Attic Mounted Raspberry Pi 3 B+

[Scanner4221]

I got around to attic mounting my Raspberry Pi 3 B+ with an RTL-SDR v3 attached to a yagi antenna. I opted to power it using a PoE injector and that's working great.

The Pi is running OP25 to decode a local Motorola Phase 2 system and Darkice to stream to here. It's working better than I expected. I'll have to monitor it when the temperatures climb in the summer. I hear some SDRs really start to frequency drift based on temperature but I've also heard this doesn't happen with the V3 of this specific one.



The OP25 web interface is especially nice to monitor the frequency drift and status:

 

[dispatchgeek]

Nice setup! How much delay do you experience between the web interface and your dark ice stream?

 

[Scanner4221]

Thanks!

I'm seeing about a minute of delay.

 

[vagrant]

Which POE injector are you using?

I use the RTL-SDR v3 and they stay tight enough. They also get hot. I use one 24/7 for APRS stuff with a Pi. To cool things down I did the following:
1. Used a short USB patch cable so the heat does not transfer to the Pi. ($10 for four) That did lower the Pi temp somewhat.
2. Attached some heat sinks to the dongle which definitely reduced the heat. ($10 for ten) I believe the side without the text is best placement, or you could put them on both sides.
3. I put a single fan in the Pi, which really helped. ($8 for two) Use the 5v GPIO pin to really spin the fan.

I have additional Pi's and dongles, so the extra quantity of the above was used up quick.

 

[mtindor]

I got around to attic mounting my Raspberry Pi 3 B+ with an RTL-SDR v3 attached to a yagi antenna. I opted to power it using a PoE injector and that's working great.

The Pi is running OP25 to decode a local Motorola Phase 2 system and Darkice to stream to here. It's working better than I expected. I'll have to monitor it when the temperatures climb in the summer. I hear some SDRs really start to frequency drift based on temperature but I've also heard this doesn't happen with the V3 of this specific one.

View attachment 79655

The OP25 web interface is especially nice to monitor the frequency drift and status:

View attachment 79658 View attachment 79657

Something you may want to consider, if/when you are on the same network as the PI and in front of a computer that'll use VLC. Sending the audio output to a PC is really nice for me in my particular case because I don't really care to listen to the system that I monitor when I'm not at the PC.

In my rx.py commandline I include: -w -W 192.168.0.107 -u 23456

- 192.168.0.107 is my laptop
- I've allowed inbound traffic from my PI4 (actually my whole LAN - 192.168.0.0/24) in through my Windows firewall on UDP port 23456
- I have VLC installed on my laptop

I created the following VLC shortcut command line :

"C:\Program Files (x86)\VideoLAN\VLC\vlc.exe" --clock-jitter=500 --network-caching=0 --demux=rawaud --rawaud-channels 1 --rawaud-samplerate 8000 udp://@:23456

When I want to listen to the audio from OP25, I just click on the VLC shortcut.

Sure, this case is specific to me. But I just wanted to share. I can watch the OP25 interface and hear the audio pretty much with no discernable delay. I know, not all what one would want to do if they wanted to monitor audio remotely.

Hopefully your attic doesn't become sweltering hot in the summer. I would have preferred to put my equipment in the attic, but I just can't keep an eye on it (and more importantly, access it fast enough) should something be going awry and it gets too hot. I am paranoid about fire in the attic. So I have my radio devices in the basement and LMR-400 runs going to the attic, with just antennas and preamps up there.

Nice setup you have there!

Mike

 

[Russell]

Scanner4221,

Very cool set up. That short coax probably really helps the signal. In Texas the heat would absolutely kill it. I'd have to move the PI into the AC and take the loss on the longer coax.

... I use one 24/7 for APRS stuff with a Pi ...

What are using for APRS?

Thanks,
Russell

 

[vagrant]

It gets hot here too, so my Pi and dongle are inside. The loss at 144.390 MHz is not that bad with LMR400. For 800+ MHz one could split the difference between coax and USB cable to at least get the Pi inside, or use LDF-450A Heliax with half the loss of LMR400. Heat kills so either throw money at replacing devices, or enjoy improved coax.

For APRS I am using Dire Wolf 1.5 and the alternate SDR configuration. No TX, just a receive only Igate.

 

[Scanner4221]

Which POE injector are you using?

I use the RTL-SDR v3 and they stay tight enough. They also get hot. I use one 24/7 for APRS stuff with a Pi. To cool things down I did the following:
1. Used a short USB patch cable so the heat does not transfer to the Pi. ($10 for four) That did lower the Pi temp somewhat.
2. Attached some heat sinks to the dongle which definitely reduced the heat. ($10 for ten) I believe the side without the text is best placement, or you could put them on both sides.
3. I put a single fan in the Pi, which really helped. ($8 for two) Use the 5v GPIO pin to really spin the fan.

I have additional Pi's and dongles, so the extra quantity of the above was used up quick.

I'm using this PoE injector.

Thanks for the links. I'm going to look into applying some kind of heat dissipation to the devices since I suspect that may be a problem for me in the future.

Something you may want to consider, if/when you are on the same network as the PI and in front of a computer that'll use VLC. Sending the audio output to a PC is really nice for me in my particular case because I don't really care to listen to the system that I monitor when I'm not at the PC.

