APRSDroid Seeing Own AFSK Packets

[Xipherisroot]

I have an exceedingly strange issue with APRSDroid...

I'm using AFSK over a cable for speaker/mic to an HT from a Motorola Moto E (XT830C)

When I transmit, the transmit function works correctly and I am visible in places like aprs.fi, however something else strange happens, I more often than not see my own sent packets as 'received' 2-3 seconds later, in fact, whenever the radio's squelch seems to open for a significant period of time with a solid signal... I suddenly am receiving packets with my own call sign, ALL packets are my own call sign, even when I haven't transmitted for a while?

Now, I know this setup works except for this specific phone because I've used the same cable and HT with a Casio C771 and an LG G4, both of which heard other stations just fine and had no real issues.

I know this new phone, the Moto E, is not def because I can open the squelch on the HT and watch the receive audio meter inside APRSDroid come right up high, and I know its not an audio level issue because the same cable and HT worked aok on other phones with the same volume settings, etc.

I'm fairly certain that I'm receiving solid actual APRS signals as I've used two locations where I've gotten quite a few packets quickly before.

What could be causing APRSDroid to be 'receiving' the packets I'm sending like this, is this a bug, or am I somehow doing something wrong?

I'm very tempted to grab another radio and phone then transmit a signal using the speaker/mic and see what happens, but before I do that I want to see whats said here.

[tarrinr]

Have you looked at the paths to make sure they're not just bouncing off a digipeater?

[Xipherisroot]

Not sure how to check the paths of received packets inside APRSDroid, can you explain?

For the record, this device has no cell service and is not connected to wifi, etc.

Sorry, ninja-edit here, how would this explain receiving packets with my own call sign when I haven't transmitted for considerable time? (5-10min, etc)

[tarrinr]

It's a little long, but this helped me understand how it works. http://wa8lmf.net/DigiPaths/ In APRS, you specify how many times you want you packet repeated, and by what kind of digipeater. If you look at the log in APRSdroid, you can see where your packet had been. Try clearing the 'APRS digi path' in Connection Preferences and see if any come back to you.

[Xipherisroot]

Decided to try something silly...

I'm absolutely certain its NOT reflected or bouncing traffic.

I disabled the HT's ability to transmit completely, and I even tried another HT with transmit disabled and got an 'interesting' result.

With the HT's unable to transmit anything and confirmed to be dead silent, APRSDroid is still reporting it is 'receiving' packets with my call sign, ALL packets are received with my callsign although I'm not transmitting anything and haven't for hours now.

[ge0rg]

Hi, this is really strange and unexpected behavior. Could you please provide a screen shot of the APRSdroid Log view that contains the unexpected packets?

Thanks, Georg

[Xipherisroot]

Sure, here is the output from a minute ago, keeping in mind this is hooked up to an HT that is totally ignoring the input from the phone. Note that the signal bars are full, its a CDMA phone, but it has no service, its not activated.

[ge0rg]

This looks like the audio input is looping bytes from the audio output. Sometimes you will decode your own packets from acoustic feedback (just run aprsdroid with no cable attached) but I've never seen the same packet being decoded twice.

Could you toggle the "HQ demodulator" option and see if that helps? It's using a different afsk decoder then.

Could you check with a sound recording app what the microphone input is actually getting when idle / when aprsdroid is running?

I have no explanation for the app receiving all traffic as copies of your own packet, though.

[Xipherisroot]

Not a problem, I'll turn off the HQ option, and I do plan on trying to record what I'm getting, I have a feeling that it might be something unique to this Android device.

I'm running it right now on an LG G5 to see if I get some good results, but there's sort of a lack of APRS traffic in the area at 9pm at night ;)

[JRWynneIII]

FWIW, I'm seeing a similar thing on my Nexus 5x, though its only "receiving" the transmitted packet once. Also in the dropdown tray the status says "digipeated by null" Which leads me to believe it may be some bug.

PS I'm using it with the BTECH aprs cable with a Baofeng UV-5R HT, if that makes any difference

[ge0rg]

"digipeated by null" is a bug indeed, APRSdroid doesn't expect to "hear" itself, only packets that got forwarded by a real digi. I've fixed that minor UI glitch in today's nightly: http://aprsdroid.org/download/builds/APRSdroid-gl-2017-03-02.apk

@Xipherisroot any news from your special device?

[aaron9412]

Similar issue. I appear to be recieving my own packets. Path is not decremented or shown as used by a digi, I am receiving exactly what was sent. Any ideas what might cause ththaththat?

[aaron9412]

I can test with HQ off, just figured I'd ask again since it's been 2 years.

[ge0rg]

You should check your audio cable and connectors. That looks like the input is receiving your own output instead of what comes from radio. Use a recorder app and open squelch.

[rockaclimba]

I FOUND A SOLUTION: I came here for same reason- radio was receiving same packet - so I was also having screen like above. I played with CELL PHONE [ Without Chip and Internet ] volume. I half ringtone volume- closed rest all volumes. This issue of TX and RX entry of same packet is solved. NOTE: I think, I am not sure- this has something to do with app setting in volume output. I opened up MEDIA volume as app was set to music ....

But....

Totally novice here - spent whole day in hit and trials..and made BTECH cable work with radio. Now I can see blue screen [ receive ] and Orange screen [ Transmission ] but no aprs.fi status VE7TGT-9 still shows OLD position - I checked RAW data...nothing.

I crossed checked working of this setup - with Anytone 878 UVii Plus - it catches my packet and showed my location too. So this means - radio is taking up GPS data and beaming out. I think there could be two reasons why I am not being updated by APRS.FI - My other cell phone is catching up my TX from setup but may be its not being catched by digipeater ....right?

2. Something somwhere is wrong in some setting - can u guys shed some light ?

[devinberg]

Same exact thing happens for me most of the time.