SDR - software defined radio



I'm devoting this post to the RTLSDR. This device is a dongle for laptops and tablets/phones that have USB ports and software written for the particular device.

The SDR is a radio frequency receiver. Sounds simple.
The radio spectrum is divided into segments dedicated to particular functions and by assorted agencies.

The idea behind a SDR is a programmable radio that can be configured and reconfigured for different  spectra and formats. Two different agencies, e.g.,governments, may transmit data in different formats. If the format information is available, the SDR can often incorporate the standards into the unit programming and receive/record transmissions from those sources.

The most common uses are to receive commercial FM radio bands, NOAA weather bands, Air traffic control bands and weather satellite imagery.

Recently, digital radio, HDRadio, receiving software became available.
The digital radio broadcasts are, for some reason, encrypted.
A researcher decrypted the code and published his results.
Others have written software to decode received transmissions.
I can now listen to/record digital radio broadcasts.
Without a SDR, several different radios would need to be purchased:
Commercial AM/FM broadcasts.
NOAA weather radio
Shortwave bands for air traffic and community radio (ems, fire, police).

For lowest frequencies, such as HAM and AM, an additional "upconverter" hardware board, is required.

Although difficult, low frequency band, gsm, cellphone traffic can be monitored.

There are other uses. No mention has been made of international radio traffic.

Comments

Post a Comment

Popular posts from this blog

Drive rack, ventilation and wiring.

 My drives have a new rack to hold them. Hot glue and square wood dowels provided the materials with which to build the rack. I used zip ties and a small computer fan attached to the end of the rack to provide cooling air ventilation for the drives. This will increase the lifetime of the drives. Previously the were stacked on top of each other and became noticeably warm during use. The wiring really was bad. Too many cables/wires held together with zip ties. I added a surge protected outlet strip of a newer, more sophisticated design. I rearranged the system wiring to minimize the number of outlet strips and the disarrayed wires. Two strips were screwed to the wall. One was removed. The circular strip was moved from the entertainment center to a work table beside the other two strips and combined with them to supply all devices attached to the system. The strip removed replaced the circular strip in the entertainment system.  Overall, the current setup works better. Both syste...
Read more

Philips Hue lights Updated

 Philips Hue lights are known for the ability to program brightness, saturation, and hue using software. Most people use one or more cellphone apps to control their Hue lights. I've a history in computrer science and electronic technology and engineering, so took this up as a new interest. WiFi control of light bulbs' colors has interested me ever since I read aboout the topic some years ago. There happened to be seven Hue bulbs available from one eBay seller and for a reaosnable fee, approximately $20. A bridge device is used to communicate with the bulbs, so I waited for a good deal on eBay and got one. Philips has evolved a developer community and resources for those who want to explore the possibilities in lamp light control. The user joins the communnity and gets a temporary API key, formerly referred to as a 'username', good for one session. Then a browser or app, can be used to send commands to the bulbs. There are other avenues of communication. Python libraries...
Read more

Jellyfin media server

 The owner of Emby has blocked my using the WebOS access method of using Emby. I discovered the method and posted on the product's forum. That software is no longer my media server and has been removed from my computers. I replaced Emby with Jellyfin. Jellyfin is the evolved Emby open sourced. Emby was originally open source (and free) but was privatized and monetized by the creator. Many considered that move unethical.  The last open source version became the basis for Jellyfin,  easily competitive with Emby and almost, if not equally, well known. I've been using Jellyfin for about a year, perhaps more. The software has issues but is in constant development but is very useful in the current state, version 10.8.5.
Read more