[SOLVED] Need help designing FM Radio transmitter using NCO and DDS in verilog.

[darkksol]

Need help getting started with verilog. Need to create a FM radio transmitter using NCO and DDS but how do I even start?

 

[Aussie Susan]

My suggestion is to start in 2 places:
- firstly understand that transmitting FM radio (which I take means transmitting in the commercial FM radio band from 88MHz to 108MHz) requires an appropriate license. Unlicensed transmissions can lead to legal problems. If you want to transmit on other ands then you will also need a license or restrict yourself to the ISM bands, limit the power and ensure no interference is being caused
- Secondly start simple and work your way up (that is what I'm doing).
You don't say what sort of experience you have or if you have any FPGA hardware or development boards available.If you are coming from the 'programming' world then thins are very different and (in my experience) it takes a while to get your thinking straight. If you are a hardware engineer then things might be easier but the syntax takes a bit of getting used to.
There are many tutorials out there to help you.
Susan

 

[darkksol]

My suggestion is to start in 2 places:
- firstly understand that transmitting FM radio (which I take means transmitting in the commercial FM radio band from 88MHz to 108MHz) requires an appropriate license. Unlicensed transmissions can lead to legal problems. If you want to transmit on other ands then you will also need a license or restrict yourself to the ISM bands, limit the power and ensure no interference is being caused
- Secondly start simple and work your way up (that is what I'm doing).
You don't say what sort of experience you have or if you have any FPGA hardware or development boards available.If you are coming from the 'programming' world then thins are very different and (in my experience) it takes a while to get your thinking straight. If you are a hardware engineer then things might be easier but the syntax takes a bit of getting used to.
There are many tutorials out there to help you.
Susan

I don’t have any experience and am not using an fpga.

I am only doing a simulation using vivado. I have looked at so many tutorials and from my understanding just creating basic modules. I believe I only need an adder, register and look up table to create a numerically controlled oscillator but I don’t know how to put them together or if I have restrictions. Still a bit lost.

 

[Aussie Susan]

My advice is still the same and, as you have no experience, the part about starting with a simple system applies even more.
What simulator are you using?
Also does the simulator properly simulate the NCO and DDS? If not, then you are on a road to nowhere.
I'd strongly recommend that you get a development board - even a cheap one will do - that has the modules that you want to use. Personally, I have used the Digilent Basys 3 board and it has let me move from the 'flash a LED' (like you I started with no FPGA experience but a rather old Electrical Engineering degree) through 'debounce a switch' and on to using the ADC and creating a UART and Low Pass FIR filer etc.. Still on the learning curve.....
Real hardware will always give more accurate results than a simulator (which in my opinion can also be a source of another set of bugs).
Susan

 

[darkksol]

My advice is still the same and, as you have no experience, the part about starting with a simple system applies even more.
What simulator are you using?
Also does the simulator properly simulate the NCO and DDS? If not, then you are on a road to nowhere.
I'd strongly recommend that you get a development board - even a cheap one will do - that has the modules that you want to use. Personally, I have used the Digilent Basys 3 board and it has let me move from the 'flash a LED' (like you I started with no FPGA experience but a rather old Electrical Engineering degree) through 'debounce a switch' and on to using the ADC and creating a UART and Low Pass FIR filer etc.. Still on the learning curve.....
Real hardware will always give more accurate results than a simulator (which in my opinion can also be a source of another set of bugs).
Susan

i am using vivado which i guess is part of xilinx. And i believe it should simulate the NCO and DDS.

How do i create the modules for the look up table or even get the values for it?

 

[FvM]

Do I understand right that it's a HDL coding exercise, you are not creating real hardware and don't need to bother about DAC properties?

I also guess that you don't want to use Xilinx DDS IP core but write everything from the scratch. So what's the specific problem? You need to understand how DDS works and how to write HDL, either Verilog or VHDL. Sine tables can be e.g. generated in your HDL code.

 

[darkksol]

Yea that’s correct it’s an exercise and how would I use Xilinx dds up core?

Yeah I’ve been using verilog but don’t know where to look to learn about the look up table or generating the sine tables.

 

[barry]

You seem to need to learn a lot before you start designing a radio. You apparently don't even know how to use Vivado or search the internet. Try searching "verilog lookup table" (170000 hits) and "verilog sine table" (130000 hits).

There are many tutorials on Vivado, look at those.

Read about the Xilinx DDS IP; it will tell you how to instantiate the module (although I'm not sure that's what you really want to do here.)

As Susan said, you need to learn the fundamentals first.