Discrete Lo Frequency Changes in GRC

Hello all,

Another question. I need to have essentially a counter that will control
what frequency I transmit out of the USRP2. I need to control the rate
at
which it changes. Currently I use a ramp function to do this. I see
there is
a vector source that is also possible solution. Im wondering if there
are
also other solutions I may not have considered that someone could
recommend.
If my previous email is accurate I might need to wait something like 2
seconds between counts to do what I want in an automated fashion. This
seems
difficult to do in a processor efficient manner within GRC being that it
is
sample based and more of a labview style of coding and not Cish where I
could set a sleep timer or some other wait function to delay the count.
If I
understand things right a possible solution is to decimate a source to
achieve this, or just use a lower frequency ramp source. However this
still
requires a lot of cpu time since the source is still outputing samples
at
the sample frequency regardless of whether they are being used. And if I
need a variable amount of time at each count, or non-equally spaced
counts
this doesn’t provide that.

I have considered going into the python code and doing this modification
in
there. However I have zero experience with python so it might take me a
bit
to do that. Just fishing for suggestions, any help offered is
appreciated.

Thanks,
Justin

It appears that the server went down yesterday. I don’t know if anyone
recieved these messages. I apologize for any Deja vu this causes. Please
see
the following:

---------- Forwarded message ----------
From: Justin B. [email protected]
Date: Tue, Nov 30, 2010 at 12:17 PM
Subject: Discrete Lo Frequency Changes in GRC
To: [email protected]

Hello all,

Another question. I need to have essentially a counter that will control
what frequency I transmit out of the USRP2. I need to control the rate
at
which it changes. Currently I use a ramp function to do this. I see
there is
a vector source that is also possible solution. Im wondering if there
are
also other solutions I may not have considered that someone could
recommend.
If my previous email is accurate I might need to wait something like 2
seconds between counts to do what I want in an automated fashion. This
seems
difficult to do in a processor efficient manner within GRC being that it
is
sample based and more of a labview style of coding and not Cish where I
could set a sleep timer or some other wait function to delay the count.
If I
understand things right a possible solution is to decimate a source to
achieve this, or just use a lower frequency ramp source. However this
still
requires a lot of cpu time since the source is still outputing samples
at
the sample frequency regardless of whether they are being used. And if I
need a variable amount of time at each count, or non-equally spaced
counts
this doesn’t provide that.

I have considered going into the python code and doing this modification
in
there. However I have zero experience with python so it might take me a
bit
to do that. Just fishing for suggestions, any help offered is
appreciated.

Thanks,
Justin