hamid159
Full Member level 3
Detection of 3 Hz doppler shift in 1.2GHz signal
Hi everyone,
Actually It's my final year project to make a system that will detect the alive human bodies under the debris in case of catastrophic situations. Well, I've got two methods to accomplish this task.
First one is, send 1150MHz wave and after receiving through receiving antenna subtract it with the reference signal ( signal that was sent through transmitting antenna) by manipulating the reference signal such that its phase and amplitude cancel out with the 1150MHz signal while the doppler shift of 3Hz (due to heartbeat 1.5Hz in forward while 1.5Hz in backword direction) will remain there and then by using FFT, we can detect the peak of that doppler shift frequency.
I think this method is a bit complicated. We would need to match the phase and amplitude exactly.
Second one is, send 1150MHz frequency. Receiving signal would be the part of 1150MHz and doppler shifted signal. We can take the signal to smaller frequency. Let's say 50Hz so that it is comparable with the 3Hz signal. then we can use the FM demodulation to extract the signal (3Hz).
I think this method is relatively easier than the first one.
I wanna ask, Is the second method is feasible to detect very small amount of doppler shift? or which method do you think can be easy and feasible?
PS: Due to range and penetration, we have decided to use 1150MHz frequency.
Any help would be appreciated.
Hi everyone,
Actually It's my final year project to make a system that will detect the alive human bodies under the debris in case of catastrophic situations. Well, I've got two methods to accomplish this task.
First one is, send 1150MHz wave and after receiving through receiving antenna subtract it with the reference signal ( signal that was sent through transmitting antenna) by manipulating the reference signal such that its phase and amplitude cancel out with the 1150MHz signal while the doppler shift of 3Hz (due to heartbeat 1.5Hz in forward while 1.5Hz in backword direction) will remain there and then by using FFT, we can detect the peak of that doppler shift frequency.
I think this method is a bit complicated. We would need to match the phase and amplitude exactly.
Second one is, send 1150MHz frequency. Receiving signal would be the part of 1150MHz and doppler shifted signal. We can take the signal to smaller frequency. Let's say 50Hz so that it is comparable with the 3Hz signal. then we can use the FM demodulation to extract the signal (3Hz).
I think this method is relatively easier than the first one.
I wanna ask, Is the second method is feasible to detect very small amount of doppler shift? or which method do you think can be easy and feasible?
PS: Due to range and penetration, we have decided to use 1150MHz frequency.
Any help would be appreciated.