AverTV/Avermedia Cards (A835) of the non RTL chipset type (af9035)

[zaph0d]

Is there any effort/experience/other interest in appling the RTL chipset support to other linux-supported DVB-TV type chipsets specifically of the AverTV type? As there  is existing DVB support in the Linux kernels for it and judging from that and the existence of firmware for it I don't think it'd be a huge jump for those more skilled than I or in conjunction.  I have attempted to install under Windows using Zadiag but I am far from an expert on driver level stuff. The drivers installed but it wasn't recognized when attempts to add via device control. Results were no compatible device found. Although I suspect if I had been using an RTL-supported chipset it would have worked using the RTL + driver hint. . . Please forgive my ignorance on these matters USB/driver god(s)

Example data on the A835 (green) of the western EU type for reference and if anyone else hopefully wishes to work with me on getting these types working as well with WinRAD/HDSDR. 

Default idVendor=07ca, idProduct=a835

Chipset type: af9035 

Firmware for DVB / linux install : http://xgazza.altervista.org/Linux/DVB/dvb-usb-af9035-01.fw

(taken from http://thuydx.wordpress.com/ who kindly gave the data on installing/usage of this device under Fedora in English. In Spanish the instructions for DVB-style installation are on http://www.nbytes.org/2011/11/instalacion-de-avertv-volar-pro-hd-a835.html for the Linux kernel driver)

If this is ground already covered or not of interest to this group forgive the intrusion. But I suspect I'm not the only one with a few of these type chipsets hanging around.

[Adam Nielsen]

> Is there any effort/experience/other interest in appling the RTL chipset
> support to other linux-supported DVB-TV type chipsets specifically of
> the AverTV type? As there is existing DVB support in the Linux kernels
> for it and judging from that and the existence of firmware for it I
> don't think it'd be a huge jump for those more skilled than I or in
> conjunction.

While I have no experience with the AF9035, generally speaking, the
problem is that what you have is a DVB-T TV tuner device.

The RTL2832 is actually a software radio, which has some extra bits for
decoding DVB-T TV channels. We're just ignoring those extra bits and
using the SDR functionality which already exists in the device.

Unless the AF9035 is also based around a software radio like the
RTL2832, it's not really possible to use it for SDR purposes. Most
devices have specialised ICs to do all the work, none of which are
designed to work like an SDR.

By way of analogy, it is possible to drive an aeroplane along the road
from your house to the shops. But just because you can drive your car
along the same road and mimic the plane, it doesn't mean your car is
also able to fly. Likewise just because a device is able to receive
DVB-T signals like the RTL can, it doesn't automatically mean it can do
SDR as well.

Depending on the hardware design, it is conceivable that writing custom
firmware for the device might allow you to implement a high speed
analogue to digital converter instead of the normal DVB demodulator, but
that would require quite a bit of experience with embedded device
development and intimate knowledge about the hardware design of the
device. Unfortunately you're probably on your own there. At this price
range, most people would rather just drop another $20 and get a device
that already works.

Probably the quickest way to find out whether your device is even
capable of SDR is to look at the marketing. I believe RTL devices are
the only ones that can watch digital TV (and *not* analogue TV) but can
also receive FM radio. FM radio is normally tacked on to analogue TV
tuners as it is essentially free, so if the device can't receive
analogue TV but it can still do FM radio, there's a possibility it
achieves that by using SDR. If it can't do FM radio, or it can do
analogue TV, it's probably lacking the hardware to do SDR.

Cheers,
Adam.

[zap...@gmail.com]

Thanks for the concise answer. It definitely has FM capability on both the Digital and Analog sides. I am learning a good bit about embedded systems on other systems (ATmega and ARM at the moment) but without the proper education from an EE standpoint there is still much I lack. But what I have is years of experience with Linux and general debugging/compiling C/C++ and generally getting stuff to work if there is already a good framework, and it appears there is such on the RTL project to say the least.

On the firmware there apparently are many similarities between the way the DVB cards communicate and smart cards - in terms of downloading it´s firmware. So thus, via that and it´s most likely proprietary standard it´s likely very configurable given the time to reverse engineer and otherwise spend a lot of time... yeah, another 20 you say? LOL

I may give some more attempts in terms of applying this to a strictly analog FM - interface if at all possible with this chipset. But if memory serves, it was it´s original function and it´s also the same chipset that some Terratec´s use.

On a possible explorative note it´s ability to do Digital FM could prove useful as well but after years of not touching radio equipment I´m quickly learning theres probably a much easier existing way to do that. After 6 years absence from the HAM scene and relegation to unrelated fieldwork in the Army I´m finding things have changed in a very beautiful way - from OpenBTS to the new soundcard decoders. Last I was checking APCO-25 was just being deployed.. 

Now being in Europe and glancing over the Tetra standard (TDMA!) it´s kind of like, WOW.

Thanks for the wakeup call. Hope I can be useful to the project(s).

Regards

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[Adam Nielsen]

> It definitely has FM capability on both
> the Digital and Analog sides.

Just to be clear, when I said FM, I was referring to consumer FM radio -
the type you generally get around 87-108MHz. It seems that a digital TV
dongle, which can't pick up analogue TV, but can do FM radio between
88-108MHz, is possibly using SDR to do the FM radio part.

> On the firmware there apparently are many similarities between the way
> the DVB cards communicate and smart cards - in terms of downloading it´s
> firmware. So thus, via that and it´s most likely proprietary standard
> it´s likely very configurable given the time to reverse engineer and
> otherwise spend a lot of time... yeah, another 20 you say? LOL

Downloading the firmware may be similar, but the real question is what
does the firmware do? Is it code for a simple CPU which sets up
registers on other chips, or is it bytecode for a full blown demodulator
running on an FPGA? If it is, do you know what type of FPGA? Can you
get the toolchain required to compile your own firmware? Do you know
which pins to assign to inputs and outputs in order to communicate with
the other chips on the device? Do you have code for a USB stack to
communicate with the host? Is the chip running the firmware even
capable of performing ADC fast enough? There are so many unknowns it's
no surprise the RTL2832's capability was only discovered by accident.

Given that you'll likely be doing all this without datasheets, it'd be
an enormous challenge. Even the RTL2832 was difficult, and some of the
people involved *did* have datasheets.

I don't mean to discourage you, it just sounds like you haven't fully
appreciated just how much work would be involved in an effort like this.
Plus you might get all the way to the end and then discover that the
hardware isn't capable of SDR anyway!

Or you might get it to work after many months, but nobody cares because
the frequency range is so limited compared to the E4000's ~50-2100MHz.
Or the devices have become obsolete and you can't buy them anyway. I'm
not really sure it's worth the effort...!

But then having said that, if you're passionate about learning the
skills involved, you'll get something useful out of it even if you can't
use the device for SDR. Don't let my negative attitude put you off :-)

Cheers,
Adam.