WiFi NTP clocks for classrooms

[mikkydoos]

Anyone got a supplier for WiFi NTP clocks?

 

Don't wanna run ethernet/POE to them.

 

I've found these but they don't do a WiFi version.

 

Wireless Clocks and Synchronized Clock Systems | PoE, Wired and Master Clock Systems | Sapling Clocks

 

 

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[mjk]

You shouldn't need WiFi / NTP for this as many radio clocks will pick up time from the air and will be cheaper and use less power.

(I guess these are DAB radio frequency but not sure how they work)

[mjk]

here:

 

https://www.kcswebshop.co.uk/store/product/24970255.aspx

[RichCowell]

I'd definitely suggest radio controlled clocks instead too - I got one at home ages ago, and have just replaced my office clock with one - far easier, no set up as it sets itself as soon as you put the battery in...

 

The one I've got is Acctim 74367 Peron Radio Controlled Wall Clock, Silver: Amazon.co.uk: Kitchen & Home so a reasonable price for a decent quality clock...

 

(My watch is radio controlled too, I'd never get a clock or watch that isn't now lol)

[sted]

You shouldn't need WiFi / NTP for this as many radio clocks will pick up time from the air and will be cheaper and use less power.

(I guess these are DAB radio frequency but not sure how they work)

 

depends on the school building ive seen them in schools where they just dont get a signal ever even in the window

[Andrew_C]

depends on the school building ive seen them in schools where they just dont get a signal ever even in the window

Welcome to my world!

 

We've got lots of the d@mned things, and since the transmitter moved to the Lake District, they have been worse than useless. If I turn off the wi-fi, and take them out onto the roof, they sometimes pick up a signal. Recently, I've taken some home via a hilly route and they still won't sync.

[mjk]

I didn't know they could be bad. We've had a few not sync and the caretaker blamed our WiFi!! - which of course it wasn't.

Ours seem to be generally reliable.

[truebluesteve]

We have used Primex wireless clocks here for a number of years and they have performed faultlessly. Wireless Synchronized Clocks | Temperature Monitoring | Primex Wireless

 

We have a central transmitter in one building which all the clocks pick up from and that's it. They take a C battery usually (depending on what size clock) and last for ages. They also do wireless relays that use the same transmitter and we have a couple that link to our fire alarm for class changes. We are a pretty large site with lots of separate buildings and signal hasn't been an issue so far.

[Andrew_C]

which of course it wasn't.

Except that it could well be your wireless swamping the weaker signal.

[mikkydoos]

Cheers for the replies guys.

 

I'm in a pretty big Victorian school with 3ft thick walls. Not sure if these would work. Hence the WiFi/NTP question.

 

Don't want to break the bank either on systems with transmitters!

There are some that have PoE on them but then I've got to cable them in ;( Erm... no.

[mjk]

Except that it could well be your wireless swamping the weaker signal.

 

Not if physics has anything to do with it.

[Andrew_C]

Sorry? Why not? Empirically, it does.

 

I suspect the recievers in the clock are very cheap, and any RF signal can overload the input stage.

[mjk]

Sorry? Why not? Empirically, it does.

 

I suspect the recievers in the clock are very cheap, and any RF signal can overload the input stage.

 

 

No they pick up time from radio waves which are much lower frequency than WiFi - in the Khz/Mhz region. They are not even in the same ball park as Wifi (GHz) so wouldn't cause any interference.

Incidentally; higher frequencies also have less penetration (which is why they use radio frequency for long distance) and this also explains why 2.4Ghz has better wall penetration than 5Ghz.

[Andrew_C]

Why, when I turn off the WiFi here, do the clocks (sometimes) pick up a 1500m signal and synchronise? They never do with the WiFi on. If the tuned stage of the clock is cheap/poor then there may be little off band filtering. I concede that there is a big difference between 2.4GHz and c10MHz but something is causing it.

[mjk]

I wonder if there is something else running on you 10MHz and it just happens to be off when no-one is around and you can switch off the wifi. perhaps. You'd need a pretty broad spectrum analyser to work out what is happening for sure.