WX radio repeater on solar power

majoco

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OMG - you are really overthinking this. A friend from years gone by lived in a valley shielded from the TV coverage from about 30 Miles away. He asked the landowner if he could put a mast up on the peak of the hill between his house and the transmitter - he could see the transmitter from there on a good day. He extended a post with about 20feet of galvanised pipe and put two TV yagi antennas up there - one pointed at the transmitter and one pointed at his house - joined the two together - another yagi at his house pointed at the hill top gave him a good signal on all three a bands.
 
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@majoco is that for real? Two yagi antennas on the hill, one pointed at the broadcast, one pointed at my house. Are they connected by a cable? Plus another yagi antenna on my roof pointed at the antennas on the hill. Would that really work? I'm just surprised no one else has suggested it.

@pb_lonny I do get some AM but no FM or WX.
 

kb4mdz

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Maybe it's time to back up juuust a little bit. Can you receive ANY sort of signal on your antenna?

And another FWIW, you said you connected the antenna with 75 ohm co-ax; really should be 50 ohm, like RG-58, for a short run, or RG-8 for a longer run, (greater than maybe maybe 25 or 30 ft?)

Check whether you have a short from center to ground of the coax, and whether you have continuity end-to-end of the center conductor and shield conductor.
 

prcguy

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Yes, it can work under ideal conditions and its called a passive repeater. You need a lot of signal available at the receive antenna, a lot of antenna gain and not too much distance from the rebroadcast antenna to your receive antenna. If you can measure signal strength at the hill top you can calculate if there is enough signal for this to work with a link budget that includes path loss and antenna gains.

@majoco is that for real? Two yagi antennas on the hill, one pointed at the broadcast, one pointed at my house. Are they connected by a cable? Plus another yagi antenna on my roof pointed at the antennas on the hill. Would that really work? I'm just surprised no one else has suggested it.

@pb_lonny I do get some AM but no FM or WX.
 
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Maybe it's time to back up juuust a little bit. Can you receive ANY sort of signal on your antenna?

And another FWIW, you said you connected the antenna with 75 ohm co-ax; really should be 50 ohm, like RG-58, for a short run, or RG-8 for a longer run, (greater than maybe maybe 25 or 30 ft?)

Check whether you have a short from center to ground of the coax, and whether you have continuity end-to-end of the center conductor and shield conductor.
I can receive some AM but no FM and no WX. You're right about 75ohm vs 50ohm but would that really make the difference here? The hill is maybe 500 feet above my house and if I put the radio on batteries it works great at the top of the hill but reception completely disappears just 20 feet down the road.

Yes, it can work under ideal conditions and its called a passive repeater. You need a lot of signal available at the receive antenna, a lot of antenna gain and not too much distance from the rebroadcast antenna to your receive antenna. If you can measure signal strength at the hill top you can calculate if there is enough signal for this to work with a link budget that includes path loss and antenna gains.
This is exciting. The top of the ridge has a gigantic view of the landscape on the other side and WX comes in nice and clear there with the built-in antenna on the Midland radio so I think there's a lot of signal. How is ~1300 feet in a straight line from rebroadcast antenna to receive antenna with perfect line of sight?

How is the initial receive antenna (not the receive antenna on my house) connected to the rebroadcast antenna?

Can you point me to one or more ideal antennas for this?
 

mmckenna

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Can you point me to one or more ideal antennas for this?
And I think that's where your problem is going to be. High gain Yagi's are going to be large and costly. Not impossible to do a passive repeater like this, but it's not going to be unobtrusive and won't be cheap. You'll need a substantial support to make this work. Even then, you do need to do the calculations. "Nice and clear" isn't necessarily a good enough calculation.
 
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Is it the initial receive antenna, rebroadcast antenna, or final receive antenna that needs to be large and costly? All of the above?

Please point me toward the sort of antennas I'm likely to need.

For calculations, what is the easiest way to get enough data to proceed?
 

mmckenna

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Is it the initial receive antenna, rebroadcast antenna, or final receive antenna that needs to be large and costly? All of the above?
All of the above.

Please point me toward the sort of antennas I'm likely to need.

$150 each, and you'd need 3 of them. One pointing at the NOAA transmitter, one pointing at your house, and one at your house pointing up the hill. You can probably find cheap Chinese antennas for a bit less money.

You'll need a 2" pipe sunk in the ground to support these. They'll need to be high enough to have a clear shot at the NOAA transmitter and a clear shot at your home.

You'll need a similar mount on your roof to support the antenna pointed back at your hill, and low loss coax to your radio. Figure that even halfway decent coax is going to be in the $1.00 or more per foot range.

That's IF it'll have enough signal to make it work.

For calculations, what is the easiest way to get enough data to proceed?
You'd need a radio that can give you a dB signal level with some sort of reliability.


As others have pointed out, yes, this COULD work, but it's not going to be cheap. If the hill top is yours and you can install equipment up there, mounting a receiver up there is going to be a more useful solution. Doesn't have to be a dedicated NOAA radio, you could use a basic scanner or even a USB type receiver stick connected to a cheap computer. Stream the audio back down to your home via WiFi point to point radio. That's would probably be more reliable, and give you the option of listening to other traffic outside the VHF band.

Or, use an online resource from NOAA or something similar. See if your city/county has some sort of alert platform already. Some will let you sign up with an e-mail or mobile number the send you alerts.

