(2017-12-01, 08:03 PM)Leigh Wrote: [ -> ]Hi,
I now have the RTL-SDR.COM USB SDR AIS receiver for my RPi3-Sensehat setup (see bragboard)
It came with both a mini and larger (maybe each arm nearly 1m long) version of a 'V' telescopic antenna.
I have read in another thread that the mini one is for FM radio, will the larger one work for AIS?
Or should I get another VHF antenna to mount on the pullpit?
Or can I use a splitter (for example this one[url=https://www.force4.co.uk/glomex-vhf-ais-am-fm-radio-splitter.html?utm_source=google_shopping&gclid=CKft3pi6uNQCFcS37QodoZUODw?utm_source=google_shopping&gclid=CKft3pi6uNQCFcS37QodoZUODw#.WT6cvTOZNjQ][/url]) with my existing VHF antenna at the mast top?
Thanks
Leigh
I have one of those however I must say that there are so many other options nowadays! Is all down to your preferences I should imagine!
A regular marine VHF antenna is the right length for AIS. If you are using a telescopic antenna, extend it to 17 inches. I use an active splitter on my regular VHF marine antenna and it works well. Don't put a passive splitter on, as you will destroy your AIS receiver the first time you transmit on your VHF.
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(2019-11-10, 09:41 AM)abarrow Wrote: [ -> ]A regular marine VHF antenna is the right length for AIS. If you are using a telescopic antenna, extend it to 17 inches. I use an active splitter on my regular VHF marine antenna and it works well. Don't put a passive splitter on, as you will destroy your AIS receiver the first time you transmit on your VHF.
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OK, I'm confused:
If people are using VHF antennas for AIS, the 1/4 wavelengths cannot be optimal?
VHF 30-300MHZ
AIS 161.975-162.025 Mhz
OpenPlotter AIS-SDR tunes to GSM-850 (USA) near
889MHz, which IS much shorter wavelength just 0.084m - Help?
VHF
center band is 165MHz or 1/4 wavelength 0.454m
AIS (162Mhz) prefers a 0.463 meter antenna
trying to be complete in my question, I answered my own question and will leave it here for posterity Searches
8.77 millimeters difference is not a significant factor for most applications
The high frequency AIS GSM-850 channel Tuning around 889MHz is still confusing. . .
Cheers
(2021-02-06, 06:41 PM)CaptnBry Wrote: [ -> ] (2019-11-10, 09:41 AM)abarrow Wrote: [ -> ]A regular marine VHF antenna is the right length for AIS. If you are using a telescopic antenna, extend it to 17 inches. I use an active splitter on my regular VHF marine antenna and it works well. Don't put a passive splitter on, as you will destroy your AIS receiver the first time you transmit on your VHF.
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OK, I'm confused:
If people are using VHF antennas for AIS, the 1/4 wavelengths cannot be optimal?
VHF 30-300MHZ
AIS 161.975-162.025 Mhz
Not VHF - MARINE Vhf. 156 - 162Mhz. You could argue slightly out centered a little low but for receive you won't notice the difference.
(2021-02-06, 08:33 PM)PaddyB Wrote: [ -> ] (2021-02-06, 06:41 PM)CaptnBry Wrote: [ -> ] (2019-11-10, 09:41 AM)abarrow Wrote: [ -> ]A regular marine VHF antenna is the right length for AIS. If you are using a telescopic antenna, extend it to 17 inches. I use an active splitter on my regular VHF marine antenna and it works well. Don't put a passive splitter on, as you will destroy your AIS receiver the first time you transmit on your VHF.
Sent from my P027 using Tapatalk
OK, I'm confused:
If people are using VHF antennas for AIS, the 1/4 wavelengths cannot be optimal?
VHF 30-300MHZ
AIS 161.975-162.025 Mhz
Not VHF - MARINE Vhf. 156 - 162Mhz. You could argue slightly out centered a little low but for receive you won't notice the difference.
Thank you , that makes sense
So the SDR-RTL Calibration routine that tunes to GSM-850 (USA, California AIS ) and finds a Channel around 889MHz can be ignored in terms of antenna frequency?