Thursday, November 19, 2020

Upcoming comparison of nanoVNA with professional equipment at 1100 MHz

In recent weeks six people have asked me if I still plan to do the comparative test mentioned at the top of the right-hand sidebar of this page.

Short answer - yes.

Long answer - we are in the process of evaluating the possible acquisition of more test equipment at my work QTH and I want to wait until - if  - that occurs.

Scattered around all big airports in the US (and many other countries) are numerous small transponders that interrogate aircraft as they taxi to and fro on the ground. This allows ATC to keep track of who's where, despite fog, nighttime or any other conditions that limit visibility.

These transponders support a 15 GHz radar called the ASDE - Aircraft Surface Detection Equipment. Next time you're at a large airport, take a look at the very top of the control tower. If you see a white saucer-shaped disk spinning around at 60 rpm, that's an ASDE and it's looking downward.

We have two complete systems like this to cover Houston Intercontinental and this include 18 transponders operating at 1090 MHz that provide an input into the ASDE system, all of which need periodic testing of SWR, transmission line measurements and other parameters that are performed by heavy, bulky and expensive equipment.

We have several small FieldFoxes but they support other radar systems in the area (of which there are many).

Since some of our equipment gets retired/obsoleted over time, the choice is to buy more FieldFoxes at 4 to 10 grand a pop, depending on upper freq limit, or something akin to a RigExpert AA-1400 at a fraction of that price. These would be used for routine measurements; the high $$$ stuff would be brought in if we needed to troubleshoot and then re-certify the system.

A few other pieces are also under consideration and I want to wait till they're all in before I make the comparisons. I'll use the opportunity to take an informal look at how the nanoVNA fares in this environment as well, just for our own ham interests.

A few more weeks...




  1. Hi John, interesting! I am working for an airliner in the Schiphol area. Many aircraft have RAAS as part of their EGPWS to track and trace taxi movements on runways. 73, Ron

    1. Good morning Ron - in the 25 years I've been doing this I've met a lot of hams in similar aviation-related careers, from DXers to moonbouncers. Is that true for you, working on the aircraft side of things?

      73 - John

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  2. Understood you are working in the Houston area, TX. ? Air Traffic Control related ? 73 Ron