Overview
For Davis wireless stations, good performance of the data link between sensor transmitters and the console is obviously vital to receiving consistently good data readings at the console. In general, the Davis wireless technology works very well and provides data of superior quality to most other shorter range wireless stations.
But if console readings on a wireless station start to misbehave, e.g. the readings go missing or become intermittent or are obviously in error, then there are a range of possible causes of which a faulty wireless link is obviously one candidate. Here’s a short guide to narrowing down the possibilities:
- If the loss of readings relates to a single sensor only (air temperature, wind speed, rainfall etc) then the fault almost certainly relates to the sensor itself and not to a wireless issue. A wireless transmitter or propagation fault will always affect all readings being sent from that transmitter – it isn’t technically possible for only one sensor’s data not to be transmitted correctly while other sensors remain unaffected. Of course, if a transmitter is sending data only from a single sensor such as wind or temperature then it’s impossible to be sure whether it’s the sensor or transmitter at fault, but the commonest scenario will be with ISS transmissions and here the distinction should be obvious. And, to be clear, even for single-sensor faults it is possible, though very rare, for a fault to develop on the transmitter board circuitry that interfaces with the individual sensor – this is effectively still a sensor fault rather than a wireless one, though the fix will usually involve needing to replace the complete transmitter board.
- If a wireless transmitter issue is suspected then the first step is always to check the transmitter battery status. There should always have been a ‘Station low battery’ warning prior to actual loss of transmission but this may have been overlooked. Note that a good new transmitter battery should always last at least 6 months even if the solar panel has been disconnected and more typically 18-24 months with a well-exposed solar panel. If the transmitter battery life is consistently (and often progressively) shorter than its expected life then a supercapacitor (‘supercap’) fault is likely – again see the ‘Station low battery’ topic in the ISS section.
- If the transmitter battery seems OK then a further check that’s always worthwhile is to confirm that the “console channel settings”: have not been changed inadvertently. Though this is an uncommon cause of wireless problems it takes only a minute to check.
- If you are experiencing odd symptoms of poor reception (especially intermittent loss of reception that it not only happening overnight) then, at least for test purposes, it can be worth switching the transmitter to another channel, remembering of course that both transmitter and console must match in the channels that they’re configured to use. If someone within eg 500m or so of you (while 250-300m is the standard range for reliable reception, signals can often be picked up at greater distances of out to eg 500-600m) has also started up a Davis wireless transmitter using the same channel as you – most often the default channel #1 of course – then there certainly can be missing or unexpected readings as a result of interference between the two systems.
- Wireless components from different regions cannot be intermixed: Wireless components (transmitters, consoles etc) from different world regions are set to operate on different wireless frequencies to comply with the wireless regulations in their home territory. The two main regions are North America and the Rest of the World (designated OV = OVerseas), though there are also a few territories such as Australia and New Zealand that also have their own regulations.A transmitter and console/receiver from different territories will never work together and it’s pointless even to try. A component’s intended region can usually be found from the last two letters (if present) of the Product Number. If the product number says simply eg 6152, ie with no trailing letters, then this will be a North America unit. But the presence of trailing letters as in eg 6152UK or 6152EU or 6332OV all indicate the standard rest-of-world frequencies. (The UK/EU designations just indicate the type of mains adapter supplied with the station and these are all of standard OV wireless frequency.) Be very wary of buying components from another territory to use with an existing station – the price may seem enticing but it’s money wasted if the new component cannot work with your existing station.
- Finally, if none of the above seems likely as a possible cause then it’s prudent to review the wireless reception quality, as described below.
Checking wireless reception quality
First, a brief recap of the general characteristics of the Davis wireless technology: The standard range for the wireless signal is 250-300m line of sight (using the standard built-in whip antennas on ISS and console). Range can obviously be increased by use of repeaters, and especially with the long-range repeaters;the standard repeater behaves exactly like a standard transmitter (ie a 7627 repeater can double effective range to 500-600m if placed roughly midway in the signal path), while range with the LR repeater will depend on the antennas fitted. Remember also that the signal essentially travels only in a straight line between transmitter and console and it’s this straight-line signal path that’s important when assessing reception quality. For example, if this line can be arranged to pass through an ordinary window (which is relatively transparent to the signal) then the best reception quality can be obtained.
But if used towards the maximum open air range of ~250-300m or especially if the signal is required to pass through multiple thick walls (remembering also that the signal cannot penetrate sheet metal or similar materials such as reinforced concrete) then missing or inconsistent readings may well be seen on the console display. Quite often it can be the combination of moderately long range (eg 100-200m) with intervening walls or other barriers that will significantly impair the signal. Note that if a significant percentage of the signal is being lost into the ground then effective range will be reduced, If possible, it’s always worth siting both transmitter and console at least a few feet above ground level (while still respecting the recommendations for sensor exposure) to minimise this effect – this can be especially important if there is higher ground between the console and transmitter positions. In situations where reception is marginal and where feasible, placing the console/WLL unit on the first floor rather than the ground floor will often help significantly, and using an upstairs window sill looking towards the sensor transmitter(s) can be an excellent solution given that the glass typically provides maximum transparency to the wireless signal.
Remember that the standard whip antennas on console and ISS need to be parallel to one another for optimum reception. Typically this will be with both antennas vertical. But if, for example, the ISS were to be above the console then reception would be better with both antennas horizontal.
There are of course 8 wireless channels available for use with all Davis transmitters, with channel #1 always being the factory default. Transmitters and console must have matching settings for data to be correctly received at the console. Each active transmitter must always be using a different channel number to other transmitters on the same site. And in the console settings, all channels not actively being used should be set to OFF.
Beyond all the configuration checks outlined above, the Davis wireless system does provide an objective numerical way of assessing reception quality using the wireless diagnostic screens – see the Wireless Reception Monitoring topic.
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