RF HDMI modulator - Daisy chain

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redwingNZ

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Topic # 236407 31-May-2018 18:02

Hi,

My parents have been recommended by their electrician to buy 2 HDMI modulators. I think they are the lenkeng ones, brought from Russels in Palmy.

They then also have a powered plitter that has gone in the roof to put this all out through out the house.

Ie:
Arial to modulator to modulator to splitter to TVs..

I have got one working with their Nvidia shield and can change the channel..

As soon as I plug the next modulator, plugged into sky, I lose the free TV channels. And sometimes can't get this to be found either when tuning.

I'm still tweaking and playing around.. but can't find any settings or walk throughs on how to Daisy chain two modultors.

Any pointers appreciated.

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Reply # 2026443 31-May-2018 19:00

What do you mean HDMI "modulators"? you should not be able to get only one running, they need two to work? one at each end of the cable...

In a normal set up you would have the powered Splitter in the roof and feed power up to it via the video connection,

Why are you "modulating" the signal between the aerial and the splitter? is there not a cable running between the two?

Spyware

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Reply # 2026476 31-May-2018 19:45

OP is talking about HDMI to DVB-T modulators that pass through the DVB-T from antenna.

redwingNZ

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Reply # 2026498 31-May-2018 20:02

Yes, as Spyware is saying its taking HDMi source, and 'modulating' it do DVB-T on coaxial so all the TVs through out the house can receive it.

Yes, the splitter is in the roof. Im wanting to inject sky, and the shield into it on new channels.
Currently have the shield working on channel 40 (636.mhz. ish? from memory) with the rest of the free channels working as normal.

skewt

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Reply # 2026502 31-May-2018 20:13

Have been using these ones at work recently.. retail for around $300

https://www.matchmaster.co.nz/amplifiers-and-modulators/10mm-dm01/

Work well and have a strong output (Probably will have to attenuate it..)

sbiddle

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Reply # 2026515 31-May-2018 20:19

Are you outputting these on different channels, and more importantly channels that don't clash with existing Freeview MUXs in your area?

redwingNZ

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Reply # 2026517 31-May-2018 20:31

They have two of these LKV379DVB-T, HDMI to RF Mini Modulator.

http://www.lenkeng.net/Index/detail/id/181

I have had both work separately on 25, 30 and 40. But just can't get both to work at the same time. Or when I did.. no normal channels.

I'll have to make notes next time I go play with them.. on what works and what doesn't. ServiceName, LCNID, channel etc.. can't at night as dad watches the TV.

lxsw20

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Reply # 2026566 31-May-2018 22:19

skewt:

Have been using these ones at work recently.. retail for around $300

https://www.matchmaster.co.nz/amplifiers-and-modulators/10mm-dm01/

Work well and have a strong output (Probably will have to attenuate it..)

Wow, it's not long ago it was over 1k to do dvb-t modulation. Thats not a bad price.

skewt

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Reply # 2026576 31-May-2018 22:48

Not sure on that model, but sounds like you may have conflicting PID's?

richms

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Reply # 2026580 31-May-2018 22:55

You really need a specturm analyser to match the levels and check that there is no intermodulation happening with the powered splitter. Those things normally put out a very strong signal so shouldnt need any more gain added, and if they are at the limits for what that powered splitter will take without distortion.

Distortion spells game over with digital signals. Analog you would just get weird effects and ghost channels showing up in random places because of the intermodulation.

Richard rich.ms

Aredwood

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Reply # 2026592 31-May-2018 23:56

Maybe the power output of the first modulator is overloading the input stage of the second one. This would explain why the won't work together. Try using a diplexer to join the outputs of the modulators together. Instead of daisy chain.

sbiddle

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Reply # 2026639 1-Jun-2018 07:21

As their is no manual online that I can see it's hard to know if these units actually support daisy chaining. Did you ask if they did or simply assumed this approach would work for the install?

In a commercial situation you'd normally combine multiple RF outputs together with a diplexer before feeding it into the tap or splitter depending on the setup.

ResponseMediaNZ

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Reply # 2026661 1-Jun-2018 08:41

So what way are you trying to set up the Sat/Freeview Feeds?

Aerial - Dish

Freeview box & Skybox

HDMI-> RF Mux

Cable

Is that how you want to do it? or something different

redwingNZ

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Reply # 2026759 1-Jun-2018 10:10

Yeah, thats pretty much it, with one box feeding into the other (shield TV to Sky or vice versa) then off to the splitter int he roof.

Its got a manual, just not much in it.. more of a setup guide. Heres a snap shot of it saying it can daisy chain.

Ive got the first box working with:

Stream:

TSID: 1
ONID: Auto
NetworkID: auto
ServiceName: Shield
ServiceID:1
LCNMode: European
LCNID:800

Modulator:

Country:NZ
Channel: 25, 506Mhz
Audio Sync: 700

Ive left these at default under advanced:

Bandwidth: 8m
Constellation: 64QAM
FEC: 7/8
GuardInterval: 1/32
Carrier Rate: 8k
dB Level: 0dB

When I change the channel to 40, LCNID to 802 and serviceID to 2 it will also work. With the free TV channels.

So I thought get one on 40, one on 25.. but then the free channels go black.

When adding the other box I changed the ServiceID to 2, LCNID to 802, and Channel to one of the ones that i can get working.

ResponseMediaNZ

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Reply # 2026763 1-Jun-2018 10:19

Looking at the web there is additional setup direct from CDLNZ

https://cdlnz.com/Content/Images/uploaded/datasheets/Additional_LKV379DVB-T_Instructions.pdf

sbiddle

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Reply # 2026779 1-Jun-2018 10:45

Unfortunately none of those instructions say anywhere if daisy chaining passthru for OTA Freeview channels is supported. In a commercial situation you'd combine the Freeview aerial feed with these modulators using a combiner, you wouldn't use these boses to pass thru the signal because a) it results in signal loss through every device and b) it creates multiple points of failure.

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