Thursday, August 12, 2010

'Sat in Sun' satpack feature?

My current iteration of the Satpack full doppler tuning device has about 30k of code space still available in the target hardware, a atmega 644p. Some of this will be eaten up with error checking around the tle loading and clock-setting, but there's still a fair bit of open space there.

PC-based tuning programs will often tell you if a bird is eclipsed or in the sun, a feature that is even more useful these days as the aging AO-51 is not transponding in eclipse. Similarly, the AMSAT-UK video entitled 'FUNcube part one' states at its end that FUNcube will have a high-power telemetry mode while in sun (roughly when school is in session), and a low-power telemetry + transponder mode when it is in eclipse (roughly when school is out). This scheme fits the FUNcube KISS principle, but won't be ideal for the small but important number of students who live in Arctic regions.

So a 'sat in sun' indicator on the LCD is going to be more important than ever, but I wonder if we can go further and include insolation in our tracking logic. A HT user in the field really doesn't want his HT to start automatically tuning AO-51 if it isn't in the sun, so we might as well exclude AO-51 if it is in eclipse. Same thing with AO-7. FUNcube is a bit harder case, since they plan to be more clever with the schedule, keeping the transponder on all the time during weekends and school holidays.

Finally, there's the schedule of AO-27. I'd love to include some 'FM transponder on' code inside satpack so that it also only was tuned in when it is in transponder mode. Right now, it hogs the tuner pointlessly far too many times.

Saturday, August 7, 2010

Less Well-known CAT Controlled Radios

Recently, I asked the amsat-bb list if its members knew of any obscure CAT controlled radios which I might doppler tune with my satpack project. Sergej, UZ2HZ, kindly pointed out to me the FT-727R. According to the previous link, "All serial data consists of single byte binary codes sent at 4800 baud, TTL levels, with two INVERTED stop bits and one INVERTED start bit." Yikes. Still, the price might be right for this HT.

Another possibility is the Yaesu FT-5100. It can be controlled at ttl levels with a modified mike interface.