Personally, if I was in your position, and I did have full rights to the hill top, I'd put a remote receiver up there that could offer more capability.
 
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The hill is on my parcel so no issue there, but the problem with using wifi is a weather radio won't alarm based on it. The great thing about a weather radio is it will *silently* monitor the WX band for alerts 24 hours a day and sound an alarm if one is detected. Also no cell reception and unreliable internet.

Wind could be a problem. This area gets unbelievably strong wind gusts. Are yagi antennas a bad choice in an environment like that? There's an advisory in place right now for 45mph gusts.

How many dB do I need from the signal on the hill?
 

mmckenna

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The hill is on my parcel so no issue there, but the problem with using wifi is a weather radio won't alarm based on it. The great thing about a weather radio is it will *silently* monitor the WX band for alerts 24 hours a day and sound an alarm if one is detected.
I think there has got to be a better way to do this.
NOAA used to send out an alert tone that would trigger older receivers. It's not hard to trick a commercial radio with 2 tone paging capability into recognizing that tone and opening the audio for a set period of time. Then all you'd have to do is feed the audio via IP connection down to your house.

Wind could be a problem. This area gets unbelievably strong wind gusts. Are yagi antennas a bad choice in an environment like that? There's an advisory in place right now for 45mph gusts.
A good quality commercial antenna will not have a problem with 45mph gusts. That antenna I linked to is rated for 100mph winds. You'd need to make sure your support structure would handle that, and if you are in a location that gets ice, the additional wind load from ice loading was addressed.

How many dB do I need from the signal on the hill?
The more the better.

The signal strength at the hill top will be boosted a bit by the Yagi antenna gain. The ones I linked to have 9.2dB of gain. You'll lose a tiny bit of that power in the coaxial cable between the antenna pointed at NOAA and the antenna pointed at the house. The antenna pointed at your house will take the signal from the coax and focus it towards your home.

Then there's path losses, that's the normal unavoidable degradation of the RF signal as it passes through the air. For the distances you are talking about, it's going to be in the 70dB range, which means what little signal you get out of the antenna pointed at your house is going to be extremely weak by the time it gets there.

Then you have the gain of the antenna on your roof, again, 9.2dB of gain that will offset a bit of the free space loss.

Then you have losses in the coax going down to your radio.

It's going to be hard to calculate all this without the right test gear, even then there's going to be some slop in the numbers. Add in poor receivers on most consumer electronics, and you'll likely have issues.
You could add a small preamp on the radio end, but that's going to add to costs and noise levels.


If this was an easy fix, more people would be doing it. It can be done, but it's not cheap or easy. I still think you need to look at a more reliable solution.
 

cg

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I would think if you placed a programmed WX alert radio on hill, quiet unless activated. Low power transmitter aiming down into the valley with VOX set on transmit. Receiver would be quiet then you would hear the message just like if the receiver was in the house. You wouldn't have a warble type alert but increasing the volume would work.

chris
 

prcguy

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A couple of solar panels, a deep cycle marine battery, a Raspberry Pi, SDR dongle and a wireless access point back to the house would work. Might cost a couple hundred $ and you would have much more than just a WX receiver.

Personally, if I was in your position, and I did have full rights to the hill top, I'd put a remote receiver up there that could offer more capability.
 

vagrant

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Think bigger and better! With a hilltop shack and a tram, one could really enjoy playing radio. I mean, do doesn't love a 1200' antenna?

 

iMONITOR

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Any weather spotters, storm trackers on 2 meters in your area? They'd probably be much more informative then NOAA.
 

RFI-EMI-GUY

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There are some outboard S.A.M.E decoders for broadcasters that can be installed at your home and connected to some "other band" receiver that picks up a relay of the NOAA audio from the hilltop. But they are not cheap and you can hack a cheap NOAA receiver to utilize its SAME decoder and audio circuitry by breaking the discriminator line.

Ideas, some of which are probably illegal

1) At hilltop, Crossband repeat NOAA audio via a low power MURS or 900 ISM band (baby monitor) transmitter. At the house, tap a MURS or 900 ISM (baby monitor) receiver into the audio and decoder line of a NOAA receiver with SAME circuitry. Basically a hack.

2) At hilltop, receive and upconvert 162.5xx MHz NOAA signal to 915 MHz ISM (752.5 MHz LO). At the house downconvert 915 MHz ISM to 162.5 MHz with same 752.5 MHz LO. This will take some skills and hardware. Do your shopping on minicircuits and ebay, get your soldering iron out. You need filters, mixers, amps and a 752.5 MHz oscillator. Easy peasey.

Both of these ideas will require continuous transmission and corresponding power drain on the hilltop. The solar system battery will have to accommodate this drain and the limited hours of sunlight.

3) Any variations to the above to limit transmission to when needed will require an active SAME decoder on the hilltop and two-way means to control it from the house.

4) There are some ham radio repeater controllers that integrate a NOAA/SAME receiver and provide for remote control operation. They are pricy and you will need a duplex radio path.

5) NOAA has 400 MHz link transmitters that are used for the 162 MHz transmitters. If you can tune in one of those links you might make your own very low power 400 to 162.5 MHz repeater NOAA station to service your house.

Do you have neighbors with similar complaints? Contact NOAA to see if they will install a fill repeater.
 
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