Re: [Discuss-gnuradio] How to receive samples after retune ?

[Patrick Sathyanathan]

Hi Youssef,

Thank you for the info and suggestions. It would have probably taken me a lot of time to discover this (if at all) from the source.

--Patrick

---

From: address@hidden
To: address@hidden
CC: address@hidden
Subject: RE: How to receive samples after retune ?
Date: Mon, 25 Jan 2016 14:41:52 +0000

Hi,

My comments below.

Regards,

Youssef

> From: address@hidden
> To: address@hidden; address@hidden; address@hidden
> Subject: RE: How to receive samples after retune ?
> Date: Mon, 25 Jan 2016 02:49:17 +0000
>
> Hi Youssef,
>
> Please read the question before firing off your standard responses like "read the wiki", "if you are new to SDR do...", etc. The Wiki you pointed me to does not contain the information I need.
>
> Let me simplify the question so you can understand:
>
>    - In _airspy_rx_callback after I received a fixed number of samples I call airspy_set_freq to retune to a new frequency.
==> That's a good strategy. The guaranteed tuning time is 5ms. You can count a worth of 5ms of samples before consuming the others.

>    - How do I ensure that the samples handed to me the next time _airspy_rx_callback is called are those at the new frequency after the retune ? Do I need to discard some samples ? If so, how many ?
==> Yes, theoretically, you need to discard 5ms * 10MSPS = 50000 complex samples. Except that the buffers are 64k size. So, I'd suggest retuning everytime you get a buffer in the callback and discard the first 50000 samples. OR, retune every two calls, this leaves you with at least 64k of useful data.

>    - Ettus B210, Nuand bladeRF, and sdrplay API's provide mechanisms to do this. What is the mechanism on the airspy ?
==> None of these radio's fit the use cases we are selling for/interested in - beside the fact that any one can add timestamps in the firmware and the host library. You are invited and encouraged to have a look.

> If you do not want to answer is there an airspy forum where I might get the information ?
==> There's more info in the code than any other place and we have high coding standards because other professionals will need to modify our code.

> --Patrick
>
> ----------------------------------------
> > From: address@hidden
> > To: address@hidden
> > Subject: RE: How to receive samples after retune ?
> > Date: Sat, 23 Jan 2016 10:59:55 +0100
> >
> > Hi,
> >
> > We mostly sell to professionals and never had to tell them they need to read
> > the wiki in our github page. You have there:
> > * Compile & Deploy procedures for the major systems,
> > * Flash procedure,
> > * The user mode driver,
> > * The diagnostic tools,
> > * Sample RX application
> > If you are new to SDR, take some time to read before asking for help. Good
> > luck!
> >
> > Regards,
> >
> > Youssef
> >
> > -----Original Message-----
> > From: Patrick Sathyanathan [mailto:address@hidden
> > Sent: samedi 23 janvier 2016 09:32
> > To: Youssef Touil <address@hidden>; address@hidden;
> > address@hidden
> > Subject: RE: How to receive samples after retune ?
> >
> > Hi Youssef,
> >
> > So this is how you respond to support requests! It would probably take you a
> > few seconds to tell me the API's I need to use to achieve what I want. But
> > all you tell me to do is wade through your entire (no documentation) source
> > base and figure it out for myself.
> >
> > Great way to popularize your product. And this is not the first time I am
> > getting "no information" replies from you...
> >
> > I will be sure to let other forums like gnuradio know of the level of
> > support that I getting from airspy...
> >
> >
> > --Patrick
> >
> > ________________________________
> >> From: address@hidden
> >> To: address@hidden
> >> Subject: RE: How to receive samples after retune ?
> >> Date: Fri, 22 Jan 2016 10:49:25 +0000
> >>
> >> Hi,
> >>
> >> Our software stack is fully open source. You can implement your own
> >> fast scanner starting from the firmware through the user mode driver
> >> to the user application.
> >>
> >> http://github.com/airspy
> >>
> >> Regards,
> >>
> >> Youssef
> >>
> >>> From: address@hidden
> >>> To: address@hidden; address@hidden
> >>> Subject: How to receive samples after retune ?
> >>> Date: Fri, 22 Jan 2016 07:52:01 +0000
> >>>
> >>> Hi,
> >>>
> >>> I have written my own scanner software on linux that works with
> >>> Ettus
> >> B210, Nuand bladeRF, sdrplay, and airspy. It does the following in
> >> pseudo-code:
> >>>
> >>>
> >>> while (not done) {
> >>> retune to next frequency;
> >>> receive fixed number of samples;
> >>> process samples (do FFT, thresholding, etc.); }
> >>>
> >>> On the B210 there is the burst mode receive so after retuning to a
> >> frequency I can receive a block of samples. The bladeRF has the
> >> timestamp feature so I can get the device timestamp after a retune and
> >> discard samples until I get to that timestamp. What can I do on the
> >> airspy to ensure that the samples I am receiving are after the retune
> >> to new frequency ?
> >>>
> >>> Thanks for any help,
> >>>
> >>> --Patrick
> >>>
> >>>
> >
> >
>