hear the signal if you put the Anytone into monitor mode. In that mode the Anytone will display the received colour code and talkgroup. What did that indicate? Was it the colour code you were expecting?

Colin G4EML

Could also be TG etc if the anytone is not in monitor mode.

[K7TLU]

Thank you everyone for your time and assistance!!

I had a few moments at lunch today to play around some more with my radios and I think the issue lies with my hot spot.

G4EML's question about what TG and CC were displaying on the Anytone helped me identify my simplex issue, User Error. Upon testing I noted the Anytone was displaying, in monitor mode, the correct TG and CC, and upon further poking around on the Anytone I discovered I failed to select the correct TG on the VFO. Once I had the Anytone with the proper TG and CC selected, simplex worked as expected.

With this discovery I am leaning toward a calibration issue with my mmdvm hotspot as mentioned by SA0BUX. I have not adjusted the calibration or calibrated a radio transmitter before, can anyone direct me toward some documentation or the like on the procedure?

If the issue is indeed within my hot spot, why would one radio work and the other not? I am asking for my own education and curiosity. I am really enjoying learning about how DMR works 'under the hood' and I would like to understand the root cause of the issue if that is reasonable in the scope of this discussion.

Thank you again!!
73s