What DVB-T signal strength is needed?

Forums › Freeview (DVB-T/DVB-S) › What DVB-T signal strength is needed?

peejayw

1913 posts

Uber Geek
+1 received by user: 123

#101659 5-May-2012 14:36

Currently getting 47-51% and poor picture quality. Transmitter is line-of-sight about 4km. I am sure I have it lined up pretty close, what about vertical adjustment, is that critical?
Thanks.

I'm supposed to respect my elders, but it's getting harder and harder for me to find one now.

1 | 2 | 3

2173 posts

Uber Geek
+1 received by user: 836

ID Verified

Trusted

Lifetime subscriber

#620118 5-May-2012 14:41

I would think anything below 75% is no good.

You may need yo upgrade the aerial and/or wiring from aerial to TV/DVB-T receiver. I guessing you've only previously had analogue TV and made the step to digital and getting signal strength problems.

This is the problem with digital vs. analogue, you need a good signal.

peejayw

1913 posts

Uber Geek
+1 received by user: 123

#620121 5-May-2012 14:48

I had satellite before but changed to get HD. Its a new aerial, new cable, new fittings. Perfect line of sight with no obstruction. Signal quality is 93% if thats significant.

I'm supposed to respect my elders, but it's getting harder and harder for me to find one now.

Behodar

11094 posts

Uber Geek
+1 received by user: 6071

Trusted

Lifetime subscriber

#620122 5-May-2012 14:50

Which transmitter are you using? It's critical to use the correct polarity.

gregmcc

2173 posts

Uber Geek
+1 received by user: 836

ID Verified

Trusted

Lifetime subscriber

#620129 5-May-2012 15:10

peejayw: I had satellite before but changed to get HD. Its a new aerial, new cable, new fittings. Perfect line of sight with no obstruction. Signal quality is 93% if thats significant.

The orginal post you said 47-51%, at 93% there shouldn't be a problem

Jaxson

8172 posts

Uber Geek
+1 received by user: 1332

Trusted

#620134 5-May-2012 15:25

Strength and quality are two different things....
50% strength is not looking too good. Time to recheck polarity and connections.

peejayw

1913 posts

Uber Geek
+1 received by user: 123

#620137 5-May-2012 15:30

Aimed at Parahaki as per Freeviews pdf. Parahaki is vertical polarity.

I originally had the aerial installed with the elements horizontal but changed that after doing some research :-) but it has made hardly any difference to the signal strength.

Thanks,

Pat

I'm supposed to respect my elders, but it's getting harder and harder for me to find one now.

Lego

Shop now for Lego sets and other gifts (affiliate link).

B1GGLZ

1961 posts

Uber Geek
+1 received by user: 136

#620140 5-May-2012 15:40

Sounds like you my have a bad connection somewhere.
At 4km you shoud have 100% or even too much signal.

peejayw

1913 posts

Uber Geek
+1 received by user: 123

#620148 5-May-2012 16:00

Been up on the roof (again :-) ) and with the cable disconnected both ends there is full resistance as far as I can measure with my wee multimeter between the inner and outer wires. The only other thing I can think of is to bring the cable back down off the roof and check for continuity along the inner and outer wires.
Any other things to check?

I'm supposed to respect my elders, but it's getting harder and harder for me to find one now.

gregmcc

2173 posts

Uber Geek
+1 received by user: 836

ID Verified

Trusted

Lifetime subscriber

#620157 5-May-2012 16:31

peejayw: Been up on the roof (again :-) ) and with the cable disconnected both ends there is full resistance as far as I can measure with my wee multimeter between the inner and outer wires. The only other thing I can think of is to bring the cable back down off the roof and check for continuity along the inner and outer wires.
Any other things to check?

What do you mean "full resistance" between inner and outer wire?

Ideally there would be and open circuit resistance between inner and outer wires (infinity resistance or above what the meter can read), if there is a readable resistance between inner and out wire then there is a problem with the wiring, check the plugs on the end, sometimes a strand from the outer core is touching the inner core if your using 'F' connectors, if you are using the older style plug/socket connectors you may find the screw that holds the center core in place is shorting to the outer casing when fully assembled.

peejayw

1913 posts

Uber Geek
+1 received by user: 123

#620158 5-May-2012 16:33

Yes thats what I mean open circuit ie no connection between the two.

I'm supposed to respect my elders, but it's getting harder and harder for me to find one now.

Brunzy

2019 posts

Uber Geek
+1 received by user: 241

Trusted

#620160 5-May-2012 16:41

You may have too much signal/ excess VHF etc .
Is it a Panasonic recorder by any chance?

Dyson

Shop now for Dyson appliances (affiliate link).

gregmcc

2173 posts

Uber Geek
+1 received by user: 836

ID Verified

Trusted

Lifetime subscriber

#620167 5-May-2012 16:55

peejayw: Yes thats what I mean open circuit ie no connection between the two.

Next cable test, make sure you have low resistance from one end of the cable to the other, unplug both ends, at 1 end connect the inner and out cores tegether, go to the other end check the resistance, should be close to zero, go back and disconnect both cores re-check for open circuit.

Other than that maybe you are suffering from too good a signal, you may need an attenuiator

peejayw

1913 posts

Uber Geek
+1 received by user: 123

#620186 5-May-2012 17:49

No its a Dish TV aerial box Ultra T1050. Will get back on the roof tomorrow and test the cable continuity. Funny thing, now that it's evening I am getting 63-65% compared to 49-51% before. Is that of any significance?

I'm supposed to respect my elders, but it's getting harder and harder for me to find one now.

joshhill96

1512 posts

Uber Geek
+1 received by user: 188

ID Verified

Trusted

#620194 5-May-2012 18:00

Have you tried testing the signals using a Rabbit Ear system, see if that fixes any issues, If you get good quality signal then there will be a case of checking for a faulty patch with your UHF aerial set-up

Is the pathway to the transmitter clear i.e. No trees, buildings in the way?

Formerly worked at iStore NZ (Rest in Peace), Sky Network Television, Freeview, Apple, Spark New Zealand Trading Limited, DISH TV Technologies.

Travel Geek: Brazil, Chile, New Caledonia, United States, Fiji, Vanuatu, Australia, Cook Islands

peejayw

1913 posts

Uber Geek
+1 received by user: 123

#620199 5-May-2012 18:03

Will see if I can find anyone with rabbits ears, haven't seen them in years. Path to transmitter is totally clear, I can see it without binoculars :-)

I'm supposed to respect my elders, but it's getting harder and harder for me to find one now.

1 | 2 | 3