LW & MW SDR

Thoughts are back on 500kHz and 136kHz.
Assume we are going SDR, RX and maybe TX, one rig could serve both frequencies.

Conceptual design:

• TCXO on 4.1943MHz

500kHz:

1. 4.1943 / 2 = 2.0972
2. 2.0972 / 4 = 0.5243 (SDR center frequency)
3. about 20kHz above the band

136kHz:

1. 4.1943 / 8 = 0.5243
2. 0.5243 / 4 = 0.1311 (SDR center frequency)
3. about 6kHz below the band

In other words, the LW quadrature LO can be directly derived from either I or the Q of the SDR center frequency.

My experience is that (for my computers) 96k sampling works best. The observable ranges would therefore be:

• 476.3kHz - 572.3kHz for MW
• 83.1kHz - 179.1kHz for LW