Re: Do these cellular amplifiers work for all cellphones?

On 2022-04-12 19:17, J. P. Gilliver (John) wrote:
> On Tue, 12 Apr 2022 at 21:01:56, Alan Browne <[email protected]> 
> wrote: (my responses usually follow points raised):
>>> How could new cars be sold in GB with cellular boosters as Martin 
>>> Brown said
>>> they were if those cellular boosters are illegal in GB in the first 
>>> place?
>>
>> I never said they were.  I was clarifying that just because a car has 
>> a sharkfin on it, and even with the requisite electronics and antenna, 
>> it does not mean the phone in the car is actually using it.
> 
> Right. It could be that you're not connecting to the internal car antenna.

It's not like you even _can_.  The ability to use the electronics in the 
sharkfin are defined by what trim level you bought.

> 
> Or it could be a single user booster instead of a multi user booster (if 
> they make both).
> 
> Or even it could be a single carrier booster instead of a multi carrier 
> booster (I know they make both but I don't know the difference other 
> than the FCC limits drop in decibels when you go from single carrier 
> boosters to multi carrier boosters (why? what's the difference?).
> 
>>>>>> I called UberSignal who said they work fantastically for all 
>>>>>> carriers.
>>>>>> https://www.ubersignal.com/vehicle-signal-boosters.html
>>>>>
>>>>> Well they would, wouldn't they! What they don't say is that it also 
>>>>> messes up phone reception for anyone else in your vicinity (and 
>>>>> quite likely radiates sidebands into other protected frequency bands).
>>>>
>>>> This is why the system still has to meet compliance.  US has its 
>>>> standard, the UK its own.  Usually manufacturers know and publish 
>>>> what countries they are compliant to.
>>>
>>> If they messed up reception as much as Martin Brown said they do then 
>>> how
>>> could they be approved by the FCC and by all the cellular companies 
>>> then?
>>
>> Because Martin's assumptions are likely wrong or incomplete.
>>
>> Facts:
>> 1) They work[1]
> 
> I'm sure they work. Otherwise there would be a lot of unhappy people.
> 
>> 2) They are meant for areas where cell towers are sparse - so you're 
>> not going to be interfering - there is no one close by to interfere with. 
> 
> The FCC and carriers wouldn't have approved them if they were interfering.
> 
>> (Competitor antennas are probably on the same tower).  Power output 
>> from the device is likely controlled as commanded by the receiving 
>> tower (reduces saturation at the receiver).
> 
> The home boosters are allowed 100 decibels but they stay in place.
> The mobile boosters are only allowed 65 decibels.
> That they move is maybe why mobile is lower?

Not sure, but more likely to accidentally jam someone or a tower with a 
mobile unit which will be varying power output as a function of changing 
conditions.

Fixed units won't transmit at max power, they will respond to the tower 
instruction on power level.  Since that will be a slow changing 
parameter (only weather affecting it), there is little risk of jamming 
others.

>> 3) They are compliant (at least in the US per FCC rules).
>>
>> To be clear, Great Britain is less than 1/3 the size of Texas. There 
>> are lots of areas in the US that have sparse, poor or no coverage at all.
> 
> Maybe that's why cellular boosters are outlawed in GB.
> Because they're not needed in such a small area.

It's my assumption.  GB is a bit less "adventurous" on rule making too 
(except sausage.  Anything goes there).

> 
>> It could be in GB that there is adequate coverage almost everywhere. 
>> Certainly not in the US.
> 
> I don't know but I think the laws on radios are more free in the US.
> But I don't know that for sure.

Funny I read that after what I wrote above.

> 
>> [1] To be sure, user expectations need to be managed, most esp. for 
>> the mobile case.
> 
> Even the lower maximum of around 50 decibels for multi carrier mobile 
> cellular boosters seems indicate that they must work when there is 
> enough signal to boost.
> 
> Would be nice to read a real world test.

There are some, Google is your friend. Most are badly done.  Likewise 
the few YouTube's out there...

-- 
"Mr Speaker, I withdraw my statement that half the cabinet are asses -
  half the cabinet are not asses."
-Benjamin Disraeli