BATC Forum

Hello everybody,
I have done a light version of the wonderful Portsdown digital transmitter (only 437 Mhz) for now but how is my pleasure to show you the result :
many thanks to all for your help !!!! but the adventure will be continued

Just an update that I now have all three camera video modes on Portsdown working correctly using my Portsdown/RPi-3/DATV-Express test set-up.
The Pi-CAM and an NTSC home video camera via EasyCAP (BATC VideoDVR unit) all work well.
* Mpeg-2 - video displays correctly
* H264 – now video displays correctly
* EasyCAP – now displays H.264 video correctly


Block Diagram of Portsdown/RPi-3/DATV-Express using either Pi-CAM or EasyCAP or even JPEG file as video source

So a Portsdown newbie can succeed.

Time to start testing audio inputs for Portsdown and creating the extension-cable for my Pi-CAM.

73...de Ken W6HHC

Hi Ken,

Good to know that you succeed and everything works.
Regarding the PI camera extension:
I spend a few dollars and bought this:https://www.tindie.com/products/freto/p ... extension/
Good quality and fast delivery

Regards
Rainer

Mine is up and running, just waiting for a few bits to finish the PA for 146.5MHz and I am waiting for an enclosure for the touchscreen from a 3D printer to mount it on the case front.

Mark
G0MGX

Hi All,

I've now completed a BPF, LPF and a PGA44 preamp from 'DDK:

http://g0mgx.blogspot.co.uk/2017/06/fil ... lters.html

I can provide build details of the filters if anyone is interested. The PGA144 is a tiny bit low in frequency which I need to address - but I think it will be OK for the time being.
Mark
G0MGX

Hi Mark

All looks great - it would make a good CQ-TV article

Don't know how I'd missed the PGA144 from Sam, looks just what we need on 146 - I run the DG8 from GM3SEK but is no longer available - I'll update the wiki.

We can put the filter designs on the wiki for all to enjoy.

Noel

The filters look pretty good. The Yellow is the PGA144 with 20dB attenuation on the tracking generator - so the gain is 20dB. The notch is supposed to be 98MHz but mine is at more like 92MHz so it's all just a little bit "low" but will be OK as-is I think.

The Blue is the BPF and the Purple the LPF.

I'll draw a quick schematic of the filters and post them here.

Mark
G0MGX

Filters:

I have mine nearly working now it is in a case. At the moment, the 2m performance isn't good, I can't demodulate the transmissions. 70cm is better and 23cm good. Performance improves at higher symbol rates. 70cm 333ks has a wide spread in the constellation, so time for trouble shooting. I am concerned the switching PSU I used may be injecting noise onto the power lines.

Incidentally. I had not updated for some time. When I came to test after updating I had a few issues. I used the reset to defaults option and this fixed it.

I will post a picture. We need a better way to mount the touch screen - that has proven the most difficult part of the project. My first screen didn't work properly for touch.

Mike

Mike

Are you using a new Serit tuner? You might want to check that your phase noise problems are not in the receiver first. Put a 10dB pad on the tuner input and see if it improves matters at 70 cm and 146.

Yes, I'm about to need a bezel. Flat to an Aluminium panel. Has anyone on the Forum got a successful 3D print design for this?

Dave