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[Discuss-gnuradio] pcHDTV use for gnuradio was: Status of BTTV/CX88 capt

From: Martin Dvh
Subject: [Discuss-gnuradio] pcHDTV use for gnuradio was: Status of BTTV/CX88 capture (pcHDTV)]
Date: Fri, 26 Aug 2005 06:09:41 +0200
User-agent: Debian Thunderbird 1.0.2 (X11/20050331)

I asked Jack kellihar about the possible use of the pcHDTV card for gnuradio.
This was inspired by the fact that this card uses a cx2388x chip.
(We are developing a driver for this chip for general gnuradio use)

It was also inspired by the fact that the goal of the pcHDTV is very similar to 
that of gnuradio.
Free (as in speech) reception for all.

He replied very positive (see below)


Jack Steven Kelliher wrote:
> Hello,
>       We would be very interested in this and I will start looking in
> what it might take to modify a card.  
>       I've looked at your project and I would like to have something to make
> it cheap for anyone to experiment with software radio/tv. 
>       One of our goals it to eventually get some type inexpensive hardware
> that would allow a full open source radio/tv receiver (ie with the
> signal processing part) using your gnuradio project.
>       The tuner is a Thomson DDT 7610 ATSC/NTSC tuner.
>       The current oren demod chip isan OR51132 and can do ATSC,NTSC,QAM256
> but not DVB-T or DVB-S at least they don't have ucode for them.
>       Best Regards,
>       Jack Kelliher
>       pcHDTV, Inc.
> On Tue, 2005-08-23 at 14:53, Martin Dvh wrote:
>>Hi Jack,
>>I was pointed to you by Seth and John Gilmore because you developed the 
>>pcHDTV cards.
>>I am one of the developers of the gnuradio project.
>>The big idea is to give ordinary software people easy access to 'hack' the 
>>electromagnetic spectrum, that is, to understand the radio spectrum and think 
>>clever ways to use it.
>>With gnuradio we do software defined radio using the processing power of a 
>>normal pc using a fast ADC and different RF-frontends to get the frequencies 
>>down to 
>>the range the ADC can capture.
>>We developed a whole bunch of signal processing blocks (in software) with 
>>which you can receive or transmit anything you want.
>>(so far we have atsc, analog TV, fm, am, ssb, gmsk,....)
>>The fast ADCs are one of the most expensive parts of the concept.
>>Matt Ettus developed the usrp (Universal Software Radio Peripheral)
>>Which is a board with a set of Fast ADCs with and USB2 connection and 
>>connections to plug in different RF-frontends.
>>One of the things we have also been trying to do is using the fast ADC of a 
>>TV-capture card to get our samples in.
>>The problem is that tv-capture chips expect a video signal with sync pulses 
>>and they don't do continuous capture.
>>I have been somewhat succesful in tricking a BT878 tv-capture chip into 
>>(allmost) continuous capture.
>>More recently I found out that the cx2388x chips have a capture_raw flag 
>>which you can use to get them into continuous capture mode.
>>(This concept was proven by a newly developed driver by Hew How Chee)
>>Cory Papenfuss and John Gilmore pointed us to the fact that the pcHDTV cards 
>>also use the cx2388x chip and also contain a tuner which could be used as 
>>We would like to try and see if it would be possible to use pcHDTV cards as 
>>frontends for gnuradio.
>>(possibly with some minor hardware modifications, and of course with a new or 
>>changed driver)
>>If this is possible then the gnuradio folks would be very happy that there is 
>>a new cheap frontend available for gnuradio.
>>This would also mean for the pcHDTV folks that there is a whole new market 
>>for the pcHDTV cards.
>>(at $450 already more then 400 usrps have been sold in just a few months)
>>To be able to do this we need to know some more technical details about the 
>>HDTV cards.
>>Can we get a look at the hardware design?
>>Or is there a technical description of how things are put together?
>>I think there are two ways of using the HDTV cards for general SDR.
>>Put an Rf-signal into the composite input of the cx2388x and modify the 
>>driver so it can do analog continuous capture.
>>No hardware modification needed.
>>If you want to capture the IF of the tuner you need to route the IF of the 
>>tuner to the composite input of the cx23888.
>>(possibly needing some DC-offset and amplification) So this needs a little 
>>hardware modification.
>>The other possibility is to see if it is possible to tell the Oren 
>>Semiconductor's ATSC receiver chip to just output the raw ADC sampled IF  
>>data it captures.
>>I don't know if this is possible but then no hardware modification would be 
>>needed too.
>>Is there a datasheet available of the atsc chip you used?
>>And can you tell me how flexible it is.
>>(can we tell it to do other things then atsc, like only passthrough or just 
>>fir-filtering, or DVB)
>>I haven't looked at the driver of the HDTV cards yet.
>>If there is a general desciption of how it works this would be great too.
>>Can you also tell me what tuner you are using.
>>Especially what IF output it has (frequency, output level and bandwidth)
>>And again if there is a datasheet available.
>>I also saw you used firmware files.
>>Is this for the atsc chip or do you also have an fpga on the board?
>>I am sorry about the many questions, but I don't have a pcHDTV card so I 
>>can't just look at or measure the board.
>>But I think if we can make this work it would be great for free reception of 
>>any signal.
>>As a sidenote. Do you have any plans on making a board which can do DVB-T, 
>>DVB-S or DVB-T and use 8MHz wide channels?
>>(I live in europe)
>>Martin Dudok van Heel  (Martin Dvh)
>>The GNU Radio Team
>>-------- Original Message --------
>>Subject: Re: [Discuss-gnuradio] Status of BTTV/CX88 capture (pcHDTV)
>>Date: Fri, 19 Aug 2005 16:03:43 -0700
>>From: John Gilmore <address@hidden>
>>To: Martin Dvh <address@hidden>,      Hew How Chee <address@hidden>
>>CC: address@hidden, address@hidden, address@hidden
>>Inspired by Martin and Hew How Chee's discussion, and Cory Papenfuss's
>>guess that this chip is in the pcHDTV card that does broadcast-flag-free
>>ATSC reception, I asked Seth about the pcHDTV card.  He pointed me to
>>its maker in the reply below.  Please ask him about whether the card
>>can be used (with some explanation about gnu radio and our signal
>>processing background).
>>         John
>>>Hi Seth!  Do you know if the pchdtv cards can digitize samples of the
>>>spectrun continuously (the way any ADC would, the way gnuradio
>>>expects)?  It's rumored below that the chip they use *can* do this.
>>>If so it's a cheap way to digitize wideband signals, and a second market
>>>for pchdtv.  At more than $500 ea, Matt Ettus has sold hundreds of USRPs;
>>>at a lower price and with gnuradio support, a lot more pchdtvs would sell.
>>It would be best to ask Jack Kelliher   I
>>have a pcHDTV but have never tried to induce it to act as a generic

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