In my rx.py commandline I include: -w -W 192.168.0.107 -u 23456

- 192.168.0.107 is my laptop
- I've allowed inbound traffic from my PI4 (actually my whole LAN - 192.168.0.0/24) in through my Windows firewall on UDP port 23456
- I have VLC installed on my laptop

I created the following VLC shortcut command line :

"C:\Program Files (x86)\VideoLAN\VLC\vlc.exe" --clock-jitter=500 --network-caching=0 --demux=rawaud --rawaud-channels 1 --rawaud-samplerate 8000 udp://@:23456

When I want to listen to the audio from OP25, I just click on the VLC shortcut.

Sure, this case is specific to me. But I just wanted to share. I can watch the OP25 interface and hear the audio pretty much with no discernable delay. I know, not all what one would want to do if they wanted to monitor audio remotely.

Hopefully your attic doesn't become sweltering hot in the summer. I would have preferred to put my equipment in the attic, but I just can't keep an eye on it (and more importantly, access it fast enough) should something be going awry and it gets too hot. I am paranoid about fire in the attic. So I have my radio devices in the basement and LMR-400 runs going to the attic, with just antennas and preamps up there.

Nice setup you have there!

Mike

Appreciate the tip. I went ahead and setup the UDP port and it's working great. Thanks!

I was concerned about the heat and potential fire hazard so I went ahead and setup a syslogging script that pushes the temperature to my Graylog server. If the heat gets above my set threshold, it triggers a shutdown script for the Pi. If that fails it shuts off the PoE to the port where the Pi is connected.

 

[RFI-EMI-GUY]

There are some clamshell heat sink cases for the RPI that provide a lot more mass for the heat to be absorbed. They also have fans. I would avoid the plastic box and go with one of those.

 

[kjfswkr]

I am sorry but what does this system actually do?


Kevin

 

[Scanner4221]

There are some clamshell heat sink cases for the RPI that provide a lot more mass for the heat to be absorbed. They also have fans. I would avoid the plastic box and go with one of those.

I will check those out. Thanks!

I am sorry but what does this system actually do?


Kevin

Monitors the San Diego-Imperial County RCS NextGen system and streams it to Broadcastify. Basically a P25 trunking scanner for the cost of a Raspberry Pi, an SDR USB dongle, antenna, some random hardware like a PoE injector, Linux knowledge and patience.

 

[krokus]

Interesting project, similar to what I have in mind for an ADSB receiver.

Has anyone tried one of these POE units?

Amazon.com: UCTRONICS PoE HAT for Raspberry Pi 4, Mini Power Over Ethernet Expansion Board for Raspberry Pi 4 B 3 B+, with Cooling Fan: Computers & Accessories

Amazon.com: UCTRONICS PoE HAT for Raspberry Pi 4, Mini Power Over Ethernet Expansion Board for Raspberry Pi 4 B 3 B+, with Cooling Fan: Computers & Accessories

www.amazon.com

 

[Dark_Hunter]

Could you link where you got that antenna?

 

[KC9QFU]

Interesting project, similar to what I have in mind for an ADSB receiver.

Has anyone tried one of these POE units?

Amazon.com: UCTRONICS PoE HAT for Raspberry Pi 4, Mini Power Over Ethernet Expansion Board for Raspberry Pi 4 B 3 B+, with Cooling Fan: Computers & Accessories

Amazon.com: UCTRONICS PoE HAT for Raspberry Pi 4, Mini Power Over Ethernet Expansion Board for Raspberry Pi 4 B 3 B+, with Cooling Fan: Computers & Accessories

www.amazon.com

I went this route:

Robot Check

 

[Scanner4221]

Could you link where you got that antenna?

https://www.amazon.com/gp/product/B00EC804SO/

It has mixed reviews but I figured for the price I'd give it a try. Seems to be perfectly fine for the frequency range I'm going for.

Maybe others have better suggestions.

 

[Scanner4221]

Revision #2:

• Upgraded the Pi to a Raspberry Pi 4 (4GB) model
• Placed the new Pi into a case with a fan and more heat sinks to hopefully lower the temperature if it gets hot
• Added a second RTL-SDR dongle with a 1090 MHZ antenna for ADS-B streaming to Flightaware
• Moved both SDR dongles from being directly attached to the Pi to lower the heat even further

The Raspberry Pi 4 CPU usage went from 99% used by OP25 to around 40-50%. The piaware software uses approximately 10% CPU.

 

[Dark_Hunter]

Have you considered feeding to somewhere like adsbexchange?

 

[Scanner4221]

Have you considered feeding to somewhere like adsbexchange?

First time I'm hearing of it. Checked out the website and I like it better already. Thanks!

 

[Dark_Hunter]

First time I'm hearing of it. Checked out the website and I like it better already. Thanks!

Send me a private message if you want to know further and maybe contribute there.

 

[krokus]

Revision #2:

• Upgraded the Pi to a Raspberry Pi 4 (4GB) model
• Placed the new Pi into a case with a fan and more heat sinks to hopefully lower the temperature if it gets hot
• Added a second RTL-SDR dongle with a 1090 MHZ antenna for ADS-B streaming to Flightaware
• Moved both SDR dongles from being directly attached to the Pi to lower the heat even further

The Raspberry Pi 4 CPU usage went from 99% used by OP25 to around 40-50%. The piaware software uses approximately 10% CPU.

How are you powering the SDRs? Is the USB hub a powered unit?