7 ms·

Lower power, but highly processed radio signals are fascinating to me. I've been playing with WSPR on the 10 meter band which is fixing (hopefully) to open up a

by th0ma5 11y ago

Lower power, but highly processed radio signals are fascinating to me. I've been playing with WSPR on the 10 meter band which is fixing (hopefully) to open up a little here over the next couple of months. With about 1/10th of the power of my Wi-Fi router and a long wire over top of the house, I've been picked up so far this year in California from Ohio. Last year I was heard almost daily in Europe. A blogger I follow with a bit more power but still less than a watt has been heard on several continents almost every other day from the UK. Anyway, signals are a function of time as well as bandwidth, and with more precise clocks in our devices and higher CPU power to make sense of it, it is an exciting time live and see what's next.

anderiv 11y ago
One of my most memorable moments in amateur radio was making a JT65 contact - 1 watt, from the north-central US to the island of Reunion, roughly 10k Kilometers. And that was on a very ad-hoc wire antenna.
olympus 11y ago
What's your callsign? I'll see if I can pick you up with my RTL-SDR+Ham-it-up and maybe once I have my ham license I'll talk back. Every now and then I find a post on HN that really makes my day and I realize how awesome this community is and how our interests overlap beyond computer programming and entrepreneurship. This is one of them.
- kc2zuf 11y ago
  Not the OP but I'm on WSPR on 20m right now as KC2ZUF!
- th0ma5 11y ago
  Well, I'd appreciate a report on the WSPRNet page once you get your ticket. I'm W8KV, but I don't know that I'm putting out all that much, and when I look at streetview of the houses of the people that pick up the signal they have some crazy setups! That said, I was able to receive PSK31 from France here in Ohio back before I got my ticket with just an old AC extension cord strung along the ceiling as an antenna, so keep playing with things, you never know what all will work.
semi-extrinsic 11y ago
Ok, since there are some radio wizards in this thread: if I want to log low bandwidth sensor data (so < 1kbps) on a unidirectional (if that helps) link over ~ 500m, almost clean line-of-sight with some trees in there, what are my options? I'd prefer to spend little money and use little power on the sensor end. I'm considering an ESP8266 (so 802.11) with a high-gain directional antenna. Sender and receiver are fixed locations.
- olympus 11y ago
  Here are two low cost options (I recommend #1 for most people and #2 if you have an impressive beard): 1. The esp8266 like you have already mentioned. Get one with a u.fl connector and make your own cantenna to attach to it. You can use the microcontroller in the esp8266 to take the sensor readings (it even has an ADC to read analog sensors). This is the new hotness and there are tons of examples. 2. Even cheaper but less user friendly is a very low tech 433 MHz RF transmitter like you can get on eBay. You then need an external microcontroller to run it so you might actually be less cost effective overall and these things take quite a bit of effort to implement a reliable comm system because of the on-off keying system and zero built in error correction. There are libraries like VirtualWire or RadioHead that take quite a bit of pain away. You can get other frequencies if your country doesn't allow unlicensed 433MHz transmissions. Example of what I'm talking about: http://www.ebay.com/itm/like/140719918135?ul_noapp=true&chn=ps&lpid=82 http://www.ebay.com/itm/like/140719918135?ul_noapp=true&chn=...
- ac29 11y ago
  ESP8266 is worth checking out because its dirt cheap, but it really depends how "clean" your line of sight is. 900 MHz radios will have better propagation. Might want to check out something like this: http://rpi900.com/hardware/introduction.html http://rpi900.com/hardware/introduction.html
- jlgaddis 11y ago
  I'm not sure what you mean by "little money" but for less than $100 per location, you could have a 100+ Mbps link using Ubiquiti NanoStations. You can use Wi-Fi or their proprietary protocol and the radios are available on 2.4, 3.65, and 5 GHz. These little things will cover your 500m link with ease but might very well be extreme overkill if all you really want is <= 1 Kbps throughput.

by th0ma5 11y ago

anderiv 11y ago

One of my most memorable moments in amateur radio was making a JT65 contact - 1 watt, from the north-central US to the island of Reunion, roughly 10k Kilometers. And that was on a very ad-hoc wire antenna.

olympus 11y ago

What's your callsign? I'll see if I can pick you up with my RTL-SDR+Ham-it-up and maybe once I have my ham license I'll talk back. Every now and then I find a post on HN that really makes my day and I realize how awesome this community is and how our interests overlap beyond computer programming and entrepreneurship. This is one of them.

kc2zuf 11y ago
Not the OP but I'm on WSPR on 20m right now as KC2ZUF!
th0ma5 11y ago
Well, I'd appreciate a report on the WSPRNet page once you get your ticket. I'm W8KV, but I don't know that I'm putting out all that much, and when I look at streetview of the houses of the people that pick up the signal they have some crazy setups! That said, I was able to receive PSK31 from France here in Ohio back before I got my ticket with just an old AC extension cord strung along the ceiling as an antenna, so keep playing with things, you never know what all will work.

semi-extrinsic 11y ago

Ok, since there are some radio wizards in this thread: if I want to log low bandwidth sensor data (so < 1kbps) on a unidirectional (if that helps) link over ~ 500m, almost clean line-of-sight with some trees in there, what are my options? I'd prefer to spend little money and use little power on the sensor end. I'm considering an ESP8266 (so 802.11) with a high-gain directional antenna. Sender and receiver are fixed locations.

olympus 11y ago
Here are two low cost options (I recommend #1 for most people and #2 if you have an impressive beard): 1. The esp8266 like you have already mentioned. Get one with a u.fl connector and make your own cantenna to attach to it. You can use the microcontroller in the esp8266 to take the sensor readings (it even has an ADC to read analog sensors). This is the new hotness and there are tons of examples. 2. Even cheaper but less user friendly is a very low tech 433 MHz RF transmitter like you can get on eBay. You then need an external microcontroller to run it so you might actually be less cost effective overall and these things take quite a bit of effort to implement a reliable comm system because of the on-off keying system and zero built in error correction. There are libraries like VirtualWire or RadioHead that take quite a bit of pain away. You can get other frequencies if your country doesn't allow unlicensed 433MHz transmissions. Example of what I'm talking about: http://www.ebay.com/itm/like/140719918135?ul_noapp=true&chn=ps&lpid=82 http://www.ebay.com/itm/like/140719918135?ul_noapp=true&chn=...
ac29 11y ago
ESP8266 is worth checking out because its dirt cheap, but it really depends how "clean" your line of sight is. 900 MHz radios will have better propagation. Might want to check out something like this: http://rpi900.com/hardware/introduction.html http://rpi900.com/hardware/introduction.html
jlgaddis 11y ago
I'm not sure what you mean by "little money" but for less than $100 per location, you could have a 100+ Mbps link using Ubiquiti NanoStations. You can use Wi-Fi or their proprietary protocol and the radios are available on 2.4, 3.65, and 5 GHz. These little things will cover your 500m link with ease but might very well be extreme overkill if all you really want is <= 1 Kbps throughput.