29MHz trans Atlantic DX...

[M0DTS]

kiwisdr's with 20KHz bandwidth that I've scraped from the map page

0-30 MHz SDR | Montreal, QC - CANADA
0-30MHz 6 x Kiwi Card SDR, VK3KHZ, Croydon, Victoria, Australia
0-30 MHz SDR | CH-9203 Niederwil, Switzerland
KA1GXR 0-30 MHZ | ASHLAND MA USA
0-30 MHz SDR, W8FSM, Fenton Michigan USA
AMSTEREO | New Castle, Pa
0-30 MHz SDR | Jersey United Kingdom
WO7I Radio Compound | SDR 1 | .5 - 30 MHz | Northern Nevada, USA
KA1GXR 0-30 MHZ | ASHLAND MA USA
SDR-PAL-1 (Kiwi) • MEGALOOP • PALLAS, ENONTEKIÖ, LAPLAND, FINLAND
PanAm Radio-Dallas, TX, USA-KiWi
K3FEF Milford PA USA
HB9HOO's 3-30 MHz SDR | Hoelstein, Baselland, Switzerland

[radiogareth]

For what its worth when the Knucker first came out Martin (G4FKK) and I did quite a lot of testing to see what worked. Forgotten most of it of course but rekindled the required bits and pieces this morning.
PD4 running a Pluto with 'For the brave' firmware.
DVB-T at 150ks TX. Another PD4 with Knucker attached, set to receive the same. Works fine across the shack with PiCam, Contest numbers and Test Card. No Audio (off on the TX).
Plugged in the C920, audio enabled, picture and sound no problem.
This is all at 149.15MHz.
Initial observations are the Knucker is slow to lock compared to DVBS/S2 and also the lower limit (unless someone can hack the SW) is 150ks which is relatively wide.
Its also harder to amplify although my MRF101 will deliver a clean 50W of DVBT (MRF300 amp under way too).
Personally I think as Rob has proved something works (18kS DVBS) and SDR Angel as an RX (presumably with any of the SDR's it will work with) would be the way to go. Phase shift and attendant cancelling/addition seems likely to prove a down-side of wider BW. Of note, I did some /M testing around Martins QTH and neither DVBT nor DVBS/S2 liked my TX when moving (either massive signal variations of the multi-pathing proving too much, I was driving around at walking pace), quickly locking when I parked up.
What would help experimentation (and me) would be a 'tutorial' in getting FFMPEG installed to work driving a Pluto and something similar to persuading SDR Angel to receive either a IQ file (I think Rob has covered that above) or direct from a RX. SDRA is clearly VERY powerful, but an absolute animal to get started with.....currently looking for a good 'getting going on DVBS with SDR Angel' that reflects the latest version.
Be nice if it worked with a RSP-1 too.....
Gareth

[M0DTS]

Ok, so 150Ks DVB-T may be good, I never got that to work in the past but ill try again.

Guess I'll have to do some videos on using SDRAngel then.

Here's a test from me on 125Ks DVB-S, look at the strength in Italy just now!!

Rob

[K0ZAK]

I guess I'll have to figure out how to use SDRAngel as a backup to my Knucker & Portsdown 4 setup. Would my Pluto using SDRAngel be a viable combination for low bandwidth receive? If so, maybe I can try to receive DVB-S once I learn how to use it. I've only ever used my Pluto for DVB-T transmit and used my other devices for receive thus far on my tests on UHF.

John Kozak; K0ZAK

[M0DTS]

Hi John,

Yes the pluto works with SDRAngel, but does not cover HF so you will need to use an up convertor.
Most RTLSDR dongles work fine for 10m too.

Rob

[G4EWJ]

This is all surmise, but there may be advantages in using DVB-S over DVB-S2, especially at low symbol rates.

DVB-S2 transmits data in frames of 64800 or 16200 bits. There is a 180 bit header (when using QPSK) before each frame that tells the demodulator how to handle the frame. If you lose the 180 bits of frame header, then you may also lose the 64800 bits in the frame. I don't know if the demodulator has a fallback position if it loses the header. Each packet has an 8 bit CRC. If the CRC is incorrect, the packet is dropped.

With DVB-S2, I would suggest using short frames and always turning pilots on, to help data synchronisation.

DVB-S is a continuous transmission with no obvious data demarcation. Each input packet is spread over 12 output packets, so any dropouts or zaps are distributed over several packets when the data is unspread. The Reed-Solomon data on each packet can correct at least 8 bytes in error. There is no CRC on packets, so it will output something even if it is wrong. The lower the the symbol rate, the greater the amount of time that any dropouts are spread over.

Brian

[K0ZAK]

I have the Ham it up upconverter that I'm using with the Knucker to get it on 29Mhz. That should work with the Pluto as well. I also have a cheap RTL-SDR that will go to 29Mhz direct, but figured it might not do so well as the more expensive stuff. I just downloaded SDRAngel this morning and am fighting its learning curve. I've already got it monitoring a 439 MHZ DVB-S signal I'm transmitting with the pluto and DATV Express. It is seeing the signal but it is flashing on and off so I've got something set wrong. So once I figure out the program, I should be able to monitor both DVB-S & DVB-T with several different setups from across the pond.

John Kozak; K0ZAK

[g0mjw]

I will attempt to explain what to do with ffmpeg on the Tuesday net tonight Gareth if it helps. If you look at the article I wrote in CQTV a while back, it's a progression from there, using Rob's settings. I have also got settings for slightly higher rates like 33ks but not yet managed to decode them. I have not tried SDR Angel and I think the TS errors and lack of any sound data fooled the minitiouner.

Mike

[radiogareth]

In the interests of 'proving' that you are decoding live video, Mikes suggestion last night on the HV net that a clock is used is 'blindingly obvious' with hindsight. So your test card (data doesn't change) with a clock shown probably gives the least possible data change but the instantly recognisable fact that it is 'live video'.
A quick google led me to this YouTube vide which describes the whole process, from free clock generator to getting it up in OBS.
https://www.youtube.com/watch?v=8gBWtbBWMPg
Excellent stuff....you can even add the date so 'proper time-stamps'....
Gareth

[radiogareth]

A nice shiny new Pluto has just arrived from Digikey - what excellent service!
Its a Rev C on the label, a Rev D Z on the actual PCB, so I have uploaded the 0303 firmware and the required 'patch' and also "fw_setenv compatible ad9364".
Next step to set up my laptop with FFMPEG and OBS and see if I can generate a 18ks stream on 149.15.
Progress....
Gareth