GPS input
Hello to all members.
I just received my Kiwi 2. I have an outside GPS antenna that is connected to an active GPS antenna splitter. There is a free port on my splitter, so I would prefer to use that instead of the GPS antenna that comes with the Kiwi.
Is there any known issue if I connect my SDR GPS input to the splitter ?
73 from Claude VA2 HDD
Comments
The Kiwi supplies 3.3V on the GPS port. Make sure your splitter has a DC block on its input if that might conflict. For example the splitter port you want to use is already outputting a voltage. Or your GPS antenna won't like an applied voltage if the splitter passes DC.
The splitter is a DC sharing splitter. I mean the highest voltage present on an input will go to the antenna so it will be powered and the DC voltage from one input will not go to another input. The antenna is rated at 5 volt, so all will be OK as long as one of the older receivers is powered. But if only the Kiwi is powered the antenna will not amplify much when powered with only 3.3 Volts. The splitter has a resistor to ground to simulate the load of the antenna's preamp, so the SDR will think that there is an antenna directly connected. I will have to test to find out !
The data sheet says the output is short circuit protected. But I’ve never actually tried that..
J'utilise ceci pour mes deux Kiwi
Hello to all members. I've used this GPS splitter since I got my Kiwi 2. It works perfectly.
Bonjour à tous. J'utilise ce partageur pour antenne GPS avec mon Kiwi 2, ça fonctionne très bien.
Price appears to be 500$ US... This seems like a VERY non cost effect solution. Surely there must be a cheaper solution.
I'm using the SV1AFN active/filtered 4-way splitter (80€ without VAT)
https://www.sv1afn.com/en/gnss-gps/-7.html
Here's an 8-way one for around US$30 if you order two.
The Triax satellite TV passive splitters mentioned earlier work OK, maybe up to four outputs.
You can get cheap inter-series coaxial adaptors and cables on AliExpress.
I use old active Satellite TV spitters, made by global, model SPLIT8AF, which I've modified to take a separate 12v DC input, and feed a 5v output to the GPS antenna, via a regulator. They occasionally appear for sale second hand on web auction sites.
Regards,
Martin
Be careful when using any GPS distribution system with the KiwiSDR, particularly with more than one. This is because unless there is HF isolation on both center and shield of the SMA, adding a distribution system adds additional HF paths through the length of the Kiwi PCB and to the world.
If and when there is only a GPS antenna puck sitting on the end of a coax cable and not connecting to anything else, the impedance 'to the world' is not infinite, after all the coax is an end-fed wire, but it is high. This means that there is little opportunity to develop IZ drop across the Kiwi groundplane and in the vicinity of the preamp and ADC reference. Only microamperes may be necessary to cause a problem.
If current does flow, either out the GPS SMA shield or the normal Antenna SMA shield (common mode current) then there is the risk of raising the HF noise floor due to a developed potential across the Kiwi's ground plane. That path is effectively in series with the Kiwi's HF input.
The GPS distribution box I mentioned has isolation on both the SMA center and shield such that insignificant HF current can flow.