Welcome to the mSDRs wiki!

mSDRs

is a multi-computer networked Software Defined Radio system

Multi-computer networked Software Defined Radio System (mSDRs) is a connected set of hardware and software that makes a state of the art Software Defined Receiver (SDR). This name is not a clever acronym but a descriptive phrase for the radio system created.

Overview

The radio system uses a USB3 or greater receiver, which captures a very large full resolution IQ sample. The sample is then subsampled to extract hundreds of subsamples at specific points in the spectrum. Each can be decode using different modulations. The system is designed in components that work on these samples, that can be processed on the same computer or on many separate computers.

This system is design to monitor activity in the radio system as opposed to interacting with a single sample.

As an example, we are using the radio system to monitor to all wspr frequencies in the HF, decode the packet and upload them to a computer database for analysis.

Parts

Antenna

This radio and any depends on the quality of the Antenna. For these receivers a broad-banded wire antenna usually work the best.

Hardware Receiver

A number of receivers can be used with the included software. However not all the receivers are suitable for scientific use for two reasons.

[!IMPORTANT]

1. The ionosphere interacts most strongly with VLF and HF. The software can work with UHF and VHF but these frequencies depend less on the interaction with the ionospheric atmosphere.

2. To achieve the maximum frequency accuracy, timing data must be provided to the receiver from a GNSS timing source. Crystal frequences are not sufficient.

Timing tools

An GNSS timing source is necessary to achieve the frequency accuracy required by the HamSci propagation science.

Computer

This radio system run on a small Linux computer, while Raspberry Pi computer can handle smaller bandwidths, the system work best of very capable Linux computers with more that 12 or more cores.

Software

Several interacting Software project complete the receiver system

• ka9q-radio

• wsprdaemon

• ka9q-web

• FFTW

[!IMPORTANT] The system uses the concept of multicast, one program reads the hardware source and provide unlimited number of streams within specific sub channels to client programs. The program can provide may hundred of sub channel feeds depended on the computer and the configuration of the local network. This type of radio can create problems with WiFi network by flood the network with data, making the network unusable by other users. There are specific settings to control this behavior, But it is best separate your radio network from you WiFi network. This can be accomplished with the use of routers to divide your network into separate sub nets

References

Resources