3 Troubleshooting and Tuning
Use this section to learn to open up SDRconnect, review the signals you are best receiving, configure your system to that signal, understand factors that may affect signal. Use this information to just purely check the different signals you could use as options in your area or to help root cause why you may not be picking up targets.
- Go to https://towers.retina.fm/, Use My Location, and make sure the correct Data Source is selected
- Take note of which systems are rated as Ideal (if none, then use Good). Prioritize VHF and then UHF. Save the Callsign, Lat, Long, Altitude, Hz, and expected Rx Power. It's recommended you save the output of the file somewhere accessible later like in a .txt file, one note, or excel
You will want to use SDRconnect mode if you you don't seem to be getting any hits on radar or if
- Confirm you have reference and surveillance antennas plugged in correctly (reference in input 1, surveillance in input 2)
- Download the SDR Connect software here
- Make sure configuration is complete go to your home dashboard, open up the config tab, click Mode: SDRconnect, and hit Apply Changes
- Figure out the IP address of your Pi by:
- logging into your router or ISP app and looking up the device IPs currently connected
- In windows open up command prompt and enter the command: ping owl.local -4, the IP address will then crop up
- we will add the IP address to the network section of owl.local in the not too distant future
- In SDRconnect navigate to the "..." button near the wrench at the top, add and name your Remote device anything
- add the IP address found, add port 50000, and leave everything else. Make sure to test the connection to make sure it is on the network and detecting it properly.
- At the top left of the screen hit the circular arrow to refresh and then it should detect the connected system, hit the green arrow to run.
- Click the 2 gears icon at the top left and make sure the sample rate is set to it's 10 MSPS and that the gain is set generally in the middle for now.
- Open the reference channel 1 input and center the Hz on one of the Hz from the table you would like to test and make sure the red selected measurement point is also centered on it
- A strongly received pilot signal will show up with +/-3MHz from the pilot Hz above the noise
- You may need to adjust your system in different ways to improve the reception of the pilot signal and then recheck the pilot signal, moving an antenna or cable in a small way can have surprising increases or decreases in signal quality. Factors that may improve your signal quality are listed in the next sections. Ideally we are looking for both a strong pilot signal that stands at least >10dB above the noise, a great SNR will be >30dB above
- If you have tried as much as you can and it does not seem to give you a good pilot signal unfortunately you may not be able to use it, sometimes weird nulls occur even with the best signals.
Image curtesy of MIT Lincoln Labs Video Introductory Series is a great introduction for those who want to deep dive.
I've tried to break it down into 3 sections, the signal itself, the hardware we use to receive it, and the Software settings you have available.
- Tower Location and Power
- Tower Antenna Direction
- VHF vs UHF vs FM reflectivity off atmosphere and trees
- VHF vs UHF vs FM off of target objects
- FM consistant signal issue
- Chosen Reference and Surveillance Antennas
- Location of Antenna, indoor/outdoor, mountains/buildings/trees, relative to transmitter and targets, minimum 3-4ft away from neighboring any antennas
- Direction of Your Antennas, including trees/buildings, vertical orientation
- Antenna Phase
- Antenna Height
- Cabling Length and Losses
- Outdoor Option
- Amplifier Optional
- Confirm your configuration settings are as intended for the tower signal you are trying to use. Confirm Center Hz, Lat, Long, and Altitude are all correctly set.
- Reference Gain Reduction
- Surveillance Gain Reduction
- Low Noise Amplifier State
