Help needed in monitor solution

[davenn]

Yes i know that idea, but your tied down by wire/cable, i had a feeling the radio operative was on the move in a rural area, might be wrong, in which case a fixed, or semi fixed installation would be fine. Dave.

the distances involved are ONLY around the house and yard, Dave,
the user doesnt need 1/2 km or more coverage
PMR etc is only going to tie up a channel for hours on end that no one else is going
to be able to use. Thats going to cause transmitter hunts by other trying to find the rouge
contineously transmitting device and have it shut off.

As far as phone systems go, there are cordless phones that have intercom features
between base and handheld unit. These would likely to be very practical in this situation

ohhh and charging of phone calls. in most other parts of the world, we dont pay for the length of a local call, Dave.
unlike in the UK. we pay an initial connection fee, here in Australia its ~ 18 cents, depending on your
service provider and you talk as long as you like Some have deals where you get say... 100 free
calls / month then you start paying that 18cent connection fee

cheers
Dave

 

[(*steve*)]

There are a number of wireless phone handsets that claim a highly extended range, so maybe this is not such a bad idea.

 

[daddles]

If the OP is monitoring all day long, battery life will likely become an issue. The FRS radio with a VOX circuit would probably be the most sensible solution; I agree with KJ6EAD that continuous transmission is probably frowned upon and will eventually get you in hot water and possibly a fine. But the VOX would fix that. While the cordless phones used as intercoms might work, I suspect they wouldn't do for e.g. 8 hour day-in day-out service.

 

[jdbob]

They died for various reasons. I had to install earphone jacks in them so I could still hear them when I was a chainsaw carver and worked all day outside. They took a beating, and lasted a couple of years. I still have many of them just in case I ever learn some electronics and can fix them or cob together a new unit. Probably wont happen.

 

[davelectronic]

Monitors

Hi again to you all. I only surgested the PMR radio as the baby monitor seemed a good idea UHF offers very good comm's, most sets have 300 + combo frequencys using CTSS, and the area is rural, but if its around the home another system might be better, i thought the care person was on the move in there local area, so more distance needed. I have no idea on telecomunication charges in the US or Australia, so maybe a semi fixed instalation is the way to go. PMR is quiet in the UK. Dave.

 

[KJ6EAD]

…most sets have 300 + combo frequencys using CTSS…

That's a common misconception. CTCSS only prevents you from hearing transmissions that don't include your tone code by disabling your receiver's audio. Your receiver's front end will still lock onto the strongest signal on frequency. Users on the same frequency still interfere with each other but the people missing calls are less aware of why it's happening.

http://en.wikipedia.org/wiki/Continuous_Tone-Coded_Squelch_System

 

[jdbob]

Actually, the phone idea might work if it has enough range because it does have the intercom feature. I've tried talking on the phone outside and it's pretty sketchy too as far as obstacles and walls and such. My old monitors would go several hundred feet from the house in almost any direction and only cut out when I was inside a tin roof shed. I wish I could fix whatever was wrong with those units. To my eye, I couldn't see any problems on the circuit board, no cracked solder or fried looking components.

 

[KJ6EAD]

A lot of low power consumer transmitters have a pi or t attenuator between the output amplifier and the antenna to reduce the power enough to comply with regulations.

 

[davelectronic]

Monitors

Hi again. I stand corrected on the CTCSS codes, ive used PMR but my family member was to far away and iam in a built up area, but with in range, IE when i moved closer and changed to a different CTCSS combination my family member could not here me at all even a few yards away. and as the intended area was rural i thought it a good idea, i still do, the manufacturers put that baby monitor feature on many of there sets, cobra/midland/uniden to name but a few, the ones i had where a uniden quad set, 4 radios, chargers set. This also had the baby monitor set on its settings, but as i say they where no good to me, to much distance, and my area is in a town built up area, i use the CB to keep free contact, phone charges in the UK can be expensive. Dave.

 

[jdbob]

Can FRS transmitters be always on? And can the receivers also be always on? I won't need to talk back to the base as the person I'm monitoring wil be listening to the computer reading to her and won't hear me. Isn't VOX the voice activated feature? It would probably have a hard time with the continous reading voice of the computer.

 

[jdbob]

A lot of low power consumer transmitters have a pi or t attenuator between the output amplifier and the antenna to reduce the power enough to comply with regulations.

What does this look like (how do I locate it) and can it be removed?

 

[davelectronic]

monitor use

What you want to do is tricky, explained wont necessarily work, you could damage the output stage, or alter its behavior, if you did get it right, as it will very depending on circuit construction, some only use components to allow the legal maximum RF output, if it can be done, and you create interference with others and there equipment, depending on what part of the world your in, you might end up in trouble having contravened current laws and regulations.
Dave.

 

[KJ6EAD]

Pi or T attenuators are made up of three components (usually resistors) on the circuit board feeding the antenna or the antenna base loading inductor. The components can be bypassed or changed. This is really a task for someone with some radio electronic knowledge and experience.