Figure 1: Vanguard 260 PL NOAA weather satellite receiver (click to enlarge).
This blog article revisits the Vanguard 260 PL, a weather satellite receiver from the seventies that I found (as a rare bargain) on Ebay. It covers the 137 MHz NOAA low earth orbit (LEO) APT (image) weather satellite frequencies, when it’s fixed up with the correct crystals. I love the simplicity of the unit, and it reportedly works well given both the time period of the technology, and the low parts count.
Figure 1: FLDigi is shown running on the Pi2, decoding a BPSK signal, using Cirrus audio.
The Cirrus adapter worked just fine on the Pi2, as can be seen in figure 1.0. I took the audio first from the “phones” jack of an old amateur radio receiver, and then from the sound card of a second PC running a browser webSDR page. This audio was connected via the “line-in” connector of the Cirrus adapter in the Pi2 box. In both cases the audio was very good, and was adequate to decode signals while using a only a moderate input level. The noise and spur levels were much less than on an i386 PC based machine I had used for FLDigi/ham activities in the past.
Figure 1: Status and printDetail() screen of the pingpair_dyn sample app (click to enlarge).
Finally, the unlicensed band nRF24 devices are talking to each other! It was a bit of a road trip. One thing to note is the importance of the status byte, and the other status data. While a hex 0x0e is normal, a hex 0x00 in the status byte, and/or lots of zeros in the printDetail() output are pretty good indicators that your SPI is not operational, and you’re not talking to the transceiver. More on this issue follows …
WB8LZR 