DVB-S to DVB-T Transmodulator

philahern

Ok this is way beyond me really but was just thinking about the possibility of converting satellite signal (freesat) to dtt signal for sharing around the house with the current dtt signal. The idea being that a box sits in the attic converting all the transponders to dtt channels and use one technology throughout the house to get the channels. Most cases just get a tv with dtt tuner.

Searching I came across this product although it looks crazy expensive and more suited to big aprtment blocks or hotels

http://www.promax.es/ing/products/fichaprod.asp?product=DT-202

Just wondering has anyone tried anything like this or heard of any consumer level products that do this?

[ Don't know if this should be in Terrestrial or Satellite ? ]

watty

no consumer product.

The cheapest solution is simply Satellite receiver with ASI digital MPEG-TS output
DVB-T modulator with ASI digital MPEG-TS input.

If you want less than a the full transport stream retransmitted, or just a few channels from a couple of separate transport streams then you need a very expensive demultiplex-multiplex box with multiple ASI in and multiple ASI out

ASI = http://en.wikipedia.org/wiki/Asynchronous_serial_interface It's a special signal on a single coax cable.

reading the http://www.promax.es/ing/products/fichaprod.asp?product=DT-202

PID Filtering with Filtering Table up to 32 PID
Bitrate of the output multiplex
Percentage of bitrate used relative to the maximum capacity of the multiplex

It is actually a Satellite MPEG-TS receiver (like can have an ASI output) and a DVB-T modulator (like can have an ASI input) in one box with no external ASI connections. As close to "consumer" as it gets. The professional stuff is more modular.

So limitation is that it can ignore channels and reduce the size of the MPEG-TS and thus DVB-T transmitted bitrate. It would be used for Hotels that want to add a few satellite channels.

For domestic it's no use as you would need one for EVERY satellite transponder!
A better domestic solution is a Multiswitch and TVs with built-in satellite receivers or setboxes. Easily does 8 rooms or 4 PVRs. Expandible to over 1000 receivers and handles entirety of FOUR satellites.

Soarsat can use simply copies of the two DVB-T MPEG-TS as it will be virtual transponders anyway, so a pair of those would work with a single output Ka-LNBF @ 9E dish and splitter. Then combiner on output and you have Saorview DTT signal.

Useless for Freesat, too many channels. I think you can buy a few satellite boxes for price of one of those!

philahern

Thanks for the detailed response. Didn't think there would be an easy solution as the one I dreamed up in my head :-)

One for each transponder defo doesn't sound feasible. Also thought about using a pc with few different dvb sources and using media extenders around the house but that's a different solution again.

Will keep looking ta.

Mike 1972

This is why DTT TV sets should include an analouge tuner.

On a vaugely related note is there actually such thing as a digital videosender or are they all analouge ?

Ive always thought labelling a device which uses FM 0n 2.45 GHz as a "digisender" is very misleading

watty

Sorry?
Why is an Analogue tuner a good idea?
No HD.

Digital TVs can have DTT or DTT + SAT tuners. All should have SCART (RGB and composite support) and HDMI

I'm just wondering is there something I have not thought of.

Mike 1972 wrote: »

This is why DTT TV sets should include an analouge tuner.

On a vaugely related note is there actually such thing as a digital videosender or are they all analouge ?

Ive always thought labelling a device which uses FM 0n 2.45 GHz as a "digisender" is very misleading

They are all analogue (click linky). Though "digital" is possible, in a sense.
You can get Video Capture to MPEG with WiFi/Ethernet about €300+ or more if full resolution. Quality is poor and it is essentially a mini pc running Linux with Analogue capture card generating a Web video stream.
Also MPEG Cameras exist, some with WiFi.
These are not "broadcast", but unicast, each UDP stream to a client Laptop or media player box is separate bit rate. They are used for Web cam and security applications. Not TV quality.

L1011

watty wrote: »

Sorry?
Why is an Analogue tuner a good idea?
No HD.

Digital TVs can have DTT or DTT + SAT tuners. All should have SCART (RGB and composite support) and HDMI

I'm just wondering is there something I have not thought of.

So you can continue to knock together bastardised "headends" for home use out of stacks of RF-out capable satellite boxes.

My HD TV with HD MPEG4 tuner still has analogue; used it for TV3 until they appeared on DTT.

maggy_thatcher

watty wrote: »

Sorry?
Why is an Analogue tuner a good idea?
No HD.

Digital TVs can have DTT or DTT + SAT tuners.

I'm just wondering is there something I have not thought of.

Subscription TV. I've the following options:

1. Use the analogue out on the Sky box and run that through coax
2. Pay for multiple subscriptions (e.g. Sky Multiroom)
3. Get a DVB-T modulator (€€€€€)
4. Only have subscription TV available in one room.
5. Rewire the house with CAT5, get an HDMI splitter, and run HD over the CAT5 cables.

