BATC Forum

A group of us are looking at the possibility of updating the main MiniTiouner PCB to enable direct connection to the Serit tuner and remove the need for an adapter board.

Don't panic if you have just bought a board, Serit tuner or adapter kit, the only real big difference is that it will be smaller!

Having said that we are looking for user comments to see if there is any small tweaks we make whilst we are at it - so far we have thought about a power socket on the board, replacing the hard to get 1v regulator, maybe a lock detect line and aligning the USB socket and F types to project through the front panel.

Note, it will still be a simple build at home board and will use the same USB module.

It you have any other comments, please post here.

73 Noel - G8GTZ

My 2 cents:

We have different NIM tuners with different voltages:
The old one which is needing 1.0 volts and
the new SERIF tuner which needs 1.1 volts.

Would it be possible to have one board for both ( using a kind of wiring adapter for the NIM pin layout like a DIP 28 socket ( 14 differences are in the table) and a jumoer to select 1.0 or 1.1 V))
or is it better to modify the voltage regulator to a 1.2 volts type which is easy to get?

The "old" Sharp tuner BS2F7VZ0169 is still available.....

Rainer

Anything is possible but what is the point behind this? You could have a daughter-board containing the NIM that plugs into a standard 40 way header on a universal motherboard, each NIM has its own daughter-board. But unless you are hot swapping NIMs there is so little else on the board its simpler just to have a PCB for each NIM.

The Regulator is adjustable so not really a problem. Going with 1.05V would probably work for either.

Mike

Mike,

I am using 2 PCBs for both tuners...

I think the benefit could be having one small board for both types, only exchanging a DIL28 socket with the appropriate wiring.
The Sharp tuner has a booster and needs no preamp, but it is not capable for 2 meters and 70 cm.

Rainer

Some ideas for consideration...

Mechanical Stability for portable operation:
1, Mounting holes on each corner and maybe a couple towards the middle of board.
Space around the mounting holes to take a washer without shorting to tracks that have been routed to close to the mounting holes.

2, NIM vertical mounting option, so the pins and lugs on the NIM can be soldered into the board.
I image that the holes for the vertical mounting option could be placed just behind the fingers for edge connectors,
so they would not take-up to much board space.

Support for second transport stream:
If Jean-Pierre, F6DZP, plans to release the software that supports the second transport stream on the Serit NIM?

How about adding the USB interface for the 2nd TS output?

As the design constraints are, keep it small and allow for easy construction.
The 1st USB interface could be kept as a standard FT2232 Module fitted into header sockets.
The 2nd USB interface could use a FT2232 chip, same as used on the module,
with 2nd USB socket soldered onto the edge of the board inline with the socket on the USB module.
The SMT components for the 2nd USB interface might all fit underneath the board to keep the size down?

73
Dave

To go a little further...

Would it be possible for amateurs to develop their own Tuner ?
I am not a specialist so I am not the best placed to answer, but my idea would be to develop
an "universal" OM tuner with specs like :

Frequency range : "as large as possible" meaning today not less than 2m to 13cms bands, perhaps more including 70 - 50Mhz ?
Systems : DVB-S/S2 and DVB-T/T2, other ?
Multiple selective preamplifiers switched depending on frequency (band) listened ?
Low to high SR
All standard FEC
QPSK / 8PSK / 32PSK....
Bus interface : USB / else ?
software running under Windows / Linux ....
Etc....

Is within the reach of radio-amateurs or am I a dreamer ?

73 - Christian
F1FAQ

Hi Noel,

Comments based on building the MiniTiouner batch for ARISS. Mostly arose from trying to fit everything into a Hammond 1590D box but several are just observations based on the experience of building ten of them

1. Vertical NIM - please, or at least the option to have the NIM vertical. Having the lugs secured via suitable PCB holes would make it a lot more mechanical rigid and remove the risk of the two "legs" on the existing PCB breaking. Note, one thing I did was to bend the lugs on the NIM so that they lay over the PCB legs (P1 & P2) and then soldered both. That way I had a firm earth connection as well as increasing the mechanical strength of the NIM/PCB combination. P2, due to its smaller size, is very fragile compared to P1.

2. PCB Mounting points - at least two, if not one on each corner.

3. Voltage Regulators - I mounted the PCBs inside a metal box and ended up securing the PCB to the box via three nut/bolts which also attached to the voltage regulators. The box therefore became a big heatsink. However, It would be better if there was an option for the regulators to be bolted to the case directly rather than through nuts/bolts.

4. PCB holes for the PSU - might just be the PSU I got (http://www.ebay.co.uk/itm/5-pack-MP1584 ... SwLVZV5Kdc) but the holes are ever so slightly off centre. I used pin headers (0.1") - fitted the PCB perfectly but didnot match the holes in the PSU.

5. Is there any reason for mixing SM and TH components? Can we stick with just one type?

6. The links for the bias voltage - is it at all possible to do these just like the LK2/LK3 links for powering the voltage regulators. Removes the risk of accidently enabling both methods and saves the NIM.

7. Having the I2C bus brought out to the J4 header is brilliant for debuging issues when the NIM doesnt respond but everything else checks out ok. Can other signals be made available?

8. Power socket - not really that bothered by that one as I used a plug/socket arrangement the supply. Connection to the board was via twin cable entering the existing holes from underneath. For me, that meant the only thing protruding from the edges of the board were the USB and NIM connections.

9. The J3 header - going to be difficult to use that with the USB module in situ. Can it be moved to the other side of CN1 if there is a plan to use it.

HTH.

73 - Ciaran M0XTD

No you are not a dreamer this is one of the things that the AMSAT-NA Phase 4B ground team are looking at.
They have chosen to use DVB-S2/S2X for their satellite and DVB-T2 for terrestrial communications.

- Charles G4GUO

Hi Charles,

Aha good to know !
Your point of view as a (mainly software ?) developer for those next steps : could this tuner be a software (ATV-SDR) tuner ?
I mean having just a zero tuner with synthetiser outputing I Q signals everything else behind treated by software ?
You see the parallel I make with RTL-SDR....

Christian

The major problem with DVB-S2/S2X (and DVB-T2) is the LDPC Low Density Parity Check decoding.
It is very computationally expensive to do in software. It is likely that a
graphics GPU card will be needed for normal bandwidth decoding.

I came across a paper where some academics have managed to use a standard
consumer GPU card to do LDPC decoding in real time so it can be done, it
just needs someone to put the effort into writing the software, it is not an easy job.
GPUs are quirky things to program efficiently.

- Charles