This forum uses cookies
This forum makes use of cookies to store your login information if you are registered, and your last visit if you are not. Cookies are small text documents stored on your computer; the cookies set by this forum can only be used on this website and pose no security risk. Cookies on this forum also track the specific topics you have read and when you last read them. Please confirm whether you accept or reject these cookies being set.

A cookie will be stored in your browser regardless of choice to prevent you being asked this question again. You will be able to change your cookie settings at any time using the link in the footer.

Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
AIS Antenna?
#11
(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!
Reply
#12
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
Reply
#13
(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

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
Idea   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
Reply
#14
(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.
Reply
#15
(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?
Reply


Forum Jump:


Users browsing this thread: 1 Guest(s)