Hello,
First thank you for this FL2000 hack, it's very nice!
I tried to make an FM & AM transmitter with it and GNU Radio. It's working fine if I save to a file and then use fl2k_file to transmit the data but with the tcp server and fl2k_tcp, my computer is not fast enough to sample in real time at 100 MHz. I also tried with a 35 Mhz sampling rate but it's not real time. Here is the diagram I used.
Is there a possibility to avoid sampling at a very fast rate if the data bandwidth is small to do the baseband to carrier shift? [cid:0115622e-668a-46ae-8e49-07a3a7aba391]
Thank you, Best regards, Jean-Paul
Well, as a VGA adapter, the FL2000 doesn't come with any mixer. So, all you can do is use images, since the DAC also lacks a proper reconstruction filter. You get mathematical repetitions at every multiple of the sampling rate – "undersampling" is the the term you want to read up on.
Best regards, Marcus
On Tue, 2018-05-01 at 12:03 +0000, azerty lr wrote:
Hello,
First thank you for this FL2000 hack, it's very nice!
I tried to make an FM & AM transmitter with it and GNU Radio. It's working fine if I save to a file and then use fl2k_file to transmit the data but with the tcp server and fl2k_tcp, my computer is not fast enough to sample in real time at 100 MHz. I also tried with a 35 Mhz sampling rate but it's not real time. Here is the diagram I used.
Is there a possibility to avoid sampling at a very fast rate if the data bandwidth is small to do the baseband to carrier shift?
Thank you, Best regards, Jean-Paul
Hello,
Ok so the Gnu Radio diagram that I did is correct? I tried a carrier frequency of 1 Mhz with a sampling rate of 31 Mhz of I should have got a signal at 30Mhz but it was not working very well. I needed a carrier of at least 2 Mhz to got a signal.
Best regards, Jean-Paul ________________________________ De : Müller, Marcus (CEL) mueller@kit.edu Envoyé : mercredi 2 mai 2018 12:42 À : azerty_lr@hotmail.com; osmocom-sdr@lists.osmocom.org Objet : Re: osmo-fl2k baseband to carrier
Well, as a VGA adapter, the FL2000 doesn't come with any mixer. So, all you can do is use images, since the DAC also lacks a proper reconstruction filter. You get mathematical repetitions at every multiple of the sampling rate – "undersampling" is the the term you want to read up on.
Best regards, Marcus
On Tue, 2018-05-01 at 12:03 +0000, azerty lr wrote:
Hello,
First thank you for this FL2000 hack, it's very nice!
I tried to make an FM & AM transmitter with it and GNU Radio. It's working fine if I save to a file and then use fl2k_file to transmit the data but with the tcp server and fl2k_tcp, my computer is not fast enough to sample in real time at 100 MHz. I also tried with a 35 Mhz sampling rate but it's not real time. Here is the diagram I used.
Is there a possibility to avoid sampling at a very fast rate if the data bandwidth is small to do the baseband to carrier shift?
Thank you, Best regards, Jean-Paul
Hi Jean-Paul,
no, as the warning in the GRC console should have told you: NEVER use a throttle in a hardware flow graph. It doesn't do anything, but will lead to continuity problems.
You can't define a signal at 35 MHz with a 35 MHz real-valued sampling rate – you'd need twice of that, at least; but since your sampling rate also defines the distance between spectral images, more careful choice of sampling rate is necessary for succesfull undersampling.
Best regards, Marcus
On Wed, 2018-05-02 at 19:10 +0000, azerty lr wrote:
Hello,
Ok so the Gnu Radio diagram that I did is correct? I tried a carrier frequency of 1 Mhz with a sampling rate of 31 Mhz of I should have got a signal at 30Mhz but it was not working very well. I needed a carrier of at least 2 Mhz to got a signal.
Best regards, Jean-Paul De : Müller, Marcus (CEL) mueller@kit.edu Envoyé : mercredi 2 mai 2018 12:42 À : azerty_lr@hotmail.com; osmocom-sdr@lists.osmocom.org Objet : Re: osmo-fl2k baseband to carrier
Well, as a VGA adapter, the FL2000 doesn't come with any mixer. So, all you can do is use images, since the DAC also lacks a proper reconstruction filter. You get mathematical repetitions at every multiple of the sampling rate – "undersampling" is the the term you want to read up on.
Best regards, Marcus
On Tue, 2018-05-01 at 12:03 +0000, azerty lr wrote:
Hello,
First thank you for this FL2000 hack, it's very nice!
I tried to make an FM & AM transmitter with it and GNU Radio. It's
working fine if I save to a file and then use fl2k_file to transmit the data but with the tcp server and fl2k_tcp, my computer is not fast enough to sample in real time at 100 MHz. I also tried with a 35 Mhz sampling rate but it's not real time. Here is the diagram I used.
Is there a possibility to avoid sampling at a very fast rate if the
data bandwidth is small to do the baseband to carrier shift?
Thank you, Best regards, Jean-Paul
-
azerty lr -
Müller, Marcus (CEL)