# Why cant I increase signal by 1 hz at a time with high frequencies?

It seems that when I create a signal source block and try and view the
signal on a waterfall plot or FFT plot, I can not increase the signal by
a granularity of 1 Hz at higher starting frequencies.

Example:
If I create a signal source block with a starting frequency of 1.2 GHz,
and in the block have a variable slider added to the frequency (assume
the variable can slide between 0 and 1000), i must move the slider 120
or more steps before the signal shifts on the waterfall plot with a gap
of 120 or more hz.

Is there a way to move the signal by 1 hz regardless of how high or low
the signal source frequency is?

Signal block screen shots attached.

On Tue, Sep 08, 2015 at 04:33:38AM +0200, Douglas Beonkey wrote:

If I create a signal source block with a starting frequency of 1.2
GHz, and in the block have a variable slider added to the frequency
(assume the variable can slide between 0 and 1000), i must move the
slider 120 or more steps before the signal shifts on the waterfall
plot with a gap of 120 or more hz.

Perhaps the frequency is stored as a (32-bit single precision) float.
This data type can store 1200000000.0 and 1200000128.0 but not the
intermediate integers.

Mike

On 09/07/2015 10:33 PM, Douglas Beonkey wrote:

Is there a way to move the signal by 1 hz regardless of how high or low
the signal source frequency is?

Signal block screen shots attached.

Using a signal source to produce a synthetic signal at 1.7GHz is simply
not going to work, unless your sample-rate is 3.4GHz, which seems
rather unlikely.

Normally in Gnu Radio, signals are represented in complex-baseband,
leaving the hardware to move this up/down to the desired “on air”
frequency.

Not sure what you’re trying to accomplish, perhaps you could share a
high-level overview?

On 07.09.2015 19:33, Douglas Beonkey wrote:

It seems that when I create a signal source block and try and view the
signal on a waterfall plot or FFT plot, I can not increase the signal by
a granularity of 1 Hz at higher starting frequencies.

Example:
If I create a signal source block with a starting frequency of 1.2 GHz,
and in the block have a variable slider added to the frequency (assume
the variable can slide between 0 and 1000), i must move the slider 120
or more steps before the signal shifts on the waterfall plot with a gap
of 120 or more hz.

Douglas,

are you saying the signal source isn’t doing as told, or the frequency
sink? If it’s the latter, it might be an artefact of how you’ve
configured it (FFT resolution, etc.).

M