3 ms·
2 miles is amazing range. Bear in mind, these aren't huge towers hundreds of feet above the ground with 50kWh power sources and million dollar price tags,
by sbierwagen 11y ago
2 miles is amazing range. Bear in mind, these aren't
huge towers hundreds of feet above the ground with
50kWh power sources and million dollar price tags,
they're battery-powered, handheld, and consumer-priced
This guy did 7,600Km at 10mW on the 30m band, using a raspberry pi and a couple passives: https://gerolfziegenhain.wordpress.com/2013/04/13/raspi-as-wspr-transmitter/ https://gerolfziegenhain.wordpress.com/2013/04/13/raspi-as-w...
Of course, the antenna was 44 feet long, and he was transmitting at 1.46 baud, using WSPR: https://en.wikipedia.org/wiki/WSPR_%28amateur_radio_software%29 https://en.wikipedia.org/wiki/WSPR_%28amateur_radio_software...
As Shannon proved in the 40s, you can get great range if you can sacrifice bandwidth: https://en.wikipedia.org/wiki/Noisy-channel_coding_theorem https://en.wikipedia.org/wiki/Noisy-channel_coding_theorem
- makomk 11y agoIt's true that you don't need much power if both parties have ham radio licences, 44 foot wide antennas hoisted 30 foot into the air, and are willing to transmit unencrypted and very slowly. License-free handheld consumer gear is basically limited to UHF, which is pretty much line-of-sight.
- freehunter 11y agoI mean, using a 44 ft long antenna is kind of what I was talking about. This thing has zero external antenna.