Posts by David IW5BNL

I write a GNURADIO block to decode psk beacon (it can decode K,L,M,N block). It need a GNU demodulator (costas loop and clock sync) .

If someone is interested I can provide the decoding block.

It will be much more interesting if some additional information should be added to the beacon: telemetry don't make sense (due to IP regarding satellite functionality) but information regading dx expedition,special call,ecc can be useful.

Regards,

David

IW5BNL

Hi,

I will share it.

Let me clean up a bit and add some comment.

73 David

I add to my GNU radio receiver the PSK CRC beacon decoder.

The CRC beacon decoder was add just for fun and to refresh my digital communication skill after 28 years from Master degree and engineering career in completely different area.

All the decoder (viterbi,syncronization,de-scrambler) is write in python.

Antenna 40Cm dish with PLL lnb,SDR dongle locked on upper beacon

ciao

IW5BNL

Hi Matteo,

Congratulation for your realization.

I'm happy to see someone working with GNU Radio..

At the moment I have GNU radio RX locked on PSK beacon with a costa loop and it work very good.

My next task is working on TX. I'm thinking to use Pluto.

I see that you are using Hack RF one. Do you think that is better that Pluto (at least working with GNUradio).

Ciao

David

IW5BNL

Hi Rudi,

good thank you.I will use more or less same power and Helix.See you soon on sat.

David

IW5BNL

hi

Very good!

Do you use a helix for uplink?

I'm progressing on transmitter.

David

IW5BNL

Hi

After better point of Antenna and lnb position I get becacon (pk with FFT) 21-22Db. That is ok for 40cm dish.

It's the time to think to the TX.

I'm thinking to use Pluto..Anyone had experience with with it on NB transponder?.

Some picture on my GNU radio RX locked on upper beacond and antenna.

David

IW5BNL

BG0AUB : it's about 38°

The dish is a offset for camping

David

Hi Thank you for answer.the

I'm using following method for measuring S/N ratio :

1) I made I^2+Q^2 average it over 1Sec. I and Q samples are collected at 16K sample rate. and after 2.7KHz ssb

2) I made ratio between reading when I tune the beacon and when I tune just the noise.

I fully agree with Michael that depend on modulation. Using FFT (That show the peak) I get about 10 db higher.

Do you know if exist a standard?.

I also have some tree in front of the dish but the blockage should be vey small.

Ciao

73,David

IW5BNL

Thank you.

David

IW5BNL

Hi

I'm using 40cm ofset dish and octagon LNB.

After pointing optimization I get that beacon level is 9Db over noise flow.

Is it a realistic number with so small dish?

Thank you

David

Hi

From yesterday I had my small RX station (40cm dish and LNB in the garden and 'home made' SDR software) up and running.

I also notice several carrier over the PSK beacon frequency limit.

I'm working on TX right now..I hope to be ready soon.

PS

Congratulation to Amsat-DL for the fantastic satellite.

Best Regards,

David

IW5BNL

Hi

Today I found some time to test my minimal RX set-up.

Antenna: Offset 40cm

LNB : Octagon Green not yet modified.

RTL dongle+ GNU radio based 'home made' rx.

PSK Beacon was about 10 dB over the noise.

NB transponder was full of signals : Very nice to listen a Taiwan station and a Brasil station.

Hi I'm building up a Station.I'm able to found on local store a LNB GTS40M. The box claim 'Powered with PLL technology'.I will test is soon.
Anyone have some experience with this LNB ?.

See you soon on satellite.

David

IW5BNL