Replies: 3 comments 11 replies
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As far as I know the rtl-sdr dongle fom ShipXplores already a build in filter: https://www.amazon.de/-/en/ShipXplorer-AIS-Dongle-Blue/dp/B09Y61CM12
And this might be interesting for you as well, a filtered pre-amplifier for AIS: https://store.uputronics.com/index.php?route=product/product&path=59&product_id=93
73, DD8PL
… Am 20.11.2023 um 09:25 schrieb OE1MWW ***@***.***>:
In my spectrum view I noticed that there was a pager transmitter in my area on 162.475Mhz. Unfortunately, the carrier is only activated to transmit messages, so the interference is very irregular. In the discussion here, a SAW filter from TAI-SAW TECHNOLOGY CO., LTD. Type TB0436A was reported. https://www.taisaw.com/upload/product/TB0436A%20_Rev.1.0_.pdf
The search on the net was very difficult, DigiKey demands 5 USD, but stock level 'zero'. I then sent an inquiry to several semiconductor distributors (China / Hong Kong) - result: horror price - up to 50 USD per piece + 36 USD handling fee and 30 USD shipping.
But I found what I was looking for at Semtke Electronic Company Limited http://www.semtke.com/. TB0436A for 7.75 USD plus 9 USD shipping, PayPal payment. Tip: send an email to "iven xie ***@***.*** ***@***.***>" right away and ask for a quote.
My filters should be in my mailbox in about 2 weeks from now.
greetings from Vienna Austria
OE1MWW
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And it is in this topic that I explain why this SAW-filter is useless for our case. It has bandwidth from 156.3 to 162.025 (all marine VHF band) and we need only 80kHz bandwidth (161.975MHz-12.5kHz to 162.025MHz+12.5kHz) |
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Out of curiosity, have you seen any benefits of using the RTL filter via -a? For me it does not make a difference but heard from others it can be a big improvement... |
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If I right understand correctly, the parameter -a sets a built in hardware tunable IF-filter. It’s hard for me to say, I installed this parameter from the very beginning when I had no SAW-filter. And now this parameter is most likely not to influence my installation. He can likely filter the neighboring radio channels, but only if they do not overload (saturation) the receiver's LNA, and most likely it happened in my case due to weather broadcasting (more then +30db above the most powerful AIS messages).
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There is why to important has input narrow bandpass filter if u have a power broadcast near. |
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The airnav ADS-B flightsticks and AIS shipxplorer USB sticks have an cheap filter before the LNA at the input signal. This means an high insertion signal loss. No metal case, no TCO and so on… These dongles are only for the easy entry / beginner. |
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An TA0395C filter is installed in the ShipXplorer. This filter is wider than the TB0436A I ordered.
And my 'interferer', the pager transmitter on 162.475 Mhz, would still fall well within the filter curve
of the TA0395C in the ShipXplorer. Have to built 'my own' filter ;-)
Am Mo., 20. Nov. 2023 um 17:28 Uhr schrieb Jasper ***@***.***
…:
Agree. I need a filter as well and the ShipXplorer dongle solved it for me
(has indeed a filter) but also the RTL-SDR V3 in combination with the GPIO
Labs AIS passband works well. The shipping cost makes the GPIO Labs a
relatively expensive option.
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Hi @OE1MWW @pbriesch |
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The TB0436A is a passive filter, not an pre-amplifier. The picture shows my home made board according to the circuit diagram on the
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Just yesterday I made another one for off grid use.
my first one here #194 |
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interresting, mine looks a little bit different ;-) |
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I double checked with high resolution (1000p/1MHz)
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In my spectrum view I noticed that there was a pager transmitter in my area on 162.475 Mhz. Unfortunately, the carrier is only activated to transmit messages, so the interference is very irregular. In the discussion here, a SAW filter from TAI-SAW TECHNOLOGY CO., LTD. Type TB0436A was mentioned. https://www.taisaw.com/upload/product/TB0436A%20_Rev.1.0_.pdf
The search on the net was very difficult, DigiKey demands 5 USD, but stock level 'zero'. I then sent an inquiry to several semiconductor distributors (China / Hong Kong) - result: horror price - up to 50 USD per piece + 36 USD handling fee and 30 USD shipping.
But I found what I was looking for at Semtke Electronic Company Limited http://www.semtke.com/ The TB0436A for 7.75 USD / pc + 9 USD shipping to Europe, PayPal payment. Tip: send an email to "iven xie [email protected]" right away and ask for a quote.
My filters should be in my mailbox in about 2 weeks from now.
greetings from Vienna Austria
OE1MWW
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