Generate chirp signal using Lime SDR

I tried the settings as mentioned by you. still i could not get the valid response. So now i have started to use the original GW provided by you. I tweaked the transmitter data to transmit the chirp signal, did some settings using the GUI and i could get the chirp signal (saw on the PC using FFT viewer).

Things are good till here, but the disadvantage is that the settings has to be loaded every time the board is powered ON. now i would like to get this settings programmed automatically. In the present design, all the configurations are happening through nios cpu.

nios cpu gets configuration data everytime the settings are modified using GUI. Instead I want this configuration to be stored in the FPGA itself and the board gets configured once only when the board is powered on. I need help on getting this auto configuration performed by the FPGA.

Hi @chandu,

You need to modify NIOS firware to be able to store the data in Flash memory. Then, after each power on, NIOS should read these data from the external FLASH memory and write it to LMS7002M.

Can you please provide me the link for downloading nios FW source code. Also i need the documentation to understand the source code faster so that i can modify it soon. I am not finding much information about the nios FW source code.


1 Like

Hi @chandu,

NIOS FW related projects (application and BSP) are here:

Main file is this one:

@chandu did you find any method to upload NIOS MCU (main.c) file in limesdr?

Ive gotta ask. Why 60MHz ? Chirp is designed to provide indication of HF Frequency Band Coverage at the time the CHIRP signal is propagated. That is, its designed to provide Comms planners with HF Band and specific Frequency Coverage such that certain Frequencies can be avoided due to high SNR ratios, weather considerations, solar considerations, and a good indicator of how the ionosphere is acting at any point in time.

60 MHz is not HF. So I am at a loss, as to why you would want to CHIRP at 60MHz specifically.

Military HF is 2Mhz to 30Mhz VHF is 30+MHz to 225 (Despite Amateur radio being different)