22 MHz .... 20 MHz

[RF_Buzzer]

Hi Andy,
Thanks for your posting the examples.

I have one more query regarding Programming of NI-TUNER / NI-SCOPE related to acquisiton of 22 MHz data.

How are the settings for NI Tuner Reference Level related to enhancing Real Time Bandwidth of 5600 DOWNCONVERTER.
Going through help, I find that you can turn on / turn off various ATTENUATORS in sequence... for the DOWNCONVERTER.

If ATTENUATORS in DOWNCONVERTORs are to be understood as RF BAND PASS FILTERs, Does specifying -30 dBm as the Reference Level allow me to capture more spectrum (say around 22 MHz) than .... a -20 dBm Reference Level ( say around 18 MHz) ?
Is this the idea ??

Thanks in advance.....

Regards,
Dharmendra

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@Andy Hinde wrote:
Sorry. I could have sworn I posted them. I'll try again...

Thanks,
Andy

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[Andy_Hinde]

I am not sure why you are associating attenuators with filtering. They have nothing to do with real time bandwidth.

As described in the help, the attenuators for the 5600 work as follows:

RF Attenuation
0-50 dB of RF attenuation (in 10 dB steps) can be applied in the 5600. The RF attenuation applied is the difference between the Reference Level (RL) and the Mixer Level (ML).
RF Atten (dB) = RL (dBm) - ML (dBm)

The RL and ML values are coerced up to the next highest multiple of 10 if a non multiple of 10 value is used.

Example:
RL = -7, ML = -20
RL coerced to 0, 20 dB RF attenuation applied.

RL = 30, ML = -20
50 dB RF attenuation applied.

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@RF_Buzzer wrote:
Hi Andy,
Thanks for your posting the examples.

I have one more query regarding Programming of NI-TUNER / NI-SCOPE related to acquisiton of 22 MHz data.

How are the settings for NI Tuner Reference Level related to enhancing Real Time Bandwidth of 5600 DOWNCONVERTER.
Going through help, I find that you can turn on / turn off various ATTENUATORS in sequence... for the DOWNCONVERTER.

If ATTENUATORS in DOWNCONVERTORs are to be understood as RF BAND PASS FILTERs, Does specifying -30 dBm as the Reference Level allow me to capture more spectrum (say around 22 MHz) than .... a -20 dBm Reference Level ( say around 18 MHz) ?
Is this the idea ??

Thanks in advance.....

Regards,
Dharmendra

---

@Andy Hinde wrote:
Sorry. I could have sworn I posted them. I'll try again...

Thanks,
Andy

---

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[RF_Buzzer]

Hi Andy,

In your previous posts, You wrote...

Yes the passband of the PXI-5600 is spec'd at 20 MHz as that is the flat part of the bandpass filter used, but the rolloff is such that the magnitude response is roughly 10 dB down at 5 MHz above and below the outsides of the 20 MHz flat passband.

Can we program this BandPass Filter to acquire more than 20 MHz... I would like to specify the Cutoff Frequency for this BandPass Filter at 10 dB ( rather than conventional 3 dB .. Flat part of Spectrum ) to acquire more than 20 MHz data... Of Course withstanding Noise that would likely come into the acquistion.

How does NI TUNER control this BandPass Filter ??

Regards,
Dharmendra

---

@Andy Hinde wrote:
I am not sure why you are associating attenuators with filtering. They have nothing to do with real time bandwidth.

As described in the help, the attenuators for the 5600 work as follows:

RF Attenuation
0-50 dB of RF attenuation (in 10 dB steps) can be applied in the 5600. The RF attenuation applied is the difference between the Reference Level (RL) and the Mixer Level (ML).
RF Atten (dB) = RL (dBm) - ML (dBm)

The RL and ML values are coerced up to the next highest multiple of 10 if a non multiple of 10 value is used.

Example:
RL = -7, ML = -20
RL coerced to 0, 20 dB RF attenuation applied.

RL = 30, ML = -20
50 dB RF attenuation applied.

---

[Andy_Hinde]

This is a fixed bandwidth 20 MHz passband filter. It is a hardware component in the downconverter and as such the bandwidth cannot be manipulated. NI-Tuner does not have any control over this filter bandwidth.

When you tune to a frequency and view the 5600 output with the digitizer-only example you are viewing the entire 5600 output. You should be able to see your 22 MHz wide signal with some rolloff on the sides.

[RF_Buzzer]

Got it Andy.
What u say is I will be able see your Spectrum of 22 MHz wide even with the 20 MHz limitation.

And with the present NI Hardware / Software setup for 5660 and SMT, I cannot demodulate 22 MHz for analyzing signals in I/Q Domain.

Can I use other NI Hardware in conjunction with 5660 to acquire > 20 MHz data ??

Regards,
Dharmendra

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@Andy Hinde wrote:
This is a fixed bandwidth 20 MHz passband filter. It is a hardware component in the downconverter and as such the bandwidth cannot be manipulated. NI-Tuner does not have any control over this filter bandwidth.

When you tune to a frequency and view the 5600 output with the digitizer-only example you are viewing the entire 5600 output. You should be able to see your 22 MHz wide signal with some rolloff on the sides.

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[Andy_Hinde]

Hello Dharmendra,
If you re-read my previous postings, here is what I am saying:

1) The 5600 has a specified 20 MHz BW. You can probably pump a 22 MHz signal through it, but we don't guarantee performance or support this.

2) Since we don't support this, the software that ties the 5600 and 5620 (i.e. 5660) does not handle this use case.

3) You can use low-level software for the individual 5600 and 5620 modules working independently to try this use case. The 5600 will output the 22 MHz signal with some of the edges of the BW attenuated. I posted this software previously for spectrum analysis use case.

4) You can use NI-Scope digitizer only modulation software in the same manner for demodulation. These examples are located at:
C:\Program Files\National Instruments\LabVIEW 7.1\examples\Modulation\niScope examples

When you say 'Can I use other NI Hardware in conjunction with 5660 to acquire > 20 MHz data ??', you must remember that the 5600 is essentially a tunable 20 MHz bandpass filter. Basic electrical engineering says once the signal passes through 5600 it has already been filtered so no additional HW will be of any help.

[abedi]

Bonjour Buzer,

Peux-tu stp me dire (ou donner le code labview D acquisition) comment tu as programmer dans Labview ton acquisition, car j essaye sans vraiment de success. J ai une antenne a 900Mhz dont j ai connecte  a PXI 5600.

Merci d avance

[Andy_Hinde]

Hello Abedi,
Unfortunately I don't speak French, so can you post a translated version of your question?

Thanks,
Andy

[鱼在洋]

I learn a lot !