SDR Television

[g0mjw]

Are you over driving the analyser? This is what I got.

LibreSDR_DATV.jpg (109.25 KiB) Viewed 1309 times

Mike

[g0mjw]

Hi Clive,

Agree regrowth is normally caused by over driving, if you use a pluto or libresdr to transmit they both do it, think you are seeing that sdr television give a higher level output than obs for a fixed drive level, that is why I have a fixed attenuated output I have never seen it directly from my pluto it maybe a firmware issue on your pluto.

Brian

Looking at the plot, the average level is -30 dBm. That is in 10kHz resolution bandwidth. The signal is around 400kHz wide, so the power is 40x, or 16 dB higher, That is -14 dBm. The analyser reference level is -10 dBm. When you increased by ~3.75dB, the total power is very close to the reference level. I don't know the specification of the Rigol but please can you repeat that test with more attenuation, just to be sure it is the SDR and not the analyser causing this.

Mike

[G3GJA]

Same result with an extra 10dB attenuation.

The SA is known to be linear to at least 0dBm, checked against an HP 8657B SG.

Clive

[g0mjw]

Something isn't right then. The level of -30 clearly isn't -30dBm. I imagine the Pluto is going into over-drive. Did you measure the power?

Mike

[Pa3fbx]

Gain with SDR-TV is very flexible when you modify the FEC or BW..
Every TX start, I need to check if my power is not way out of the need range..

And yes stop the selection of big 2MHZ BW if you are TXing only 333. Its a recept for bad signals so far.

For RX sensitivity I made some nice comparison on terrestial between Pico, Minitiouner and SDR-TV..
With default settings (made for the satellite I guess) the signals are slightly less.
But if you select the RX gain and BW to be at 1.1 you get a 1 to 1.5 DB MER improvement on signals..
Tested with 125 to 333 Ks on 70cm..

I love Simons work so far.
A great BETA release...

Only 1 real problem found...
My Left and Right Audio Tune does not work as sdr_TV only is 1 channel MONO...

[g3uis]

I'm still having RX issues. TX is fine, and the Pluto with the narrowband SDR is also fine. However noting happens in receive. (I have changed Bias to 18 V)

Something obvious I'm sure, but getting punch drunk from looking. Its so deaf , like its not even switched on

Tony

[g6hfs]

Hi Tony,

Both Pluto and LibresDR work fine for me, you have to set the bandwidth correctly or it will give problems.

Brian

[g3uis]

Hi Brian

I’ll give that a try, but I’m sure I’ve tried several bandwidth settings.

Tony

[g0mjw]

I'm still having RX issues. TX is fine, and the Pluto with the narrowband SDR is also fine. However noting happens in receive. (I have changed Bias to 18 V)

Something obvious I'm sure, but getting punch drunk from looking. Its so deaf , like its not even switched on

Tony

Hi Tony,

Post a screenshot. We can't tell if it is set up correctly without that.

Mike

[g3uis]

Mike

Of the converter settings ? Or what please ?

Tony