Mobile ADS-B receiver build for JBV1: Questions and Comments

johnboy00

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Same here, I think Android 11 changed some stuff, I used to be able to connect to wifi and mobile data at the same time.
It's like I keep saying: With every new release, they don't add great new stuff. They remove and/or disable stuff.
 

johnboy00

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And when they do add something new that could be great, it often turns out to be not so great. Like the LocalOnlyHotspot introduced in Oreo. When I first started on the carputer stuff, I thought the LocalOnlyHotspot feature would be perfect for connectivity. However, the SSID and password are randomized, with no means to set them manually or programmatically, so I'd have to connect to the Pi to tell it how to connect to me. Stupid.
 

Errol W

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Just following up on this.
Verizon Galaxy S9 running Android 10. Will not connect to internet using mobile data when connected to wifi (without internet access). This is true even if developer options mobile data always active is always on.

Moto X4 running Android 9 (google-fi version). Does allow internet access via mobile data even when connected to wifi, which it correctly identifies as having no internet connection. However, although the status bar shows the wifi network as connected, I can't browse the network unless I turn mobile data off. So I have a suspicion that wifi networks without internet access are shut off, when mobile data is on--even when the connection is set to static and the gateway is blank.

Bummer.

I've got the parts for the ads-b build coming in next week so I'll give it another try, but I am not hopeful.
 

SwapFile

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I updated my bracket design to have a filter-less version, I had some trouble getting the full sized version to mount where I wanted it.

Both styles are available here:

1614546184414.png
 

Errol W

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Just a note for those that might be playing with the PCB antenna shown in Post #3 of the locked build thread.
Although @johnboy00 reports good luck with this laying flat on the rear deck, I think this antenna really wants to be positioned vertically. Testing yesterday with a laptop in my 4Runner in the driveway, I had much better luck positioned vertically on one of the rear cargo windows vs when laying flat on the molding of the same window.
I will also be testing a roof mount antenna once it arrives to see if the potential improved reception is worth the hassle. Looking at aircraft tracks here in New England the speed enforcement aircraft is always within 2nm of the road, but I am concerned given the low flight level of the plane (typically <FL2500) and the need for detection *in front* of the vehicle, that placement in the rear window/deck may be suboptimal. More to come...
 

johnboy00

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Just a note for those that might be playing with the PCB antenna shown in Post #3 of the locked build thread.
Although @johnboy00 reports good luck with this laying flat on the rear deck, I think this antenna really wants to be positioned vertically. Testing yesterday with a laptop in my 4Runner in the driveway, I had much better luck positioned vertically on one of the rear cargo windows vs when laying flat on the molding of the same window.
I will also be testing a roof mount antenna once it arrives to see if the potential improved reception is worth the hassle. Looking at aircraft tracks here in New England the speed enforcement aircraft is always within 2nm of the road, but I am concerned given the low flight level of the plane (typically <FL2500) and the need for detection *in front* of the vehicle, that placement in the rear window/deck may be suboptimal. More to come...
For longer distances, yes, vertical orientation is better. However, a dipole antenna will having trouble picking up a source in the direction the antenna is pointing. 20+ miles of range is enough for me, and I'd rather be sure that a plane above me is being picked up reliably.
 

Errol W

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What I observed with my very brief experience with a 4Runner is that there was no problem with aircraft immediately overhead.
The issue was that detection of low flying aircraft out in front of the vehicle was suboptimal. I was not picking up aircraft immediately forward of the vehicle that were taking off and landing at an airport around 5-10nm away when the antenna was horizontal. I could see them on the ADSBx website, but not on my local receiver until they were at least at FL3000. The issue may be much more dramatic with my placement of the antenna in the 4Runner cargo window because there is quite a bit of metal between the antenna and the sky forward (and especially diagonally forward) of the antenna in that location.

I asked my crusty ham radio loving neighbor about my experience and he claims that the "hole" at the tip of the antenna is less of an issue than the signal mismatch (trying to receive the vertically polarized ADS-B signal on a horizontal antenna). He claims the signal mismatch results in a huge 10-20dB loss in signal strength. I am not smart enough to know whether he is correct.

I suspect this is all largely academic, and like you I could care less about planes 20+ miles away. In fact I could care less about planes 10 miles away. But I don't want to miss a plane 5 miles away due to marginal reception and terrain.

Too cold and windy to sit outside and test more today.
 

Smason

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What's the UI like on this? Building one for cannonball.
 

Smason

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There really isn't a UI, it's more like a better (local) datasource for JBV1.
Gotcha, i was looking through the code and didnt see where it routed the info to JBV1.

I use HR more than JBV1 so id needs to figure out if this could be used for his servers as well.
 

johnboy00

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Gotcha, i was looking through the code and didnt see where it routed the info to JBV1.

I use HR more than JBV1 so id needs to figure out if this could be used for his servers as well.
This in-car receiver replaces external servers as a data source, so any other apps would need to support pulling data from it directly.
 

codesplice

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I finally had a chance to put this build together yesterday (thanks again for the brilliant instructions!).

