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« Last post by Rhino on Today at 05:55:30 PM »
Rain or simply very high humidity can have a negative affect on all RF communications. Fortunately, at 433 mhz and relatively small data packets, most light to moderate rain doesn't seem to impede the signal (unless there is some dense vegitation between the TX and RX, then the rain soaked vegetation CAN basically behave as a wall). Heavy rain has the effect of being a big lead wall, depending on the distance between TX and RX. That is unavoidable and these units are maxed out as far as how much "power" the transmitter can use to transmit- all regulated by FCC, and verified in rigorous and repeated testing.
The helical, or spring like transmission coil is made up of a laminated length of copper wire- the spring like shape takes the signal and broadcasts it in as close to an even 360º transmission as possible, that is why transmitters have that type of antenna- and it is an exact science how long the coil should be, and where on the PCB it is located for best RF performance. I know users tend to think these things are just thrown together, but believe it or not YEARS of testing and development go into these. The RF TX and RX antennas are carefully tuned based on RF science and well known methods, and then are rigorously tested to perform the best that they can while still being within the specs that the FCC requires. Each unit is also tested during development with whats called a polar plot, where RF is tested to receive at 360º around the transmitter antenna to find any potential "blind spots" due to the structure of the PCB or other components in or around the TX housing. After polar plot testing, anything that shows up there is addressed, then the unit is tested again to verify any improvements. Everything else is out of the control of the product- from environmental conditions, structures in the install environment, and most importantly other RF communication and electronic interference in the installation environment. Remember that these units are governed by FCC part 15 rules, which state that the product must receive interference, even if harmful to the products operation and/or performance. SO, if there is ANY interference around from similar frequencies- they will for sure occasionally affect the communication between the transmitter and receiver- by law.
Other environmental considerations apply, for example- many users report that the display RX is not receiving data from the outdoor sensor and they have the display right in front of the window- they can actually see the display and the sensor together right through the window, and it frustrates them when they have reduced signal strength. I get that it seems that should be the best possible scenario for communication- right through the window. In actuality, most modern windows from the past 30 years or so have special coatings on them to keep UV and other light spectrums out of your home for thermal efficiency and for the longevity of items inside your home (prevent fading, etc.). These special coatings can essentially act as a sheet of aluminum, preventing RF signal from getting through. In MANY cases, when those users move the display a foot to the right of the window, on a wall, they suddenly get reception again.
Now, having said all of that, these AcuRite units are engineered to perform as best as possible, even with these known issues that will for sure affect the performance in many users environments. Take this specific issue for example, of the receiver NOT receiving updates during a heavy rain storm- which, again, is a normal occurrence in many cases. That is why the transmitter sends a signal containing the number fo rain bucket tips- NOT the actual inches/mm or rain observed. In this way, the receiver can lose signal at 1 tip (.01") reconnect a few minutes later and get an updated signal containing how many bucket tips there were in the LOS period and update the total in the display memory. Even though you MAY not see the total update during the 20 minute LOS period, the rainfall record will always be updated and corrected upon re-acquiring the TX signal.
Since AcuRite receivers do not show true RSS strength, and each "bar" represents an expected data packet either received or missed, users tend to think the unit is having communication issues if there is anything less than 4 "bars." It was done this way to give the user the most up to the minute way of seeing if they are getting the most recent data- not meant to be a way to "babysit" the signal strength and be concerned whenever it is bouncing between 2-3 "bars". As long as you have at least 2-3 bars, you are still getting all of your data, you are just getting delayed updates. If you were to monitor other devices in the same manner- regardless of operating frequency, you would also see MANY missed packets of data. RSSI signal strength shows an average of connection power in a way, and translates that to the specific device as a signal strength number, which can then be translated to "bars" or other graphical methods.
This is the only downside of a wired connection to the sensors, in that case you would get instant updates all the time, but we all choose the convenience of wireless communication instead- just realize there are the downsides I just laid out. There is nothing that can be done to "get around" many of the issues that occur with RF communication- some is physics, others is FCC stipulations.