Re: [Discuss-gnuradio] Frequency sweep using GNU

[Marcus Müller]

Hi Abhilash,

I want to experiment in the wifi band (i.e 2.4-2.8GHz).

That kind of annoys me: that's not the "WiFi band". It's the 2.4 GHz ISM band, which different WiFi standards tend to use. However, there's a bazillion other things using that band, so you'd do me (and all these other applications) a favor if you're not naming it as if it was spectrum that is assigned to WiFi usage. It's not; there's RC toy controls, camera links, bluetooth, door openers, mesh networks, medical devices, wireless mice and keyboards, …

I am not sure about how long to linger on one frequency.

Well, obviously, this is a system design challenge that we can't answer for you: dwell time increases resolution and certainty, but inherently means your sweeping takes longer. So, **you** will need to define a reasonable timing first, and after you've done that, let's discuss how you could implement that. The other way around doesn't make any sense. Since your signature says "research scholar", I'm pretty optimistic you can describe your signals of interest well enough in a simple signal model that you can derive a formula for how long your observation per step needs minimally be.

I am trying to understand basic wireless channel effects like path loss, fading for different frequencies in the specified band.

Well, that's pretty close to a description of the channel model that is of interest here. You might just want to define bandwidth that you'd want to describe your channel under. Obviously, more bandwidth means more info about the channel, but also more data, and also more chance for multi-path to take effect, and make the channel frequency-selective ("coherence bandwidth"), and in that aspect maybe even time-variant ("doppler spread"). So, start by defining the bandwidth of the channel you need to describe.

Then, there's textbooks worth of common knowledge about how long a channel is expected to stay as it is ("coherence time").

Best regards,

Marcus

On 02.10.2017 07:44, abhilash b wrote:

Thank you for your reply in GNU radio forum for the message ID

 <e513aad6-c81f-3232-ece1-88d7address@hidden>

Here are the details: 

I will be using USRP N210 with CBX daughter board. I want to experiment in the wifi band (i.e 2.4-2.8GHz).

I am trying to understand basic wireless channel effects like path loss, fading for different frequencies in the specified band.

Currently, I am not sure about how long to linger on one frequency. I will be placing the transmitter on a drone and hover it. Hence I will have control just before the flight and I want the sweeping to repeat at regular intervals. I will be placing BladeRF on the drone and USRP will be on the ground.

If it's not possible to sweep with such little steps, I have the freedom to vary the step size.

Please provide me the approaches (or any links) to solve this frequency sweeping issue. 

-Regards
Abhilash B

Research Scholar

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