Just if anyone is planning to do something similar, here you have some pictures to take ideas.
It will provide weather info for LERO aerodrome air traffic. All elements are WMO rules compliant, info available via web, e-mail, mobile, and a led sign on ramp (thanks Brian). Weather Display, of course !!
Station is a VP2+ mounted on a separate pole, anemometer on a 10m high tower, long range Davis repeater with a normal RX antenna (inside the repeater) and a high gain directional TX antenna. Top of mast on the tower is signaled by a solar led beacon (2 miles visibility).
Led sign is a two row one from Hangzhou Boshi Electronic, it admits fonts up to 15 points but WD only use 7 points fonts. Brian, do you think it would be easy to implement a selectable font? With capital 15 pt fonts it is readable from almost 100m. I have all technical info.
I’m experiencing some problems at night, 93% humidity in the fog. But during daytime I have a 95% packet reception, antenna is on 868 MHz band, 9 dbi: http://www.dmd.es/smp918.htm
I’m never quite sure why fog or heavy rain should make a difference to VP2 reception (@868MHz) - rain seems worse if the signal path passes through foliage and a significant layer of liquid water builds on the leaves. But every time I’ve tried to look up a reference it tends to suggest that there should not be much signal loss by rain at this frequency - higher frequencies yes certainly - a serious problem. But at 868MHz there shouldn’t be a problem. Anyone have any clues? Is it scattering rather than absorption, for instance?
I have had exactly the same thoughts, it’s no longer a problem with the VP2 but my VP reception suffered from “wet weather syndrome” and I couldn’t find a good explanation either :dontknow:
Foggy now, the link is down again (flatline periods on the graph below). Curiously my DSL link on the aerodrome is 21 km long with a 5 GHz antenna, it never goes down.
What’s the actual measured signal strength like (ie on the VP2 wireless diagnostics screen - assuming that you have the standard console and not the Envoy). Can you see a difference in the strength between standard reception coonditions and when the link drops out eg in fog? It’s a shame that signal strength isn’t one of the fields logged by the Weatherlink logger; the information is obviously there in the console but there’s no field for it in the current logged data formats. I have asked Davis to think about doing this if there’s any future revision of the formats.
I’m not there now, anyway I think the signal strength showed when the link drops out is “—” (no reception). It would be nice to have this parameter logged, it could be checked in remote.
OK, I understand. But what’s the signal strength (the strength on the second diagnostics screen, not the reception %) when reception is OK (maybe next time you’re there). I always think that around 30 (out of a max of 60) is the lowest that’s likely to give reliable reception, with a small amount of margin for adverse conditions. Obviously it would be better to see 35-40 as a strength. Did you align the yagi and console antenna so as to give maximum measured signal strength? (The displayed strength value refreshes with each new packet received so it’s quick and easy to see the effects of any changes you make.)
Yes, the figures are some posts up. In normal conditions I have about 32-33 signal strength with 98% error-free packets received. Patch antenna is pointing directly to the console. I tried reorienting the console antenna, but I can’t get more strength.
Is it possable to extened the antenna? The stub antenna on the Console & The Envoy is hard wired to the receiver, but how about using an second full wave antenna mounted as high up as possable, say on the roof, and feeding the signel down to the consoles antenna via coax. At the console a few wraps of the coax center conductor around the existing antenna should improve the received signel strangth and the S/N ratio. The shield should be grounded at the receiver end and should also be feed thru a ground block at the building entry. What think you?
I have concerns about Stuart’s passive repeater idea that unless you use an antenna with significant gain (or the receiver is completely screened from the transmitter) it will be a crap shoot whether the signal you feed to the console’s antenna will add or subtract from the one it is seeing already.
Back to this topic. I’ve been relocating my console in the office, small changes in position results in 2-3 points of signal strength gain as Niko suggested. So I have now about 35-37 readings, but the problem persists.
I went to the aerodrome during one of those drop down episodes, took the console with me and started walking towards the repeater, always in front of Tx antenna. No signal at all. At about 80 meters from the station I changed the console to receive from the ISS, resync was quick and I had data again. Back to receive from the repeater and no signal at all again (resync timeout till “L” sign appears on the console). Minutes later it started to receive normally without no other action taken.
I see no signal strength deterioration prior to drop down, it occurs suddenly. Always at night time and restarts sometime in the morning. Curiously many times it shows a transitory working period early in the morning. You can see it clearly on my daily graphs, flatlines and 000
Breitling, it seems that you are relying on the Console electronics to show the signal quality.
May I suggest that you get hold of a standalone Field Strength Meter (FSM) to take some independent readings.
You can then compare those readings with readings from the console and especially look at those measurements when the console drops out.
You may be able to find a FSM with a local Radio Ham or hire one from a specialist company.
. How’s the signal strength?