[amsat-bb] idle comments

[Zach Metzinger]

On 03/15/18 21:07, Mac A. Cody wrote:
>> At the sacrifice of some bandwidth, the following advantages can be
>> had with
>> using DSB modulation:
>> 1) DSB modulation is relatively easy to achieve.  The band-limited audio
>> is fed into a double-balanced mixer, bandpass filtered for harmonics, and
>> fed into a PA for transmission.  The resulting hardware is comparatively
>> inexpensive to construct and to tune.
>> 2) Sideband inversion caused by some linear birds is no longer an issue.
>> Having both sidebands present in DSB modulation means that the correct
>> sideband will always be available for reception.
>> 3) Interoperability with SSB stations would be maintained, as DSB
>> modulation
>> is a superset of SSB modulation.

Why not use the new LimeSDR Mini and do a SDR-based design for satellite
work? It already has separate TX and RX paths, ready for duplex operation.

One simply, for various values of simple, needs to design a
receiver/transmitter design to go into the Altera FPGA, bolt on a
suitable CODEC (might I suggest the MAX9860?), and then add some
filtering and a PA.

[Mic/Spkr] <---> [MAX9960] <---> [FPGA] <---> [Limechip] <--> PA/Filter

I'd bolt on a LCD, rotary encoder, and a few buttons for user I/O. No PC
needed for control. Add antenna and you're done.

You'd have a complete all-mode (SSB, AM, FM, etc.) solution for perhaps
$200.

(This is a back-burner project for me -- I won't be offended if anyone
gets there first. hihi)

--- Zach
N0ZGO