GPS distribution
28 views
Skip to first unread message
morrisodell
Apr 7, 2012, 11:41:46 PM4/7/12
to neonixie-l
Hi All,
I'm sure this subject has been discussed here before but now I need
to pay attention ;-) I have made several clocks that use GPS receivers
to get a time reference. That's all very well but it does restrict
them to needing an antenna and being near a window. I want to build a
system to get the time signal from one optimally located receiver and
distribute it to my various clocks anywhere in my house or office
using a low power RF link.
What I want is something that will accept the serial stream from a GPS
receiver and reproduce it at the receive end. 2 way communications is
not really required.
Any suggestions?
Morris
I'm sure this subject has been discussed here before but now I need
to pay attention ;-) I have made several clocks that use GPS receivers
to get a time reference. That's all very well but it does restrict
them to needing an antenna and being near a window. I want to build a
system to get the time signal from one optimally located receiver and
distribute it to my various clocks anywhere in my house or office
using a low power RF link.
What I want is something that will accept the serial stream from a GPS
receiver and reproduce it at the receive end. 2 way communications is
not really required.
Any suggestions?
Morris
jpea...@madlabs.info
Apr 8, 2012, 12:15:34 AM4/8/12
to neoni...@googlegroups.com
I use linx modules:
http://www.linxtechnologies.com/products/rf-modules/
Used 'em for years, work great.
Jonathan
Adam Jacobs
Apr 8, 2012, 12:53:16 AM4/8/12
to neoni...@googlegroups.com
These are neat, too. Kind of pricey.
--
You received this message because you are subscribed to the Google Groups "neonixie-l" group.
To post to this group, send an email to neoni...@googlegroups.com.
To unsubscribe from this group, send email to neonixie-l+...@googlegroups.com.
For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
fixitsan
Apr 8, 2012, 5:29:45 AM4/8/12
to neonixie-l
When I first did this I felt it was counterproductive. Having GPS
accuracy, but then losing it by inserting a protocol for
retransmission. That was improvedupon by using the 1pps signal output
from my GPS.
But there was still lag, so for fun I set the GPS unit to only
transmit data exactly at the 1 second epoch and transmitted it via a
433MHz module.
Again, there was a small amount of lag, so instead of trying to tell
the current time, I always had my timekeeping registers set 1 second
(approx) ahead of the received GPS time, but delayed displaying them
by "Current time + 1 second - transmission delay(lag)" seconds. No
matter how bad the transmission delay was the time displayed on the
times, specifically the point when the display shows the correct time,
was always accurate.
As for modules, I used 433 MHz FM units which were okay.
If i were to do it again I would just buy the cheap ETRX2 Telegesis
Zigbee modules, which can create a self healing mesh network, and
which are cheap and reliable as well as having checksums built in for
data integrity testing and automatic retries if the data transmission
fails.
The ETRX2 is probably overkill in terms of specification, but almost
as cheap as any other module, with the added benefit of being
bidirectional as well as giving huge ranges due to the ability of each
unit to retransmit via mesh networking.
Chris
accuracy, but then losing it by inserting a protocol for
retransmission. That was improvedupon by using the 1pps signal output
from my GPS.
But there was still lag, so for fun I set the GPS unit to only
transmit data exactly at the 1 second epoch and transmitted it via a
433MHz module.
Again, there was a small amount of lag, so instead of trying to tell
the current time, I always had my timekeeping registers set 1 second
(approx) ahead of the received GPS time, but delayed displaying them
by "Current time + 1 second - transmission delay(lag)" seconds. No
matter how bad the transmission delay was the time displayed on the
times, specifically the point when the display shows the correct time,
was always accurate.
As for modules, I used 433 MHz FM units which were okay.
If i were to do it again I would just buy the cheap ETRX2 Telegesis
Zigbee modules, which can create a self healing mesh network, and
which are cheap and reliable as well as having checksums built in for
data integrity testing and automatic retries if the data transmission
fails.
The ETRX2 is probably overkill in terms of specification, but almost
as cheap as any other module, with the added benefit of being
bidirectional as well as giving huge ranges due to the ability of each
unit to retransmit via mesh networking.
