Hi Eric,
1. I had initially purchased a Tiny Ultra from AliExpress which turned out to be a clone. I have since then returned it and have purchased from the recommended store Zeenko.
2. It passed the calibration test, level test and also got the FW updated to the latest version and again passed the calibration and level test.
3. I could also connect it to the windows PC with the tiny sa app.
I am quiet happy with the performance with the Tiny Ultra.
What I note is someone in the group posted that HW version? V04.5.1.1 to be a clone. The unit I received is V0.4.5.1.1

We are a drone service provider and use the Tiny SA Ultra to check GPS availability and to look out for GPS jammers. I understand from Google,?.?

Any help in resolving this matter is highly appreciated.

Menon.

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Surely the drone (or if not a handheld GPS) will tell you the number of satellites available in a given area and if there are none indicated then the TinySA will show whether there is a jamming signal? Any jamming signal should be visible on the TinySA.

Menon,

I am curious.? What are you doing with your drones that would make bad actors want to jam your signal?

On Sun, Feb 4, 2024 at 09:11 AM, P M Menon wrote:

Will it help, if I replace the stock antenna with a high gain GNSS antenna (42dB)

Only very slightly.

Don't expect the GPS signal to suddenly appear 42 dB above the SA noise floor, it doesn't work like that.

The actual antenna is still likely to be a relatively low gain omnidirectional Puck or Helix, followed by a low noise, high gain amplifier, which is intended to help to overcome cable losses, but it needs to be powered in order to work.

I suggest you have a look at the previous threads on this subject.

This is a good overview too.



Regards,

Martin

Jamming versus spoofing……Spoofing may be hard to see as it will be a Gold code chipped signal and about 2MHz wide.?
Jamming can be a simple GNSS receiver overload condition. ?It does not take much narrowband (in-band) power to saturate a GPS receiver. ?In terms of the spreading math used to de-spread the satellite signal the theory suggests that an incoming narrowband jamming signal gets?spread?in the receiver while the synchronized satellite signal becomes?de-spread?in the receiver. ?Mathematically this would imply coding?loss?for the narrowband jamming signal while also providing coding?gain for the satellite signal. ?That all sounds peachy until the narrowband jammer overloads the receiver IF and the satellite signal is blocked due to receiver overload. ?This is common problem in aircraft avionics when the aircraft’s COM radio is transmitting near 121.186 MHz and the 13th harmonic of the transmitter lands smack in the middle of the L1 band. ?In fact 13th harmonic filters are available to be added in-line with the aircraft’s COM transmitter coax. In conclusion a narrowband terrestrial carrier?can?“jam” GNSS receiver. ?There is a good paper on this topic out there on the web and if I find it I’ll post it here.

I just uploaded a good paper on narrowband GPS jamming to the FILES section.

-Charlie
W5CDT

A bit off the TinySA topic but there may be better ways to accomplish the OP's tasks than trying to use a spectrum analyzer.

One could use a dedicated GNSS receiver that can provide signal strength of the received satellites and output data on jamming. The UM960 or 980 is a 3 band (L1/L2/L3) receiver that can provide this information. It is about $125 on Ali. Team it up with a 3 band antenna from Ali for about $50 and you would have a pretty good platform for surveying GPS signals and detecting potential signal jamming / interference. The free Uprecise software provides nice graphs on the signal strength of satellites in view. Simple commands on the serial console in Uprecise can send back the jamming data.

Can you provide a link? I see various UM982 modules on Aliexpress but no mention of the Uprecise software?

Thanks, Mike N2MS

Any recommendations? ?I spent a lot on antennas that turned out to be worthless when I first ventured into radio, and I’d like to avoid repeating this mistake with my TinySA Ulra. ? ( my SDR too). ?Thanks to all for your time and excellent feedback. ?

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Will it help, if I replace the stock antenna with a high gain GNSS antenna (42dB)?

No.?

Certainly a good antenna is always good, but more gain won't help with the specific problem that satellite navigation signals are very weak in the best of circumstances: The strength of the signal you want is competing with noise, so more gain will make the signal and the noise both louder.?

So once the signal from your antenna is loud enough louder won't help.

-kb

AC1HJ

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Surely the drone (or if not a handheld GPS) will tell you the number of satellites available in a given area and if there are none indicated then the TinySA will show whether there is a jamming signal? Any jamming signal should be visible on the TinySA.

