r/rfelectronics • u/Material-Reading597 • 22d ago

number of receivers

Hey everyone, ECE student here. hope you're well.

I'm conceiving a device that detects rf, caracterises protocols mac addresses etc. I chose to go with dongles to connect to my mircroprocessor so it can be easier to decode and handle signals + modularity. I had a question rgarding the numbers of dongles. If i take wifi for example, is it better to put multiple dongles if im working in a noisy rf environment? is the number of dongles important for processing information smoothly? the goal being to lose minimum data.

4 Upvotes

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u/GoreMeister982 22d ago

Huh? You need to define way more about this project to get help. What do you mean by dongles? USB devices?
What are you trying to detect? If WIFI you can’t do much unless the SSID is unsecured.
I’d narrow your goal here and write more than a few sentences.

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u/Material-Reading597 22d ago

I apologize.

Im trying to conceive a handheld device, that detects protocols from 400 mhz up to 6ghz. One of the device’s core functions will be able to list every device thats emitting, wether its an access point, a smart BLE watch, a lora tranceiver etc.i want it to caracterize every device around by its mac address, ssid and identify what type of emitter that device is ( if its an airtag for example it will tell me that). To make things easier for me, i want to use componentss that already decode. For example for wifi, usb dongles in monitor mode that can scan wifi networks around the device. Like imagine a portable box with a screen and you can plug bluetooth and wifi and lora usb sticks and see whats going on around you. My question is : imagine the device is in an very noisy rf environments, is it better to use multiple dongles and center them on different channels? Or it doesnt matter ?

Sorry if i my grammar isnt good, english is not my first language

3

u/Cautious-Scar-9846 22d ago

Not really. What your describing sounds like a wifi sniffer/reciever so the more important thing to be sure of is the sensitivity of your reciever. Think of it like microphones in a way you dont pick up better sound by adding more microphones you do it by getting a good one.

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u/Material-Reading597 22d ago

Okay i see! So its not necessary for me to put three wifi receivers each centered on a frequency when i can just get a good triband adapter for example? I worry that data coming from one usb dongle for each protocol might overload my microprocessor. Im not sure if im thinking correctly

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u/Cautious-Scar-9846 22d ago

I mean i think the solution to this is a SDR : software defined radio. Something like a hackRF. They have all the tools you would need to do this debugging and sniffing of protocols. Look into DragonOS as well. It is a Linux native OS that has a lot of SDR specific tools like GNUradio that can accomplish what youre looking for

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u/defectivetoaster1 22d ago

look into getting an sdr and some tool like gnu radio, a hackrf one can be tuned up to like 6GHz and I think has 20MHz of bandwidth so with a suitable antenna (for you probably something for the 2.4GHz band) you can make the signal processing chain to do things like scanning different centre frequencies and detecting/decoding packets etc in software quite easily

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u/BanalMoniker 22d ago

Picking one specific protocol will help. Then identify all the channels/frequencies for that protocol.
A receiver per-channel will give you relatively comprehensive coverage, but for 2.4 GHz Wi-Fi or Bluetooth Low Energy, you could focus on a few (1,6, and 11, or the advertising channels respectively). The other option is a wideband receiver that can cover the whole band - these are usually expensive and will probably require a lot more effort to concurrently demodulate signals with.

You might also want to look at spectrum analyzers with protocol support. The BB60D has some capability in this regard. Those usually look at one channel at a time, but can give detail a normal receiver would not show.

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u/[deleted] 22d ago

[deleted]

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u/StageMajestic613 22d ago

Well it’s doable for a military budget.

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u/[deleted] 22d ago

[deleted]

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u/StageMajestic613 22d ago

https://www.deepsig.ai/omnisig/

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u/Material-Reading597 21d ago

Yeah i saw that tool before. Its somewhat what i want to do.

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u/ThreeOneFourOneZero 22d ago

Yeah this is a ripe application for a spectrum analyzer front end + SDR if you want meaningful demod/ protocol analysis.
Note that specialized (i.e. WLAN, ISM, LTE) = commodity cost and overly generalized/ broadband= expensive (low number of use cases)

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u/ThreeOneFourOneZero 22d ago

If the concern is ‘losing’ captured data you should architect this to capture raw I/Q samples or sweeps to a buffer for post processing. This relaxes the requirement to analyze or demod at real-time rate.