I've used an RTL-SDR receiver with a Nexus5X phone, this driver and the SDR Touch app. It works nicely but would consider it for occasional use. The setup eats up the battery rather fast (high CPU usage + the need to power the SDR).
On the plus side, if you have the cable and the SDR with you, it's quite nifty to use it on a whim.
> i guess the bottom right black box
I think it's what it says on it, a battery, but that seems at odds with what I assume is a standard switch-mode power supply above it (I can understand using a battery, possibly lead-acid, to avoid line noise, but then to introduce the noise you're trying to avoid with an 'off the shelf from china' SMPS seems bananas).
Even if the SMPS is just feeding the SBC and USB hub, any noise'll still end up in the SDR via the USB power rails.
The white device, I think, is a combined USB hub and USB ethernet adapter, such as this:
Which means the black device in the corner is probably some SBC type thing like a raspberry pi or NUC, although not in a form factor I've seen before.
People are saying "bad antenna" and they are correct. Here is a good enough 'starter antenna' for the VHF and UHF bands: https://www.amazon.com/Bingfu-136-174MHz-400-470MHz-Handheld-Magnetic/dp/B07WPWK5JK/
that way sounds pretty challenging. But, I was recently looking at some frequency analyzers on amazon, and maybe one of them could do this? https://www.amazon.com/Upgraded-50kHz-6-3GHz-Seesii-Measuring-Parameters/dp/B09M6HPB4L/
I'll definitely check out medium wave. Thanks! (I only mentioned shortwave because so far that's been the only non-commercial audio I've been able to pick up :) ).
Thanks for the tip about the USB cables, too. I've been wanting a longer one, but AirSpy doesn't give any specs on the cable they ship with the HF+ Discovery. It's a pretty thick cable, though, and does appear to have chokes on it, so I assume it's at least got some shielding.
Is this the kind of TrippLite cable you're talking about?
https://www.amazon.com/Tripp-Lite-Hi-Speed-Ferrite-U023-006/dp/B003MQ29B2?th=1
The sell them on Amazon, that's where I got mine.
You reduce signal strength by using RF attenuators. Also, your RTL-SDR might need better shielding as it might pick up too much signal even without an antenna. This is a common problem during fox hunts - when you get too close it doesn't matter which way you point your antenna, the signal is going straight in to the radio (we use a special "offset attenuator" to shift the frequency so the signal going straight in is ignored.
You can get them in Type-N, BNC, SMA, etc. usually with one male and one female connector and you can stack them end to end to get more attenuation. There are step attenuators with switches (check the upper frequency limit) and as digital step attenuators (which may overload easily as well). You can get high power versions which you can use like a dummy load with the advantage of being able to tap of a lower power version of the signal (which will probably need to be attenuated even further before going into sensitive devices like spectrum analyzer or receiver). So for example, you could use a 30dB 10W attenuator to reduce 5W to 5mW and another 30dB to reduce it to 5uW.
https://smile.amazon.com/Nooelec-SMA-Attenuator-Kit-Line/dp/B07YYMT65T
Overdriving a spectrum analyzer into the non-linear region is a good way to see lots of spurious emissions that aren't actually there or in some cases even damage it.
Try using t with a different machine. Same interference? Use a bcb filter or a ~3.5 mhz high pass filter. Something like: https://www.amazon.com/dp/B07XKY8YKB/ref=sspa_dk_detail_2
Noise no longer there? Probably, as it appears to be PS ripples. Use a USB extension (attenuate the ripple) and put an rfi choke on the cable at both ends. You can grab a pack of these for a few bucks.
Best part, together this is a $25 solution and if it doesn’t totally solve the problem, you should still get use out of the items.
No one antenna is going to be optimal for all things. That being said for international (shortwave) listening this is one of the best things you can get:
https://www.amazon.com/MLA-30-Antenna-Active-Receiving-100kHz/dp/B085ZSXF8Z
This is a highly directional antenna designed to cover the 470-860 MHz. This isn't going to work well for RX across the dongle's 24-1700 MHz range. For your price range, your best bet is a discone. Something like this: https://www.amazon.com/Tram-1411-Discone-Scanner-Antenna/dp/B00QVNI1V0
Thanks for taking the time to go through the question.
> The problem you’re likely having is that the LNA in the active GPS antenna is not being powered in your custom setup, but your commercial receiver is providing the needed DC bias.
Unfortunately, I don't think that's the case. In the first setup (Figure 1), I used the AirSpy's built-in biast-tee to power the antenna (and verified it was working with a multimeter). For the second approach (Figure 2), I used an external bias-tee.
Just to add to the previous answer.
If you have an Android phone with OTG, you can install this app https://play.google.com/store/apps/details?id=com.mantz_it.rfanalyzer&hl=en , tune to the right frequency and look for the beacon on the screen. You can tweak the gain, frequency and a few other settings. A phone might be easier to use in the forest than a laptop.
Additional requirements:
Natively, you're probably not going to find an affordable SDR that will cover this range.
Your best bet is probably one (or both) of two options: 1. If the camera is wifi based, look into a wifi scanner app for your phone: https://play.google.com/store/apps/details?id=com.ubnt.usurvey 2. Use a standard SDR with a 'downconverter'. https://www.rtl-sdr.com/receive-up-to-4-5-ghz-on-your-rtl-sdr-for-5-using-a-directv-downconverter/ A few bits of hardware and a little modifications would allow you to see the signals from that frequency range.
NOTE: The SDRs will likely not be able to decode anything from that frequency range. The bandwidth is usually much wider than the receive bandwidth of the devices. It will work if you're just trying to do direction-finding style "point an antenna at it" to see if its transmitting or not.
Also, another idea that would be cool...
This nifty pipe heater says its conductivity automatically changes based on the temperature, so you wouldn't need a thermostat.
The "turn-on" temperature of 37 degrees does not look adjustable though.
hey OP, since we know what the connector is, do you just need one of these? https://www.amazon.com/Female-9-5mm-Satellite-Antenna-Adapter/dp/B007PPZXU0
Looks to be the cheapest one available with free Prime shipping. :)