Author Topic: Spurious Emissions, Davis VP2 Dropouts  (Read 585 times)

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Offline captbrando

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Spurious Emissions, Davis VP2 Dropouts
« on: September 27, 2017, 12:01:30 PM »
Fellow enthusiasts.

I've been a Davis Vantage Pro II station user for over a decade. My current setup has the connection out of the back of the wireless console dumping to a Raspberry Pi (Model 3B today). This gathers information and then dumps it to a database elsewhere in my house.

I have been fighting temporary dropouts for YEARS. To the point that I think Weather Underground hates me for my steady reports of the wrong temperature. Anyway... I've been doing some experiments. I have two consoles, and the one connected to my RPi (after moving to a new location) is still dropping out randomly. I am now suspecting that either the RPi or the Serial cable is causing spurious 900MHz emissions at times that is causing the console to lose signal. We're talking 30 feet, line of sight.

Has anyone else observed spurious emissions with the RPi platform?

Offline captbrando

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Re: Spurious Emissions, Davis VP2 Dropouts
« Reply #1 on: September 27, 2017, 07:37:34 PM »
Correct. I ended up turning off the Bluetooth radio on the RPi, wondering if it broadcasting was somehow overloading the receiver. Will have to watch it.

Offline dalecoy

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Re: Spurious Emissions, Davis VP2 Dropouts
« Reply #2 on: September 27, 2017, 08:39:27 PM »
The console diagnostic screens might provide a useful clue or two.

Offline eyecue

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Re: Spurious Emissions, Davis VP2 Dropouts
« Reply #3 on: September 27, 2017, 09:15:54 PM »
Correct. I ended up turning off the Bluetooth radio on the RPi, wondering if it broadcasting was somehow overloading the receiver. Will have to watch it.
  The 900 Mhz band is open to medical devices, baby monitors and other devices, you might have a tough time tracking down the issue.
Cocorahs, Skywarn, Aficionado of weather. Davis VP2  pro wireless, Oregon Scientific and DIY.

Offline captbrando

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Re: Spurious Emissions, Davis VP2 Dropouts
« Reply #4 on: September 27, 2017, 09:19:48 PM »
The only thing I've been able to track it down to definitively is the presence of the Raspberry Pi with a serial cable. I'm cautiously optimistic at this point. There are no 900MHz baby monitors or medical devices around here, but I'm wondering if I hit on a harmonic close enough that could have overloaded the receiver in the console. The messages in the console just had a lost signal. (starting with R, then L).

I'm going to see if this latest item solves anything. If so, will post back. 900MHz is such a funky band.

Offline captbrando

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Re: Spurious Emissions, Davis VP2 Dropouts
« Reply #5 on: September 27, 2017, 09:49:09 PM »
2) Are those dropouts happening at repeated 'cyclic' intervals?

It seems like it happens during the day from late morning to late afternoon. TYPICALLY. The time varies as far as how long it is dropped out, but that's about all I can predict.

3) Does the power meter at your house 'automatically' transmit data back to the power company?

I do have a new power meter, so I am guessing it does. I thought Zigbee was a 2.4Ghz frequency. That said, the meter itself is on the exact opposite side of the house.

Offline dalecoy

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Re: Spurious Emissions, Davis VP2 Dropouts
« Reply #6 on: September 27, 2017, 11:07:51 PM »
The console diagnostic screens might provide a useful clue or two.

So, have you looked at those?  [Before and after your change]

Offline Bashy

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Re: Spurious Emissions, Davis VP2 Dropouts
« Reply #7 on: September 28, 2017, 12:33:41 AM »
HI, do you have a WiFi dongle close by?
I had data dropouts, turned out to be the WiFi dongle interfering with the Weatherlink dongle thingymajig out the back of the console
Kind regards
Bashy

Offline miraculon

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Re: Spurious Emissions, Davis VP2 Dropouts
« Reply #8 on: September 28, 2017, 07:55:45 AM »
2) Are those dropouts happening at repeated 'cyclic' intervals?

It seems like it happens during the day from late morning to late afternoon. TYPICALLY. The time varies as far as how long it is dropped out, but that's about all I can predict.

3) Does the power meter at your house 'automatically' transmit data back to the power company?

I do have a new power meter, so I am guessing it does. I thought Zigbee was a 2.4Ghz frequency. That said, the meter itself is on the exact opposite side of the house.

Some smart meters use the 900MHz band. I have one and don't have any problem with the multiple Davis transmitters and receivers. See this for more details on RF from the smart meters.

