Introduction

There are many ways to capture radio waves from the air and convert that to audible signals. The current (April2024) WebSDR in Maasbree uses SDRPlay RSP1A  and FIFI radio modules. For delivering the complete HF band to a websdr, software package such as the software of Pieter Tjerk de Boer are needed, and we need many RSP1A's and FIFI's. These radio's receive the HF band and convert that to I/Q signals, which are send to the websdr software via USB. 

In the new design we use only one  RX888MKII radio, which receives the complete HF band, by digitizing the analog signal directly into a stream which is sent via USB-3 to a computer. The used sample rate can go up  128Ms/s, but we use only 64,8 Ms/s, because that is high enough to extract signals from it up to 30MHz. This produces a stream of more than 1 Gb/s continuously. So, the computer to be used should be able to process this high data rate.

Furthermore the computer needs to extract all the different bands from that stream, to convert that into pcm streams for the websdr software. How this all works will be explained in further pages.

Another interesting aspect of the new design is that the reporting of wspr spots is fully integrated and automated. This aspect will also be described in detail.

The WebSDR software of PT de Boer can handle 8 bands but we can run multiple instances of this software. In our new design we run two instances, so 16 bands are active.

The software we use on the Computers is Ubuntu 20.4 LT, and we use 3 of them (NUC's). Small computers with low energy consumption comparing with laptops or desktops. On these three computers we run the following packages:

1 - KA9Q-radio software (created by Phil Karn KA9Q), to control the RX888MKII radio

2 - Whisper Daemon software to decode the wspr spots and report that to wsprnet and wsprLive.

3 - WebSDR software to process all HF bands for making it available on the internet.

 

These computers are connected to each other and to the internet via a router  with VLAN capabilities.

In further pages we will go through all aspects of this design up to a full working installation.

 

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