The objective of the test is measuring the performance of CRPA adaptive pattern (resolution), does the pattern has a sharp null or wide null for jamming source.
Our planned scenario is putting a jamming source between the receiver and any satellite. Then, shifting the transmitter position in elevation and azimuth for each run. Then, the signal level of the satellite will be noted to get an idea about the sharpness of the CRPA pattern.
We wonder that how many degree of elevation and azimuth between the satellite and the transmitter is enough for tracking that satellite. Is there any advice or best practice for this scenario?
I hope it is clear, if it is vague I can add some visual diagrams. Thanks.
We’ve 4 radios, and a wavefront distribution module for CRPA. Our receiver has 4 RF input, I connected these to the outputs of the WF module. Why do you think we don’t have a wavefront simulator, what is the exact setup for it?
We would like to see whether our CRPA solution detect the jamming source correctly or not, and its resolution especially. To see that, we plan to put a transmitter on the LOS direction of any satellite, then we plan to shift the transmitter in elevation and azimuth until the satellite behind the transmitter is being trackable by the receiver. This test may give us about the resolution of CRPA antenna pattern (Less shift means better resolution, adaptive antenna detect the transmitter sharply). I am not sure if it is a practice method or not, but wondering the result.
The simplest way to explain my need is to set “Transmitter X” position as the same elevation and azimuth values of any satellite for a static scenario.
I found a workaround for it, let me explain it. The lat/lon values of any satellite can be seen during the simulation. I am adjusting lat,long,alt values of the “Transmitter X” to be the same as the values of the satellite chosen. But it takes time to adjust.
The CRPA electronics operate on the phase of the signals. Therefore, the radios must be phase coherent. This video (click here to watch on YouTube) explains how CRPA can be tested with a wavefront simulator. About 10min in the video, you will see what I mean. In your setup, the USRP initial phase is most likely random and will move overtime as the radio temperature changes, or even when you touch the cable. Orolia developed a system designed specifically to ensure the simulation is phase coherent. As an alternative, if your CRPA electronics is software-defined and can take IQ data as an input, you could simply use Skydel to generate IQ stream: one stream for each element. The IQ data will be phase coherent.
On a wavefront simulator, the scenario you want to simulate can be done. First step is to create a virtual transmitter (you need Advanced Jamming feature, which is enable on OAPP license). You can move that transmitted to any location, simply place it in between the receiver and the GNSS satellite. You can then have the virtual transmitter programmed to transmit signals of your choice. Skydel include a variety of modulation you can choose from or you can import your own IQ file for maximum flexibility. The transmitter position can be changed to steer away of the line of sight between the receiver and the satellite and you should be able to measure the effect.
Would you like me to schedule a direct discussion with our engineering team in Montreal? We often do this on complex topics like this so that there is direct communication. Let me know and I can coordinate this directly or feel free to e-mail me directly at robert.burke@orolia.com.
Thanks for your detailed explanation. Our Skydel is already calibrated, the phase of radios are aligned. The video you mentioned is perfect, the visuals in the presentation are so nice and simple to understand the fundamentals.
We have the feature “Advanced Jamming”. What does “Virtual Transmitter” mean, is it regular “Transmitter” in interference tab? If they are the same term, currently I am following this way, it seems ok!
However, during the placement of the interference transmitter between the receiver and GNSS satellite, I am adjusting lat/lon/alt values of the transmitter and verifying its elevation/azimuth on MAP tab… I do this adjustment in a few try to find the correct position. Is there any way to directly set the azimuth/elevation of the transmitter?
Because, I plan to use API to automatize our tests, I do not know the commands for now, but I can not imagine the workflow of the API script in this way.
Btw, thank you all, I am getting motivated a lot as you reply.
Your behavior is so kind, I am so glad. The answers here also are perfect!
The Skydel product we have is just new in our lab. And we are trying to explore it in advance ​:) Now, I am taking a few notes about our questions, scenarios, feature requests. Then I would like to have a direct discussion with the team.
Yes, you seem to have found the right place to add the transmitter. In the Settings → Interface menu, you simply click on Add Dynamic. After you added the transmitter, you can see in the Automate tab the corresponding command “AddIntTx”. If your scenario is predefined, you can import a trajectory where you could stay in one location for few seconds, than move away, etc. Another possible approach is to setup multiple transmitters at different elevation and azimuth and turn them on and off as needed.
A simple approach to compute the location of the jammer on the line of sight is to use the raw log file to get the position of the satellite and the receiver in the ECEF system. This is a cartesian system so you can easily compute a XYZ position that would be on the line of sight with the desired distance with the target. In the API we provide functions to convert from different reference system: ECEF, LLA and ENU. Take a look in the folder Skydel-SDX/API/Python/skydelsdx and you will find a library called units.py. You have everything you need in there.
Hello @JoBack, can you share with us a description of your hardware setup and how you drive it with Skydel? I’m really curious to understand how you guaranty the phase alignment in your setup.
That is the answer what I need! As far as I understood, there is no direct way to set azimuth/elevation of a transmitter. As an alternative, I should calculate LLA and use it, good approach, thanks.
Sure, it’s a commercial setup for our CRPA tests. In the cabinet, we’ve 4 radios (USRP N310), 5 PCs (1 monitor 4 radio nodes), and a WF distribution unit. After unboxing, we adjust the system(all configurations for acceptance) with an engineer from Orolia. I can not give more details here, publicly. But if you need information further, we can use DM.