I have a Davis long range repeater that I use to receive the ISS signals from the local marina which is 2000 ft. (610m) away. I had a lot of interference issues that I eventually solved with a band-pass filter. I realize that this is not helpful in terms of a standard ISS-to-console communication configuration. When I was troubleshooting the problem, I used an "RF Explorer" and I could see strong interference in the 750MHz and 850MHz areas. The county communications tower for the Sheriff department is a few blocks away and I suspect that some of this is the 800MHz band that they use.

While it does cost some money, I found the RF Explorer particularly useful in hunting down these kind of problems. I have the most basic model, which is fine for this purpose. http://rfexplorer.com/models/ The peak modes are good at viewing the Davis transmissions. I was able to see broadband interference when I expanded the range to include the 750-850MHz bands.

Greg H.




Blitzortung Stations 668, 706 - CWOP CW4114 -  CoCoRaHS MI-PI-1

Offline archae86

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Not necessarily 900 MHz
« Reply #9 on: September 28, 2017, 08:54:05 AM »
My one clear-cut case of Vantage Pro 2 reception trouble linked to a specific device must surely have involved trouble at the intermediate frequency not the primary frequency of 900 MHz. The offending device was the wall wart style charger for a cell phone.

The trouble started when I began routinely operating the charger as I switched from using the cell phone only on trips to carrying it around town. The trouble ended when I moved the charger from less than 5 feet away from the Davis receiver to the other end of the house.

I have several other wall warts and several other chargers, none of which seem to have induced the same problem.

Good luck finding your source.

Offline captbrando

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Re: Spurious Emissions, Davis VP2 Dropouts
« Reply #10 on: September 28, 2017, 02:39:08 PM »
OK, It is happening again. My anemometer is on another channel, so it's fine and still transmitting. My ISS however is not. The values are all zero. I've attached a picture (ignore the black piece over the top, I have it temporarily secured to a rafter, and am now going to permanently mount).


Offline dalecoy

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Re: Spurious Emissions, Davis VP2 Dropouts
« Reply #11 on: September 28, 2017, 04:41:53 PM »
The console diagnostic screens might provide a useful clue or two.

So, have you looked at those?  [Before and after your change]

So, have you looked at those?  [Before and after your change]

Offline captbrando

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Re: Spurious Emissions, Davis VP2 Dropouts
« Reply #12 on: September 28, 2017, 05:01:35 PM »
It's pinging again. See the new screen now. I have attached both diagnostic screens here.

Offline dalecoy

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Re: Spurious Emissions, Davis VP2 Dropouts
« Reply #13 on: September 28, 2017, 05:34:22 PM »
Signal strength is good (58).  Percentage of good packets = 17%.

From this single sample, the "cause" would seem to be "CRC errors" - which would strongly suggest interference.

Offline captbrando

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Re: Spurious Emissions, Davis VP2 Dropouts
« Reply #14 on: September 28, 2017, 05:35:40 PM »
I've ordered a new cable, and I hope that helps to solve!!

Offline dalecoy

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Re: Spurious Emissions, Davis VP2 Dropouts
« Reply #15 on: September 28, 2017, 05:50:11 PM »

I have been fighting temporary dropouts for YEARS. T

... I am now suspecting that either the RPi or the Serial cable is causing spurious 900MHz emissions at times that is causing the console to lose signal. We're talking 30 feet, line of sight.


So, turn off your RPi and remove it from the area, and see if the console reception dropouts go away (and see if the Console Diagnostics confirm that). 

Or, if you really suspect the cable (?), just remove the cable and see what happens to the reception.

Offline WxLover16

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Re: Spurious Emissions, Davis VP2 Dropouts
« Reply #16 on: September 28, 2017, 05:54:38 PM »
Why does it say -1326 CRC errors, why in the negative?
Davis Wireless VP2 SHT31 24hr 24CFM FARS

Offline mcrossley

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Re: Spurious Emissions, Davis VP2 Dropouts
« Reply #17 on: September 28, 2017, 06:07:15 PM »
Why does it say -1326 CRC errors, why in the negative?
The value has overflowed the display, 17% and 868 gives the failed packets pushing 5000, so I suspect the first figure is actually a 4?
Mark

Offline eyecue

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Re: Spurious Emissions, Davis VP2 Dropouts
« Reply #18 on: September 28, 2017, 10:15:10 PM »
ZigBee uses 902 to 928 Mhz.  If you  got a distribution node you might be prone to severe interference.
Cocorahs, Skywarn, Aficionado of weather. Davis VP2  pro wireless, Oregon Scientific and DIY.