Re: [Discuss-gnuradio] sps in receiver

[Nemanja Savic]

Hope you (Marcus) didn't change your mind not help me :)

Actually I just wanted to ask for some literature, and the question is not directly connected to GNU radio, but rather indirectly.

Best

On Fri, Dec 6, 2013 at 1:04 PM, Nemanja Savic <address@hidden> wrote:

Yes, that's true, but actually I am using USRP/WBX and GNURADIO, everything works, but I think I can make it better if I redesign it in the spirit of SDR.

I want to receive both fsk and on-off, and at the moment I have two parallel processing paths.

On Fri, Dec 6, 2013 at 12:54 PM, Marcus Müller <address@hidden> wrote:

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Ah ok, I think I can make out some misunderstandings:
* You use an USRP / WBX System
* You want to use GNU Radio to decode a signal
  - transmitted at 434 MHz
  - having a symbol rate of 19.2 kHz
  - being binary coded
  - that binary coding being on-off keying

Is that correct?

On 06.12.2013 12:49, Nemanja Savic wrote:
> Ok, i should put more info. I have USRP and WBX., and I designed
> receiver for operating withing 434 MHz. Since I am more hardware
> oriented electrical engineer, I didn't know how to make it in
> "correct" way, and there are a few blocks there that are based on
> simulating hardware that I know how functionate. So, I use sampling
> frequency of 500k, and after demodulator, I have a block that works
> literally as diode min max circuit and is usually implemented in
> some receivers. That block, extracts threshold (which is half way
> between min and max). After that, the same input is compared to
> threshold signal in order to derive signal that has only zero level
> and one level (so digital signal). Derived "digital" signal is sent
> to something that I call clock syncronizer, and there I search for
> the edges in order to allign my sampling period, and I do sampling
> in order to get symbol values. So my question is what would be the
> correct way to design this, because I think that my approach is
> definately not correct one and in my opinion too robust.
>
>
> On Fri, Dec 6, 2013 at 12:22 PM, Marcus Müller <address@hidden>
> wrote:
>

> Hi Nemanja,
>
> uff, that's quite a lot of text I hardly understand. Could you
> please confirm:
>
> * You want to design a receiver * the receiver should have an
> Analog-to-digital converter * You already have a design for mixing
> from RF to baseband
>
> The rest I don't understand. What is your question? How is it
> related to GNU Radio? But it really does sound exciting!
>
> Greetings, Marcus
>
> On 06.12.2013 11:26, Nemanja Savic wrote:
>>>> Hi all guys,
>>>>
>>>> this time :), my question is regarding soem reference book or
>>>> any other kind of literature, where I can find about how
>>>> digital receiver should be designed regarding sps. Namely, my
>>>> current receiver is more or less simulation of some analog
>>>> circuitry that I understand better than DSP. For example,
>>>> after demodulation I use a block that is apprximation of
>>>> diode min max circuit for setting the right threshold for
>>>> getting dgital signal out of "analog" demodulator output.
>>>> After that my bit slicer works more or less like the one
>>>> found in the UART. For this reasons, the signal needs to be
>>>> highly oversampled, for example, symbol rate is 19.2kb and I
>>>> use sampling frequency of 500ksps. When lowering sampling
>>>> frequency to 250ksps, the performance of the receiver
>>>> degrades a lot, plus probably to many processing effort than
>>>> it should be.
>>>>
>>>> Thanx,
>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> Discuss-gnuradio mailing list address@hidden
>>>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
>>>>
>>
>> _______________________________________________ Discuss-gnuradio
>> mailing list address@hidden
>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
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>
>
>
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Nemanja Savić

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Nemanja Savić