[RF induction problem - Solved] Hotspot mode failing after 2/10/2020 updated

VK3KYY
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Re: Hotspot mode failing after 2/10/2020 updated

Post by VK3KYY » Tue Feb 25, 2020 10:26 am

SQ7PTE wrote:
Tue Feb 25, 2020 10:17 am
5 ++ power all the time
Nothing happens. Works great. I note that on the 2m band
Range around 15km
Amazing.

Actually on DMR, its not really a problem, because its only 50% duty cycle.

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SQ7PTE
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Re: Hotspot mode failing after 2/10/2020 updated

Post by SQ7PTE » Tue Feb 25, 2020 10:33 am

I usually talk to my colleagues on the 26079 group
Yes Roger I confirm DMR 50% duty cycle.

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F1RMB
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Re: Hotspot mode failing after 2/10/2020 updated

Post by F1RMB » Tue Feb 25, 2020 10:33 am

VK3KYY wrote:
Tue Feb 25, 2020 10:13 am
SQ7PTE wrote:
Tue Feb 25, 2020 10:06 am
It looks like this to me.
No problems whatsoever.
Regards.
Wow...

Max power. 5W++!
With a nice loop antenna :D
Your Pi is bulletproof ;)

Cheers.
---
Daniel

VK3KYY
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Re: Hotspot mode failing after 2/10/2020 updated

Post by VK3KYY » Tue Feb 25, 2020 10:37 am

F1RMB wrote:
Tue Feb 25, 2020 10:33 am
With a nice loop antenna :D
...
I noticed that.

I think perhaps it would be better to put not have a loop of cable in that location. Perhaps put the loop at 90 deg and flat on the ground

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SQ7PTE
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Re: Hotspot mode failing after 2/10/2020 updated

Post by SQ7PTE » Tue Feb 25, 2020 10:40 am

The antenna is external. Daniel, the connection can be seen in the picture.

Oh, and now I understand it's a joke on your part :lol: :lol: :lol:

The main thing is that the whole works reliably, perfectly.

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F1RMB
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Re: Hotspot mode failing after 2/10/2020 updated

Post by F1RMB » Tue Feb 25, 2020 10:47 am

Hi Piotr,
SQ7PTE wrote:
Tue Feb 25, 2020 10:40 am
The antenna is external. Daniel, the connection can be seen in the picture.

Oh, and now I understand it's a joke on your part :lol: :lol: :lol:

The main thing is that the whole works reliably, perfectly.

:D ;)
loop.png
loop.png (397.3 KiB) Viewed 4484 times

You can disconnect the SMA :D

Cheers.
---
Daniel

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kd2lh
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Re: Hotspot mode failing after 2/10/2020 updated

Post by kd2lh » Tue Feb 25, 2020 2:38 pm

Running all night, no problems with dumping out of hotspot mode.

I think we should close this problem, and recognize that the RF can get into the USB cable supplied by Radioddity with the radio (that we use to interconnect the RPi and the GD77.

Documentation should be added to recommend installation of one or two ferrite filters on the USB and power feeds to the RPi, and that the RPi operate in a metal enclosure if it's in the proximity of the radio. Keep cabling 90 Degrees to the radiation plane of the antenna used.
- - - - - - -
Separately, it's good to see the GD77 used on DMR at full 5 watt power in hotspot mode. Since the Radioddity development lab in China has not responded about power dissipation and continuous duty cycle use of the radio, experimentation like this is the best we'll have.

Recently surfaced documentation of the final amplifier (posted on this site) has also been helpful.

RF Power LDMOS Transistor
High Ruggedness N--Channel
Enhancement--Mode Lateral MOSFET
Freescale Semiconductor Type: AFT05MS004NT1

viewtopic.php?f=13&t=609&p=5256&hilit=aft05%2A#p5256

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F1RMB
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Re: Hotspot mode failing after 2/10/2020 updated

Post by F1RMB » Tue Feb 25, 2020 2:49 pm

Hi Marc,
kd2lh wrote:
Tue Feb 25, 2020 2:38 pm
Running all night, no problems with dumping out of hotspot mode.

I think we should close this problem, and recognize that the RF can get into the USB cable supplied by Radioddity with the radio (that we use to interconnect the RPi and the GD77.

Documentation should be added to recommend installation of one or two ferrite filters on the USB and power feeds to the RPi, and that the RPi operate in a metal enclosure if it's in the proximity of the radio. Keep cabling 90 Degrees to the radiation plane of the antenna used.
- - - - - - -
Separately, it's good to see the GD77 used on DMR at full 5 watt power in hotspot mode. Since the Radioddity development lab in China has not responded about power dissipation and continuous duty cycle use of the radio, experimentation like this is the best we'll have.

Recently surfaced documentation of the final amplifier (posted on this site) has also been helpful.

RF Power LDMOS Transistor
High Ruggedness N--Channel
Enhancement--Mode Lateral MOSFET
Freescale Semiconductor Type: AFT05MS004NT1

viewtopic.php?f=13&t=609&p=5256&hilit=aft05%2A#p5256
Nice to read that fixed the problem on your side.

And now, for a good laugh, here is my super shielded setup that never get any USB problems (but with 250mW selected, I don't know real power value).
cameringo_2020-02-25_154244-cropped.jpg
cameringo_2020-02-25_154244-cropped.jpg (305.35 KiB) Viewed 4471 times

Yeah, I need to finish my 3D printed enclosure for this Dual hotspot ;)

Cheers.
---
Daniel

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kd2lh
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Re: Hotspot mode failing after 2/10/2020 updated

Post by kd2lh » Thu Feb 27, 2020 2:33 pm

Well, I had the hotspot dump out, frozen during mid-transmission again.

It took a couple of days for this to fail. The dmesg log has what looks like the same USB failure. This was on the PiZeroW with plastic enclosure.

I've switched to my Pi4B, which has a metal heatsink enclosure. I also have a 4b with a complete metal enclosure to try if this fails again.

Here's the dmesg file. (attached)
Attachments
dmesg4.zip
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EB3AM
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Re: Hotspot mode failing after 2/10/2020 updated

Post by EB3AM » Thu Feb 27, 2020 3:26 pm

Code: Select all

usb usb1-port1: disabled by hub (EMI?), re-enabling...
[44282.786486] usb 1-1: USB disconnect, device number 2
[44282.786891] cdc_acm 1-1:1.0: failed to set dtr/rts
[44282.986352] Indeed it is in host mode hprt0 = 00021d01
[44283.266178] usb 1-1: new full-speed USB device number 3 using dwc_otg
It seems very clear that this is an RF problem. I probably read it, but I don't know if you wrote it.
Things to keep in mind.
1- the standard usb cable is not shielded
2- Use external antennas and without SWR.
3- UHF is sure to generate more RF than VHF
4- You need to use a good quality shielded network cable.
5- do not use the maximum power of the walkie, you will do the same with 3w as with 5w.

Now I have been without problems for a week, my configuration is:
3W, VHF, "NanoPI Neo", Diamond X30 external antenna.
I did not change the USB cable, but yes, I put 2 ferrites, one at each end, and it does not make a loop. The firmware is February 21.

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