Chris
Tidak Ada
Apr 8, 2012, 6:05:11 AM4/8/12
to neoni...@googlegroups.com
What do you think about one mother clock in your house and several displays
elsewhere ? Gives only the need of one clock to be set if necessary.
Or distribute the 0,1 or 1 second pulse through your house by wire or
wireless,,,
elsewhere ? Gives only the need of one clock to be set if necessary.
Or distribute the 0,1 or 1 second pulse through your house by wire or
wireless,,,
eric
Hi All,
Any suggestions?
Morris
--
MichaelB
Apr 8, 2012, 10:58:29 AM4/8/12
to neoni...@googlegroups.com
We did this with our MOD-SIX where one RF-LinK Repeater will drive several Mod-Six's. http://www.youtube.com/watch?v=CZFoHOqHKuA
What about a generic TX and Rcvr pair for any GPS capable clock with a PS2 connector? Hmmm..this might be a nice follow up product. Lot of NixiChrons out there!
Jonathan Peakall
Apr 8, 2012, 11:06:13 AM4/8/12
to neoni...@googlegroups.com
I use the xbee's to get data from my windmill, it's
too far away for the Linx modules. I like 'em and they are worth the price if
you need the range. Also have a lot of neat features, like some ADC and I/O
pins.
Jonathan
fixitsan
Apr 8, 2012, 11:50:05 AM4/8/12
to neonixie-l
I tried the Xbee, Jon, but my project had to be priced for 1,000 off
so I rejected them in favour of the much cheaper ETRX2's
is it worth mentioning the different flavours of Zigbee ? I'm a year
or so out of date wiht the Zigbee protocols but there were some
differences to protocols which meant that some Zigbee Pro modules
could not be mated with Zigbee vanilla modules, despite there supposed
to be a standard protocol.
I think the easiest Zigbee solution is to buy the modules that suit
you best, either for price, for features EG I used the ETRX2 battery
voltage monitor register, like you also mentioned the A/D pins whcih
can be sued for other things, such as reading temperature, and then
just buy enough modules and maybe a couple of spares, all of the same
type.
Microchip have lagged behind a bit on Zigbee but they're getting
there, they have always had this (cheapest yet)
http://uk.farnell.com/microchip/mrf24j40ma-i-rm/rf-transceiver-module-2-4ghz/dp/1630202
but yoiu need to start driving that with an off-cip controller loaded
with yoiur protocol stacks, or just write your own protocol and make
use of the built in features.
On Apr 8, 4:06 pm, "Jonathan Peakall" <jpeak...@madlabs.info> wrote:
> I use the xbee's to get data from my windmill, it's too far away for the Linx modules. I like 'em and they are worth the price if you need the range. Also have a lot of neat features, like some ADC and I/O pins.
>
> Jonathan
>
> These are neat, too. Kind of pricey.
>
> http://www.sparkfun.com/products/8664
>
so I rejected them in favour of the much cheaper ETRX2's
is it worth mentioning the different flavours of Zigbee ? I'm a year
or so out of date wiht the Zigbee protocols but there were some
differences to protocols which meant that some Zigbee Pro modules
could not be mated with Zigbee vanilla modules, despite there supposed
to be a standard protocol.
I think the easiest Zigbee solution is to buy the modules that suit
you best, either for price, for features EG I used the ETRX2 battery
voltage monitor register, like you also mentioned the A/D pins whcih
can be sued for other things, such as reading temperature, and then
just buy enough modules and maybe a couple of spares, all of the same
type.
Microchip have lagged behind a bit on Zigbee but they're getting
there, they have always had this (cheapest yet)
http://uk.farnell.com/microchip/mrf24j40ma-i-rm/rf-transceiver-module-2-4ghz/dp/1630202
but yoiu need to start driving that with an off-cip controller loaded
with yoiur protocol stacks, or just write your own protocol and make
use of the built in features.
On Apr 8, 4:06 pm, "Jonathan Peakall" <jpeak...@madlabs.info> wrote:
> I use the xbee's to get data from my windmill, it's too far away for the Linx modules. I like 'em and they are worth the price if you need the range. Also have a lot of neat features, like some ADC and I/O pins.
>
> Jonathan
>
> These are neat, too. Kind of pricey.
>
> http://www.sparkfun.com/products/8664
>
Reply all
Reply to author
Forward
0 new messages