My evaluation of the ASIair PLUS continues. We are still experiencing cloudy nights down here, so I decided to focus on someting I can test without seeing the sky: WiFi performance. I've read/watched a number of other reviews and everyone agrees the PLUS performs well. But I wanted to dig a little deeper, so I set up an experiment to quantify the WiFi performance of the ASIair PLUS and compare it to the ASIair PRO. Here's how I approached it.
Test Design
The testing focused on measuring signal strength between the access device (iPad or home WiFi base station) and each model of ASIair. The goal was to see how much improvement the new PLUS model shows over the previous model.
Disclaimer: This test wasn't designed to be scientifically rigorous. Ideally, I would have repeated the measurements multiple times and averaged the results. It would have been nice to measure data throughput changes at various distances, too. Still, I think this test design is adequate to get a feel for how much improvement the PLUS brings over the PRO.
The Direct Connection Test
My plan to test the performance of the direct connect mode was pretty simple. I would place both ASIair models on a table, power them up, and measure their signal strength at varying distances.
To take my measurements, I used an app called WiFi Explorer. WiFi Explorer is designed to discover, monitor, and troubleshoot wireless networks. It proved a convenient way to collect the signal strength data I needed for my tests.
Both ASIair's were configured to use the 2.4Ghz range. To avoid having them interfere with each other too much, each used a different channel (see Figure 1).
Figure 1: Each ASIair was configured to use a different part of the spectrum.
The Station Mode Test
I also wanted to test Station Mode. That's what ZWO calls the configuration that has the ASIair connect to your iPad through your home WiFi network instead of directly. This is a very convenient way to run an imaging session if you're doing it at home. Why sit out in the yard in the cold when you can control things from inside your nice, warm house? My previous experience told me that ASIair PRO's ability send WiFi signal through walls was pretty poor, so I wanted to find a way to compare it to the PLUS.
I accomplished that by placing both ASIair units outside where I normally set up my telescope, and measuring their signal strength at the WiFi access point inside my house.
Taking Measurements
The measurement process for the direct connection experiment was straightforward. First, I marked out a series of measurement points at 15-foot intervals. Next, I carried my MacBook (running WiFi Explorer) to each point and took a signal strength reading. I stopped measuring at 150 feet and plotted the results.
Measuring station mode performance was even easier. Read on to see the results of both tests.
Duelling Astro-Controllers
Results
Ok, this is the part you really want to hear, right? The bottom line is that The ASIair PLUS performed significantly better than the PRO at all distances.
Direct Mode
The first set of results is from my simulation of a direct connection to the ASIair. Measurements were taken using a MacBook and WiFi Explorer instead of an iPad. The results are shown in this chart (see Figure 2).
Figure 2: Signal Strength measured over increasing distances.
As you can see in Figure 2, the ASIair PLUS maintains a fairly constant advantage over the PRO at every distance measured. My anecdotal experience backs this up. I found that I could walk much farther away with my iPad during an imaging session without losing the connection to the ASIair PLUS.
I wanted to quantify how much better the PLUS is than the PRO. While the signal measured varied quite a bit in my tests, when I took an average of all the measurements, the ASIair PLUS showed a 110% improvement in signal strength over the PRO. Impressive.
What about Station Mode?
We know that ASIair PLUS outshines the PRO for a direct connection while outdoors, but what about station mode? This chart (Figure 3) taken directly from the WiFi Explorer screen shows how much signal each unit delivered into the house.
Figure 3: Signal strength measured at the house's access point.
The ASIair PRO clearly has a much harder time sending its signal through a wall. It's easy to see why I had so much trouble using station mode with the ASIair PRO. The signal from the PRO was just too attenuated after traveling from the telescope location and through the walls. The signal from the PLUS was also attenuated, however, it remained strong enough to be usable. No more and stringing a long ethernet cable outside for me.
Conclusion
Based on what I saw in these tests, the WiFi performance of the ASIair PLUS is consistently better than that of the PRO. Of course, that's what we expected from the PLUS with its external antenna, but it's reassuring to see the expectation backed up with real data. The extended range in Direct Mode will help when you're out in the field and don't want to stay right next to your rig. For example, it can get pretty cold when imaging at a dark site in the desert here in Southern California. It's nice to take refuge in the car and still be able to monitor the session. This wasn't always possible with the PRO. The PLUS gives you more options.
The ASIair PLUS will give you more options for where to place your. Rig when doing back yard imaging too. In my case, having the scope far enough away from the house to polar align on Polaris put it a bit too far away for the ASIair PRO to connect reliably. With the PLUS, I can image from that location without any problem.
With its small size, extra features, and 110% better WiFi signal, I call the ASIair PLUS a real winner. Recommended!