I am trying to come up with a practical solution for a low cost DRM transmitter.
The software side I think it pretty much well covered by DREAM in TX mode (dream - t).
Then, there is where I get lost, but I think I have found a relatively simple solution.
In the "Output" tab I have the following parameters: Intermediate Frequency set at 6000.00 Hz default; Format set at I/Q (pos) default; Options: +12 dB checked and High quality I / Q checked.
Now, the hardware setup is not 100% clear to me; with the above SW setup, does it means that the two outputs of the sound card (i.e., the left and the Right outs) are used one for the I and the other for the Q? And if so, which is which? I / Q (neg) means simply that the signals are inverted in polarity? Real val. and E / P: what do they stand for and what are they for?
Assuming that with the above configuration I get the I on the Left channel output and the Q on the Right channel output, are they good to fee an LTC5599 from Linear?
I have accidentally found this video ... http://www.linear.com/solutions/5429 which shows a demo board (http://www.linear.com/solutions/5356) that can be driven by the baseband I and Q signals somehow generated.
So, the idea would be to hook up diirectly the Left and Right outputs from the sound card to the Demo Board.
But, as you can see in the drawing of the Demo Board, there are two Is and two Qs: I+ and I-, and Q+ and Q-;
And there is also a common chassis ground.
So, how should I go at connecting the audio card's outputs to the Demo Board's inputs?
Thank you all for any help :-)
Regards,
Stefano.
.
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Update:
I have received clarification about the I+ and I-, Q+ and Q- signals; Regarding you question about I and Q, positive and negative. You will need all 4 signals to make the chip work. The balanced modulators in 5599 need the the differential signal of I and Q, without the differential signal they cannot produce the Double Sideband Supressed Carrier or DSSC.
.... Regarding the I -and Q- negative signals, you will have to build two simple inverting unity gain op-amp circuits to complement the I+ and Q+. The following circuit would do:
.... A good quality op-amp like the NE5532 would cover the range of possible IF frequencies that the sound card can I Q output.
.....
I'll keep experimenting ...
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
HI all;
I am trying to come up with a practical solution for a low cost DRM transmitter.
The software side I think it pretty much well covered by DREAM in TX mode (dream - t).
Then, there is where I get lost, but I think I have found a relatively simple solution.
In the "Output" tab I have the following parameters:
Intermediate Frequency set at 6000.00 Hz default;
Format set at I/Q (pos) default;
Options: +12 dB checked and High quality I / Q checked.
Now, the hardware setup is not 100% clear to me; with the above SW setup, does it means that the two outputs of the sound card (i.e., the left and the Right outs) are used one for the I and the other for the Q? And if so, which is which?
I / Q (neg) means simply that the signals are inverted in polarity?
Real val. and E / P: what do they stand for and what are they for?
Assuming that with the above configuration I get the I on the Left channel output and the Q on the Right channel output, are they good to fee an LTC5599 from Linear?
I have accidentally found this video ... http://www.linear.com/solutions/5429 which shows a demo board (http://www.linear.com/solutions/5356) that can be driven by the baseband I and Q signals somehow generated.
So, the idea would be to hook up diirectly the Left and Right outputs from the sound card to the Demo Board.
But, as you can see in the drawing of the Demo Board, there are two Is and two Qs: I+ and I-, and Q+ and Q-;
And there is also a common chassis ground.
So, how should I go at connecting the audio card's outputs to the Demo Board's inputs?
Thank you all for any help :-)
Regards,
Stefano.
.
Update:
I have received clarification about the I+ and I-, Q+ and Q- signals;
Regarding you question about I and Q, positive and negative. You will need all 4 signals to make the chip work. The balanced modulators in 5599 need the the differential signal of I and Q, without the differential signal they cannot produce the Double Sideband Supressed Carrier or DSSC.
....
Regarding the I -and Q- negative signals, you will have to build two simple inverting unity gain op-amp circuits to complement the I+ and Q+. The following circuit would do:
....
A good quality op-amp like the NE5532 would cover the range of possible IF frequencies that the sound card can I Q output.
.....
I'll keep experimenting ...