Is there anything in the hardware path I should remove to use a carrier frequency that low? Maybe short C11?
Tagging @Karolis.
can I use Lime Suite GUI to TX on the HF bands? How do I go about setting to something like 20MHz TX?
Just from configuration perspective, 30MHz is the lowest that the LMS7002M local oscillator can be set, to achieve lower frequencies, the sampling rate has to be appropriately increased, and a digital numerically controlled oscillator has to be configured to downconvert the signal to your desired frequency.
I see the NCO in the lime suite GUI tool. If I go to the TxTSP tab and set the FCM(MHZ) to -10.0 and upload NCO that does seem to shift things. Am I missing anything else?
The NCO can shift only up to half of the sampling rate, so sampling rate should be set first, and then the NCO configured.
Where in the LimeSuite GUI do I shift the sampling rate, exactly?
Just to clarify what is your expected use case?
You want to configure the transmitter for desired frequency and simply transmit raw samples from a file? Or are you expecting to do that in some other software package?
You want to configure the transmitter for desired frequency and simply transmit raw samples from a file?
Correct. I have a 20MHz QPSK signal I want to play over and over where Fc will be 20MHz. I use the Modules->FPGA controls to play my waveform file.
I think I got it actually.
Setting clkgen to 30MHz and CLKH_OV_CLKL to 1, in SXT setting the VCO to 30MHz and in TxTSP setting interpolation to bypass and NCO to -10 seem to do it!
I guess the hardware can handle the signal but its about 8dB less output power, so I adjusted the TXPad to compensate.
Thanks!