Back in December 2016, Shaun Whitehead of ThumbNet sent me of their new rtlsdr-based N3 Nongles but I was too busy to do anything serious with SDR. Now that I got a 137 MHz turnstile antenna up for testing I had an obvious opportunity to try it with the weather satellites.
Some time ago I got a 137 MHz turnstile antenna from Jørn OZ6TA. We decided to build an automated NOAA weather satellite image receiver using a modern SDR device. He also had an Airspy he wasn’t using and so it became the SDR radio we were going to use for this.
Some of you may have noticed that my website has undergone significant changes. This was a consequence of my old website being compromised and and infected by malware.
Now that I finished my Omnia SDR for the 60, 40, 30 and 20 meter bands, I started looking into how I could use it on Linux. I remembered reading some emails on the project mailing list about using Quisk, which is a mature SDR transceiver application written by James Ahlstrom, N2ADR. I decided to give it a try.
Tonight I completed the TX part of my Omnia SDR for the 60/40/30/20 meter bands 😀
I have collected a bunch of old Raspberry Pi model B’s equipped with the Wolfson audio board. You may find these board lying around and collecting dust, as they have been obsoleted by an increasing number of multi-core boards. I will use these boards as simple Softrock SDR receivers, but first I want to do a little experiment. I am going try using them as a headless FreeDV modem similar to the SM1000.
Following the successful receiver tests yesterday, I continued today with the band pass filters completing the receiver chain. I decided to build for 60/40/30/20 meters, which can provide a good all round, day and night transceiver.
I mentioned in my previous update that following my noise floor measurements I tried connecting antenna to the receiver input through C27 but did not have any signals through. Today I found out that I had a bad solder at L11 and so the antenna switcher wasn’t working.
The receiver is now complete and only the band pass filters are missing. The local oscillator is working well as does the computer interface. I could measure the noise floor on all bands and check how much USB noise there is on the different bands of interest, see the screenshots below.