Depends on how strong the jamming signal is and what the jamming looks like.

Certainly a strong enough jamming will be visible on your Tiny SA, but the desired signal is so weak that the jamming might be pretty dang weak, too, yet still be a problem.

As for what the jamming looks like, it might range from white noise to something that looks a bit more like a legit signal to very good spoofing.

Detecting spoofing might be very hard, and potentially a cat-and-mouse game as detection techniques get better and so the spoofing gets better.

Detecting spoofing by analyzing the radio signal alone is probably going to be doomed in the end. Rather, detecting spoofing is going to need correlating the apparent (maybe spoofed, maybe not spoofed?) signal with other information.?

For the simplest example, if you know the receiver is not moving yet the satellite signal makes it appear as though the receiver is moving, then you are being spoofed.

For the hard example, detecting spoofing while moving, this probably requires correlating the apparent satellite signal with other navigation information:?

• Other satnav systems,?
• inertial information,?
• dead reckoning (From my last known position, how fast do I think I am moving and in what direction, looking at wheel speed and direction, or speed in water and rudder, looking at airspeed, looking at magnetic or gyroscopic compass, etc.),?
• bearings to known beacons (broadcast radio, VOR signals, cell tower signals, wifi hotspots),
• Loran (doe it still exist?),
  
• celestial navigation…

See how some set of those change over time, correlate, figuring who might be lying to you.?

Other ideas:

• If you have stationary "friends" who are near, perhaps they can report any spoofing they detect.
• Very carefully characterizing the "satellites" being received and whether they seem right in what they say and how they say it. (Do satnav satellites have distinctive "fists" on the analogy of a CW ham operator?)

In general, a very hard problem. The really good techniques are probably classified. Others patented.

-kb

AC1HJ

N2MS,

For simply surveying and checking for jamming a UM980 single antenna receiver would do.?
Antenna?
Uprecise -??You will need to create your own login to download the software. The software is in the "Tools" section of the download center.

Thanks,

N2MS

GPS antenna's like the one linked are tuned to two specific frequency ranges 1165-1278MHz and 1559-1612MHz. In those bands, it has gain of ~6dBi at 90 degrees elevation. At ~20 degrees elevation, it drops to 0dBi. So a 3D cone shaped pattern facing upwards. The LNA is mostly there to overcome cable losses. As mentioned earlier, the GPS system uses spread spectrum and digital signal processing to distinguish the signal from the noise. The receiver is able to tell the direction, distance and elevation angle of the satellites by processing time delays, doppler shifts and carrier phase measurements. Hence my suggestion to use a GPS receiver, antenna and software to accomplish the OP's tasks instead of a spectrum analyzer.

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Hi All,
I am certainly no expert here, but my experience with GPS problems have mainly been due to severe multipath in high rise city areas giving erroneous location data or thick trees in heavily wooded areas blocking the GPS signal altogether.
I would have thought that a basic normal GPS receiver (like a Garmin Etrex, etc) would be able to determine GPS satellite coverage and if the?reported position is erratic, suspect jamming or spoofing. The TinySA Ultra should be able to locate the jammer. The use of a directional antenna should enable narrowing down the source or at least the direction. If you are really serious, I would also use a band pass filter, or a combination of a high pass and a low pass filter between the antenna and the TinySA. By using pre-selection, you could enable the internal LNA and drop the noise floor even further.
Even if it is a more sophisticated spread spectrum jammer, you should be able to see a "bump" in the noise floor as you sweep the antenna through its location.
I agree the use of a normal GPS puck is impractical because it is basically omnidirectional as stated by others AND it requires power.
Cheers...Bob VK2ZRE

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I would have thought that a basic normal GPS receiver (like a Garmin Etrex, etc) would be able to determine GPS satellite coverage and if the?reported position is erratic, suspect jamming or spoofing.

I expect it depends on the details of the jamming or spoofing. It might be jamming as simple as a broadband noise source, or it might be an sophisticated spoofing signal that slowly drives the apparent position of a military user off by a great distance. Or something in between.

Commercial airliners have problems with GPS, and I would hope they have better receivers than do us consumers who paid maybe only a hundred-ish bucks for a GPS receiver. If so, your Etrex is not immune.

-kb