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TINYSA: HOW TO INCREASE THE FREQUENCY RANGE #tinysa

 

Hello,

I just published a new post on my blog on how to use the TinySA in combination with moRFeus (a RF signal down/up-converter):



Regards,
Vitor
Re: Can the TinySA measure DAB signals?

 

Re: Can the TinySA measure DAB signals?

 

@OneOfEleven that's what i'm trying to find out. I guess it's the PA causing the issue, but i'm not sure :)

@Toni Yes i agree

Seems that the Tiny is unfortunately not suitable for analyzing this kind of signals

In a R&S manual i also found a video BW setting that is needed apparently..

I would like to thank you all for the very helpful feedback!
Re: Can the TinySA measure DAB signals?

 

Also consider that, due to the attenuation, you are looking at the upper 30-32 dB of the signal. Perhaps the shoulders are below the noise floor, as several people have indicated.

?ToniC
Re: Can the TinySA measure DAB signals?

 

Well if the modulator is OK, and the PA is OK, then what's left to be at fault ?
Re: Can the TinySA measure DAB signals?

 

For some reason the images are scaled by this board, one post lower you can find the ImgBB URLs.

The modulator should be oke, as it is almost a standard for low power licenced community radio here in NL
Re: Can the TinySA measure DAB signals?

 

I guess your DAB modulator/Tx has a problem if the noise floor is high and flat going out from the OFDM edges (possible RF compression occurring in your RF modulator). Can't tell from your low resolution images what the dB scale is.
Re: Can the TinySA measure DAB signals?

 

Thanks Tony!

My measurements where made with a of RBW 10KHz - i will measure the signal again with RBW 3KHz, curious if this makes a difference
Re: Can the TinySA measure DAB signals?

 

As can be seen in the screenshots, i have a signal of -70dB which should be low enough - or am i wrong?
Re: Can the TinySA measure DAB signals?

 

I'm using a EasyDAB, which looked fine on a Siglent - and also on the Tiny.
Or i'm overlooking something, or the Tiny is not accurate enough to display sidelobes.
Unfortunately i cannot use the Siglent anymore to cross check

My amplifier is linear - it was formely used for DVB-T
Re: Can the TinySA measure DAB signals?

 

tinySA can discriminate as far as the RBW allows. Be sure that the 3KHz RBW is selected, as in the figure?
Re: No DAB Signals

 

No, but we do have HD Radio here.



73

-Jim
NU0C


On Tue, 19 Oct 2021 21:57:03 -0400
"Mike C." <mg@...> wrote:

Interesting subject, this DAB signal. We don't have it here in the US,
look what we have for leadership.

Mike C.
Re: Schematics for MAX2870

 

I suggest you use MAX2871, which is an improved version of MAX2870, you can refer to this project.
Re: Schematics for MAX2870

 

¿ªÔÆÌåÓý

Yeah, I read the spec sheet but what I'm looking for are some instructions or users and their comments regarding the ebay item.

Mike C.

On 10/19/2021 10:34 PM, Ray Anderson wrote:

How about:

Ray WB6TPU





On Oct 19, 2021, at 6:29 PM, Mike C. <mg@...> wrote:

?Hi Guys,

Has anybody come up with package information like schematics on the MAX2870? i.e. ebayism # 363099163574

Mike C.
Re: Schematics for MAX2870

 

¿ªÔÆÌåÓý

How about:

Ray WB6TPU





On Oct 19, 2021, at 6:29 PM, Mike C. <mg@...> wrote:

?Hi Guys,

Has anybody come up with package information like schematics on the MAX2870? i.e. ebayism # 363099163574

Mike C.
No DAB Signals

 

Interesting subject, this DAB signal. We don't have it here in the US, look what we have for leadership.

Mike C.
Schematics for MAX2870

 

Hi Guys,

Has anybody come up with package information like schematics on the MAX2870? i.e. ebayism # 363099163574

Mike C.
Re: Can the TinySA measure DAB signals?

 

Be aware the tinySA is feeling the total power (summed power) at the mixer and not just the peak power at one single frequency so if the bandwidth is wide you have to reduce power further than the automatic attenuation will do.
Start by ensuring the peak of the input is below -40dBm (after the internal attenuator) and see if that makes a difference versus -55dBm or -25dBm
------------------------------------------
For more info on the tinySA go to https://tinysa.org/wiki/
Re: Can the TinySA measure DAB signals?

 

I don't know how you're generating your OFDM signal, but try looking at it on the TinySA BEFORE you feed it into your transmitter amplifier chain, see how it compares. If your transmitter chain is compressing (non-linearity) your Tx signal in any way then that will reduces it's quality very quickly, no matter how strong it is when it reaches any receivers.
Re: Can the TinySA measure DAB signals?

 

Yours looks clean enough, though there must be something a bit wrong somewhere if 100W's only gets you short distances.

The thing about OFDM is that it requires very linear transmitters, the PAPR (peak to average power ratio) is unfortunately very high, the peaks of the RF carrier are very much higher than the average power, it requires quite a high dynamic range to see the side lobes so not to compress the RF peaks - an OFDM spectrum might look nice and flat but the RF envelope.is far from it, the more OFDM sub carriers you have the higher the PAPR.

Maybe you're right, maybe the TinySA doesn't have the required dynamic range t o show the side lobes ?
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