WA6FXP HSFDG WiFi Router
The photos are missing from the author's website, sorry
The High Sierra Field Day Group has chosen to use WiFi to connect the laptops used to run WB6ZQZ's FdLog logging software. In the past, the WiFi network was set up as an "ad hoc" network, with each laptop talking directly with every other laptop which it could hear. This turned out to limit the group's ability to arbitrarily place operating positions, as most laptop WiFi cards do not have adequate range to reach from one side of the allowed FD operating circle to the other. Comment - FdLog handles Ad-Hoc just fine, relaying across the stations, so it does not care about edge-to-edge capability. The problem with Ad-Hoc is just the complexity of getting all the WiFi cards to work (configuration), and some of them never do work in this mode. AlanB
In the last few years, the group has attempted to set up a WiFi Access Point (AP), with mixed results. Many WiFi routers previously available did not run on 12 volts, and thus required a DC-to-DC adapter of some kind. This wasted energy, and resulted in premature shutdown on the router when run on a battery, even one recharged during daylight hours by a solar array.
In addition, the heat generated by the DC-to-DC convertor created problems.
There are now several routers on the market which run directly on 12 VDC, allowing them to be run directly from a solar-charged battery system.
This year, I decided to try my hand at setting up an AP for FD using one of the new WiFi routers which runs Linux, and which can be flashed with an alternative version of Linux. This allows the AP to be configured exactly as we desire, and also allows the AP to serve other FD needs: for instance, as a central time server (NTP) and as a small web server which can host the various builds of the HSFDG logging software and other utilities. In addition, it should be possible to have the AP keep track of all logging software traffic, serving as a "backup storage" mechanism. With the proper scripts, it could even serve up a dynamic web page giving the current FD statistics.
I chose the LinkSys WRTSL54GS as the AP to use. It runs on 12 VDC, appears to use only about 300 - 500 mA, and has enough memory to load the OpenWRT operating system and quite a few other application programs. In addition, it has a single USB port, which can be used to support a USB flash drive (to increase its storage for programs and logfiles); this port may also be able to support a USB cellular modem for internet connectivity.
Here's what the WRTSL54GS looks like from the outside:
Removing the four plastic feet on the back/bottom of the unit, access to four screws (with weird heads--not Phillips and Torx) allows diassembling the unit. The top of the circuit board is shown here:
The next step in the process will be to remove the fixed antenna and cable from the unit and replace them with a pigtail cable, soldered to the PC board, with an appropriate connector to mate with the a high-gain WiFi antenna. The proper pigtail is on order, and should arrive in the next few days. When it does, I will provide a description of the next steps in the process of completing the router installation.
The pigtail arrived, and here's what the WRTSL54GS looks like when it's installed:
In the meantime, here are photos of the enclosure I've chosen to receive the router, battery and charge controller, with the WiFi antenna installed. The PVC adapter in the center of the top of the enclosure is designed to receive a PVC pipe which will hold the solar array (two 10-watt panels). Once the entire unit is assembled, it will be a self-contained, weatherproof unit capable of being mounted in the most appropriate location for use during FD07.
A few problems left to solve:
- Will the unit require cooling? Almost certainly, so I have to figure out how to allow air circulation without compromising the weatherproofing of the unit.
- How can the unit be set up to attach to a tree, post or some other attachment point, rather than just setting it on a flat surface? Again, this needs to be done without sacrificing weatherproofing or preventing easy access to the interior (say, for resetting the router).
- Should I provide access to the ethernet and/or USB ports from outside the box?
- Should I provide the ability to power the unit from an external power source? The internal battery is a 12 VDC, 12 Ahr gel cell, but perhaps having access to outside power would also be useful.
-- RichFall
AlanB Suggestions and Thoughts
- A pole mount system (support it up in the clear with guyed military pole, 15' or so high)
I'm thinking that a set of u-clamps on the back of the box may be the most
efficient and flexible way to have a range of mounting options. Given that this
will put holes into the box that may provide an ingress point for water, I will
have to silicon seal these. RichF
- A sun shade
I'm thinking that the solar panels themselves, which will be mounted on a
3/4" PVC pipe which fits into the adapter on the top of the box, will provide
sun shading the will be sufficient. But, I will do some testing to verify this. RichF
- A connector (Anderson PowerPole) for external 12V input (diode protection?)
- GPS connected NTP??
- FdLog Program Distribution (and support files such as Python, etc)(web/http service?)
httplight has now been installed on the router, and can be used to serve content.
I plan to bring the router to the FD2007 meeting, where we can test it and decide
which files to have it serve. RichF
- Fan Cooling through tubes on bottom (rain drip-resistant)
I've added a small 12 VDC fan, which pulls air into the box, and uses about 80 - 100 mA. RichF
- Cables through tube on bottom (air exhaust?)
I've added a 3/4" PVC coupling to the bottom of the box, for air exhaust and for bringing
cables out of the box. Since the power cables from the solar panels come through the
coupling in the top, this can be used for external power, ethernet, or anything else that's
desired. RichF
CategoryFieldDay
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