# Radar SNR for a LFM Waveform

How do you estimate the detection SNR for a radar transmitting an LFM (chirp) waveform? I'm looking for an SNR equation that is a function of chirp bandwidth and compressed (or uncompressed) pulsewidth.

Do you use the uncompressed pulsewidth or the compressed pulsed width? Do you add a term for pulse compression gain (proportional to the time bandwidth product = bandwidth*pulsewidth?) to the radar range equation?

According to Mahafza, "For a given set of radar parameters, and as long as the transmitted pulse remains unchanged, then the SNR is also unchanged regardless of the signal bandwidth. More precisely, when pulse compression is used, the detection range is maintained while the range resolution is drastically improved by keeping the pulse width unchanged and by increasing the band-width."

• I think the SNR you are talking about is the SNR without pulse compression, as matched filtering introduces the processing gain so you should also add this processing gain too. – Zeeshan Apr 3 '17 at 7:36
• you can also look here might be this will provide some help signal detection- Pulse Compression SNR Gain – Zeeshan Apr 3 '17 at 7:47

In the equation you listed, $\tau$ can be interpreted as the uncompressed pulse width, in which case that you'd need to add a factor for the pulse compression gain.