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In: Amateur Radio
With: 2 Comments

The Icom IC-9700 frequency stability can be improved by synchronising the internal master crystal oscillator with an external GPS disciplined one using the Leo Bodnar injection board. The 9700 internal oscillator is sort of pulled to the external frequency by placing a small coil close to the crystal. On the Leo Bodnar site the setup procedure is described. This procedure creates so many misunderstanding and questions that I decided to spend some words on it. First of all, the external GPS based oscillator (GPSDO) cannot be calibrated. You can set the right output frequency and level and that’s it. Now when you switch on theRead More →

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In: Amateur Radio, Computer
With: 0 Comments

The last months I’ve been quite active on FT4 on LEO satellites. A number of challenges come together doing FT4 on sats such as accurate doppler control and time, multiple WSJT-x applications and CAT transceiver control. The doppler control is basically identical to SSB, however the update rate and/or the maximal frequency error must be set different. MacDoppler only supports update rate, which can be set up to 10 times per second. SatPC32 also supports update rate based on frequency error. Many set this to 0, meaning highest update rate. But I think that 10 Hz should do it as well. In order to listenRead More →

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In: Amateur Radio, Computer
With: 2 Comments

FT4 via LEO satellites is becoming more and more popular. With FT4, there is less need for yagi antennas and elevation control, given the (at least) 10 dB gain over SSB communication. Or, with Yagis and elevation, you can reduce power to below 1 W. However, FT4 requires accurate doppler control and a stable transceiver, especially given the fact that many sats have a 70cm uplink. The de-facto standard for doppler control is SatPC32. This is a windows only program, and not really intuitive to configure and use. However, when configured and up and running, it’s a very powerful and accurate program. Since programs suchRead More →

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In: Amateur Radio, Audio, Computer
With: 4 Comments

Dire Wolf is a sound card based modem for packet radio. It can be downloaded for Windows and Linux here: https://github.com/wb2osz/direwolf Although there is a reference to MacOS, there are no further build instructions for Mac. Google reveals some info: one site references an outdated version, the other one proposes to install the brew build/port environment to provide the cmake tool. Installing an environment like brew for just one tool, which actually is a build tool by itself, is .. well .. odd. So I decided to build Dire Wolf on Mac without any hacks or special tools. After using the result for some time,Read More →