CAI Standards (1)

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The above specification has croppped up as a question on a new installation.

Whilst I understand it is for average signal strength areas and provides minimum gain and front/back ratios , does the standard include any reference or manufacturer recommendations on the mobile mast radiation and interference at the upper UHF band ?

Installation is to be pointed towards Crystal Palace and whilst most aerials on sale that have this rating are wideband, I'm slightly concerned that the introduction of the full band into the head end is only going to require yet another device (LTE cut off filter ?) to be included in the price, which really wouldn't be needed if I offer another antenna.
 

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I use log periodics mostly now and they have a built in LTE filter. Is this an architect who has cut and pasted the spec?
 

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I use log periodics mostly now and they have a built in LTE filter. Is this an architect who has cut and pasted the spec?

I don't know how they arrived at the specifications on the RFQ. Upper band interference is not something that I have ever needed to worry about, though I use my own methods to eliminate the possibility and they have always worked well.

What sort of spread gain do log periodics have these days (before amplifying ) ? Are any designs incorporated in CAI documentation (even if not Standard 1 ?)
 

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I only use their summary of outlet signals, recommended against actual and benchmarked cable. The kit I use will vary dependent on the job. Just completed the rig on one over your way, small log periodic, massive signal from CP, DAB and omni FM, TD78 dish with Fibre LNB and combiner for terrestrial, this will serve two blocks and a similar setup will serve another three.
 

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'Over here' of course the massive signal from Crystal Palace means that terrestrial can be picked up with a key-ring. One you get past Tolworth Rise the transmitter tower itself is a major part of the scenery.






This is an installation about 20 miles away which, whilst not difficult to achieve, does have a less than ideal signal path to the transmitter. None of the log periodic antennas in the suppliers are mentioned in the CAI specifications viewed so far.
 

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CAI standards 1 never had LTE in mind when it was launched I don't think.
Just fit a group T log aerial and additional filtering if required.
 

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CAI standards 1 never had LTE in mind when it was launched I don't think.
Just fit a group T log aerial and additional filtering if required.

Filtering is the variable that has always been under scrutiny though, the cut-off is dependent on the signal ratio on site and the points at which the swithover occurs.

For Crystal Palace everything changes again in the next couple of years with further intrusion of the upper UHF band by the 4/5G stuff. For now there are local transmissions operating at, or near this limit with a four to five year life span.

The rigs I have created on Crystal Palace and Guildford work well enough to capture all muxes available, though in the past week I have run into one issue in Cobham, but this looks to be down to third party hardware failure, rather than the installation.

Iffy YouView Box from TalkTalk
 

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If a systems istallation, price and factor in for a profiler on the front end.
 

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If a systems istallation, price and factor in for a profiler on the front end.

Are you aware of one that has variable (or perhaps plug-in) bandpass adjustment, I know only of those that used simple attenuation and those were some years ago (Taylor from memory )
 

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Are you aware of one that has variable (or perhaps plug-in) bandpass adjustment, I know only of those that used simple attenuation and those were some years ago (Taylor from memory )

You maybe referring to the older DCL level cluster tuned for TX.

Fully adjustable Profiler, Johansson

_unitrongroup.com/en/products/CAT/PROF/PROF/6600.html

Programmable filter amplifier: 6 inputs: BI-FM / BIII / VHF-UHF / 3 x UHF 10 Clusters / 24 V remote power

All profiler models have an automatic signal level equalizer, helping you to find the optimal gain for each filter.
The profilers are equipped with a display, indication LEDs and a rotary button to make the configuration an easy task.
Thanks to our memory-stick (ref. 6604), settings can easily be transferred from one unit to another. To avoid
unauthorized people changing the settings, all Profiler products can be locked with a security code.


  • 6 inputs: BI-FM/BIII/VHF-UHF/3 x UHF (UK version : FM/BIII/VHF-UHF/3 x UHF)
  • 10 UHF programmable clusters from 1 to 7 channels bandwidth.
  • high gain (55 dB and high power (120 dBμV)
  • 24 V remote power on UHF and VHF-UHF inputs (12V for 6600UK and 6600A)
  • VHF-UHF split band amplifier with inter-stage attenuators
  • -30 dB test output
Several models available, this may be more suited. Has 30dB attenuation adjustment. _unitrongroup.com/en/products/CAT/PROF/PROF/6600.html
 
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