While my preferred option would be to have the DVB-T modulator (that way programs that I set to record on Sky+ I can receive in every room), they're just too damn expensive right now. I currently use RF2 which is connected to a coax loop that runs around the house; as that's by far the cheapest solution. The picture is grand (sound is average), but until DVB-T becomes affordable I need that analogue tuner in the TV sets.

Unless you've any better solutions?

mossym

maggy_thatcher wrote: »

The picture is grand (sound is average),

sound is mono, it's far from average....

maggy_thatcher

mossym wrote: »

sound is mono, it's far from average....

On small sets with crappy speakers anyway, it's average...I did ask if anybody thought stereo modulators were worth it, but got no replies

watty

There are no consumer Stereo modulators for UK/Ireland as Analogue here uses NiCam Digital for Stereo. No domestic equipment at all does stereo on built in RF modulator. A NiCam encoder is too expensive.

maggy_thatcher

watty wrote: »

There are no consumer Stereo modulators for UK/Ireland as Analogue here uses NiCam Digital for Stereo. No domestic equipment at all does stereo on built in RF modulator. A NiCam encoder is too expensive.

Yeah, I thought of that -- but then wouldn't a Western Europe modulator work? (e.g. if I just change the country code of the TV to Germany or something)

Something like this. While we use PAL/I here, this modulator has stereo support for PAL B/G...

mossym

maggy_thatcher wrote: »

On small sets with crappy speakers anyway, it's average...I did ask if anybody thought stereo modulators were worth it, but got no replies

ah was really only voicing a pet peeve of mine, it's a pity it's not stereo

watty

MYOB wrote: »

So you can continue to knock together bastardised "headends" for home use out of stacks of RF-out capable satellite boxes.

My HD TV with HD MPEG4 tuner still has analogue; used it for TV3 until they appeared on DTT.

Very limited number of channels. Surely a Satellite Distribution system and put the sat receivers at each TV makes more sense. Unless you have 30+ TV sets. Even, then it's dubious.

Subscription TV. I've the following options:

1. Use the analogue out on the Sky box and run that through coax
2. Pay for multiple subscriptions (e.g. Sky Multiroom)
3. Get a DVB-T modulator (€€€€€)
4. Only have subscription TV available in one room.
5. Rewire the house with CAT5, get an HDMI splitter, and run HD over the CAT5 cables.

1, 2 & 3 give SD, no HD.
1 is mono and the Sky modulator is rubbish. Terrible RTE compared to RTE analogue via aerial.
5: The only way to have HD on multiple sets with one receiver. you need 2 x CAT5e per HDMI. You can also do this Cheaply with Scart (Stereo + composite = one Cat5e, Stereo + RGB = two CAT5e, can swap for HDMI later.)
2x CAT5e is cheaper than coax and easier to install as it can go tighter corners.

For more than one alternate TV it's nearly pointless as all TVs get the same channel. Over 90% of TV watching time in Ireland is FTA TV, so makes more sense to have DTT + satellite IF (can go over same coax) and have each have DTT and Sat tuner, or DTT tuner only + cheap sat Freesat HD box.

maggy_thatcher

watty wrote: »

Very limited number of channels. Surely a Satellite Distribution system and put the sat receivers at each TV makes more sense. Unless you have 30+ TV sets. Even, then it's dubious.


1, 2 & 3 give SD, no HD.
1 is mono and the Sky modulator is rubbish. Terrible RTE compared to RTE analogue via aerial.
5: The only way to have HD on multiple sets with one receiver. you need 2 x CAT5e per HDMI. You can also do this Cheaply with Scart (Stereo + composite = one Cat5e, Stereo + RGB = two CAT5e, can swap for HDMI later.)
2x CAT5e is cheaper than coax and easier to install as it can go tighter corners.

For more than one alternate TV it's nearly pointless as all TVs get the same channel. Over 90% of TV watching time in Ireland is FTA TV, so makes more sense to have DTT + satellite IF (can go over same coax) and have each have DTT and Sat tuner, or DTT tuner only + cheap sat Freesat HD box.

I fully agree that 1 gives SD only (2 can include HD if you're prepared to pay the extra subscription; 3 could give HD depending on what modulator you had). They're workarounds to the problem that are not ideal but are sufficient.

Right now, we've 3 TVs...1 has the Sky-HD box hooked up. Another has an FTA box hooked up to it. All 3 have access to the Sky-HD (while 90% of TV watching time in Ireland is FTA, that doesn't apply in my household). There are only two of us, so the restriction that we can only watch one channel isn't that bad (and it's also one person can watch one channel from subscription). DTT signal strength is pretty poor inside the house though that's probably due to a poor aerial (maybe one day soon I'll get around to replacing it...we are very close to the Dublin transmitter, but we're in a dip which may be making things awkward.), and one of the TV sets isn't MPEG-4 enabled, so doesn't work.

I recall talking to you before about running CAT-5 around the house...realistically it isn't an option any time soon...(and running 3 sets of CAT-5 is even less of an option )

The nice thing of a single Sky box is that for Sky+ I don't have to remember "which box did I set that to record on". We watch about 10% of TV live - everything else is timeshifted...putting separate boxes in each room means we'd lose that ability.

watty

maggy_thatcher wrote: »

Something like this. While we use PAL/I here, this modulator has stereo support for PAL B/G...

