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Television Standards Converters, Modulators etc Standards converters, modulators anything else for providing signals to vintage televisions.

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Old 20th Sep 2022, 12:39 pm   #1
gridrunner
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Default Working with HackTV

Hello everyone,

I just wanted to give an update on my adventures with HackTV.

Just a bit of background. Iíve recently acquired a 405 line TV from Tas on the forum, a GEC BT318. I havenít played with 405 line in a good few years and so Iíd long ago sold my Aurora converter. When I started casting around for options it became clear that finding a new converter is quite difficult and expensive. What I did notice from googling about was people using a piece of software called HackTV in conjunction with a software defined radio, specifically a HackRF One. This allowed 405 lines to be broadcast from the SDR using a variety of computer sources. I just happened to have a HackRF One handy and so I went about installing it.

There are two builds, a Linux build and a Windows build. I started out with a Linux build running on a Raspberry Pi4. Installation is straightforward by adding the packages listed in the ReadMe of the Github project.

https://github.com/fsphil/hacktv

Another fork of HackTV offers support for emulating a range of retro satellite scrambling systems.

https://github.com/captainjack64/hacktv

What is less than obvious however was the impact a lack of processing power has on HackTV. Iíd used the Raspberry Pi because it was handy, but the Pi4 is not powerful enough to run HackTV. What this looks like in practice is a poor signal, with a lack of lock and noise in the picture. This had me fiddling with the antennas, trying a different TV (I was testing with 625 lines initially) and isolating all sources of RF in my shed. What it turned out to be was a lack of CPU power. Itís not a limitation of USB. The Pi4 has two USB3 ports, but the HackRF One (at least my build) only works at USB2.0. USB2.0 can still theoretically deliver 480Mbps and so the bottleneck is clearly elsewhere. A default sample rate of 16Mhz defeated the Pi4 and an older i7 laptop that I own also struggled a little bit. 405 line transmissions are less burdensome at half the sample rate, but a Pi based solution is best avoided.

The Windows distribution of HackTV has to be compiled from source, but a working binary is available here (thanks to Captain Jack!):

https://filmnet.plus/hacktv/hacktv.zip

To this you can add a Java based GUI, here:

https://github.com/steeviebops/hacktv-gui

And you can also stream direct from Youtube by adding yt-dlp, which is a fork of youtube-dl. Youtube-dl is supported, but I didnít have any luck getting it working.

https://github.com/yt-dlp/yt-dlp/releases/

Just put everything into the same folder.

There are some dependencies if you are running Windows 10 that you need to install (you should use a 64 bit OS):

Visual C++ distribution (x86 version) Ė to run youtube-dl/yt-dlp

https://www.microsoft.com/en-us/down....aspx?id=26999

Java 17 SDK Ė to support the GUI

https://www.oracle.com/java/technolo...downloads.html

Here is a screengrab of a Youtube stream of the Queenís funeral being broadcast by HackTV. Iíve also tested MP4 streaming successfully.

There is talk of the RF amplifier stage in the HackRF being very vulnerable to damage. I donít have the TX amp turned on for my experiments and the gain is set to 47db. Itís not advisable to attach the HackRF directly to the receiver. I use the ANT500 telescopic antenna that comes with the HackRF kit.

This is an awesome project and I must congratulate the authors. The flexibility of being able to emulate a number of different standards is great, as is the ability to stream from Youtube and from MP4. You do need a reasonably fast, modern PC to operate it, but it doesnít need to be a monster. Iíve settled on a HP ProDesk 280 G2 i5 6th Gen and it runs just fine. If you want to get into the satellite crypt cards scene, you might need a bit more grunt. The only limitation is that your sources are computer based and so it would be difficult to broadcast an analog source for example.

