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SDR

From dankwiki

Software-defined radio moves the majority of radio processing into software, facilitating relatively inexpensive wide-band hardware interfaces to the electromagnetic spectrum, especially those frequencies below 3GHz. Pairing advanced SDRs with software-defined antennas yields dynamically optimal cognitive radio. Perhaps most famously, DVB-T television tuners built around the RTL2832U chip, and available in USB form factor for less than $30 (particularly the Rafael Micro R820T2), can reliably provide 2MHz of RX bandwidth anywhere from ~30MHz to ~2GHz (still lower frequencies are supported via direct sampling). For $500, powerful units capable of tremendous bandwidth and range (as well as transmission capabilities) are available, and from there it's not that great a leap to building your own stingray.

Hardware

Device Tuner Bandwidth Sample Rates ADC Freqs Xmit?
NooElec NESDR SMArt R820TR2 2.4MHz sustained
3.2MHz peak
225--300kHz
.9--2.56MHz
8 25--1750MHz No
NooElec NESDR SMArt XTR E4000 2.4MHz 8 65--1100MHz
1200--2300MHz
No
HackRF One 20MHz 8 Yes
AirSpy 10MHz 12 24--1800MHz No
RTL-SDRv3 R820TR2 2.4MHz sustained
3.2MHz peak
8 25--1750MHz No

Software