GPS antenna alternatives
I bought one from via eBay for $48 and with its 40 dB gain will work with a long feedline and can be split to run other devices. It's not in the permanent mounting spot yet.
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Comments
antenna.com/artifacts/2016129GPSL1-TMG-SPI-40NCB.pdf
https://www.ebay.com/itm/PCTEL-GPS-26dB-Outdoor-Antenna-GPS-TMG-26N-w-Pole-Mount-Collar-Lucent-Maxrad-/362002051789
The one I used is a higher gain variant, was cheaper and works well with long coax and/or splitters.
https://www.ebay.com/itm/PCTEL-GPS-40dB-High-Gain-Antenna-GPSL1-TMG-SPI-40NCB-w-Surge-Protect-Mount-Kit/282851759313?epid=2006284562&hash=item41db4754d1:g:OHwAAOSw-xVZ81uA:sc:FedExHomeDelivery!64118!US!-1
The KiwiSDR GPS software only seems to allow a maximum of four Galileo satellites in the 12 channels. Is this intentional? While it all works fine, it would be nice if the limit could be raised - either by allowing more than four Galileo sats, or by allowing more than 12 channels. Also, surely there isn't much point in scanning for QRZZ satellites in Region 1?
Galileo is different than Navstar or QZSS in that you have to use a lookup table instead of a simple LFSR to do the PRN generation.
Yes, QZSS acquisition could be bypassed in many parts of the world if you assumed the Kiwi was fixed and used some of the other initial geolocation information. I've actually seen some of the Swedish Kiwis acquire QZSS sats. I guess the geometry works out.
Attachments:
https://forum.kiwisdr.com/uploads/Uploader/76/21eff6e61a767c5dabad85e0839f75.jpg
Regards,
Martin - G8JNJ
If it lives up to expectation (and gets to me from China) then it should allow for some decent coax and further elevation.
I can't get the image upload to work (says uploading wait....) so you can see a picture here.
https://www.ebay.co.uk/itm/HUBER-SUHNER-1315-17-0008-1575MHz-34dB-N-female-gps-antenna-antenne-Aerial/173430871903?hash=item286149175f:g:bukAAOSwIWxapNjI
https://www.google.co.uk/search?q=HUBER-SUHNER-1315-17-0008-1575MHz-34dB-N-female-gps-antenna&tbm=isch&tbo=u&source=univ&sa=X&ved=2ahUKEwjkm76m4NXcAhUIIcAKHeEhCGAQsAR6BAgGEAE&biw=1888&bih=956
Dave
M0TAZ
Most of the cheap Chinese 'marine' GPS antennas I looked at were basically patch types and perhaps had an extended ground plane.
I'd certainly be interested to see how well one performs in comparison to the patch antenna supplied with the KiWi.
Regards,
Martin - G8JNJ
I've ordered a higher gain antenna to test.
Attachments:
https://forum.kiwisdr.com/uploads/Uploader/f6/d6d4b36257615bbd76d4d3e48197f0.png
Also check the connectors are not just position critical, wiggle 'em.
You may have to power it from a separate bias tee if the KiWi can't deliver sufficient voltage or current.
Regards,
Martin - G8JNJ
It supplies 3.3v and will current limit at 50mA.
So if your antenna requires a 5v supply or draws anything close to 50mA, that may be the problem.
Regards,
Martin - G8JNJ
DC Voltage:
3.3-9.0 V (operating)
?28.0 V (survivability)
DC Current:
< 30 mA @ 5 V
I think this may be the problem, if the current limit (required to prevent damage if the GPS antenna or coax becomes short circuit) in the chip used in the KIWi is getting close to its operating point, it may start to shut down or reduce the voltage being fed to the antenna.
Try searching on your favourite web auction site for a 'satellite tv dc injector' they look like this
http://telesatshop.com/1314-large/televes-injecteur.jpg
One side connects to your KiWi the other side with the DC present goes to the GPS antenna feed. The DC supply cable goes to a suitable power supply.
You may need some adaptors to convert from F connectors to whatever you are currently using, but the whole lot shouldn't cost more than about $10 USD if you shop around.
Regards,
Martin - G8JNJ
"Bias Tee" is a productive search term on Ebay BTW.