Hello everyone,
I am trying to figure out the best way to approach simulating doppler
shift on my BPSK transmitter. Does anyone know of how I may be able to
approach this?
Thank you in advance for any information.
Ryan
2007/10/26, Ryan R. [email protected]:
Hello everyone,
I am trying to figure out the best way to approach simulating doppler
shift on my BPSK transmitter. Does anyone know of how I may be able to
approach this?Thank you in advance for any information.
Hi,
You can just multiply the BPSK signal with the signal from a
gr.sig_source_c block. This should be sufficient if you do no take the
effect of the Doppler frequency shift of the BPSK signal into account.
This assumption might be valid for your application, but that depends
on the rate of the BPSK modulation.
Trond D.
Ryan R. wrote:
Hello everyone,
I am trying to figure out the best way to approach simulating doppler
shift on my BPSK transmitter. Does anyone know of how I may be able
to approach this?Thank you in advance for any information.
Doppler shift will affect both the center frequency and modulation
frequency proportionally. However, once you have translated the
received signal to baseband, those two are no longer proportional, so
you have to handle the effects separately.
For the center frequency delta, just use a complex mixer. In gnuradio
that would be sending the signal into a complex mixer, and feed the
other mixer with a complex sine wave at the doppler frequency (which is
positive or negative).
For the modulation frequency, the easiest thing to do is to do
fractional sample rate conversion, using a gr_fractional_interpolator.
However, you may not need to do this if the doppler effect on your
modulation frequency is small. If the doppler effect on your signal
bandwidth is much smaller than the range of your symbol timing recovery,
then most would just ignore it.
Matt
Ryan R. wrote:
Hello everyone,
I am trying to figure out the best way to approach simulating doppler
shift on my BPSK transmitter. Does anyone know of how I may be able to
approach this?Thank you in advance for any information.
Ryan
Depends on the channel model you are interested in. There is plenty of
literature on this. If you just want a simple frequency conversion,
just
use a mixer, as others have already said. For a mobile channel, Jake’s
model is often used.