BATC Forum

Hello,

If you have an Adalm Pluto, you can use DATVexpress transmitter to send DVB-S or DVB-S2 at frequency 3457 MHz.
As the signal is not filtered, you have a beautiful Harmonic 3 on 10371 MHz that is usable.

I just hold by hand my Avenger LNB at about 1M and receive the video with Minitioune on 621 MHz.

So we can try different LNB and choose the one that gives the best MER.

Another remark:
For DATV we don't need any TCXO or better, the LO can be a soap. When we are receiving HamTV the doppler effect make the frequency to change slowly up to about 110 kHz in 6 mn and Minitioune can follow easily the signal and as we don't acquire the HamTV signal at the same position, we don't have always the same frequency when we lock on the signal.
Most important thing about the LO is to have a very low Phase noise? if the frequency change with temperature that is not a problem.
if your LO is a soap it's just like a "virtual doppler" Hi.
Perhaps I am wrong, it is just my opinion.

Jean-Pierre F6DZP

Hi Jean Pierre,

I believe you are correct.

Firstly G7JTT and I have done RB-TV tests at 333ks with an old DRO LNB which drifts up to .5MHz at switch on but once warm proved OK for RB-TV.

Second - externally locking the Octagon PLL LNB does increase the phase noise and Dave G8GKQ has seen a decrease of 2dB MER.

So if you are just using Es'hail-2 for DATV you don't need lock the PLL LNB. If you are using for narrow band SSB and CW, you will need to lock unless you want to keep adjusting the tuning dial - and you won't really notice any increase in phase noise.

73

Noel - G8GTZ

Or - we will see but there is another option to lock the SDR to the beacon and overcome the drift that way.

Mike