Listening to police and fireplace calls was a fairly easy proposition: purchase a scanner, punch in some frequencies — or in the event you’re sufficiently old, purchase the proper crystals — and also you’re off to the races. It was a fairly low-cost and straightforward pastime, all issues thought-about. However progress marches on, and with it got here issues like trunking radio and digital modulation, requiring ever extra subtle scanners, typically commanding eye-watering costs.
Having had sufficient of that, [Top DNG] determined to roll his personal digital trunking scanner on a budget. The primary video beneath is a short intro to the receiver based mostly on the mix of an RTL-SDR dongle and a Raspberry Pi 5. The Pi is ready up in headless mode and runs sdrtrunk, which screens the management channels and frequency channels of trunking radio techniques, in addition to decoding the P25 digital modulation — so long as it’s not encrypted; don’t even get us began on that pet peeve. The receiver additionally sports activities a small HDMI touchscreen show, and all the things will be powered over USB, so it needs to be fairly moveable. The most effective half? Every little thing will be had for about $250, significantly cheaper than the $600 or so wanted to get right into a purpose-built digital trunking scanner — we’re our Bearcat BCD996P2 proper now and shedding just a few tears.
The second video beneath has full particulars and a walkthrough of a construct, from begin to end. [Top DNG] notes that sdrtrunk runs the Pi fairly arduous, so a warmth sink and fan are a should. We’d most likely go along with an enclosure too, simply to maintain the SBC secure. A greater antenna is a good suggestion, too, though it looks as if [Top DNG] is within the thick of issues in Los Angeles, the place LAPD radio towers abound. The setup may most likely assist a number of SDR dongles, opening up a number of potentialities. It’d even be good to group this up with a Boondock Echo. We’ve had deep dives into trunking earlier than if you would like extra particulars.