I'm having a hell of a time getting JBV1 to detect the Pi when its connected to the phone's mobile hotspot. I can confirm that the Pi is indeed connected and that I can open up the http://<IP_ADDRESS>:8080 page on the phone's browser. The app just never connects to the Pi. Pixel 5 on Android 11, FWIW.

Works brilliantly when both are connected to my home WiFi though. I think tonight I'll test with the phone and Pi connected to another phone's hotspot to see if that makes a difference.

Any other ideas of things I could check/try short of getting a dedicated hotspot for the car?
 

johnboy00

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I finally had a chance to put this build together yesterday (thanks again for the brilliant instructions!).

I'm having a hell of a time getting JBV1 to detect the Pi when its connected to the phone's mobile hotspot. I can confirm that the Pi is indeed connected and that I can open up the http://<IP_ADDRESS>:8080 page on the phone's browser. The app just never connects to the Pi. Pixel 5 on Android 11, FWIW.

Works brilliantly when both are connected to my home WiFi though. I think tonight I'll test with the phone and Pi connected to another phone's hotspot to see if that makes a difference.

Any other ideas of things I could check/try short of getting a dedicated hotspot for the car?
Are you starting JBV1 *after* the hotspot is created and the Pi is connected to it? That seems to be most reliable for me. I hope to be able to work on it more soon, since there's definitely room for improvement when the hotspot is on the JBV1 device.
 

codesplice

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Are you starting JBV1 *after* the hotspot is created and the Pi is connected to it? That seems to be most reliable for me. I hope to be able to work on it more soon, since there's definitely room for improvement when the hotspot is on the JBV1 device.
Hmm, that could be a factor. I was using Tasker to automate enabling the hotspot when I launched JBV1. I'll test again with manually enabling the hotspot, confirming the Pi is connected, and then launching JBV1 to see if that helps. Thanks!

Edit: Nope, unfortunately no change when starting the hotspot first.
 
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SwapFile

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If anyone is looking for a Pi4 case, this one looks promising:

There is no cooling, but I think that will be OK given the low load and external SDRs. If I run into problems I'll report back (and switch to the fan version).

It has enough room to add strain relief and protection to all the USB plugs. I'm also going to hook up the 5V power internal to protect the jacks.

The HDMI ports don't quite line up with a Pi4, but it's close enough, and I plan to just dremel the holes into slots on the end.

I figure I'll put a dab of hot glue on all the plugs to make sure they can't wiggle out, and zip tie the USB cables for strain relief through the vent cracks.

1616516632964.png
 

SwapFile

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I noticed that JBV1 now it allows specifying the Carputer's MAC address.

I'm curious, does JBV1 only search wlan0 for the Carputer MAC address? Or does it search all interfaces, such as bt-pan?

I was trying to see if it would be viable to use a bluetooth tethering (with the JBV1 phone sharing) to my carputer while using wifi tethering (with my main phone) sharing internet to my JBV1 phone.

The idea being that my "car" could boot up my JVB1 phone and Carputer and they could connect to each other over BT without relying on my main phone to be there to bridge the two.

It seems like it should work, when I manually initiate the connections my JBV1 phone can access both the internet and my carputer SkyAware page, but JBV1 can't seem to find the Carputer on bt-pan even if I specify the MAC, so I'm not sure what's missing.
 
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johnboy00

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I noticed that JBV1 now it allows specifying the Carputer's MAC address.

I'm curious, does JBV1 only search wlan0 for the Carputer MAC address? Or does it search all interfaces, such as bt-pan?

I was trying to see if it would be viable to use a bluetooth tethering (with the JBV1 phone sharing) to my carputer while using wifi tethering (with my main phone) sharing internet to my JBV1 phone.

The idea being that my "car" could boot up my JVB1 phone and Carputer and they could connect to each other over BT without relying on my main phone to be there to bridge the two.

It seems like it should work, when I manually initiate the connections my JBV1 phone can access both the internet and my carputer SkyAware page, but JBV1 can't seem to find the Carputer on bt-pan even if I specify the MAC, so I'm not sure what's missing.
wlan0 only.
 

SwapFile

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I ran a temp test today. I put my Pi4 in my 3d printed stratux case (linked above) and started it running in my trunk down by my spare tire. I kept the SDRs up above in the trunk, similar to where I proposed installing them. The car was parked in the shade to reduce variables.

Ambient trunk temp: 20C (approximately constant through the test)
Final Pi4 temp: Leveled out at 57C about two hours later.
SDRs: Not specifically monitored, but not significantly hot.

A Pi4 throttles at ~80C, so I'm actually considering adding a small cooling fan. Anyone else care to comment on their Carputer temps? Or should I just not worry about it until it's a problem?
 

Jason Diaz

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I don't have a Carputer, but I do have a dedicated android and hotspot for the car, would that be enough?

Anyone building these for profit?
 

SwapFile

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After doing more temperature testing I decided to change my installation plans.

I made a bracket that will keep my Pi4 and SDRs down near my battery with my dashcam battery packs. Then I'll run some RG317 up to my antenna installation positions.

I'll make a full write up later, but if anyone needs the STLs they are here:
 

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