Is anyone able to make the DOA Compass work properly weather using the ULA or UCA?
I would like to see examples of the ideal signal form we need in order to get a working direction on the compass.
Example in the user manual are good but not clear on the exact peak or shape of spectrum needed.
Thanks
Share your results
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Re: Share your results
Not sure what you mean by the peak or shape of the spectrum required?
Almost any type of signal should work, but continuous digital signals will probably work best.
Almost any type of signal should work, but continuous digital signals will probably work best.
Re: Share your results
During my test I used my HackRF to create a SSTV signal. If you are in an area with a digital trunked radio system you could also try it out with the control channel frequency. I was able to successfully locate a tower site with that method.
You'll want to make sure when you set your frequency and such that you have your filter frequency close to the bandwith of the signal you're looking to RDF.
In my case I was working with a 25khz wide SSTV signal so my filter was set to 30khz and worked quite well.
You'll want to make sure when you set your frequency and such that you have your filter frequency close to the bandwith of the signal you're looking to RDF.
In my case I was working with a 25khz wide SSTV signal so my filter was set to 30khz and worked quite well.
Re: Share your results
Initial bench test: I'm able to reproduce the Linear test same as https://www.youtube.com/watch?v=HE1BFeteBo0
I'm using a 915MHz Dipole on a metal ground plane with antennas spaced a 9.8cm. Using an HP8920A for Tx 904.28MHz @ 5KHz dev with a 1KHz tone. Once the BW, FIR and Decimation are right the arrow points to the direction of the Tx from -45 to 45 degree properly.
Mobile test: Installed the mag mount Dipole on the roof of a vehicle, set de same adjustments as bench test. Tx is a radio tower atop a building I can put in test mode (continuous Tx with data) and could not get the arrow to point to the Tx.
I was wondering if anybody had good results. Thanks Corrosive for your reply.
I'm using a 915MHz Dipole on a metal ground plane with antennas spaced a 9.8cm. Using an HP8920A for Tx 904.28MHz @ 5KHz dev with a 1KHz tone. Once the BW, FIR and Decimation are right the arrow points to the direction of the Tx from -45 to 45 degree properly.
Mobile test: Installed the mag mount Dipole on the roof of a vehicle, set de same adjustments as bench test. Tx is a radio tower atop a building I can put in test mode (continuous Tx with data) and could not get the arrow to point to the Tx.
I was wondering if anybody had good results. Thanks Corrosive for your reply.
Re: Share your results
Happy to help where I can.mdacosta wrote: ↑Mon Apr 08, 2019 4:48 pmInitial bench test: I'm able to reproduce the Linear test same as https://www.youtube.com/watch?v=HE1BFeteBo0
I'm using a 915MHz Dipole on a metal ground plane with antennas spaced a 9.8cm. Using an HP8920A for Tx 904.28MHz @ 5KHz dev with a 1KHz tone. Once the BW, FIR and Decimation are right the arrow points to the direction of the Tx from -45 to 45 degree properly.
Mobile test: Installed the mag mount Dipole on the roof of a vehicle, set de same adjustments as bench test. Tx is a radio tower atop a building I can put in test mode (continuous Tx with data) and could not get the arrow to point to the Tx.
I was wondering if anybody had good results. Thanks Corrosive for your reply.
I did try this atop my car and can confirm the linear array to be far easier to setup and use than the circular.
I'll be doing some more tests later in the week and plan to release a video of my RDF'ing a tower site.
I did notice while moving that multi-path was an issue and my best readings were often then I stopped my car and waited a moment for the reading to settle out.
Here is a quick setup video I recorded last week ( due to release tuesday ) that shows my test of a linear and circular array atop my car. https://www.youtube.com/watch?v=n5aWrz-42qc
Next time I'm planning to work harder on my circular array and attempt to get a recording of a mobile RDF session.
Re: Share your results
After several hours of fine tuning, I'm able to get a nice bearing on the ULA (linear array) but, could not get the UCA (Circular array) to get a nice bearing. Anyone else having the same issue?
Are we sure the drawing and info on the UCA is good?
Antenna radius = λ*s or should it read
Antenna spacing = λ*2
Thanks
Are we sure the drawing and info on the UCA is good?
Antenna radius = λ*s or should it read
Antenna spacing = λ*2
Thanks
-
- Site Admin
- Posts: 2410
- Joined: Mon Nov 19, 2012 11:54 pm
Re: Share your results
What frequency, spacing factor and antenna radius are you using? λ*s is correct.mdacosta wrote: ↑Wed Apr 17, 2019 5:11 pmAfter several hours of fine tuning, I'm able to get a nice bearing on the ULA (linear array) but, could not get the UCA (Circular array) to get a nice bearing. Anyone else having the same issue?
Are we sure the drawing and info on the UCA is good?
Antenna radius = λ*s or should it read
Antenna spacing = λ*2
Thanks
Re: Share your results
This is the calculation i've used:
Freq of 925MHz @ 1/1 = 32.4cm x 0.3535 = 11.45cm
From this drawing, between antennas 4 and 2 I have 22.90cm (2x 11.45cm)

Using dipole antennas on a 50x50cm ground plane.
Freq of 925MHz @ 1/1 = 32.4cm x 0.3535 = 11.45cm
From this drawing, between antennas 4 and 2 I have 22.90cm (2x 11.45cm)

Using dipole antennas on a 50x50cm ground plane.
Re: Share your results
On which side channel 1 should be on ULA? Its not numbered on the picture. I mean should channel 1 be most left or most right of the antennas?
Re: Share your results
for me 1 is at left...