Using an Antenna Switcher with the SparkFun RTK Express?

GPS/GNSS
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I want to put 3 different masts on my dozer blade and affix antennas to each one. I will have all the antennas wired separately into the cab connected to a switcher that allows the operator to choose which antenna is being connected to the SparkFun RTK Express unit to help geolocate their blade.

A quick search brought me to this item, and I’m guessing I would just need to get 4 adapters to connect the antenna cables to?

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I hope to use SW Maps.

Maybe there is a better item for this task?

The adapters that I think I’ll need are:

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The cost isn’t too much. Found one on Ebay for like $30 so I’ll give it a shot. If it doesn’t, I can use it for HAM radio later.

Here are the adapters I ordered.

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The dual attitude determination methods tend to anticipate two concurrent connections where the receivers solve the relationship and carrier cycles and relative position of one vs the other.

uBlox has a paper on Moving Base configurations.

The switcher looks more related to a broadcast transmitter, but if its a one of three with good isolation, it might work to switch the 3.3V DC to each antenna individually. You could check with a multimeter. Might glitch, not sure, but would need to pass DC.

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That antenna switch is only good up to 500MHz. GPS uses frequencies up to nearly 1600MHz.

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Thanks for pointing that out when I wonder why it doesn’t work.

This one appears to go up to 1.6 GHz

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This one is listed as going up to 3,000 MHz.

So maybe I can daisy chain two of them to get a 3-way.

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Probably the SO239 connector. It and the PL259 connector it mates with were designed for lower frequencies. The N-type connector in your other choices are better at high frequencies.

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I called their sales line and they stated perhaps the 800 Mhz switcher may work, but depends on attenuation, so we’ll see.

They also have a 4-way switcher that goes up to 1.3 Ghz on paper, and possibly may work up to 1615 Mhz, but once again, the attenuation is unknown.

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Someone might make a 3 port version of one of these, or you might be able to cascade two of them.

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On the chip side there’s HMC7992 (4x) and HMC253 (8x) RF Switches, with examples on Amazon, need power, and jumpers, or connection to Arduino, MCU, etc

The boards I saw on Amazon didn’t look to pass DC, and had DC blocking capacitors.
Sort of stuff the could probably modded, with say a 10R and 47nH.
Heck might make a fun product…

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The OPEK CX-5 Did not work for what we needed. The switching was inconsistent, and are better off just manually reconnecting the cable we need.

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Those antenna switches are for lower freqs and, for OP’s needs, super overbuilt to withstand their 1000 Watt (!) transmit rating yet flimsy and leaky and cheap in a way only we hams could love. The SO/PL259 connectors are alone reason enough to stay away from these, the mechanical conversions will insert-loss all of your signal away. And all of this sets aside whether an operator’s switch is the right way to go.

Since you’re making it from scratch and not transmitting, the usual approach for multiple receive sites ‘listening’ for the same signal is a voting system where the best signal is selected. In fact, it seems that your operator is currently performing this function. It’s only a step away from direction finding.

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Yeah, 1KW, that’s going to toast your nuts…

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This did not work either. CX210N.

Sometimes it will switch within 7 seconds, and other times in 5, and then other times more than a minute.

At that point you might as well just manually switch out the cables.

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I’m going to retest, but this time, I’m going to keep it in the “off” position, which is the middle position. And then when the circle disappears, try connecting it to the next location.

Rather than switching right away.

This may be an issue with the software, rather than the hardware, which will mimic the unplugging of one antenna for another.

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SUCCESS!

All you need to do is essentially turn the switcher slowly. That’s it. It gives the software time to “lose signal” so that once it’s reestablished it jumps to the new antenna.

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