Up converter for RF transmission - Digital

[graphene]

Hi,

I need to develop an up-converter for an TV transmission sender. I have the modulator from a vendor and I need to do the hardware and FPGA setup for the up-converter.

Can some one help me with the principles/functionalities of an up converter ?

1) Though I have a vague idea, I still feel I dont have a good theory source or book or ieee paper. Can some one hint/share me such sources?

2) I would also like to know any ideas regarding RF modulation techniques that should be learnt for this.

Thank you in advance

 

[FvM]

What are modulator and intended final output frequency?

I presume you are talking about analog TV?

A real TV transmitter uses vestigial side band (VSB) for the AM video signal to save bandwidth, a simplified modulator mostly uses DSB. What's your reguirement in this regard?

 

[graphene]

Thank you, first of all.

The input is ASI signal.. and the output is RF from 470-800 MHz approx.

I am using this for Analog Tv and also DVB series

The modulator I use is not a complete modulator. It can be imagined a partial modulator where the ASI signal is converted into baseband signal of I/Q.

The baseband signal from this modulator is to be upconverted and processed by me.

 

[FvM]

O.K., I/Q baseband needs a quadrature modulator. I would use my Agilent E4432 for this purpose. If you want to design the modulator yourself, there are e.g. vector modulators from Analog Devices.

 

[graphene]

thank you again. will check those.

well, only the up-conversion part is my goal.

I am going to do that through logic circuits in FPGA.

I need to understand as in what exactly are the roles of an upconverter, rather than the blackbox idea of modulating.

I need to also have some hints of how it shall be feasible in FPGA. The later being the second step, now, I need to understand and design an upconverter myself.

Can you shower some tips on this?

 

[FvM]

Maybe I didn't yet understand your setup completely. I understood that baseband I/Q means analog signal. Then it has to be digitized to be processed in a digital system. Or do you mean a digital I/Q signal?

 

[graphene]

a digital I/Q signal is available to me. I need to upconvert it.

Can you also please suggest some source to leanr these if you know any.

 

[BigBoss]

a digital I/Q signal is available to me. I need to upconvert it.

Can you also please suggest some source to leanr these if you know any.

Since digital I/Q signals are available, convert these signals into base-band format by using DAC and then modulate up-convert these signals with a I-Q Modulator+Up_converter.
There are many I-Q Modulator in the market.For instance...
https://www.linear.com/product/LTC5598
https://www.hittite.com/products/view.html/view/HMC696LP4E
https://www.analog.com/en/rfif-components/modulatorsdemodulators/adrf6755/products/product.html

 

[FvM]

There are also complete digital up-converters like AD9957 https://www.analog.com/en/rfif-components/direct-digital-synthesis-dds/ad9957/products/product.html

Your previous posts sound like you want to implement the digital part in FPGA, what's the intended output sample rate?

 

[graphene]

@Bigboss :: Thankyou for the resources.


@FvM :: you are right... thats exactly what I intend to do.. for now, I dont have an idea of sampling rate for the project. and I am not understanding how to proceed ahead or what to learn at this point..

 

[FvM]

I dont have an idea of sampling rate for the project.

That's a question of available or projected D/A hardware and intended output frequency.

 

[graphene]

I find the sampling rate be 400M samples/sec and the O/p freq is btwn 470-800MHz