See why this won't ever give stereo here. http://www.boards.ie/vbulletin/showthread.php?t=2056064351
I'd only believe it's stereo on B/G using Zweikanalton, if (a) it mentions that and (b) a spectrum analyser verifies it. I have a suitable spectrum analyser and such a test is about as quick as connecting up the Modulator.

watty

maggy_thatcher wrote: »

I fully agree that 1 gives SD only (2 can include HD if you're prepared to pay the extra subscription; 3 could give HD depending on what modulator you had).

No it couldn't as AFAIK an HDMI input DVB-T modulator doesn't exist. Though I'll grant theoretically possible. Only the HDMI gives HD.

watty

maggy_thatcher wrote: »

I recall talking to you before about running CAT-5 around the house...realistically it isn't an option any time soon...(and running 3 sets of CAT-5 is even less of an option )

The nice thing of a single Sky box is that for Sky+ I don't have to remember "which box did I set that to record on". We watch about 10% of TV live - everything else is timeshifted...putting separate boxes in each room means we'd lose that ability.

Only 3 TVs..
You only need to run 2 xCat5e to two locations.

maggy_thatcher

watty wrote: »

Only 3 TVs..
You only need to run 2 xCat5e to two locations.

True, but they're perpendicular to each other in direction, and about as far away from the primary box as you can get, so in practice it would mean running very long lines...and given that it's an open-plan house, would mean either leaving cables very visible, or punching into a wall and ducting it through all over the place...neither of which would be pleasant.

And wouldn't it be a lot simpler to just make a DVB-T modulator? People who already have houses wired up for analogue wouldn't have to go and rewire their house; it could be a simple one that didn't have to multiplex multiple programs on top of it, just hog an entire channel and use it. I really see that there'd be a definite market for it...I guess we just have to wait for prices to come down.

watty

There is very little market.
Existing coax can handle DTT + Satellite in one coax, or CableTV&Broadband + Satellite in one coax.

It makes no difference at all to a DVB-T modulator if there is one channel or twenty! It takes a serial input stream in ASI format on a coax.
You need analogue capture, MPEG encoder(s) and an MPEG2-TS multiplexor. That then has an ASI output. The Transmodulator is simple because there is no encoders or decoders and it can't add to the internal MPEG2-TS, only mask out PIDs (individual channels).

A PC 3.7GHz can only manage one channel in real time. I used both €1,200 and €2,200 DVB PCI card modulators in a PC. If I generated a file with five channels in it, a 40 minute loop took about 8hrs to generate.

An off the shelf Analogue in to MPEG4 DVB-T out solution for 10 Channels is about €8,000 per channel.

Run the CAT5e using STP at ground level outside or in the attic. You can also get skirting board that is actually trunking. About 200m for HDMI and 500m for SCART (composite or RGB) is possible. About 2km for stereo audio over Cat5e!

There really is a tiny market for home DVB-T modulators. The most expensive bit is decent real time encoding and Multiplex. The actual raw DVB-T modulator (with encoded MPEG-TS input via USB, ethernet, PCI or ASI) might come down to about €200 I suppose ... But given lack of mass market, I doubt it.

maggy_thatcher

watty wrote: »

There really is a tiny market for home DVB-T modulators.

Okay - that being the case, then I guess analogue tuners are going to be staying in TV sets for quite awhile...as I'm sure I'm not the only one using them that way (indeed that's why Sky boxes have dual RF outs on them).

Mike 1972

watty wrote: »

Sorry?
Why is an Analogue tuner a good idea?
No HD.

Theyre a good idea in households with multiple TV's as distribution is much easier. The lask of HD is unlikely to be a serious disadvantage on your average Kitchen/Bedroom telly.

watty

yes, but what would you want to distribute unless you only had a single payTV box and want the same channel at same time on different TVs?

I'd use Cat5e now (RGB scart + Stereo, or S-video + stereo or HDMI etc) as the Analogue RF modulators are really poor.

Anyway, they are likely to keep putting analogue tuners in TVs for another 5 to 10 years. Most of Africa has not even started DTT yet.

maggy_thatcher

watty wrote: »

yes, but what would you want to distribute unless you only had a single payTV box and want the same channel at same time on different TVs?

I'd use Cat5e now (RGB scart + Stereo, or S-video + stereo or HDMI etc) as the Analogue RF modulators are really poor.

Anyway, they are likely to keep putting analogue tuners in TVs for another 5 to 10 years. Most of Africa has not even started DTT yet.

More than just pay Tv, also there's things like integrated planners for recording and watching later. Unless of course you're willing to shell out for a DLNA client on each tv and set up a central mythTV server or something similar. Analogue is rough and has questionable picture and sound quality, but it is simple and cheap to set up so will almost certainly be here to stay for awhile.