Ronald,
No need to apologize, It was simply a request to make it clear to all the context of the messages.? It helps to keep confusion and misinterpretation out of the thread.

Thank you for posting and sharing.
73
Evan
AC9TU

My apoligies Evan,

I'm new here, and due to not refreshing my screen - i missed some posts..

On Thu, Oct 21, 2021 at 02:04 AM, <frikandelmetmayo@...> wrote:

Correct.
The amp i'm using has 2 BLF368's capable of doing 300 watt each for an analog signal.
Bias is set for lineair operation

frikandelmetmayo,
Who are you referring to in the above message?? It is always best to give some sort of identifier at the start of your reply as I did in this message.? you do not need to do include the quoted text, but the name (or email address in this case) helps us readers follow the thread.? This is because there can be other messages between the one that you are replying to and your response.

It is also customary to sign your message, as this is what is normally used in the response.

73
Evan
AC9TU

Correct.
The amp i'm using has 2 BLF368's capable of doing 300 watt each for an analog signal.
Bias is set for lineair operation

On Tue, Oct 19, 2021 at 08:47 AM, <frikandelmetmayo@...> wrote:

Did some tried to measure a DAB signal already?

I have never measured one, and having never had to design or repair a DAB, I don't really know a lot about them.? However, one of the first things I do when asked about something I don't know a lot about is to consult with somebody that does know a lot about it.? According to Rohde & Schwarz, this is not a particularly easy thing to measure:

"The high dynamic range of the signal after the mask filter makes it impossible to check
adherence to the tolerance mask directly using a spectrum analyzer. This is why an
adjustable notch filter is typically used to reduce the useful band power."

Their list of required equipment includes:

"For Shoulder Attenuation and Adjacent Channel Emissions measurements
(3.3.1) using the variant 'after mask filter'
Notch filter to attenuate the wanted signal by 40 dB or more"
Source:
https://cdn.rohde-schwarz.com/pws/dl_downloads/dl_application/application_notes/7bm104/7BM104_1E.pdf

As I said, I'm not the expert on this.? But I'm inclined to accept Rohde & Schwarz's opinion on this.? I'd probably start by building a notch filter to take out much of the in-channel power.? You might try an open quarter wave coaxial stub at the channel center frequency to start with.

On any of my recent laptops, I had to purchase a USB 2.0 hub to plug into any of the USB 3.0 ports on a recent PC, then plug the TinySA into the hub in order for it to be recognized correctly. It seems the TinySA was not correctly negotiating the the USB 3/2 connection and “downshifting” into USB 2.0 mode.

Inserting the strictly USB 2.0 hub in the chain provided a USB 2.0 connection to the TinySA without having it struggle with whatever was failing with the negotiation process. This provided a reliable connection for me and I was able to do firmware updates without a problem.

Steve

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178eur for a niche RF product in a machined shell is not too outrageous.
More than what I' d be willing to pay for a hobby device, but perfectly ok if you are not comfortable homebrewimg one from junkbox parts and ebay modules like I did for my 50-5000MHz downconverter.

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Roger,

I did not know that. I don't own an SDRplay, but this information certainly made me reconsider buying one!

Perhaps I should not have written "all SDR" but "most SDR". i stand corrected!

regards,
Vitor

On Wed, Oct 20, 2021 at 08:50 AM, Vitor Martins Augusto wrote:

However, all SDR devices share one common issue: they cannot be directly used to perform signal level measurements. While they can show the spectrum in dB, you won't find any software that shows the spectrum in dBm. That's because the device has no reference and is not calibrated.

This is why the TinySA is so interesting: it not only renders the spectrum, it allows to do measurements!

The SDRplay SDR products are calibrated in dBm when used with their SDRuno software.? They receive from VLF to 2 GHz. The accuracy is +/- 1 dBm.? As a beta tester for their hardware I can verify that they are accurate for measuring dBm.

Roger

The moRFeus os available at Mouser:

The Adalm Pluto is, like the HackRF One, an SDR based device that works by sampling the input signal.

The spectrum can be shown in frequency domain by processing the sampled data with FFT (Fast Fourrier Transformation).

However, all SDR devices share one common issue: they cannot be directly used to perform signal level measurements. While they can show the spectrum in dB, you won't find any software that shows the spectrum in dBm. That's because the device has no reference and is not calibrated.

This is why the TinySA is so interesting: it not only renders the spectrum, it allows to do measurements!

regards,
Vitor

I could not resist....

Have a look at this video on how you can do the same using one extra tinySA and a cheap eBay mixer module

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With OFDM having a very low average transmitted RF power compared to it's RF peaks, it means to run say 100W's of RF you'll need at least a 1kW PA, probably more. It depends on what the peak to average power ratio is for a typical DAB OFDM carrier is, with DAB having around 2000 sub-carriers the PAPR will unfortunately be high (10 or 20 even), so you'll certainly need a 1 or 2kW PA to provide 100W of DAB signal to the antenna, otherwise you'll destroyed the OFDM signal quality before it reaches the antenna by driving the PA into compression (you must maintain linearity throughout to keep the peaks clean).