Poor man's SDI  

A low cost SDI adapter:

I built an SDI adapter for my satellite receiver using the National CLC020 chip. About the time I got it working, I received the SD020EVK developer's kit I had ordered previously from National Semiconductor. Price $100. What a neat item! It is a small PCB (2" X 3") with everything needed--including the BNC connectors. The board can be mounted easily on the rear panel of a host device via the BNC's, since they are threaded. A 26 pin header allows you to pre-install the host connections (a ribbon cable) then just plug-in the adapter. Sounds like a piece of cake, doesn't it? Well, I said low cost. I didn't say the wiring to the host device is necessarily easy or for the faint of heart.

The EVK board needs SMPTE compliant 8 bit parallel data and the 27MHz clock signal. On my satellite receiver, these were easily available at the input of the digital encoder. This is the device that creates S-video, etc. Note that some equipment now uses a combined MPEG decoder and encoder. If you have this in your host device, you can't add the SDI board. I suspect there are still lots of equipment available with a separate encoder.

CAUTION: If you are not experienced in working with surface mounted devices with SMALL pins, I strongly suggest you use the services of an experienced technician.

I mentioned earlier that the input data must be SMPTE compliant. This means the parallel data must have the SAV (start of active video) and EAV (end of active video) signals in the data. If these are not present, they must be added. This can be done with a programmable logic device, however I won't get into the details of the task here.

How do you know if the data is available AND if it is SMPTE complaint? Answer: You don't, and the manufacturer probably doesn't know either. I've heard that Sony satellite receivers are compliant, but this doesn't mean their other products are compliant. After establishing that the data is available, you pretty much need to install the adapter and see if it works. If the SDI receiver doesn't lock properly, the data is not SMPTE compliant. People with SDI adapters already installed might see if they are implemented with a one-chip adapter. If so, then the equipment is compliant. This forum will be a good place to let others know.

Good luck to all...

damon: The EVK kit is MUCH easier than building from scratch. Shop around. I got mine from AVNET.

I have no experience with the Vitesse chip. I am only looking to serialize SD data from DVD and satellite. The speed required for HD (1.5GB) will likely be fussy to work with as compared to SD.

Mr_Tube:

I have a Hughes Platinum receiver. I am now installing logic for adding SAV/EAV. I tested the SDI output and it worked, except no lock. I always seem to have the more difficult things to work on. For me, SDI will allow me to have max picture quality from my library of 1000 plus titles recorded in SD D-VHS from DirecTV.

I don't know about specific DVD players. I would hope this forum can be used to compile a list of 'mod' candidates.

Mark:

Yes, this can be used to feed a Vigatec or other processor with SDI inputs.

The digital video signal needed by the EVK board is parallel YPrPb video digitized 8-bits (256 levels) and compliant with SMPTE standards. The sampling frequency is 27MHz.

Mark: Correct about 8 bits not being involved. As to adding SDI to the 300 disk device, you need to check:

1) Are the digital signals available (separate encoder) and 2) are the signals SMPTE compliant?

Maybe somebody here alway knows?

Greg: Although I successfully created the SDI signal, the SDI receiver would not lock because SAV and EAV weren't present in the data stream. I am now adding a small programmable logic array ($6 cost) to insert SAV/EAV in the data path. This part is inserted between the data source and the SDI generator, i.e., the EVK board. A pain in the neck, but hardly rocket science. I will post more info when I've got the SAV/EAV inseter board installed and working. My itch is missing SAV/EAV is probably the exception, not the rule.

Jay: I have never looked inside a Tivo. Check the PCB near the S-Video connectors and note the device numbers. If there is a separate encoder (a must for modification),it's probably a PLCC device with 40 to 52 pins. Do a search on the web to identify the devices.

Steve: I don't think the chips care about NTSC or PAL. SMPTE 259 applies to both. The '021 device sounds like a slight variation of the 020--with a PAL data sensor. The detection could be done several ways, e.g., NTSC frame rate is 30; PAL is 25.

I think this thread is likely to become a place where people can check for modification candidates. Right now, my experience is with the Hughes Platinum satellite receiver.

Steve: The CLC020 wants 8bit data. This is multiplexed YUV, e.g., Y,U,Y,V,Y,U, etc at a 27MHz sample rate. I think you will find the encoder does not use separate Y, and U/V although it can. Since Y is sampled twice as often as U and V, Y (luminance) has twice the bandwidth.

Damon: You are over the big hurdle. You've got an encoder (Bt865). I'll bet the encoder is set for 8 bit multiplexed YUV and a 27 MHz clock. Pins 16-25 are probably grounded and the encoder is using the 8bit connection pins 28-35. You will need clk (43) plus power and ground. I don't know if Dish implemented SMPTE.

Damon:

My original 'Poor Mans SDI' post was intended to show SDI need not be expensive. Forum members should realize each SDI candidate is a different story and it is not possible for me to describe the specifics for every device--because I don't know myself. Since your satellite receiver uses the same encoder chip as mine, I will describle the connections I made to the Hughes Platinum satellite receiver by way of example. Note that the Hughes designers did not implement SAV/EAV and I am now in the process of adding these signals by interposing a programmable logic chip between the encoder (a convenient place to pickup the signals for the EVK board) and the EVK board itself. IF your 6000 has SAV/EAV, I suggest the following:

Wire D2 thru D9 on the EVK board to P0 through P7 on the Bt865 chip (pins 28--35). Since only 8 bit data is available, no connection is made to D0 and D1 on the EVK. Wire the clock signal from pin 43 on the Bt865 to the Pclk line on the EVK board. I found it necessary to install a 75 ohm (1/8 watt) resistor is series with the clock lead. The resistor is located at the Bt865 connection point. I also ran a lead from pin 36 (gnd) to the EVK board ground point. Power (5V) for EVK can be obtained from any convenient point on the 6000. Note that the EVK board provides 2 BNC outputs, SDO and SDO bar. Use the SDO output.

In the case of the Hughes receiver, the EVK board is conveniently mounted by drilling two 1/2 inch holes in the back panel of the receiver and securing the board with nuts that fit the threaded BNC connectors. I always use a step-drill when making a large hole in thin sheet metal to avoid tearing the metal.

Before you mount the EVK in your receiver, you might want to make a temporary connection to check operation--especially for SAV/EAV signals. You could do this using a ribbon cable connected to the Bt865 pins plus a pair of wires for 5V and ground. Of course you will need something that accepts SDI for the test.

Finally, be extremely careful soldering to those small pins on the Bt865. I used a large magnifier with ring light and a very small tip iron. Use minimum heat. I practiced soldering on a junker VCR before attempting the real thing.

Good luck (and take your time!)

Dan: I think you are asking how does one get parallel YUV video from the serial bit stream? National and several other companies offer SMPTE259 decoders. The National chip is CLC010. Check the National web site for the latest info.

Dan:

Correction--The deserializer is a CLC011. This will get you back to parallel YUV. If you want analog video, you will need an encoder, etc.

Dan: The MPEG decoder output is usually 8 bit, parallel, multiplexed YUV (27MHz sampling) and is used to drive the encoder to produce the analog outputs. In order to transmit this digital signal over a distance, you must serialize it and that's what SDI is all about. For the SDI serializer to function properly, it must receive data that conforms to SMPTE component video standards which means the signal must contain information for SAV/EAV, etc (timing reference signals).

The benefit of SDI is you can carry the video signal in pure digital form to another device such as a processor or display without the degradation of D/A and A/D conversion. The improvement can be considerable.

I will post a photo when I am all done with the project.

[This message has been edited by Robert Cobler (edited 06-25-2001).]