# Radar - How to keep IF constant?

A basic block diagram for FMCW radar I will be using, modified MIT radar project: MIT block diagram I My transmit frequency is 2200-2600 MHz, my receive frequency is ~2200-2600. I want my IF frequency to be a constant 1 MHz (or 100 MHz; I haven't decided on bandwidth yet). The only way I can think of doing it is is introducing another VCO2 and having it produce constant 1 MHz RF signal, so it will mix with first filter, giving me LO 2201-2601 MHz. The LO is then mixed with receive frequency and I get a constant IF of 1 MHz.

Is there a better way to approach it? Introducing second VCO, second mixer and filter seems like too much.

EDIT: my specific question is about keeping IF constant, I put the whole block diagram just for illustration.

• According To the Figure It looks Like You are Using A VCO To generate a 2200-2600MHZ as a Carrier Signal??? Is it A model For Gain/Directivity Measurement Model?? Because You have Directly Fed the S/G from the Splitter To Receiver. Do You have A Information Source as a Triangular Wave?? That You Mean To Receive At the Receiving End,You have Also used a Splitter, if So then Why You Use A ADC at Receiving end. As Your Motive is Quite Not Defined in Question, I Suggest That you use a Superheterodyne Reciever You Will Need A Additional Oscillator. But It Quite Gives A Constant IF. Mar 6, 2015 at 19:03
• Is the TX waveform going to be a short pulse of constant frequency? Or are you planning to do a frequency chirp? And what is the radar for? Mar 6, 2015 at 19:14
• Yes, I'm using VCO to generat 2200-2600MHz signal. This model if FMCW radar. Triangular wave is used to oscillate VCO. I needs ADC at receiving end to process the signal. Mar 6, 2015 at 19:16
• It's FMCW radar which will be used to determine speed and distance Mar 6, 2015 at 19:18
• FMCW is used to detect Surrounding Objects (Rest/Moving) uses dropler effect,as the Object Position is Varied The If will Vary Why Do You Want A Contant If ..A Superheterodyne Reciever Might Help, Mar 6, 2015 at 19:21