APRS not connecting

nicolet

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Three Lakes, WI
I run three APRS devices and configurations. Mobile is a TM-D710g. In the shack is a TM-V71A with a Tiny Trak 4 configured as a digipeater. Also in the shack is an Android phone running APRSDroid, connected to a Baofeng UV-5R with a Btech K1 APRS cable.

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The two Kenwoods run fine, the digipeater digipeats. The smartphone is unable to connect to the digipeater in the shack, or with a friend’s Igate when I took the device to his QTH. I have reviewed the configurations on the phone and ht multiple times checking them against several websites on how to configure them. APRSDroid has been reinstalled. The radio transmits, the red tx light lights and I can hear the signal on another radio set to 144.39. In short, everything appears to be working like it should. Except that it is not heard by other APRS devices.

Can anyone offer any direction to further troubleshoot this issue? Thanks for your help.
 

kayn1n32008

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What is the channel bandwidth set to on the baojunk? Have you looked at the signal it is putting out? Is there any audio distortion? Is the amplitude at a decodable level? If I had to guess, the problem is using the lowest quality radio there is.
 

KB3KBR

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Thanks for your response. Yes, VOX and squelch are both set at 1.
When I had a Beofang long time ago I tried using the vox feature. Found iI had to turn the preamble time way up to get the radio to start transmitting and not clip off the front of the packet. It was something stupid high like 1 sec or so. If the other radio are not getting the whole packet they can't decode anything.
 

k7ng

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Consider the tx delay setting and related timing issues. If the data (as opposed to the preamble) has started by the time the transmit function is fully running, there will be a bad CRC at the receiver and the packets will be rejected. Some radios have a mighty slow T-R turnaround.
 

nicolet

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Three Lakes, WI
Consider the tx delay setting and related timing issues. If the data (as opposed to the preamble) has started by the time the transmit function is fully running, there will be a bad CRC at the receiver and the packets will be rejected. Some radios have a mighty slow T-R turnaround.
Thank you for this Dave. My protocol is AFSK with a Prefix of 200. I have tried greater prefix settings with no result. What adjustment can I make to continue troubleshooting? Thanks for your help.
 

k7ng

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I'm really no expert. As has been mentioned before, if your RF isn't up to snuff you may have problems. Many times it may be over-deviation. It isn't scientific but a coarse evaluation might be to listen to the strongest APRS digi signal you can find and compare the 'loudness' of that with what your radio sends. If yours is appreciably louder, you may be too wide. Compare with the D710's too.
Another thought - The farther off frequency, the more distortion is on the signal received after demodulation. See if you can get a look at an unmodulated carrier out of your CCR with a frequency counter - any frequency will do. A kHz or more error will start to cause a higher percentage of errored packets. Remember, a packet has to decode perfectly to be accepted. A combination of small issues can cause you large issues.
 

k7ng

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I'm not familiar with APRSDroid, but if you are using an audio signal into the microphone jack of the radio, and the CCR has a really heavy pre-emphasis, the 2200 Hz B202 tone will be a much higher level than the 1200 Hz tone of the AFSK. That too can cause problems in error-free decoding.

You didn't say how well the CCR / APRSDroid setup RECEIVES. Do you get as many good decodes as the other setups?
 

nicolet

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Three Lakes, WI
I'm really no expert. As has been mentioned before, if your RF isn't up to snuff you may have problems. Many times it may be over-deviation. It isn't scientific but a coarse evaluation might be to listen to the strongest APRS digi signal you can find and compare the 'loudness' of that with what your radio sends. If yours is appreciably louder, you may be too wide. Compare with the D710's too.
Another thought - The farther off frequency, the more distortion is on the signal received after demodulation. See if you can get a look at an unmodulated carrier out of your CCR with a frequency counter - any frequency will do. A kHz or more error will start to cause a higher percentage of errored packets. Remember, a packet has to decode perfectly to be accepted. A combination of small issues can cause you large issues.
Thanks Dave. Before I look at this in APRSDroid, I cannot find CCR on Google, can you tell me what it stands for please?
 

nicolet

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HA! Here I was looking for some reference to the packets. Guilty as charged. I will go back and look at this thread again with this new information....
 

k7ng

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The CCR/APRSDroid receives and decodes as well as the two APRS Kenwoods.
So does this mean your difficulties have ended?
A lot of us want to hear about success stories too. If you have one, share it, please!
 

nicolet

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Three Lakes, WI
No sir, the problem persists. Believe me if I can have a success story I will share it! I am looking through this thread again to see if I can find something I missed.

The radio transmits, the red tx light lights and I can hear the signal on another radio set to 144.39. In short, everything appears to be working like it should. Except that it is not heard by other APRS devices.
 
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