On 10/7/21 12:01 PM, msat via groups.io wrote:
@Jim Lux
While I'm pretty sure the nano only uses the fundamental as well as the 3rd and 5th harmonic for measurements, your point is taken. You did give me an idea for a potential solution, and that's to feed the nano S11 into a PLL and then multiply the frequency by 5, and low pass filter the output as you state, then go on to the PA stage. The filtering issue would be simplified, and the nano wouldn't know the difference. I think this would work well.
The Tx and Rx sides of the Nano use different multiples (so that the receiver doesn't "detect" the fundamental or "wrong" harmonics from the Tx side)
The code seems to say 5 and 7 for Tx, Rx respectively, but if you're in the fourth zone, it might be 7 & 9
it's in config.harmonic_freq_threshold - the default is 300 MHz (but might be different, it depends on YOUR particular Si5351's range)
My copy of the source is pretty old..
in si5351.c
? /* if (freq > config.harmonic_freq_threshold * 5 ) {
??? ??? freq /= 7;
??? ??? ofreq /= 9;
? }else */
?? if (freq > config.harmonic_freq_threshold * 3) {
??? freq /= 5;
??? ofreq /= 7;
? } else if (freq > config.harmonic_freq_threshold) {
??? freq /= 3;
??? ofreq /= 5;
? }
in main.c
config_t config = {
? .magic =???????????? CONFIG_MAGIC,
#ifdef __DAC__
? .dac_value =???????? 1922,
#endif
? .grid_color =??????? 0x1084,
? .menu_normal_color = 0xffff,
? .menu_active_color = 0x7777,
? .trace_color =?????? { RGBHEX(0xffe31f), RGBHEX(0x00bfe7), RGBHEX(0x1fe300), RGBHEX(0xe7079f) },
? .touch_cal =???????? { 370, 540, 154, 191 },? //{ 620, 600, 160, 190 },
? .default_loadcal =?? 0,
? .harmonic_freq_threshold = 300000000,
? .vbat_offset =?????? 480,
? .checksum =????????? 0
};
@Roger
I'm in the US. I may very well be wrong, but I don't think operating in the ISM band is as restrictive as you state. I'll certainly look into it more carefully to ensure I'm complying with all applicable laws. Thanks for your concern.
