STEMlab 122.88-16 SDR

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DD8JM
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Re: STEMlab 122.88-16 SDR

Beitrag von DD8JM » Do Apr 18, 2019 9:09 am


Hello, Yevgeni,

thanks for your contribution, I have put it on CQ-NRW.de, not all read it here in the forum.

Greetings Jörg, DD8JM
Die Bässe breit die Höhen schmal das ist der Funk aus Wuppertal.

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Re: STEMlab 122.88-16 SDR

Beitrag von DC9OE » Do Apr 18, 2019 3:04 pm


Hi Yevgeni,

brilliant measurements - many thanks, you filled some gaps for me which we could not measure because our own equipment was to noisy.
The trick of changing the input voltage settings is a good one, I will test it on our stemlabs.

Interesting to see that you came up with 2dB more sensitivity for MDS (our measurements came up with -122dBm).

Anyway, many thanks again, you provided a very good overview and in fact it underlines that STEMlab 16 can either match or outperform any other Direct Sampling TRX currently on the market.

73,Edwin - DC9OE

PS. und Jörg danke dass Du die Messergebnisse hier reingestellt hast, sie haben für uns eine Lücke geschlossen und ersparen uns weitere Arbeit

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Yevgeni
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Re: STEMlab 122.88-16 SDR

Beitrag von Yevgeni » Do Apr 18, 2019 4:17 pm



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DC9OE
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Re: STEMlab 122.88-16 SDR

Beitrag von DC9OE » Do Apr 18, 2019 6:06 pm


Hi Yevgeni, thanks for the Video's - interesting but somewhat difficult for me to follow.

One question on sensitivity measurement because I'm not sure I understood your method correctly.
From what I understood from the video it looks to me as if you have taken the noise floor in a bandwidth of 500 Hz and the outcome was -124dBm.

In this book: http://www.arrl.org/shop/Amateur-Radio- ... ce-Testing

the ARRL describes the test procedures they are using in their labs and according to them, MDS is defined by a signal which is 3dB above the noise floor.
In your case MDS would be roughly -121dBm using this definition.

When using this method, I ended up with -122dBm and as I was wondering where the differnce to your measurements came from - this might be the answer.

You might find the book interesting it gives good definitions on the procedures used by ARRL (I think the text is also available on the internet somewhere).
The same procedures are used by Sherwood Engineering for their Sherwood List.

Thanks again for the good work and best 73, Edwin -DC9OE

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Re: STEMlab 122.88-16 SDR

Beitrag von Yevgeni » Fr Apr 19, 2019 2:48 pm


Hello
MDS RP16Bit
Dateianhänge
RX1-124dBm--.jpg

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Re: STEMlab 122.88-16 SDR

Beitrag von DC9OE » Fr Apr 19, 2019 3:06 pm


Hi Yevgeni,
thanks this was the type of picture I was missing.
However, to me it looks as if your noise floor is -124 dBm, your signal is +3dB above which should result in an MDS of - 121 dBm.
Your S-meter shows -121,6dBm which is pretty close - my own measurent was -122dBm (using an R&S SML03 as Generator).

Anyway, I think this is just an academic discussion - end result is that STEMlab 16 has become a great RX.
Especially RX Noise is much lower now, both in terms of A/D Noise as well as clock noise.

Would hope to meet you on the HF bands one day with STEMlabs on both ends....

73, Edwin - DC9OE

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Yevgeni
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Re: STEMlab 122.88-16 SDR

Beitrag von Yevgeni » Do Apr 25, 2019 8:00 am


Hello
Direkter Empfang der Reichweite von 2 m Am Eingang des RP sind LNA PGA103 + und BPF 145 MHz. NF vom Eingangs-LNA ca. 5 dB.

https://youtu.be/jXlnpfgMRds

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Re: STEMlab 122.88-16 SDR

Beitrag von Yevgeni » Do Apr 25, 2019 10:01 am


Hello
Messung von MDS durch ARRL-Test des HF-Transceivers.
Dateianhänge
MDS_G_OFF.jpg
MDS_G_ON.jpg

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