The HackRF itself sells for around £100-£120 on Aliexpress. Purchasing on there will result in a clone board. The real deal is a bit more expensive but at least youíll have a warranty and some guaranteed quality. https://www.hamradio.co.uk/sdr/great...rf-one-pd-7799

Hope this helps someone!
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Old 20th Sep 2022, 5:31 pm   #2
Tazman1966
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Default Re: Working with HackTV

It looks like my old TV is giving a good account of itself with your homebrew standards converter. Nice work Stu.
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Old 21st Sep 2022, 11:01 am   #3
Petedox
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Default Re: Working with HackTV

Thanks, that's really useful info.
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Old 21st Sep 2022, 12:24 pm   #4
mickm3for
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Default Re: Working with HackTV

Hi the hackrf is damaged very easily on receive the rf pre amp is not protected in any way so is damaged if strong signals are used. I damaged the rf amp ic by using 300mw on 2 mtrs at a distance of 9ft the hack had a wifi aerial about 2 inches long. The input protection on the hack is rated at 15v so only protect against static damage no rf protection. I am going to mod the circuit to give said protection as its to easy to damage and the chip is small u13 in pic Mick
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Old 21st Sep 2022, 4:08 pm   #5
gridrunner
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Default Re: Working with HackTV

Thanks Mick, do you know if there's a plug-in/screw-in form of attachment that could shield the pre-amp?

From the testing I’ve done, I think HackTV with HackRF is a great alternative and potentially a lower cost alternative to a dedicated standards converter. Plus, you have the benefit of a versatile SDR that you can use for other radio projects.

The caveat here is lower cost. The HackRF One is an open source project and so the inventor and distributor, Great Scott Gadgets is not against clone hardware but he does put out a caveat emptor warning about how quality might vary between clone builds (and he doesn’t want to support them!). There’s a breakdown of an analysis of a piece of clone hardware and its weaknesses over here:

https://greatscottgadgets.com/2021/1...-hackrf-clone/

For the purposes of a TV converter running on VHF, or UHF for that matter, I doubt having a clone would be any real issue, unless it was pure trash. My own board is likely a clone.

On that basis, finding a clone on Aliexpress for a standards converter project at around £120 might represent good value if you have a recent PC to drive it and your sources are computer based.

The case I’m using is 3D printed, but alloy cases are available. Something called a ‘PortaPack’ is available for HackRF that turns the device into a portable radio and a powerful one at that if you use the Mayhem firmware.

https://github.com/eried/portapack-mayhem

If anyone wants to give it a whirl, I’ve put the software in a single bundle for convenience, this includes all the components you need to get started as described in the previous post. Everything is open source or in the public domain. Please PM me if you'd like a link.
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Old 21st Sep 2022, 6:16 pm   #6
mickm3for
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Default Re: Working with HackTV

Hi i have used some pin diodes on the pre amp input to protect from excess rf seems to work i will send you some as i got the last lot from Farnell as they are discontinued pm your address if you want some and i will explain how to fit but just soldered across the preamp chip Mick
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Old 21st Sep 2022, 8:13 pm   #7
gridrunner
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Default Re: Working with HackTV

Thanks Mick, I'll PM you!
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Old 21st Sep 2022, 8:13 pm   #8
gridrunner
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Default Re: Working with HackTV

Quote:
Originally Posted by Tazman1966 View Post
It looks like my old TV is giving a good account of itself with your homebrew standards converter. Nice work Stu.

It's a great Telly, thanks Tas!
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Old 22nd Oct 2022, 10:40 am   #9
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Default Re: Working with HackTV

Interesting.

I have only just found this thread.

I had bought a 405 line TV for the Queen's funeral, and watched that using a hedghog standards converter.

But since then I independently decided that longer term I would prefer to have a hack rf one based solution, which I got working in its most basic form last Sunday (local sound and video retransmission of BBC).

My experiences mirror/support everything the initial poster has said, even down to my extreme nervousness about turning on the output amplifier ( or fiddling with the aerial ) after reading very alarming threads elsewhere. I interpret those threads as providing compelling evidence that (for all its excellence in other areas) there are some glaring and simple omissions in the hack rf one's aerial ESD protection which ?bizarrely? the original creator seems reluctant to even acknowledge let alone fix. This is a shame as it means there is a small but not insignificant blight on what is otherwise a fantastic product.

Anyhow, fragile aerials aside, I am very pleased with hackrf and hacktv, and get good reception with just 41db gain and a Yale front door key or coat hanger as the reception antenna with the transmitter 1m away.

Longer term I need 80m range, though, so will have to get a better transmitting and receiving aerials, which I don't yet possess. (See a wanted post I made elsewhere on this forum earlier today: https://www.vintage-radio.net/forum/...d.php?t=195335 )

Last edited by KesterLester; 22nd Oct 2022 at 10:46 am. Reason: Added link to wanted post mentioned in text.
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