Up converter for RF transmission - Digital
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
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?
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.
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.
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?
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?
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...
http://www.linear.com/product/LTC5598
http://www.hittite.com/products/view...iew/HMC696LP4E
http://www.analog.com/en/rfif-compon...s/product.html
There are also complete digital up-converters like AD9957 http://www.analog.com/en/rfif-compon...s/product.html
Your previous posts sound like you want to implement the digital part in FPGA, what's the intended output sample rate?
@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..
That's a question of available or projected D/A hardware and intended output frequency.
I find the sampling rate be 400M samples/sec and the O/p freq is btwn 470-800MHz